is part of the Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them. Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.


Articles from 2000 In January

Euromold '99 takes an art-to-part approach

Now in its sixth year, the Euromold show organizes around an interesting premise, one that seemingly has no parallel in the U.S. Specifically, the trade fair is aimed at moldmaking, but has broadened its scope to include product design and development as well as prototyping and production. In addition, the show has a decidedly automotive flavor.

Witte Design developed the concept for a special area of the show floor dedicated to design and engineering, which showcased the work of various industrial and product designers. Kay-Uwe Witte, president, explains that designers need to be present at a trade show centered on moldmaking because it is now necessary for those who design and engineer products to be aware of the entire production chain.

"Designers have gone beyond the mere creation of ideas and concepts," says Witte. "We are developing realizable products today. This calls for accompanying a product from first thought to series production. The times when industrial design meant developing a nice shell are over. Designs must work, and this can’t be reached without profound technical knowhow."

With this in mind, IMM presents the following collection of highlights from the trade fair, many of which point to the increased role of design and engineering in bringing new products to market.

Concept Vehicles Euro-style
Creating a concept vehicle is the exclusive domain of automotive OEMs, right? Not so in Europe. Several automotive product design and development firms exhibiting at Euromold displayed their own concept vehicles, built on chassis supplied by the majors.

Engineering + Design AG (EDAG—Germany), for example, developed an SUV called the Scout based on the chassis from Mercedes A-class SUVs (see Figure 1). Dubbed a design study, the Scout appeals to a sports-minded, outdoor-loving demographic with its cargo hold and clean lines.

EDAG calls itself an engineering partner for the automobile industry, and its client list reads like a who’s-who in automotive—namely, all major OEMs, both U.S. and European, as well as Tier One suppliers worldwide. The company prides itself on understanding and integrating all aspects of the process chain, from concept and styling through toolmaking and molding.

According to EDAG’s Winfried Knack, its strength lies in this integrated process development, made possible by computer-aided tools. "By logically applying simulation technology, also called virtual prototype and testing, we can shorten development times and secure process efficiencies for the vehicles of tomorrow," he explains. To accomplish these and other feats, EDAG recently partnered with an automotive toolmaker, WMU (Germany).

Rapid Prototyping Perks
Time-to-market pressures are driving demand for rapid prototyping and tooling, according to Terry Wohlers, Wohlers Assoc., who chaired a seminar on RP/RT at Euromold. Judging from the activity at RP/RT supplier stands at the fair, it appears this observation is based on both U.S. and European trends. (For more on the seminar, check the March 2000 issue of IMM.)

Wolfgang Kraschitzer, production manager for Rapid Product Development GmbH (RPD—Austria), explains, "Our customers are now shifting away from the need for simple look-alike prototypes. Instead, we are seeing demand for functional parts and tools that can withstand the typical strains of actual service." One such customer, Austrian motorcycle manufacturer KTM, recently partnered with RPD to bring its Duke 625 motorcycle to market.

According to Kraschitzer, KTM wanted a functional fairing prototype to perform preliminary tests. RPD built each of the large parts (up to 1000 by 400 by 250 mm) that make up the fairing in several segments using a DTM Sinterstation and Duraform PA material. Segments were then bonded together, lacquered, and used in actual road tests. "KTM was able to conduct its tests well before the injection mold was cut," adds Kraschitzer. "As a result, its engineers were free to add necessary adjustments based on test data without incurring huge costs."

At Jaguar’s Whitley Product Development Centre (U.K.), SLA prototypes played a major role in optimizing vehicle aerodynamics. Using 3D Systems’ SLA 5000, engineers prototyped 3/8-scale versions of complete front and rear suspensions for wind tunnel testing. Results allowed Jaguar to modify the full-size vehicle for drag reduction. SLA prototypes were also used for instrument panel design (Figure 2), wing mirror housings, and body styling components.

Models for Success
Automotive suppliers have long relied on model makers to produce mock-ups of concept vehicles from clay models. The role these suppliers fill today is changing, according to Manfred Mack of Josef Hofmann Ingolstadt (Germany).

"We have developed an extension to our original modeling, or cubing, technology," he says. "Called testcubing, this process builds a model of the complete car body to exact design data out of aluminum, to which we can attach plastic components such as interior trim, instrument panels, and body panels."

To prototype the plastic parts, Hofmann uses both silicone-rubber tools with cast resin and an FDM system (Stratasys). A recent project with Audi to bring its TT roadster (Figure 3) to market made extensive use of both the testcubing model and FDM prototypes.

"Audi uses a just-in-time production system that extends to its product development phase," Mack says. "We developed the testcubing and FDM prototypes for the HVAC bezel on the Audi TT to meet its tight schedule." Hofmann also specializes in models for automotive lighting, and worked with Volkswagen on headlamps for the new Beetle.

Back Issues
New IM designs on display at Euromold were not entirely automotive. For instance, Styles RPD (U.K.) presented an innovative molded oxygen tank, part of a new system for firefighters that’s designed to be lighter in weight, yet just as safe as metal versions.

Even the lobby of the exhibition contained design innovation. Several child-sized mannequins were fitted with molded backpacks (Figure 4), representing a current product on the market in Germany.

Market Focus: Computers and business equipment

The computer and business equipment industries are on a strong pace due to continued demand for their products, which has been fueled by lower prices. But all is not rosy, particularly in the computer industry. Prices have been in a free fall for nearly two years-down more than 17 percent in 1998, with analysts expecting another 15 percent drop in 1999-putting the squeeze on computer makers' profits and putting a big dent in growth (expected to be less than 5 percent).
Sales are dropping as well, which is evidence of saturation in the U.S. PC market according to Martin Reynolds, a research fellow with Dataquest in San Jose, CA. "There's more than 50 percent computer penetration in the home PC market," he says, "with no new [areas] to go to."
Reynolds says computer makers are still shipping some 30 million units a year in the U.S. market. Japan, Europe, and Asia still represent the best opportunity for increases in sales, since a much smaller percentage of their populations has PCs. Incremental sales there may gradually become a smaller percentage annually as the growth rate slows. However, these countries will add "gargantuan numbers" of PCs, he says, about 12 million this year and an estimated 10 million next year.

PC shipments, U.S. (million)

1997   31.5
1998 36.3
1999  36.0
Source: and International Data Corp.

New Directions

With computer prices as low as $499 and predictions of $299 PCs, some companies are giving away hardware to consumers in exchange for contracts to buy monthly Internet service, and others are looking in new directions for growth and profits. The result is a move into e-commerce and other technology, as these three examples show:
  • Earlier this year, Compaq Computer launched a new company around its AltaVista search engine. It's also hopeful that sales from an online store,, which Compaq purchased in January 1999, will give the company a boost.
  • Dell Computer's offers consumers some 30,000 products, and the company has plans for further expansion of that site.
  • Hewlett-Packard plans not to sell servers in the traditional method, but H-P and its partners will play host to others' websites on H-P servers, and collect monthly service fees, lessening their dependence on the fickle movements of hardware sales.

Disposable PCs?

To sell more PCs, computer makers are targeting ways to get consumers to replace their PCs more often by eliminating older technology and designing computers with limited expansion capabilities. "If it were a very simple device, you wouldn't have to change it out," explains Roger Kay, manager of Desktop Practices at International Data Corp. (IDC) in Framingham, MA. "It goes out of date, so you just toss it and buy another. There's definitely a clear trend toward junking the old and buying new."
However, another argument suggests the opposite. Documented research by IDC asking consumers how long they intend to keep their PC shows that most people aren't planning to get rid of their PCs as quickly as some predict.
All could be moot, however, as new technology promises to supplant the PC in the home PC market. Both Compaq and H-P, which have lost business to Dell, hope to boost sales by making their business PCs less expensive to make and more
user-friendly to install and operate.
Computer makers are also turning to new types of products outside the PC business, such as mobile phones and other types of information devices. As computing becomes more ubiquitous and portable, consumers will see an array of new devices springing up to compete with 3Com Corp.'s PalmPilot.

Forecast shipments of mobile computers, U.S. (million)

1998   5.8
1999   6.8
2000   7.7
2001   8.7
2002   10.0
Source: and VAR Business

Business Equipment

Competition in the business equipment market is also pushing consumer prices down. Xerox Corp. is making moves to reduce its costs to manufacture and cut its supplier base in the face of an onslaught of rivals such as Canon Inc. in the copier business, and in the consolidation of printers and copiers into single units used for the same task. Lexmark International and Hewlett-Packard both plan to introduce new products that will go head-to-head with Xerox's lower-priced machines.
Research provided by IDC indicates that 16 million printers worldwide, representing $6.9 billion in sales, were shipped during the third quarter of 1999, up 12 percent from the second quarter. The growing low-cost PC market presents both opportunities and options for sub-$100 inkjet printers and flatbed scanners.
Inkjet printer sales are expected to continue to soar, notes an IDC market report. The market had its best third quarter performance ever in U.S. shipments of color inkjet printers, shipping in excess of 4.8 million units-34 percent growth over the same quarter the previous year. IDC also predicts double-digit growth worldwide for the scanner market.

Total personal digital assistant (PDA) market:
Unit shipment and revenue forecasts, U.S.

Year   Units (million)  Revenue (million $)  Revenue growth rate (percent)
1997  1.1  191.6 332.2
1998  2.1  531.3 177.3
1999  3.2  1037.6 95.3
2000 4.6   1673.5  61.3
2001  6.3   2386.8  42.6
2002  8.1   3072.7  28.7
2003  9.8   3686.4  20.0
2004  11.7   4254.6  15.4
2005  13.8   4681.2  10.0
 Source: Frost & Sullivan

For Molders and Moldmakers

With revenue essentially flat for PC makers, molders serving this industry can't expect much better. Computer makers that could once be counted on to invest heavily in molds to make parts for the long haul are now becoming as cost-conscious as the automotive industry. The business equipment market isn't far behind and is watching its costs as competition drives down the prices of printers and copiers.
Under the new model of short-lived computers-an estimated two-year life for many consumers-we can expect this market to move to less expensive tooling. Many are already having tooling built in China and Singapore to offset their costs. Don't expect to quote much high-priced, long-lead-time tooling for anyone in the computer or business equipment industries.
Dataquest's Reynolds says molders need to explore new design and material alternatives with their OEM computer customers. "Traditionally computers have been a big metal box with a plastic front," he says. "Shape, texturing, and color have typically not driven the market, but in Japan the market has shifted toward more color and creative designs. The hot color now is metallic silver."
Although Reynolds says that U.S. manufacturers are more inclined to "stick with the beige box," the U.S. market should see some leakage of new designs and colors, such as those Apple's iMac offers.
Obviously, as new data products get smaller and thinner, there will be much less plastic required per unit; however, Reynolds believes plastics use will be kept up by the increase in demand for these newer devices.
Reynolds also suggests that molders need to understand how to combine their technology with metal injection molding to help produce the computers of the future. "It [metal molding] offers design flexibility that you can't achieve with [plastics] injection molding," he says. "The same argument is true for handhelds."

New Business Model

Given the new business models of mass customization for both Dell on the computer end and Lexmark on the printer end, molders can expect to see other companies follow suit. That means a variety of tooling configurations, fast changeovers, and little finished goods inventory. Plant scheduling will be critical if you're a molder for these industries. And you can expect lean margins, which means productivity and efficiency is everything.
Some opportunities will exist in new low-end entrants into the computer market, but expect most of those units to come from places like China. However, one new startup, Gobi Computer, is purchasing PCs from contract manufacturer Solectron Corp. Other opportunities exist in new information equipment such as handheld data devices.
Compaq Computer, in an effort to gain on Dell's lead in computer customization, announced last month the purchase of Inacom Corp.'s custom assembly operations. Compaq said the purchase would give it the means to provide U.S. customers with tailor-made PCs and the ability to track their purchases over time.
With assembly and distribution plants in Indianapolis, IN, Omaha, NE, Swedesboro, NJ, and Ontario, CA, there may be more opportunities for molders to establish molding plants nearby to service these facilities, notes Dataquest's Reynolds.
The keys to manufacturing for this market will be fast time-to-market, thin-wall molding expertise, shielding capabilities, and assembly operations. Molders will also need to provide a flexible manufacturing environment with fast response times to accommodate the increasing trend toward mass customization.

PC/ABS drives down
costs in server panel

Sequential injection molding and gas assist molding were combined in a low pressure process to help make these Hewlett-Packard server cabinet panels more durable, lighter in weight, and stylish when compared with their sheet metal predecessors.
The 35-by-16-inch panels, winners in the computer and business equipment category at the Structural Plastics '99 conference, are molded of Cycoloy PC/ABS from GE Plastics on a 650-ton press. The panels snapfit onto the H-P Rack System/E, designed to house computer servers, peripherals, and instruments. H-P set out to redesign the rack system to eliminate the need for one-piece metal panels that are heavy, hard to handle, and vulnerable to denting. The company also wanted to incorporate design features to help its cabinet stand out.
"Our goal was to design a smaller modular sheet metal panel to reduce the overall field replacement costs significantly, but we found that a single, smaller sheet metal panel had nearly the same manufacturing cost as the original one-piece large side panel," says Horst Zittlau, H-P design engineer. "Plastic panels turned out to be less expensive, more durable, and they can be shipped individually for much less money."
H-P eventually teamed up with GE Plastics to develop a manufacturing process that would address some challenges that the new concept created. "Valve gate control allows for the manipulation of the melt flow fronts to achieve a surface without visible knitlines," says Peter Zuber, gas assist/low pressure program leader at the GE Polymer Processing Development Center in Pittsfield, MA. "Gas-assist molding helps ensure that textured surfaces, as well as internal features, are true and crisp because of the more uniform packing pressures that gas supplies."
The resulting system uses a two-drop hot manifold system with hydraulic valve gates as the primary resin gating method. This allows a relatively large part to be molded on a 650-ton press, rather than a 1200 or 1500 tonner as would be required for such panels with a nominal wall thickness of .14 inch. The sequentially triggered valve gates also help H-P control flow fronts and enable the movement or elimination of weldlines.

For more information:
GE Plastics, Pittsfield, MA
Phone: (800) 845-0600
Fax: (800) 433-2925

Handheld computer built
with specialty compounds

The Itronix T5200 is a portable, wireless computer that was launched early in 1999 and used primarily by telephone company, utility, and field service technicians to perform a variety of maintenance duties. The handheld device uses a Windows CE operating system, weighs 3 lb, and features packet data communications capabilities.
Manufacturer Itronix historically sourced resin for its products from large suppliers and selected from their standard offerings. But Bill Erler, principal mechanical engineer at Itronix, says the complexity of the T5200 demanded a variety of different materials. "It took a project of this magnitude to open our eyes to the benefits of a specialty compounder," he says.
Those compounds are provided for the computer by RTP Co. The most prevalent material is a flame-
retardant RTP 300 Series polycarbonate that provides impact resistance for the housing, battery pack, handle, I/O bezel, and other latches, doors, and bezels. A lithium battery power source, as well as UL intrinsically safe product ratings, dictate a UL 94 V-0 rating for the compounds.
For the hand strap and
D-rings, the company provides an impact-modified 200 Series nylon 6/6. A precolored 800 Series acetal is specified for the touch-screen pen. That material's natural lubricity and smooth surface prevents abrasion and wear. Finally, a 2800 Series precolored Santoprene elastomer is molded over the handle to provide a soft grip. All components are molded in Taiwan.

For more information:
Winona, MN
Phone: (507) 454-6900
Fax: (507) 454-8130
E-mail: [email protected]

ABS, structural web light office spaces

Many cubicles and offices are uninspiring; they often lack the proper light and atmosphere required to stimulate employees to be more productive. Recognizing this, furniture designer Herman Miller designed this all-plastic workstation to radically change the workplace environment.
Just half the weight of metal workstations, the Herman Miller units feature a U-shaped 4-ft-wide desk, pullout shelves, adjustable table legs, a swinging side table, and a computer keyboard tray. Some elements of the workstation are translucent and change color in sunlight from deep blue to luminescent orange. This feature is not just stylistic, but also helps to provide better surface illumination, keeping office workers more alert, say Herman Miller designers. "We wanted to create a structurally strong, lightweight, and durable system that creates a feeling of openness," says Don Karaus, design and development project engineer at the company. "In the past we couldn't do this with injection molded plastic. The tooling costs alone would have been astronomical."
The designer found the solution in structural web technology from Uniloy Milacron. It's a low pressure, gas-assisted molding process that uses multiple nozzles and sequential injection. This combination reduces clamping force requirements and allows for the use of less expensive aluminum molds.
The workstation is molded from an ABS blend material, supplied by Diamond Polymers and custom-formulated for the structural web process. The components are molded by Horizon Plastics Co. Ltd. in Cobourg, ON, which uses a 750-ton structural web Uniloy press. The single-cavity mold used to produce the desk surfaces was made by MSI Mold Builders in Cedar Rapids, IA.
Structural integrity and material savings are achieved by injecting gas into the ribs of the honeycomb web reinforcement on the underside of the workstation's components. The result is a topside surface that is smooth, free of sink marks, and suitable for writing.

For more information:
Diamond Polymers Inc.
Akron, OH
Phone: (330) 773-2700

Uniloy Milacron
Manchester, MI
Fax: (734) 428-1165
Phone: (734) 428-8371

Cleaner compounds benefit
data storage equipment

Microprocessor trays and disk carriers, other hardware handling systems, and internal components of disk and tape drives-such as load ramps, latch levers, crash stops, and actuators-are notoriously sensitive to plastics material contamination. Such parts are the beneficiaries of a specialty compound designed to meet the data storage industry's growing need for cleaner resins.
As disk and tape drives go to faster speeds and lower flying head heights, the effects of ionic contamination in resins are more pronounced. The manufacturer of the pictured components, molded by Entegris Inc. (Chaska, MN), chose resins that use LNP Engineering Plastics' Clean Compound Systems (CCS), specifically a statically dissipated polycarbonate composite. The CCS materials have a low ion content and provide minimal contamination for sensitive
data applications.
"When disk drive components and handling devices are kept as clean as possible there is less opportunity for product damage," says Bill Feldman, business machine industry marketing manager at LNP. "For example, if you have a lever within a disk drive that's made out of higher ionic content material, the chemical embedded in that material can outgas and cause corrosion on the disk itself or on other components of the drive. This can limit the drive's life expectancy."

For more information:
LNP Engineering Plastics
Exton, PA
Phone: (610) 363-4500
Fax: (610) 363-4749

Intelligent approach to buying barcoders

Who is barcoding today? According to Al Wilson, president and ceo of Project Management Inc. (PMI), the list includes custom molders and OEMs that make extensive use of plastic parts in their products. "Most users don’t give barcoding much thought," says Wilson, "but addressing key issues can help to save money and reduce downtime."

PMI is a full-service supplier of barcoding products—labels, ribbons, printers, printer supplies, and printer repair—with annual sales of $5 million. In order to help potential and current customers navigate the hurdles of equipment, supplies, and service, Wilson often takes to the road to present seminars. One recent such event, held for the Mid-America Plastics Partners, an alliance of plastics processors based in Indianapolis, revealed that buying equipment for barcoding is really just the tip of the iceberg. In the following, Wilson gives IMM readers an excerpted version of his seminar.

What kind of printer should you buy? It depends on the volume needed and the typical label size. Printing thousands of labels per month requires a large printer with prices ranging from $1500 to $4000. If you expect to be printing hundreds of labels monthly, you can opt for the smaller size printer that costs from $500 to $1200.

Wilson advises looking ahead when making a printer purchase. "If you’re only doing 100 per month today, but know that you’ll be doing more volume in the future, it’s more cost-effective to buy the bigger machine," he explains. "You will end up buying the larger one anyway, and not even using the smaller one." Another reason that smaller printers are not a long-term investment is that many can’t handle the factory environment. The cost of repairs often equals the cost of a new printer.

When looking at equipment, consider that smaller printers may weigh only 4 or 5 lb, while the large ones weigh 40 to 70 lb. If you need portable equipment, opt for the lightweight model. However, always consider label volume first.

Also check the availability of service and spare parts. Most manufacturers offer this, says Wilson, but you have to send the printer in, and there is no guarantee as to when you’ll get it back. Purchasing from a distributor, some of which offer rentals or service contracts that provide a loaner free of charge, can offer a solution.

However, beware of suppliers with hidden agendas. "A printer supplier offers a good printer at a good price," says Wilson, "so you buy it. But suppliers also have patents on media supplies—ribbons, labels, etc. So when you need service, they will identify media supplies as the problem, hooking you into buying only their supplies at their prices." To avoid this, Wilson recommends looking for a distributor that offers a broad range of supplies and knowledge of the industry, one that understands the interaction of printer, labels, and ribbons.

There are more than a few label-making programs out there, some from third-party vendors and other custom packages from printer manufacturers. PMI has seen its share, and after testing them, the company voted for a software package called Label Matrix, which it considered easy to use and comprehensive.

First and foremost, the program gives users options and flexibility. It also allows use of other printers in the event that the primary one goes down and a loaner must be used.

All the necessities for barcodes and fonts are included in the program. "Automotive suppliers and UPS, for example, are going to 2-D barcodes that carry more information in a square graphic design," he adds. "You need software that’s flexible enough to do both traditional three-of-nine barcodes and 2-D." An aside: Printers themselves may not support 2-D and may need to be upgraded.

Technical support for the software comes from Label Matrix, and is free of charge. The program allows uninitiated users to make labels within five minutes. "When I go to a customer location, I ask them to perform certain operations with their software, and invariably, they have to look at manuals. With Label Matrix, you have online help and access to tech support phone numbers," he says.

Molders and OEMs may choose to equip their printers with cutters and rewinders. If so, PMI has a few guidelines to follow.

Cutters are used with one continuous rollstock of label media, from which different length labels can be cut. The idea is good, but there is always the potential for adhesive buildup on the cutters, which almost always requires service. PMI recommends die-cut labels to eliminate buildup. For different sized labels, users can change label stock, which only takes a few seconds.

Rewinders, both internal and external, can be installed in the printer. External models (generally for large label runs) can be moved from printer to printer. Keep in mind that internal rewinders hold fewer labels in general than external.

If not using a rewinder, the only other option is fanfold, which feeds from and into a box. The question to ask is whether you need to leaf through labels quickly, which is easy to do with fanfold, or whether you prefer to have your labels on a roll.

Paper Stocks
There are a variety of label materials. Tag stock has no adhesive and is used for labels to be put in an envelope or hung from a product with string or wire. Direct thermal, like fax paper, is used on short-lived products. It is heat sensitive, and does not use a ribbon, which wears out print heads. Finally, thermal transfer paper, like laser printed paper, has a longer shelf life. Wilson recommends staying with stock sizes and colors, both for availability and cost effectiveness.

If you are putting together a custom label and need to specify adhesive, make sure you test before buying in quantity. Test the adhesive with the material to which it will be applied, taking into account issues such as temperature (containers stored outside) and contaminants (residue from the manufacturing process).

There are three types of ribbons—wax, resin, and wax/resin. With thermal transfer paper, wax is considered the best choice for most situations. But if labels see any time in weather or are exposed to contaminants, it is better to use wax/resin for greater durability.

If labels will be placed directly on products, PMI strongly recommends a resin ribbon. OEMs such as Motorola typically use this type of label on electronic products. Glossy, polyolefin label stock won’t wear off and is waterproof.

Service and Maintenance
After servicing not only the brands of printers it carries, but also competitive brands, PMI realized that there will always be service issues with barcoding equipment. What is the best insurance? Make sure you have a good service provider. "Computers are the same," says Wilson. "You will always need MIS people."

Replacement parts for printers include print heads and platen rollers. Keep them clean with alcohol after every ribbon to cut down on the amount of replacement. If an environment is very contaminated, like a paint shop with extraneous paint spray, for example, consider a special enclosure for the printer.

Contact information
Project Management Inc.
Al Wilson
Twinsburg, OH
Phone: (330) 405-0300
Fax: (330) 405-0301
E-mail: [email protected]

Q&A: Leading the way to a metal molded future

Editor’s note: Thixomat Inc. (Ann Arbor, MI) holds the exclusive rights to the patented TXM process, which it has trademarked Thixomolding, and provides education, technology, research, and sales and marketing support to parts manufacturers and OEM end users. Neil D. Prewitt, president and ceo, and Raymond F. Decker, chairman, recently found a few moments in their increasingly busy schedules to chat about the present and future state of the TXM marketplace.

IMM: How’s business?

Prewitt: Very good. We now have more than 40 licensees and there are presently anywhere from 130 to 140 TXM machines in the field. But that is not nearly enough to meet the demand. Meeting demand is the biggest challenge we face. There is a tremendous amount of business that we presently are unable to address because the number of machines delivered has not reached the critical mass required to service those market segments.

In any event, one of our licensees has 40 different parts running now and is prototyping and testing many more. Another has already invested some $80 million in capital expenses and has found it necessary to buy a local moldmaker to make its TXM tooling to keep up with demand.

IMM: What sort of new technologies are in the works?

Decker: New magnesium alloys are in development that will provide even easier moldability and greater heat resistance for applications like automotive transmissions. And even with all of the growth in the consumer electronics market, we have yet even to scratch the surface of the potential for magnesium TXM in EMI/RFI shielding applications.

There have been some investigations into using TXM zinc for high-volume applications, like molded door handles. And we have already seen some encouraging results from working closely with the DOE [Dept. of Energy] and Alcoa on aluminum TXM. It is a much more aggressive material, but we are confident that aluminum TXM will happen. We expect to see commercial TXM aluminum parts within a year’s time.

There have been some recent developments in machinery and molds to increase energy efficiency and part yield in magnesium molding to more than 90 percent. And work has already begun on what we call "macrocomposite manufacturing cells," which are designed to overmold plastics on TXM materials. It is a value-adding concept combining the best of both worlds.

Prewitt: There is also considerable work being done on the part design engineering front, especially when it comes to CAE mold flow simulation and analysis. Meanwhile, the first edition of our basic design manual is nearing completion. It will be a living document, perhaps a ring-bound manual that users can add to over time. We are also considering a CD-ROM format.

As you can see, Ray and our team are constantly working on new technologies and we are getting a tremendous number of calls and inquiries about the process. One thing we noticed is that there is still confusion about TXM compared with other metal injection molding processes. TXM is a one-step, closed- machine process where a metallic feedstock goes in and the part comes out. The process eliminates the need for feedstock compounding, binders, debinding, and sintering.

IMM: Earlier you spoke of aluminum. How will all the mergers and acquisitions among aluminum suppliers last year influence the TXM marketplace?

Prewitt: It is still too early to tell, but we do not anticipate that it will have any negative impact.

IMM: What kind of interest are you getting from automotive suppliers?

Prewitt: One plastics automotive supplier came to us to find out about magnesium TXM. He told us he refuses to put diecasting machines in his plastics plant and told his customers he would not get into magnesium unless it could be TXM magnesium, strictly because of the environmental problems with diecasting.

IMM: Do you foresee any raw material supply problems this year?

Prewitt: There has been a tremendous amount of recent activity among magnesium producers. Several new refineries are coming onstream all around the world, and existing producers are expanding because of increased demand for magnesium, particularly in the automotive sector. All of the major automakers have staffs dedicated to increasing usage of magnesium because it is such a strong, lightweight, and environmentally friendly material. Rossborough and JSW are our only licensed chip suppliers so far, but we are talking to others.

IMM: Have you been satisfied with JSW and Husky as your licensed machinery builders?

Prewitt: Yes, extremely satisfied. Both are gearing up their TXM operations and continue to show a true commitment to the technology and to the business. Both have guaranteed us that they can fill the market’s need for machines. We have mostly been involved with the small end of the market—companies with five to 10 machines. To date, we have not addressed the really big end of the market, companies that need turnkey systems involving 50 machines or more per sale. That requires more resources than we currently have on board. We are investigating various alliances along with JSW and Husky that would bring the resources necessary to address large turnkey operations.

Decker: We continue to support both with our R&D. We have added a metals laboratory manager, a project engineer, and a plant superintendent, and we plan to add more. We spent about $1 million this year on R&D and we are looking to spend more. Our R&D activities are mainly concentrated on the heart of the system, on screws and barrels, materials of construction, and processing. And we have entered into discussions with moldmakers to forge alliances so that we can avail ourselves of their expertise and recommend them to new licensees.

Also, we will have two TXM machines on the floor here in the not-too-distant future to help in process and product development efforts, and to assist licensees with pilot runs. We will have a 220-ton JSW and a 500-ton Husky.

IMM: Do you have any plans to intensify your sales and marketing efforts?

Prewitt: Absolutely. For example, we are planning a formal dedication of our technical center where we will have the two machines Ray has already mentioned on display. We will also have a conference seminar here in Ann Arbor in between the SAE show, which runs from March 6 through 9, and the NDES show, which runs from March 13 to 16. We will also be exhibiting at both of these shows in a booth of our own for the first time. And we plan to have licensees in attendance at both shows that will display some of their innovative TXM parts.

Contact information
Thixomat Inc.
Ann Arbor, MI
Neil D. Prewitt
Phone: (734) 995-5550
Fax: (734) 995-5558

Understanding molds that form threads

Editor’s note: Consultant Bill Tobin of WJT Assoc. spends his time helping molders diagnose molding problems, and offers his comments on how to get molds for threaded parts to work best.

This article is not about screw thread design. There are some fine design manuals put out by resin companies to help you design threads. The important rules are to radius everything, don’t forget draft, and put a generous lead in.

The purpose here is to look at the molds and figure out how to get them to work the best. What kind of molds make threaded parts? The three basic ones: two plate, three plate, and hot runner, depending on your budget. All of them can work equally well with the proper design features.

Ways to Design the Mold
Discussions of thread-forming tools make people immediately think of unscrewing tools. But this type of tool is only one way to mold threads. When the requirement is for deep, small-diameter female threads, an unscrewing core driven by a motor, chain drive, or rack and pinion will do the job. But ejection can become the problem. The most common way is to put "dogs" (these look like miniature saw teeth) on the core plate to keep the part from twisting with the core, advance the stripper plate at the same rate the core is unscrewing, and then let the parts fall free. Another way is to keep parts in the cavity and unscrew with the slow open movement of the clamp, and then use front ejection (usually with a poppet valve).

But do we really need to unscrew a female thread anyway? If we are making reasonably large items, such as bottle caps, why not just strip them off the core? If the material is flexible and the thread is not complex, this is easy to do.

A second option to investigate is a collapsing core. During ejection, core parts move, collapsing the diameter and freeing the threads. Conventional ejection can now remove the parts. While this will leave a witness line, it is a lot cheaper and demands less maintenance than a rotating mechanism. No matter what type of thread forming you use, keep in mind there must be some kind of cooling in the cores. Without it the cycle will slow, and it will cost you.

Male threads, for some reason, are often considered the same as female ones. In my experience many molders go to the expense of building an unscrewing/collapsing-core tool because they are uncomfortable with the alternatives. In reality, male threads are best made with split cores that are opened and closed in one of two ways: in gangs with a large slide block and horn pins, or individually with a split, spring-loaded core that goes into a tapered pocket.

While making male threads with these mechanisms will leave witness lines, there are advantages.

  • Cycle time. Since a male thread is really a boss with a contoured outside, it presents a thick section. Thick sections take a long time to cool. When a soft, thick section is subjected to the torque of an unscrewing device, there is a high probability that it will break off. Cooling a thick section is most easily done if the cooling is direct and intimate. A cooled slide is easier to make and more effective than attempting to cool a rotating core.

    While there is some disagreement on the issue, using slides usually means faster cycle times. This is not an argument based on the mechanism; you can take the part out of the mold faster because it doesn’t need to be fully cooled. There is no torque obstacle when using slides.

  • Maintenance. Unscrewing molds are precision tools requiring high maintenance. Everything must be timed, and that timing must be maintained to get the best productivity. Tools with slides, on the other hand, are easy to maintain.

  • Cost. Unscrewing tools are expensive when compared to tools with slides.

  • Venting. The problem with an unscrewing male thread tool is venting. Usually the thread is formed in a blind pocket. While cooling is the main issue, trapped gas (dieseling) will be an ongoing problem.

    Molding Issues
    With all threaded parts, the size of the mold compared to the requirements of molding is often overlooked until it is too late. It is all too common that a 6-oz shot is put into a 50-oz machine. This is because the parts are small, but the mechanisms for unscrewing take up so much space that the distance between the tierods mandates the larger machine.

    We now have a residence time problem for the plastic. If it lives in the barrel too long (more than 15 minutes) most resin will begin to degrade; at the least the colors will shift. Along with buying the mold, you may have to pay for a smaller-diameter barrel simply to keep the residence time within a controllable limit.

    When all is said and done, there will still be a lot of argument over which tooling philosophy is best. To aid in your decision, think like a banker. Tooling is an investment. It is the means to an end to produce parts. The real cost of the parts is the tooling, maintenance, setup, and all other costs factored into the lifetime production of the product.

    The usual rule of thumb is to have the tooling pay for itself in no more than one year’s full production. You’ll need to build robust tools for the life of the product, but you don’t have to spend a king’s ransom and get a tool that never pays for itself.

    This decision is best made doing a side-by-side budget comparison, one example for each tooling approach. Look at delivery, tool cost, mold productivity, and cost of the parts. Whichever provides the best balance is probably the proper decision.

    Bill Tobin has a number of books available from the IMM Book Club that address both business and technical issues in the injection molding industry. For more information, call Renee Leatherman at (303) 321-2322, or use the Internet and go to

    Contact information

    WJT Associates
    Louisville, CO
    Bill Tobin
    Phone: (303) 499-3350

  • Insert molding: Ripe for automation

    Automation can lead to faster cycle times, improved quality, enhanced production efficiencies, and in the end, new business opportunities-all of which two Connecticut companies were banking on when they recently took on the daunting task of completely automating insert molding.

    "Quality. That is the biggest improvement we anticipate from automation," says Michael Sansoucy, program manager at Seitz Corp. (Torrington, CT). "And it increases the volume potential of our machines by eliminating human error and inefficiencies, so now we can go after projects involving higher volumes. Automation does all this by stabilizing the insert molding process."

    For Plastic Molding Technology (PMT) of Seymour, CT, the driving force was not necessarily fostering new business opportunities, but keeping its existing customers happy. "Our customer needed output and wanted the piece price down, too," says Gordon B. Sanford, PMT's plastic process engineer. "We had one part running with two operators. Cycle times were around 50 seconds. With automation, the cycles now are around 21 seconds. We doubled the output by automating. Otherwise, we would have had to buy more molds and more machines."

    To get to where they are today, both companies worked closely with systems integration specialist Injectech Engineering LLC, also based in Connecticut.

    Creating New Sales Opportunities
    For Seitz Corp. the goal was to automate the production of nylon parts for a bill validation device that involved the insert molding of manually loaded metal shafts in a 30-ton Newbury shuttle press. Seitz, a custom molder and moldmaker, operates 40 molding machines from 28 to 400 tons at its plant in Torrington, and six presses up to 770 tons at its Rockford, IL facility. Though the company has considerable experience with parts removal robots, it relied on Injectech's expertise to help it automate the insert molding operation.

    "The robot itself is not the key thing in this kind of cell," says Sansoucy. "The interfacing-that's the big thing." Injectech and Seitz Corp. worked closely to design the gear shaft production cell. Currently, the insert molded gear shafts are running around the clock, unattended.

    Shafts are bowl-fed over the cell guard to a Scara robot. It places a shaft in the mold where its presence is sensed. The table shuttles the mold under the shooter as the Scara rotates on its vertical axis to unload finished gear shafts from the other side of the table.

    Injectech Engineering specializes in vertical injection molding and supplies custom-built vertical presses to a select customer base. The company is also an authorized integrator for Intelligent Actuator's Scara robots. Ken Heyse, Injec-tech's president and general manager, sees the auto-mation of insert molding as a niche with great potential. Because of the Scara robot's programmable versatility in a nearly hemispheric, horizontal-axis work envelope, Heyse feels these units are ideal for handling inserts and parts molded on vertical presses that are equipped with rotary or shuttle tables.

    Sansoucy, for his part, expects that the higher-quality yields at higher-volume throughputs, which automation provides, will foster new high-volume business opportunities for Seitz. And Seitz is using the building blocks of the cell to benchmark new standards for future automation projects since the Scara can be easily reprogrammed and retooled for other insert molding jobs.

    High-speed Automation
    Many of the benefits from automation have already been seen by PMT, which has long been a proponent of advanced automation. In fact, PMT was one of the first companies to use digital vision sensing technology from DVT (Norcross, GA) to verify accurately that its extremely small inserts are properly loaded (see January 1998 IMM, pp. 93-94). Digital imaging is designed to help further reduce insert molding costs by automatically verifying the accuracy of insert loading.

    PMT, which runs 30 machines up to 110 tons in Connecticut and a full-service molding venture in Slovakia, has now taken the next step by working with DVT and Injectech to automate insert molding. It has completely automated a rotary-table Autojectors press that insert molds Noryl GTX automotive E/E parts for braking systems in four-cavity tooling. Twelve small metal inserts are loaded during each shot-three in each cavity. The cell can run unattended with three or four mold stations, 24/7, and now produces parts in a 21-second cycle, down from 50 seconds.

    Inserts from a vibratory bowl are transferred into a mold loading bar. Fixed-axis slide robotics are used. Highly accurate linear servomotors drive the slide robot arms.

    Strategically located load sensors and fiber optics support automated insert handling. DVT cameras, one for each cavity, ensure proper insert loading. If inserts are improperly placed the process is not allowed to continue. Plastic would shoot into the mold where the insert should be, causing mold cleaning downtime.

    Another linear servo robot removes finished insert molded parts and deposits them by cavity into individual Lexan tubes for traceable packaging. Rejects, based on eight key machine setting parameters, are automatically segregated.

    Safety standards and communication protocols
    for insert molding machines

    Now is a good time to review and comment on the final version of a proposed American National Standard for Vertical Clamp Injection Molding Machines. The Machinery Div. of the SPI has recently completed the document, and wants input from the molding community before the standard is submitted to the American National Standards Institute for approval.

    To obtain a copy of the proposed standard, contact SPI's Betty Drake at (202) 974-5340, or e-mail [email protected]. There is no charge for copies. The committee working on the standard is eager for input as soon as possible, before the final draft is sent out for balloting.

    On the protocol issue, Ken Heyse of Injectech is working with the SPI to develop a communications protocol between vertical insert molding machines and automation support systems. "You are always making a part in automated insert molding. There is no dwell time, as there is with horizontal machines. There are enough subtle differences in the processes that call for a different communications protocol," Heyse says.

    Contact information
    Injectech Engineering LLC
    Torrington, CT
    Ken Heyse
    Phone: (860) 496-7167
    Fax: (860) 496-2062
    E-mail: [email protected]

    Seitz Corp.
    Torrington, CT
    Michael Sansoucy
    Phone: (860) 489-0696
    Fax: (860) 489-4286

    Plastic Molding Technology
    Seymour, CT
    Gordon B. Sanford
    Phone: (203) 881-1811
    Fax: (203) 881-1801
    E-mail: [email protected]

    Rapid growth in global electronics: How can U.S. molders participate?

    Editor’s note: This report looks at electronics and computer markets from an international viewpoint, albeit with the view of how U.S. molders can participate. A companion look with a domestic slant appears in this month’s Market Focus.

    Products based on electronics are the fastest growing product group around the globe. This includes PCs and notebook computers, laser printers and copiers of all types, mobile phones, PDAs, and electronic books. Growth rates of at least 12 percent/year are common, and in many areas of the world growth rates in excess of that have been recorded for the past five years (see Table 1).

    Sales of products are not the only thing growing so fast. Injection molders—and that includes many in the United States—producing parts for these products have seen their sales grow at the same rates and in some cases even faster. It is an enormous market; in 1999 consumer electronics, which excludes PCs and related office equipment, reached $82 billion in sales.

    Most projections for the next three years call for the average growth of PC sales to exceed 18 percent/year. Some specialty products—such as mobile phones—may grow even faster.

    So how can U.S. molders benefit from this growth even more? In the past few years, injection molding in the United States for electronics applications has outperformed every other market segment. Yet many molders supplying components to the electronics industry complain that a surge of lower-cost imports is taking away market opportunities. "It is tougher than ever to compete," says a Texas-based molder of keyboard parts.

    Trade data collected by the U.S. Government support this fact: Imports of electronic items—fully or partially assembled—have grown twice as fast as corresponding exports.

    How Suppliers are Selected
    We spoke with key buyers for components at powerhouse firms such as Dell, IBM, Hewlett-Packard, Gateway, Motorola, and Nokia. Just how are suppliers of parts selected and what does a molder have to do to be well-positioned for additional business?

    The most interesting finding was that the ability to produce parts at low prices is not necessarily the most important factor. While price is clearly a consideration, location and proximity to assembly plants appear far more important. But the most critical requirements—and this was the consistent response from these buyers—are the abilities to change product design very quickly and to be a full partner in bringing new products to market rapidly.

    Product life cycles continue to shrink. In the 1995-1998 period, say component buyers, the typical life cycle of a PC or notebook computer was about 14 months. This shrunk to less than eight months in 1999 and may shrink to six months or less in 2000-2003.

    The rapid evolution of electronics technology and swiftly shifting consumer demands favor molders that can act as full partners in minimizing the time between product concept development and actual production. Molders working in close contact with moldmakers and machinery suppliers have been performing best in this market. And those molders with the most recent, up-to-date production equipment in terms of molds and secondary assembly operations have also done best.

    The fact is that the often brand-new molding plants in countries such as Thailand, Malaysia, Singapore, the Philippines, and Taiwan were selected primarily because their equipment is so new and advanced. Proximity to assembly plants helps as well.

    Table 1.
    Growth in computers and electronics products, Nov. 1998 to Nov. 1999


    % increase

    Singapore 17.9
    South Korea 17.0
    Malaysia 14.4
    China 14.0
    Thailand 13.5
    United States 13.0
    Canada 12.3
    France 12.0
    Sweden 9.0
    Indonesia 8.9
    Belgium 8.9
    The Netherlands 8.5
    Denmark 8.0
    Philippines 7.5
    Euro-11 7.1
    United Kingdom 6.3
    Australia 6.1
    Taiwan 6.0
    Italy 6.0
    Hong Kong 5.8
    Norway 5.0
    Japan 4.3
    Germany 4.0

    Where the Market is Going
    It may be helpful for molders to look at just where the market is going and position their operations accordingly. U.S. molders have the benefit that the ultimate headquarters of most of the leading electronics firms are in the United States. It is this proximity to decision-making power that should favor them in getting the foot in the door on new products. And molders that have seen their U.S. output grow by more than 20 percent in past years have done just that: They are always ready to do prototype work and always ready to take on development projects that may not be that profitable.

    Additionally, major U.S. molding houses have been exporting manufacturing expertise to manufacturing plants in Asia. Often these molders own such plants or have some kind of investment with them.

    We had the opportunity to discuss these issues with buyers for Nokia during a recent Scandinavian trip. Nokia works with molders all over the world and has carefully selected those firms that are willing to "go the extra step" in supporting concept development. "We are looking for technology partners that offer new solutions in product design, materials selection, and the ability to help us bring new designs to market more quickly," our Nokia contact says.

    Key Trends for the Future
    Now, in early 2000, we anticipate a post-Y2K mini-boom as businesses and consumers resume buying computers without concern for the millennium bug. Major computer firms forecast accelerated sales for now, having seen many potential buyers shy away until after the turn of the year. Major research firm International Data Corp. found in a study late last year that 37 percent of the 2100 North American companies it surveyed deferred spending last year on nonessential technology projects unrelated to the Y2K glitch.

    At the same time, PC makers are trying to move away as rapidly as possible from the money-losing low-cost or no-cost PCs. Such products created enormous pricing pressures for molders and generated little profit for PC makers. "The percentage of retail buyers willing to sign up for long-term Internet service to earn hefty rebates fell from 4.1 percent in July 1999 to only 1.4 percent in November," says a report from Allison Boswell Consulting Inc.

    In a year when global PC shipments are expected to grow at a rate of more than 18 percent/year, the major opportunity for molders lies in new devices that are now in the concept stage. Internet appliances likely to hit the market late in 2000 are just now in development and offer new opportunities for aggressive molders. What are we talking about? These are devices connected to washing machines, cooking ranges, refrigerators, and other household appliances. These devices may connect consumers to the Internet.

    This year’s Consumer Electronics Show was the launching pad for a variety of products—many still in the concept stage—that will likely dominate the electronics industry for the next two years. At the January show companies demonstrated products from mobile phones with Net access and electronic organizers to television set-top boxes that let users log onto the Internet.

    Such Net appliances are products that move away from traditional PC design and focus more on the utility of electronic devices as Internet products. Companies mostly unknown now—such as Vivo and Research in Motion—will be looking for parts vendors shortly. And major houses such as Dell and Compaq will look at expanding their vendor bases for these new products. But the real opportunity for molders new to this business will be found in upstarts that compete in areas such as specialty mobile phones, DDS technology, or PDAs.

    Here is one item that highlights the importance of new players. Texas Instruments—a major supplier of chips for mobile phones—sold more than 30 percent of its output in this product category to new telecom companies.

    Worldwide sales of semiconductors rose 18 percent in 1999 and will increase even faster this year on rapid growth in Internet use and mobile phones, according to Gartner Group Inc.’s Dataquest unit. Semiconductor sales jumped to $160 billion in 1999 from $136 billion a year ago, the biggest gain since 1995.

    Dataquest expects sales to accelerate in the next few years as the rest of the world catches up with the U.S. in Internet use. Demand for chips that power mobile phones and electronic devices is prompting companies such as Royal Philips Electronics NV, Europe’s biggest semiconductor maker, to increase production.

    But Asia is likely to see the most growth and this will create opportunities for molders that have worked at getting access to that market. Segment data by Dataquest show that global semiconductor sales climbed 25 percent in November to a record $14.2 billion, based on data collected by the Semiconductor Industry Assn. Sales in Japan and other Asia-Pacific countries grew the most, rising about 39 percent from a year earlier. Sales in the Americas rose 16 percent, while European sales gained 11 percent.

    According to Dataquest, analysts project growth of Internet subscribers in the Asia-Pacific region to explode from 13.7 million in 1999 to 40 million by 2003.

    Contact information
    The Repton Group
    New York, NY
    Agostino von Hassell
    Phone: (212) 750-0824
    Fax: (212) 752-5378
    E-mail: [email protected]

    The Materials Analyst, Part 29: Defining responsibility for field failure

    This series of articles is designed to help molders understand how a few analytical tools can help diagnose a part failure problem. Michael Sepe is our analyst and author. He is the technical director at Dickten & Masch Mfg., a molder of thermoset and thermoplastic materials in Nashotah, WI. Mike has provided analytical services to material suppliers, molders, and end users for the last 12 years. He can be reached at (414) 369-5555, ext. 572.

    We would all like to think that in these times of increased competition, cooperative efforts between suppliers and customers are an important part of the new business climate and a key tool in the process of solving problems rapidly. Unfortunately, all too often the large end user, when confronted with a product performance problem, no longer possesses the in-house expertise or the inclination to assist in the problem-solving process. It often turns to the supplier for the solution.

    Frequently the implication of the request for help is that the supplier has in some way caused the problem, and a solution is needed yesterday or else. In such a situation, where guilt is presumed, the only salvation for the supplier may be an objective analysis of the problem. The responsibility must land somewhere, but in order for the solution to be a lasting one, the determination must be based on data and not on opinions.

    In a world where the design and material selection process is pushed further and further down the supply chain, it becomes imperative that the general specifications provided by the end user accurately reflect the end-use conditions that the part will see. This particular case involved an automotive part in an under-the-hood application where the environment was oil immersion at elevated temperatures. The general criteria called for the part to have good ductility, moderate strength and stiffness, and an ability to handle oil immersion at a constant temperature of 110C (230F) for the anticipated life of the product, approximately 4000 hours. Given these specifications, and using past experience with successful applications, a heat-stabilized, impact-modified nylon 6/6 with 14 percent glass fiber was chosen for the part.

    Testing to Extreme
    At this point we come to our first problem. Engineers like to perform what they refer to as reliability tests. Often these involve running the application at very aggressive conditions in order to accelerate the deterioration of possible weak links in the system. The presumption is that if a product can withstand a punishing environment for a certain amount of time, then it is certain to sustain the normal exposure conditions for the anticipated life of the product.

    The test bed conditions for this particular product were not specified, but when one part being tested under an accelerated protocol failed in a brittle manner during a routine check, the investigative machinery was set into motion with a vengeance. The molder that had produced the part received a portion of the broken piece back with a stern letter demanding an explanation and a corrective action plan. Also requested was a mountain of technical data concerning maximum and minimum time-temperature performance profiles, information that should have been requested and studied before the application was launched. We in turn received the same package of information from the molder with the assignment of finding out what went wrong.

    Visually there was an obvious problem. The part that went into the application was white, but the piece that we received was a very dark brown. This suggested the presence of a significant amount of heat. Nylons are well known for their tendency to change color when they are exposed to elevated temperatures. Even in a resin dryer, nylon pellets that are dried at high temperatures begin to darken as they undergo a chemical reaction known as oxidation. This oxidation process eventually results in a breaking of the polymer chains and a reduction in molecular weight. As we have mentioned repeatedly in previous installments of this column, reduced molecular weight compromises properties, especially ductility and impact resistance.

    Figure 1 compares the melt-flow rate of two nylon parts aged at two different temperatures. One part was aged at 80C (176F) while the other part was aged at 120C (248F) for the same period of time, 11 1/2 days.

    In that short time, the part aged at 80C retained its as-molded molecular weight, while the part aged at 120C exhibited serious problems early on. By the end of the test, the melt-flow rate of the latter part had tripled, signaling serious degradation. Property tests performed on each of these parts showed a significant decline in impact strength for the degraded part but virtually no change for the part aged at the lower temperature.

    Identifying the Chemical State
    The selection of the two temperatures in this study was not an accident. The product was a general-purpose nylon with no special stabilizers. Materials of this type can withstand a maximum temperature of only 80C without breaking down. In our client’s application, the added heat stabilizer was designed to extend this protection up to 120C, but above this point the data from the material supplier showed that the rate of property decline would increase rapidly. The appearance and physical condition of the sample led us to believe that the part had seen temperatures well above the prescribed 110C.

    Normally, melt-flow tests would be used to confirm the presence of degradation as they were in the study shown in Figure 1. The problem here was that the entire part weighed less than half a gram. A good melt viscosity determination requires at least 20 times that amount. We were forced to turn to more sophisticated tests that could work with small quantities of material.

    The first step was to compare the chemical state of the failed part with an as-molded part and the raw material. We did this by infrared spectroscopy. Figure 2 shows the results of these scans. The raw material and the molded part give an excellent match, but the failed part shows a significant problem.

    At 1740 cm-1 there is a very strong absorption peak that is associated with groups that form when a polymer like nylon oxidizes. Some of these groups are present naturally in nylon materials, but clearly the incidence of these groups had increased dramatically. In addition, we saw changes in the spectrum that indicated that the original polymer chains were being broken and that there were now many short chains where once there had been a few long chains. Of course, all of this spells trouble for the polymer.

    Solution Viscosity Test
    While the infrared detects the problem, it does not quantify it. For this we still needed a viscosity test. When only small amounts of material are available, the test of choice is a solution viscosity test called an inherent or an intrinsic viscosity (IV) test. This measurement may be familiar to processors that work with bottle-grade PET polyesters. A full description of the principles and procedures behind the IV test are well beyond the scope of this article. However, in brief the technique involves comparing the viscosity of a known amount of the polymer dissolved in a solvent with the viscosity of the pure solvent. As with all viscosity tests, the higher the viscosity of the solution, the higher the molecular weight of the dissolved polymer. One of the big advantages of this test is that it can be run with a very small amount of material.

    As with the melt viscosity tests that we have discussed in previous articles, there are rules governing acceptable and unacceptable changes in intrinsic viscosity. When comparing pellets to parts, the IV should not decline by more than 10 percent if the process is sound. Above 10 percent properties will begin to drop off, although good part design can add a safety factor and permit parts with 15 to 20 percent decreases to survive. In this case we compared pellets, the failed part, and as-molded parts. We wanted to be sure that the effects of processing were isolated from those of field exposure.

    The as-molded parts showed a reduction of less than 7 percent from the IV of the pellets. This established the process as capable in terms of producing parts with good property retention. The failed part, on the other hand, showed a shift of more than 13 percent. This put an exact number on the qualitative data provided by the infrared. We now knew that field exposure was chemically changing the polymer and was reducing its average molecular weight in the process.

    Signs of Crosslinking
    But there was more. During the process of dissolving the various samples, the technician working on the IV tests noted that a substantial portion of the failed sample did not dissolve readily. Given the strength of the solvent we were using, this was remarkable. Typically, failure of a polymer to dissolve is a sign that crosslinking has occurred. We normally associate crosslinking with thermoset materials. In these systems a network solid forms that is very resistant to heat and solvents. This network also prevents the system from remelting once it has formed.

    Crosslinked materials are very rigid, but they also possess limited elongation and are therefore extremely brittle for the most part. Certain thermoplastic polymers are also capable of crosslinking in a limited manner, and often this occurs in the advanced stages of molecular weight reduction. Reactive sites on the chains of reduced size begin to link together. In fact, if you look carefully at Figure 1, you will notice that the material aged at 120C had actually started to come back down in melt-flow rate. This can be an early sign of crosslinking.

    If carried to extremes, it is possible that much of the initial change in melt-flow rate can be erased. Why is this important? Because as these crosslinks begin to form, the viscosity test reads this as an increase in molecular weight without giving any consideration to the fact that it is the wrong type of molecular weight increase. If this had happened to our part, then the reduction of 13 percent could represent a more drastic reduction in chain length followed by a competing buildup in molecular weight through crosslinks. If this were occurring, it would shed new light on the severity of the test bed conditions.

    To test for this possibility, it was necessary to repeat the IV test and subject the solution to a more sophisticated test known as gel permeation chromatography (GPC). This is an expensive and time-consuming test, and for this reason it is seldom used in standard problem solving. But a lot was at stake in this case, and it was the only viable method for examining the anatomy of the IV results.

    Again, the principles of GPC are complicated, but if you have worked with SPC, you can understand the relationship between IV and GPC. IV is a reflection of the average molecular weight of the polymer sample, while GPC provides a histogram of all of the individual chain sizes that make up that average. Obtaining an IV number is like getting a mean dimension on a sample population, but the GPC is analogous to seeing the entire distribution of measurements that make up that average.

    Figure 3 shows the results of the GPC for the as-molded part and the failed field material. This confirmed our suspicions. The field failure had a wider distribution, proving that while some chains had been reduced in size during initial degradation, some of these chains were now joining up to produce a higher molecular weight fraction as well. The average effect on the IV tended to cancel out to a point, but the real problem was much worse than the 13 percent test value suggested. Here was a case of chain scission followed by oxidative crosslinking, a process that required considerable heat to initiate. This told us that the temperature of the test bed was well beyond the stated 110C.

    Cons of Accelerated Testing
    A review of property retention data as a function of temperature revealed the problem, and it is a common problem with a lot of accelerated testing. The material that had been selected was designed for long-term exposure at temperatures up to 120C. Up to that point, the polymer and the stabilizers in the compound were designed to protect the material from the harmful effects of oxidation. Test data from the material supplier showed that after 5000 hours at 120C property retention was essentially 100 percent. But above this point deterioration begins to set in quickly.

    Degradation processes such as oxidation tend to proceed exponentially according to a rule of thumb that says that for every increase of 10 deg C a particular level of degradation will be achieved in half of the time. This means that an increase of 20 deg C shortens the life of the product by a factor of four, a 30 deg C rise cuts it by a factor of eight, and so on. But below the threshold temperature, the degradation will not occur to any appreciable degree. This is the fallacy of some accelerated tests. They venture into territory where they provoke changes in a material that could not occur in the actual application. They are predictors of catastrophic failure, not true accelerated testing.

    Armed with this collection of test data and property information from the material supplier, our client was able to go back to its very imposing customer and explain that the material was properly molded and was designed to handle the application conditions as they were originally specified. In this case, the material was doing exactly what it was supposed to do. Exposed to temperature extremes beyond its limits, it was undergoing physical and chemical changes that rapidly caused the product to deteriorate. This had led to the field embrittlement. A little time spent evaluating and understanding the fundamental behavior of the material saved the molder, and ultimately the end user, many thousands of hours of continued testing and failure analysis. It also placed the responsibility firmly with the end user to define better the conditions under which it expected the material to operate.

    Effective plastics design for durable goods

    Editor’s note: Robert J. Cleereman, global director of the Materials Engineering Center at Dow Chemical, recently addressed an audience of designers at the Appliance Show in Nashville, TN. His message? How to create customer-preferred, innovative, and cost-effective appliance designs based on the intelligent use of plastics. Portions of his discussion, excerpted here, challenge the status quo among designers of durable goods.

    Today, the use of plastics as engineering materials in durable goods markets remains minimal. In fact, less than 3 percent of all durable goods are plastics-based. Despite their potential to create superior solutions that meet market needs, these materials still face several obstacles to achieving widespread acceptance. Several pioneering projects, however, have shown how plastics can be used alone and in combination with traditional materials to bring costs down and add product function. The key for designers is to understand their options from a more complete perspective so that they can develop alternative solutions based on plastic’s strengths.

    Reasons for the perception about plastics in the appliance industry are numerous, but the most compelling rationale involves the structural performance of plastics. Specifically, most appliance designs (and many others as well) are based on modulus of elasticity, or stiffness.

    While plastics compete well with metals on a tensile strength basis, they are not as attractive from a stiffness point of view. For example, 30 percent glass-filled PP gives 1000 kpsi modulus per dollar, while cold-rolled 4340 steel offers 7000 kpsi for the same dollar. Add to this the fact that designers are more familiar with steel, and you see why the motivation for switching to plastic dwindles.

    On the other hand, plastic-based durable goods designs can support significant loads, be more economical, and demonstrate inherently higher quality than traditional-material-based products. Plastics can do this because they can be fabricated in complex net-shape or near-net-shape geometries that eliminate or reduce secondary operations. This quality, dubbed fabrication functional performance, refers to the free-form nature of plastics, one that is foreign to steel, aluminum, and wood.

    Classic System
    Durable goods are generally complex because they exist to provide features that accomplish some functional purpose. When the product is based on traditional materials achieving this purpose normally requires elaborate assemblies. That’s because these materials are available only in flat or constant shape geometries. Therefore, constructing complex products from these very simple forms dictates a multitude of pieces and parts.

    Picture nearly any durable goods product (Figure 1). Basically, it consists of a base upon which everything that makes it function is mounted. Achieving the proper spatial arrangement of these parts requires complex use of brackets and fasteners. Once the assembly is complete, a cover or enclosure is needed to hide all the ugly brackets and fasteners.

    The end result of this type of design is a large number of pieces, parts, and finishing costs. Figure 2 depicts the manufacturing cost breakdown for typical, high-production durable goods. Obviously, the raw material and reform (stamping) steps are not very expensive, but costs escalate when it’s time to put the pieces together and make them look good and perform properly.

    Technology has come a long way with respect to mass production, but all the efforts and investment since Eli Whitney invented the process have been based on improving this last step—namely, putting pieces together. Raw material cost is not an issue when you can still get a pound of 30,000-kpsi modulus steel for 25 to 35 cents.

    When designers try to substitute plastics in this system, using it as a pseudo-traditional material, they are bound to fail. In other words, substituting plastics directly into traditional-material-based designs actually raises the manufacturing cost (Figure 3). This is due to the higher cost per stiffness issue discussed early. Note that this is part-for-part substitution, not new system solution thinking.

    Application Solutions
    It is clear that plastics cannot compete unless their intrinsic advantages are used to offset the stiffness disadvantage. To do this, designers need to examine the durable good product’s function and create a design solution that addresses these functional requirements without constraints on form. This change in thinking allows fabrication functional performance to exert its leverage, which can then create lower-cost products with superior performance (Figure 4).

    Reducing manufacturing cost by using materials that cost more on both a per pound and per stiffness basis is the result of creating designs as application solutions based on the advantages of plastics. The reality of this statement has been demonstrated many times over in the past 10 years.

    For example, the John Deere Stealth rear engine riding mower used engineering polymers that cost more than $2/lb. Yet the end cost of making the mower was lower than the steel version, which had been assembled at a state-of-the-art manufacturing facility. Why? Because the plastic redesign consolidated 153 pieces down to three and eliminated secondary operations.

    Using the same systems solution approach, Dodge redesigned a passive restraint instrument panel for its 1997 Dakota truck. The plastic-based design eliminated dozens of parts, reduced costs, and gave a higher structural performance in terms of femur loading during crash. In addition, the plastic IP is torsionally stiffer than its steel-based predecessor, quieter on a noise, vibration, and handling basis, and is perceived as higher quality by passengers.

    Appliance of the Future
    What could the next appliance solution look like? Let’s examine the question from the perspective of what we would like to do today that we can’t because it costs too much. For a refrigerator, that would be a large-capacity, highly energy-efficient model that takes up the same floor space as today’s lower capacity and efficiency versions. How can plastics help achieve this solution?

    High capacity equates to a small volume of insulation. Conversely, high efficiency equates to extensive insulation. To avoid the trade-off, one answer would be vacuum panels, thin but highly efficient insulators. The problem is that the cost would be high if these panels are used in today’s complicated refrigerator liner designs. If we could move to a simple liner, however, we could make use of the vacuum panels more cost-effectively. Using plastics’ advantages, we can change the liner design.

    In a typical cost breakdown for a $1000 side-by-side refrigerator, roughly 30 pieces and parts account for nearly half the cost of manufacture. Replacing these with a comprehensive molded-plastic subassembly would eliminate the need for a complex liner and give us the solution we need.

    Using plastics’ part-consolidation advantage, we can mold one module to replace many of these parts, and then use the vacuum panels in the simplified liner. Product identification would then occur at the end of the production process to allow for mixed model manufacture.

    Challenges Ahead
    A few obstacles to this vision of the future remain. One of the primary challenges is that the design cycle time for plastics-based product designs appears significantly longer than traditional-material-based designs. One answer: change the design/development process to fit the material. Replace design-build-test with do-it-right-the-first-time. Using an application solutions approach, designers can evaluate all options before selecting the best one.

    In terms of design cycles, durable goods designers typically follow a design-build-test sequence that includes many prototyping test iterations. It works well with traditional materials because prototyping is quick and low cost, with mock-ups produced in the shop with a band saw, welder, and drill press. These prototypes can be tested for functionality, kinematics, and stress-strain issues, and problems are addressed by sawing the offending design apart and rebuilding the prototype.

    Even with traditional materials, this process is less efficient on a speed-to-market basis than many realize. But the situation is exacerbated when plastics are simply substituted, because prototyping a plastic part is not quick or cheap. Prototype tooling, for example, can take 12 weeks or more to make and can cost from 30 to 80 percent as much as production tools. Moreover, when product design and engineering efforts are curtailed to fit a build schedule, insufficient testing leads to plastic parts that perform poorly. More time is wasted in corrective action, and the cost of the after-the-fact fix-up leaves everyone with a poor taste for plastics. Worse yet, the lack of engineering time results in field failures. Remember, however, that this scenario refers to simple plastic substitutions.

    How can designers execute the design-build-test process if they cannot build cheap, timely plastic prototypes? One answer: change the design/development process to fit the material. Replace design-build-test with do-it-right-the-first-time. Using an application solutions approach, designers can evaluate all options before selecting the optimum one. It may sound obvious, but it rarely happens, because one part of the solution is locked in before considering other factors. For example, if the fabrication method is assumed, that decision locks out many options.

    Keeping solutions open means evaluating concepts using sound engineering to identify fabrication and materials combinations early and often. Feasibility studies on several option combinations can often quickly target the one or two best concepts, which can then be engineered in more detail. Once this phase is complete, rapid prototyping can be used to verify functionality, kinematics, ergonomics, and customer issues. Mock-ups can suffice for focus studies and marketing efforts.

    Other engineering testing, such as stress-strain, dynamic impact, and vibration, can be prototyped virtually in the computer. Designers need adequate data on product performance specs, design, fabrication techniques, and raw material properties. While virtual testing doesn’t eliminate the need for final product testing, it does give greater confidence in the engineering phase.

    Contact information
    Dow Chemical
    Robert Cleereman
    Midland, MI
    Phone: (517) 636-5425
    Fax: (517) 636-3926
    E-mail: [email protected]

    IMM's Plant Tour: Attention to quality is rewarded

    It is a fact often overlooked in our fast-paced culture that when a company dedicates itself to producing its wares to the highest standards of quality, the logical outcome is success. GW Plastics is no exception. The custom molding company has made a habit of attending to quality, and this philosophy shows up in both its products and the bottom line.

    Founded in Bethel, VT in 1955, GW has grown by 15 to 20 percent annually since a 1983 management buyout from then-owner Sohio. In the past five years the company has doubled in size, with two plants in Vermont, one in Texas, and a fourth in Arizona.

    Precision in Bethel
    After passing through the front office spaces, visitors to the Bethel plant are first met by a 4000-sq-ft cleanroom set up with 10 presses ranging up to 85 tons. Although certified to Class 10,000, GW runs the medical molding area as a Class 100,000 cleanroom, with more stringent specs for air quality and contaminant reduction.

    Three of the machines (50-ton Van Dorns) are placed in separate workcells that each produce parts for a blood analyzing device. Ventax robots pick up four parts at a time and drop them into tubes separated by cavity. The parts are then shipped to customers in the same tubes. A 7-ton Nissei with .23-oz shot size, also located in the cleanroom, gives GW the added ability to produce micromolded parts.

    Robotics are a way of life not only in the cleanroom, but also on the general molding floor. To improve cycle time, sprue and/or part removal robots are installed on all of the 42 machines located here. Because GW focuses on high-volume, precision molding, it also uses quick-mold-change systems and an automated finished goods conveyor to expedite processing and shipping times.

    On a mezzanine separated from the molding areas all materials are dried and conveyed to molding machines via two Motan material drying and handling systems. Resins are dried in a central area, then sent by dry-air vacuum to each machine’s small Motan hopper that is fitted with an autoweigh chamber.

    One drying system supports the machines located in the general molding area and consists of 46 drying bins with capacities from 60 to 800 lb. The 10-machine medical molding cleanroom operates on a separate system that contains 10 drying bins. Both systems use closed loop reclaim of regrind. One outside silo feeds directly into the drying units, and gaylords below the mezzanine feed material up.

    Quality Built In
    All GW molding sites share integrated manufacturing and quality systems. The GW plant layout and equipment are identical at all facilities. "Although we statistically qualify all new tooling or transfer tools at our Tech Center," says Jim Symonds, director of customer service, "they must be requalified when they reach our production floor. Having a standardized approach at all facilities reduces the turnaround time required."

    Rather than waiting for quality problems to arise on the molding floor, GW begins eliminating them at the start of a project. A quality engineer is assigned to work with each project engineer and with the customer during planning, design, moldbuilding, and mold qualification stages.

    During this period specifications are developed, including functional testing, gauging systems and methods, dimensional requirements, aesthetic standards, and characteristics that will be monitored via SPC. Once the mold is built, engineers conduct a process capability study and a complete layout inspection to ensure products will meet requirements.

    Once it hits the production floor, every job has a packet that contains its quality data and samples. After process capability is proven and final approvals are received, quality assurance and manufacturing departments continue to monitor each of the SPC characteristics with various traditional control charts. In addition, GW technical staff calculate and monitor real-time Cpk values, with a company standard of 2 or greater for all jobs.

    SPC monitoring is done every four hours, and parts are checked during each shift inspection, in which up to 200 dimensions are measured. At the machine limits are set by the process capability study, and parts from any press that diverge from those limits are sent to a scrap bin via diverter chutes. "We will divert any product that is not within a 3 standard deviation limit," says Bob Carpenter, manager of quality assurance.

    GW’s goal is Six Sigma manufacturing, according to Carpenter. Currently, every process must be twice as good as it needs to be, and every department establishes a continuous improvement plan to meet short and long-term goals.

    Several other groups within GW contribute to overall quality levels. One, the engineering department, is located on the second floor of the Bethel facility. It provides design consultation services and program management for part design, prototyping, material selection, mold design, and mold construction issues.

    Nearby to the Bethel site is a 27-acre compound in Royalton, VT, where the Mold Making Div. and Technical Center are located. Both buildings were inaugurated in June 1998. Adjacent to the Tech Center is the newest plant (Plant 4), which is operated under procedures similar to an actual cleanroom.

    Royalton Resources
    With its staff of 50, the 12,000-sq-ft Mold Making Div. operates 24/7, and during half of that time machines are attended by just enough staff to make sure they keep running as they should. That’s because most of the equipment is CNC-controlled. This includes a Makino high-speed machining center outfitted with an 80-position tool changer. Machine tools are tied to Unigraphics (20 seats) and SDRC I-deas CAD/CAM systems with 3-D solid modeling and translation capabilities for IGES, DXF, and Parasolid.

    Roughly 50 percent of the tools that GW runs are built here. "We typically receive CAD data from customers via e-mail, an ftp site, or DAT tape," explains Scott Rosen, director of the division, "and most often, these are not manufacturing-ready—no draft, seals, or clearances. We work with both our engineering department and customers to create a solid model with manufacturing and moldability changes—draft, ejector pins, bosses, and other modifications aimed at bringing down cycle time. Customers then review this version prior to moldbuilding. We find that the system helps to cut down on back-end engineering changes."

    Four years ago tool designers at the division switched to 3-D solid modeling and found an exponential improvement in productivity. All EDM electrodes are now solid models, according to Rosen. "There are no pencil sketches any longer," he says. "Solid models allow us to check whether or not a tool’s dimensions are the same as the customer’s CAD file. And it is much faster to put the part geometry into the tool design and subtract the part to create the tool."

    Molds are next sent to the Tech Center to be qualified on one of three Van Dorn presses (80 to 300 tons). That means producing a robust, consistent process that will be repeatable on the shop floor. Every mold and part receives a viscosity vs. flow rate curve to determine optimum fill times. Many of the mold designs undergo moldfilling analysis as well.

    First runs are often conducted at the material manufacturer’s suggested settings, and then a window of high and low parameters is set. Taking the midrange, or nominal, set of process parameters, parts are then run for dimensional consistency. Results, charted from highs to lows, help the Tech Center zero in on the optimum process.

    Plans at the Tech Center include bringing in a 110-ton two-shot press in a joint venture with Van Dorn to prove the feasibility for production. GW recently decided to specialize in two-shot molding, and is building quality into this process as well.

    In adjacent Plant 4, two-shot applications are already under way. Currently, the shop floor houses 10 presses, but the plant was built to hold 14 machines and will probably reach that level by the end of this year, according to Symonds. Technicians run this plant using cleanroom procedures—hair nets and no floor storage. Jobs here are cross functional. Two people are responsible for materials handling, running the machine, and setting up the tools. The ultimate goal for this facility is to be a 12-hour, two-shift, lights-out operation.

    Planning Ahead
    Talking with Symonds after the tour is over, it’s clear that GW has no plans to rest on its laurels. At Plant 4, new presses continue to be added. "We may build another cleanroom as well," he says.

    As for the end markets, Symonds and other GW management believe that the health care market will grow quickly along with the automotive and consumer/industrial markets. "We’re focusing our sales and marketing efforts and production capabilities to meet this growth," adds Symonds. "As companies within these markets consolidate and reduce their supplier base, we hope to be the beneficiaries." In fact, a focus on marketing segments on the plant floor seems to make sense at GW, and Symonds foresees that this will continue.

    What about forecasts for additional facilities? "We are looking seriously at Mexico," he says. "This is where many of our customers are, and we can seed the new plant with this business."

    On the process side, GW plans to specialize in micro-, lights-out, multishot, and insert molding. It will also focus on precision gears. As expected, there will be no letting up on process control. "It is vital that we target improvements in our response time to customers," says Symonds.

    Contact information
    GW Plastics Inc.
    Bethel, VT
    Jim Symonds
    Phone: (802) 234-9941, ext. 128
    Fax: (802) 234-9940