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Industry Watch

With more than 3000 attendees including 150 U.S. customers, Arburg called its Technology Days exhibition an unqualified success. New technologies, including the company's latest Allrounder press and its new Advance line, were featured prominently.
Betting on a recovery
Taking the attitude that, slow economy or not, the show must go on, Arburg held its annual Technology Days gathering in March at the company headquarters and production site in Lossburg, Germany. Its optimism was rewarded with an attendance of more than 3000 customers, including about 150 from the U.S. Arburg spokesperson Christoph Schumacher says the company has not cancelled any new product developments despite the slowdown, and thus had new technology and applications it wanted to show. Foremost were two new machine series in the Allrounder line: the Alldrive Series modular technology systems and the Advance Series with electric drive technology (see New Products).

The heart of the event, however, was the showcase of application technology scattered around the facility. There were more than 30 machines or cells molding and producing multimaterial products, optical disks, PET bottle preforms, MIM and CIM products, thermoset parts, micro parts, LSR products, water- and gas-assist parts, products with inserts, cleanroom products, and more. A variety of presentations were held during the day, including a comprehensive overview of multimaterial mold design options given by Weber Formenbau. Herbert Kraibuehler, Arburg managing director of technology and engineering, said the good attendance at the event provides still more evidence of pent-up demand for new machine technology in many of the injection molding market segments. He said Arburg will show a 400-ton machine at its Fakuma exhibit this fall that will be the largest machine in the line, plus other new technology in anticipation of an economic recovery.




Automotive OEMs, suppliers power fuel cell advances
The internal combustion engine is a long way from being relegated to the scrap heap of automotive technologies, but a new report claims fuel cell systems are surging forward on an influx of research and development cash from automotive OEMs.

According to the report, fuel cells are slowly emerging as a viable market for suppliers and manufacturers, with fuel cell assemblies expected to reach $3 billion in factory-gate value by 2003. Car manufacturers are allotting more time and capital to the technology, and the government is prodding the industry forward in response to concerns over the environmental effects of combustion emissions, a dearth of domestic oil supplies, and petroleum's finite reserves worldwide.

In essence, the fuel cell functions as a battery, with the obvious benefit of not running down or needing recharging as long as fuel is supplied. Consisting of two electrodes surrounding an electrolyte, the fuel cell operates by having oxygen pass over one electrode and hydrogen over the other. The byproducts of the ensuing reaction are electricity, water, and heat. Potential applications include electrical generators for homes and industry, power systems for cars, and even a replacement for the conventional batteries found in devices as small as mobile phones and PDAs.

Principia Partners consulting firm has released a report entitled "Material Opportunities in Fuel Cell Technology: 2002 & Beyond" to address the current situation of the market and gauge its future prospects. The report predicts continued growth through 2010 with thermosets, thermoplastics, elastomers, and nanofibers contributing to many components. High conductivity, corrosion resistance, thermal stability, low creep, dimensional stability, and flame retardancy were targeted as essential material properties, with resins like PPS, LCP, PBT, and nylon potentially playing prominent roles.

Liquid or gaseous hydrogen has emerged as the early fuel of choice, but where it will be derived from remains uncertain. It could potentially be drawn from existing fuels such as gasoline and propane, but resource uncertainty and the lack of infrastructure for pure hydrogen production has slowed development. DaimlerChrysler has plans to deliver buses using fuel cells in 2002 but will wait on passenger cars until 2004.

Another alternative energy vehicle that's experiencing growth and increased investment is the hybrid car. Using a small internal combustion engine to generate electricity and batteries to supplement power when accelerating or climbing hills, hybrids are one alternative that have already entered the marketplace in the form of Honda's Prius and Toyota's Insight.

Hybrid designs remain the primary focus of many automakers, with most estimates putting widespread use of pure fuel cell vehicles 10 to 15 years down the road. In the interim, automotive OEMs are planning hybrids for mass consumer use. DaimlerChrysler is currently working on a hybrid SUV, the Jeep Commander 2, that's powered by a 2500-lb hybrid-electric fuel cell powertrain. The powertrain weighs 1100 lb more than a standard combustion engine, but use of lightweight molded thermoplastics in a lower-mass body brings the vehicle's total weight to just 5715 lb—slightly more than existing, full-size SUVs.




Berry weighs options, mulls selling
Completing 15 purchases since 1992, Berry Plastics (Evansville, IN) is very familiar with mergers and acquisitions as the buying agent. But in one of the moves that the company is considering to stoke its blistering growth, Berry might experience life as a seller.

Founded in 1967 and currently owned by First Atlantic Capital Ltd., J.P. Morgan Partners, and Aetna Life Insurance, the packaging molder has grown exponentially since an infusion of capital following its 1990 purchase by First Atlantic. Sales in 1990 were $57 million, but following a slew of acquisitions that began in 1992, they grew to $408 million by 2000, and most recently posted a company record of $462 million in 2001. Now, to keep up this torrid pace, Berry's CEO Ira G. Boots says the company is evaluating ways to maintain its policy of expansion.

"With the performance that we've just come off of," Boots says, "it's simply time to look at the financial package around us, and we are looking at all the alternatives. We want to continue the growth. We really want to put a larger package around us so that we can continue to be in the acquisitive mode that we've been in and actually even accelerate the growth."

Boots stresses that Berry and its ownership group are truly evaluating all available options, and there's no set timetable for action.

"All our options are open, including not doing anything," Boots says, "which would be very acceptable. [Our options] could range from a refinancing of the company to a sale of the company, and again we don't have to do anything."

Any move by Berry, which counts giants like Gillette, Procter & Gamble, and Wal-Mart among its 12,000 customers, would reverberate throughout the consumer products, caps, and closures markets. It has more than 3000 employees at 14 plants in 10 states, England, Italy, and Mexico.

"This is a very positive step in the path of Berry Plastics," Boots explains. "Due to the growth of our business, we're looking to see what alternatives will actually pave the future to allow us to continue to do the things we've done in the past."




Tool shops polled to expose American moldmakers' plight
Taking their cue from U.S. steel producers, American moldmakers are building a case for unfair foreign competition to present to the International Trade Commission (ITC). A May 21 hearing will decide if ITC action is warranted.

Spearheading one effort to form the U.S. case is mold component manufacturer D-M-E. The company has organized a survey to assess the state of domestic moldmaking and as of early April, it had received more than 600 responses.

"The purpose of the survey is to do a fact-finding mission to learn more about the issues facing moldmakers, toolmakers, and diecasters," says Bob Starr, D-M-E's marketing services manager.

Veris Consulting will compile the results and release aggregate data, keeping individual responses confidential. The survey examines sales, number of employees, dollar value of molds, and capital equipment purchases. Other questions ask moldmakers to identify two factors that have hindered their business since 1997 and to list two countries outside of NAFTA that represent the biggest threat to their business over the next three years.

To learn more about the survey and for the latest news related to the ITC hearing, visit www.moldanddiefairtrade.org.




Short shots
Hyundai Motor Co. will join Toyota, Honda, and DaimlerChrysler as another automotive OEM with facilities in Alabama. A new $1 billion assembly and manufacturing plant will employ 2000 and open in 2005 in Montgomery.

Reeling from the bankruptcy of its largest customer Kmart, StyleMaster Inc. (Chicago) has declared bankruptcy itself and in April, as IMM went to press, was scheduled for auction.

ASK Plastics (Philadelphia, PA) completed the acquisition of Jamison Plastic (Allentown, PA). The company says the new facility will become its primary assembly and supply-chain management plant.

The Materials Analyst, Part 52: Where does the moisture go? (Part 2)

This series of articles is designed to help molders understand how a few analytical tools can help diagnose a part failure. 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 15-plus years.
Editor's note: This month's Materials Analyst is the second part in a series on measuring moisture content in resin. In the June issue of IMM we will publish a rebuttal to some of the arguments stipulated by Michael Sepe regarding the accuracy and effectiveness of loss-in-weight moisture analyzers.

In our last article, we began a discussion of the effects of moisture on polymers during melt processing and outlined the importance of being able to accurately measure the moisture content of a material. We also began to deal with the different approaches to moisture measurement on the market and the importance of method development in arriving at the correct value when a moisture test is performed. In this segment, we will discuss in greater detail the different methods of measurement that are available to molders and point out the advantages and pitfalls that come with each of them. Once we have established a scientific method of measuring moisture content, we can then start the discussion of where the moisture goes as the pellets travel through the molding process.

Moisture-specific Analysis
As we mentioned in our last article, the methods for measuring moisture that are recognized by ASTM all involve a chemical reaction that ensures that the only thing being measured is water. Most of these methods utilize a method known as Karl Fischer titration. This sounds intimidating, but an adaptation of the instrument that allows moisture to be extracted from the plastic in a remote location, combined with the wonders of the microprocessor, has turned this into a very manageable technique.

The method that is most commonly used conveys volatiles from a heated sample of polymer into a chemical solution. The water produces a chemical reaction that changes the electrical conductivity of the solution and an electrode records this change and converts it into a calculation of collected moisture.

The benefit of chemical techniques such as Karl Fischer is that they are moisture specific. A number of chemicals may be swept out of the heated pellets, but ideally the only substance that registers in the test is water. As we mentioned last time, method development is important.

First, it is essential that the polymer sample not degrade during the test. Some degradation byproducts can react with the chemicals in the titration vessel to produce water or create chemicals that interfere with accurate moisture measurement. PET polyester is one that was mentioned in the last article; acetals can pose the same problem. PPO materials have been known to give impossibly high moisture content values when run at elevated temperatures in air. Materials that contain halogenated flame-retardant additives will also pose problems. The best way to extend the acceptable range of test temperatures is to run the tests in a relatively inert atmosphere such as nitrogen or argon. Any instrument that does not permit the use of an oxygen-free gas stream is suspect.

A second problem, and one that the use of an inert atmosphere will not prevent, is a phenomenon known as solid-state polymerization. This problem is particularly common in nylon materials. When a material like nylon 6/6 is synthesized, the reaction is known as a condensation reaction and water is produced as a byproduct. This water is removed from the system during synthesis and finishing.

However, if the polymer is heated to very high temperatures,
a small amount of additional polymerization may occur, particularly in materials that are very dry. This reaction can occur at temperatures where the material has not melted, hence the name solid-state polymerization, or solid phasing. If this occurs, new water will be created and it will register in the moisture content test as though it were part of the original sample.

ASTM D 789, which deals primarily with nylon materials, shows a method development curve where the measured moisture content rises with increasing temperature, levels off into a plateau, and then rises again. This second rise may be due to either degradation or solid-state polymerization. In nylons, it is usually the latter, and it is therefore important to keep the measurement temperature in the plateau region.

Shop-floor Ingenuity
While methods like Karl Fischer are recognized techniques, moisture measurement takes many forms on the shop floor. The most rudimentary method involves either examining parts for cosmetic signs of moisture like splay and silver streaking or purging a shot into the air and looking for bubbles and froth in the air shot. Many molders who actually invest in a moisture measuring instrument are surprised to find that only about half of the cosmetic problems that appear to be caused by excess moisture actually involve wet materials. Worse yet, some materials like PET polyester give no cosmetic clues that they are being processed with excess moisture.

A small step up from the purge-and-look technique is the glass slide and hot plate method. This involves heating a glass slide on a hot plate on which several pellets of material have been placed. Once the pellets have softened, a second slide is placed on top of the pellets and they are pressed into a thin film. The cooled press-out is then examined for bubbles. This method gained considerable credibility in the 1960s when it was dubbed by one material supplier as the Tomasetti Volatile Indicator (TVI) test. Who is going to argue with that? This test actually worked fairly well for many unfilled materials, particularly PPO-based alloys. It was far less successful for filled systems in which air can become trapped between the polymer and the filler and produce bubbles. The test did what it was advertised to do—it detected volatiles, including but not limited to water. And it was most certainly not quantitative.

Measuring More Than Water
Given this level of sophistication, it is understandable that most molders who take the time to monitor moisture use a loss-in-weight system and consider it a huge leap forward. But these systems have two problems. One is that most of them run the test in ambient air. The second problem is that they assume that all the mass lost during the test is due to water. Unfortunately, a lot of other substances such as lubricants, other additives, and residual monomers can also be driven off, and there is no way to distinguish between the various substances in the weight loss fraction. This is particularly true if the test is run at a temperature high enough to remove all of the water. If loss-in-weight moisture tests are run at an appropriate temperature, they will almost always produce a result that is higher than the actual moisture content.

This leaves builders and users of loss-in-weight systems with a difficult situation. Even dry material tests as though it were wet. You may have noticed that as the loss-in-weight system manufacturers have become more sophisticated, they have begun to check their instruments against—you guessed it—Karl Fischer. Manufacturers of loss-in-weight systems even publish lists of moisture measurements made using their system and the Karl Fischer system in an effort to show how well their instruments work.

But there is a problem. At a given test temperature, a Karl Fischer test and a loss-in-weight system will produce similar reductions in sample mass. But assuming that no polymer degradation has occurred, the Karl Fischer system will only count that part of the weight loss that is water, while the loss-in-weight system counts everything. To get the loss-in-weight system to provide the correct values, the test temperature is reduced until the answer agrees with the Karl Fischer determination. It is important to understand that by reducing the test temperature we have not ensured a moisture-specific measurement; we have simply reduced the sum total of all the collected gases so that it agrees with the actual moisture content measured by the chemical technique. This can be made to work, but it is an exercise that must be conducted one grade of material at a time and a Karl Fischer technique or an equivalent must be available to provide the final word on measurement accuracy.

Litmus Tests for Analyzers
There are some litmus tests that should be run on an instrument to check its method of operation. First, as we noted, the temperature region where the moisture measurements for a given material are not influenced by temperature is typically 20 to 30C. A measurement system that truly removes all of the moisture in the material will produce a sample at the end of the test that has been completely dried, as long as an actual collection rate endpoint is used to stop the test. If you want to check a moisture measurement system's principle of operation, run a moisture test at the desired temperature and make sure that the endpoint of the test is triggered by a collection rate of zero rather than an extrapolated endpoint based on the first few minutes of the test. Allow the sample to cool and then run the test again using a test temperature 10 to 15 deg C higher than that used in the first test. If the first test has really removed all of the water, then the result of the second test should be zero. Loss-in-weight systems that run at an inappropriately low temperature in order to suppress excess weight loss will not meet this criterion, particularly if the tests are run in air.

Second, most moisture measurement devices, regardless of their fundamentals, can use the microprocessor to predict the outcome of the test based on the first few minutes of the actual test. This is designed to save time, but it is possible to select conditions for the extrapolation that can introduce error. If you plan to use the "predict" function instead of the "actual" measurement, be sure that the two methods give the same answer.

Third, allowable moisture content parameters provided by material suppliers are usually given in terms of percent moisture. Many of the more sensitive materials have upper moisture content limits in the hundredths of a percent. If the system you are evaluating measures in percent, be sure it has a working third decimal place. Instruments that go directly from .02 percent to .03 percent give a result of .02 percent for materials that contain up to .025 percent moisture. For some materials like PET polyester and polyurethane, this is already high enough to cause problems. If your system measures in parts per million, make sure that it provides a significant figure in at least the "tens" column so that it can distinguish between 210 and 220 ppm (.021 percent and .022 percent).

Don't Get Too Simple
Finally, the results coming from the instruments should be reasonably repeatable, and they must agree with the reality of the process. The repeatability aspect need not be at the analytical laboratory level. For processors, the moisture measurement is designed to distinguish between wet and dry material. While .012 percent to .016 percent may represent a 33 percent variation, the conclusion is the same. But an instrument that reads .02 percent one time and then .06 percent the next is of
no use in plastics processing. If a material checks in the moisture analyzer as dry, and repeated attempts to process encounter obvious signs of wet material, there may be a problem with the instrument. Many times processors are baffled by obvious problems with processing because they have a moisture monitor that tells them the material is dry, and they believe it unwaveringly.

Einstein said that things should be made as simple as possible and no simpler. He could have been talking about moisture analysis in the plastics industry. The reality is that the loss-in-weight techniques that many processors have adopted were developed for industries in which the accuracy of the measurement is acceptable in terms of tenths of a percent such as the food or textile industry. For materials where the difference between 180 ppm and 240 ppm is the difference between good parts and bad parts, and where a host of other substances can be driven off during the test, they may be simply inadequate.

Accurate Solutions
There are two alternatives. One is the chemical approach. A lot of processors are hesitant to work with an instrument that looks like a piece of laboratory apparatus. There is glassware, tubing, and chemicals. But once these instruments are set up and the methods are developed, they are surprisingly user friendly and the annual operating costs can be less than $1000 even for an instrument that sees frequent use.

If these types of instruments still look too scary, the other option is a system with a moisture-specific sensor. These instruments drive off volatiles just like any other system, but they monitor the gas stream and recognize only the water. These systems are more hardened for the production floor, but in order to be accurate, they must still be kept in a controlled atmosphere. They can also be influenced by changes in humidity and temperature, just as a Karl Fischer system will. The moisture-specific systems eliminate the chemicals, but they may have other disposables that actually cost more. And in the final analysis, these instruments still must give results that match those of the time-honored chemical methods.

In the end, an inaccurate instrument is almost worse than no instrument. Processors who don't check the material for moisture at least know that they don't know. But those with substandard instruments believe that they know, write procedures around the use of the instrument, and might still make bad parts. So if it's worth the time and money to do these measurements—and it certainly is—then it pays to use an instrument based on sound scientific principles. These are the principles we will use next time to track our moisture as it travels with our pellets through the molding process.

Contact information
Dickten & Masch Mfg. Co.
Nashotah, WI
Mike Sepe
(262) 369-5555, ext. 572
www.dicktenplastics.com
[email protected]

Moldmakers fight back against nonpayment

The number one complaint from moldmakers is their inability to get paid in a timely manner or, in some cases, at all. Custom molders are the primary offenders, and often are more problematic than working directly with OEMs. In today's economic climate, this problem is approaching epidemic proportions.

Stiffing moldmakers for monies owed on molds is so common because it's generally known that this group of tradespeople have little legal recourse and shallow pockets when it comes to being able to collect. There are very few mold shops that haven't suffered severe losses caused by defaulting molders at one time or another.

Mark Krajniak closed his company, Hale Molds Inc. (Rochester Hills, MI), early last year after being unable to collect much of $1.6 million in receivables from various customers. "Tier One suppliers that we dealt with were taking six months to [sample and approve] a mold, continually missing dates, which kept delaying payment," Krajniak says. Others don't ever pay their toolmakers, he adds. "In reality, the moldmaker is the last to get paid."

So what can moldmakers do to prevent or at least react to this problem? At the moment, not much. But a new law recently passed in Michigan could be the first step toward the creation of a new, more even playing field for moldmakers across the country.

Leveling the Playing Field
On Feb. 28, a new mold lien statute was signed into law in Michigan that allows mold shops to attach a lien on a mold even if the moldbuilder is not in physical possession of the mold (see "Amended Mold Lien Law Passed in Michigan," April 2002 IMM, p. 12). This is a critical component of the new law, which was sponsored by the American Mold Builders Assn.'s three Michigan chapters and Public Affairs Assoc. Inc. in Lansing.

Although most states have a mold lien law created by the SPI, Michigan moldmakers discovered that possession of the mold was the key element in enforcing a lien and receiving payment. Consequently, these laws favor molders over moldmakers, allowing molders to retain the mold in cases of nonpayment of molded parts, but not allowing moldmakers any claim to the mold in cases of nonpayment of the tool or tool components.

Michigan's new mold lien law, however, specifically allows moldmakers to take possession of the mold. After giving written notification of nonpayment and the amount owed, if the moldmaker does not receive payment within 90 days, it then has the right to take possession of the mold, die, or form "without judicial process if this can be done without breach of the peace."

In Need of Protection
Allowing a company that hasn't been paid for a mold to repossess that mold is a major step for Michigan toolmakers looking for leverage. In fact, Michigan's mold lien law could offer a template to moldmakers and AMBA chapters in other states that want to launch a bill to gain more legal recourse in cases of nonpayment.

Such legislation would certainly help toolmakers such as Carson Tool & Mold (Asheboro, NC), Accuchrome Tool & Mold (Asheboro, NC), and Iowa Mold & Engineering Inc. (Belle Plaine, IA), all of which are currently in disputes over nonpayment with now-defunct Complex Tooling & Molding Inc.

Complex Tooling & Molding's North Carolina molding facility owes Carson Tool & Mold $113,000, and Accuchrome Tool & Mold $116,000. Although OEM Sanford Pen says it paid Complex for the molds, Complex reportedly did not pay either moldmaking company.

To complicate the situation, Complex then sold its Asheboro, NC plant to an investment company, Bridge East Capital LLC (Boston, MA), which renamed the facility Carolina Precision Plastics. Chris Crockett, vp of Bridge East, claims his company purchased the assets of the facility only, not the debts. However, he said in a telephone interview that Bridge East made "good faith payments to a couple of moldmakers we feel are important to our business, and since they're not going to get paid by Complex, we wanted to pay on that liability to develop the relationship."

The molds were sold as assets of Complex, despite the fact that they are the property of Sanford Pen, explains Accuchrome's Jim Sides, who recently filed suit against both Complex and Carolina Precision Plastics in Randolph County. Sides says Complex has not responded to the filing and Carolina Precision Plastics has made two offers to settle, "but not enough to satisfy me," says Sides.

Brad Cook of Iowa Mold & Engineering Inc. (Belle Plaine, IA) has had his problems with Complex as well. Cook built molds for Complex's Boulder, CO facility. Even after Cook had the molds sampled and received first article approval to validate the tooling, Complex refused to pay for the molds, saying the molds wouldn't run right. Cook hired an attorney and on Oct. 16, 2001, he got a default judgement against Complex for $159,000 and obtained writs of garnishment against the company's receivables.

Cook says he agreed to allow Bank One, the primary creditor of Complex, to proceed with an auction the week of March 11 if Bank One would agree to several stipulations, including one that says it won't challenge any garnishments. Money from the auction goes into a trust account. A final court ruling on March 19 decreed that Iowa Mold should be paid before other accounts receivable.

Some mold shop owners who deal with molding companies go around the molder to the OEM when experiencing payment problems. "We've done that in a few cases," says Cook, "and it seems to work when the customer puts pressure on the molder." Perhaps the pressure needed, however, is the kind that comes backed by legislation.

For complete text of the Michigan mold lien law or for more information, contact Jeanette Bradley, executive director, American Mold Builders Assn., (630) 980-7667, [email protected].

How about repairs and tool changes?

What about nonpayment for mold repairs and requested engineering changes performed by moldmakers? Companies like Kno-Mar Mold (Clearwater, FL), which says it's owed nearly $30,000 by large, publicly held custom molder Alltrista Corp., can also benefit from legislation like Michigan's mold lien law, which allows the moldmaker to repossess the mold until paid for these repairs or tooling changes.

Kno-Mar's invoice in question involves work done for Alltrista's subsidiary, Unimark Plastics (Greer, SC), on a three-plate stack mold that required a major engineering change. Kno-Mar sent a truck to pick up the tool at Unimark's plant in Greer. The ECO was quite extensive and reportedly required several moldmakers to work on the project throughout the weekend so that Unimark could get the mold back into the press on Monday.

At the time of pickup Kno-Mar says it questioned Unimark's molding engineer about a PO for the job. Kno-Mar was assured that the engineer's word was good and that the company would be paid for the work. "We had no reason at the time to doubt him," says a spokesman for Kno-Mar.

The bill for the work came to $48,000. Unimark paid $25,000, but has since refused to pay the remaining balance. When questioned about this Unimark's engineer reportedly told the moldmaker that the ECO should not have been necessary and should have been covered in the original design. Kno-Mar argues that it was an ECO and that it created a change in the function of the tool. Unimark has since directed Kno-Mar to contact Alltrista's legal department concerning any nonpayment complaints in this specific case.

Kno-Mar says Unimark also owes the company $5500 on another mold in which it was asked to move the gate. After the gate was moved, Kno-Mar claims that Unimark said the moldmaker should have known the gate belonged there in the first place, and refused to pay the bill.

In response, Kno-Mar showed Unimark the original print for the tool on which Unimark's engineer signed off on the gate location. Still, Unimark continues to refuse payment. Bruce E. Whelchel, division controller for Unimark, gave this comment: "In instances where there is clear nonperformance we withhold payment."

Putting a new spin on toothbrush design

In the $1.2 billion toothbrush industry, these battery-operated brushes (above and left) with two spinning heads and eye-catching designs are part of a growing segment of innovative products that both kids and parents like. For designers at Zooth and TriMax, these brushes offer a good example of collaboration. The project went from concept to production in less than six months.
Parents have long struggled with the morning and night "brush your teeth" routine. On the one hand, most children eventually learn to put the paste on the brush and drag it across their teeth. Proper brushing, however, is another matter entirely.

A recent wave of affordable, motorized spin brushes attempts to help in this regard, but these models offer only one spinning brush head. A major toothbrush OEM, Zooth, is now bringing a dual-spinning-head product to market that should cover even the slowest of brushers. The method by which this innovation came to market illustrates why collaboration between design and manufacture is becoming essential to new product success.

Tight Timeline
Believe it or not, the $1.2 billion toothbrush industry plays in one of the most competitive of consumer markets. While a toothbrush isn't a one-use product, it is purchased once every few months. If you've taken a stroll down the toothbrush aisle lately, you've also noticed how many choices are now available. High volumes and multiple competitors make this a market ripe for product differentiation and innovation.

Zooth Inc., a privately held OEM based in Wichita Falls, TX, made a name for itself by working effectively with licensors such as Disney, Mattel, and Hanna Barbera to make manual children's toothbrushes with molded likenesses of cartoon characters. In fact, it is ranked No. 2 in the U.S. in the children's toothbrush category.

Early in 2001, the company made a decision to expand its business
significantly with the development of a line of unique motorized toothbrushes. Zooth marketers began working with TriMax, the product design and development division of resin distributor Prime Alliance, to determine what kind of product they should take to market. Several focus group sessions attended by Zooth and TriMax designers identified strong and weak points of current motorized toothbrushes.

According to TriMax Principal Rob Banning, Zooth developed an aggressive timetable for bringing the new spin brush to market. "We began in late August 2001 with a concept and by January 2002, we were debugging and preparing production volumes," he says. "This timeline could not have been a reality unless all parties involved worked collaboratively and simultaneously. This project involved a true teamwork approach with a dynamite team. For me, it is a blueprint for reducing product development time and managing a project effectively."

Team Effort
Exactly who were the players in this exemplary project? First came Zooth, of course, an OEM supplier to the Wal-Marts of the world. Then came the North American vendor team, consisting of TriMax and two contract manufacturers to build the brushes—Tecco and Fortune Electronics. Finally, an Asian team headed by TriMax Asia General Manager Caudio Chu cut every injection mold from prototyping to production for 29 separate parts in nine weeks.

"This was a military-style attack on tooling," explains Banning. Often the team worked around the clock, with the North American tool designers taking the first "shift," sending designs to Asia, and then letting the Asian team cut tools on the second "shift," he adds. The motto was to make every 24 hours count—to accomplish something specific and tangible every 24 hours.

To coordinate between industrial design, mechanical engineering, prototype design and tooling, tool design, and electrical engineering, the team used ftp sites to exchange files and information. Primarily, part design was done with SolidWorks, with tool design completed using Unigraphics.

Global Resin Supply
In addition to the technical and manufacturing challenges, the Zooth toothbrush program also faced certain material sourcing issues. Since the toothbrushes would be molded in China, Zooth needed a seamless, global approach to material selection and sourcing from its resin distributor Prime Alliance.

"This project really epitomizes what our Total Solutions Provider strategy is all about," says Tom Irvine, Prime Alliance president and ceo. "We were involved from beginning to end and even coordinated the supply of BASF resin in China."

According to Irvine, the global nature of the plastics industry now affects everyone, even plastics distributors. In the past, most plastics distributors in the U.S. were regionally or nationally focused. By taking a global approach, Irvine's group can coordinate product development and material sourcing on a global basis to help its customers get to market faster and with fewer headaches.

Scooby Doo, Anyone?
The new Zooth brushes will hit retail shelves this quarter at a price
between $5 and $9. Keep an eye out for three initial products: Scooby Doo, Barbie, and Hot Wheels. Consumer studies have shown that these brushes should have a major appeal among children. Beyond that, the two spinning heads are not found in any other commercial toothbrush.

Banning and the North American vendor team also did some serious design work to come up with a soft-grip feature where the character is located. "We use a soft PVC overmolded onto ABS, and getting the soft material into the character area was a major achievement. We've actually applied for a design patent," says Banning. "In the end, though, this product's strong point is that it is fun for kids and has functional benefits."

Contact information
TriMax-St. Louis
St. Louis, MO
Rob Banning
(636) 458-0003
www.trimaxllc.com
www.primealliance.com

Injection molding aluminum

Figure 1. Advanced Materials Technologies of Singapore has developed a process for the high-volume powder injection molding of complex, tight-tolerance parts in aluminum. Here, an aluminum sample (left) is compared to one molded of stainless steel.
In early March 2002, a custom molder successfully demonstrated the powder injection molding (PIM) of aluminum. Part densities exceeded 95 percent. The molder, Advanced Materials Technologies (AMT, Singapore), has filed a trademark for its proprietary aluminum metal injection molding (MIM) process as "aluMIM." Company sources say they hope to start commercial production by early next year.

Aluminum and its alloys are widely used in a number of markets, including automotive, electronics, and aerospace. Its excellent thermal conductivity and strength-to-weight properties make it the material of choice for many applications.

But conventional methods of manufacturing aluminum parts like casting and pressing leave a lot to be desired, according to AMT officials, especially when it comes to part mechanical properties and design freedom. They believe that their aluMIM process will bring to aluminum the same cost-effective benefits that PIM has brought to a number of other popularly used metals and ceramics.

AMT specializes in MIM and ceramic injection molding (CIM) and has been a pioneer in expanding the horizons of the PIM process for more than a decade. For example, just last year reports surfaced that AMT had molded a consolidated magnetic, nonmagnetic metal part on a twin-barreled Arburg press (see "A Multimetal Molding Machine," April 2001 IMMC, p. 25). Mass-producing aluMIM parts of consistent quality is its latest frontier.

Chained Reaction
Lye King Tan, AMT's senior technology manager, says aluminum's temperamental and volatile nature poses a number of challenges. "Finding suppliers of aluminum powders is not an issue. However, the reactive nature of aluminum is. We must address the issue of creating a controlled environment for working with this material."

Tan says special handling procedures are being fine tuned to prevent the possibility of aluminum being exposed to air. "We make our own proprietary binder system and coat the powders."

Tan also says no special materials of construction are required either for injection units or molds. "Feedstock preparation requires some attention. Sintering may be even more important. Once our coatings have been removed in the debinding process special attention has to be paid to controlling our sintering furnaces. This is where much of our proprietary technology comes into play."

An immediate target market in AMT's sights is in heat sinks. "Because of the grain structure of the aluminum powders we use, aluMIM heat sinks will function much more effectively than those that are diecast," Tan explains. "We also have a better ability to make tight-tolerance parts. Additionally, there is less flash and far fewer secondaries are involved, so manufacturing costs are reduced. I believe aluMIM will be very competitive, especially when it comes to producing complex parts."

Contact information
Advanced Materials Technologies Pte.
Singapore
C.K. Tan
+65 6567 7223
www.amt-mat.com

Pricing games: Building a winning hand

In the January 2002 issue of IMM (pp. 29-30) there was an excellent article on reverse auctions. This is one of several games buyers are playing with molders to squeeze down pricing.

The essence of this game is the "there are a dozen molders like you" scenario. Everyone is chatting up the win-win thing. But look at the matrix (Table 1): If you only look at winning and losing, your odds of success are 25 percent, which is not very good.

Remember, winning is perceived. In molding this means you ship parts and get paid. The buyer gets parts and makes salable product. While your goals are different, the perception of winning is mutual for everyone in the transaction. Losing, however, is measurable: You lose profits or the buyer doesn't get acceptable parts. Few people remember good outcomes but they always remember losing.

Now let's expand the matrix (Table 2). What if you had two more options? You could neither win nor lose but simply maintain the status quo, or you could not play and neither win nor lose. The odds of a successful outcome double. So much for game theory.

The problem with most molders is that they
are afraid of their customers. As a consultant, I've listened to the whining about mandatory price reductions, auctions, and everything else done to a molder. Even with the whining, the molder usually caves in, thinking that keeping the business is better than losing it. It's kind of like the schoolyard bully stealing your sandwich and then telling you what he wants for tomorrow's lunch. Didn't you stop playing that game in grade school?

Think for a minute: Is it better to have a job that loses money or machine capacity you can fill with a job that makes money? Enough said.

Assessing Your Gamesmanship
Most buyer games are really comprised of bluffing. Most molders fold because of the bluff. However, it is easy to call the bluff and either stay in the game or get out before you lose. So how do we do it? First dispel the myth. If there were a dozen other molders like you out there, your customer probably would have picked someone else! Second, somewhere you have a competitive advantage that made you the vendor for the job. You need to communicate to the buyer why it needs you (and not the reverse). Here are a few metrics you should consider first when assessing your strengths:
  • Technology. Not all molders need new machines, robots, vision systems, automatic packaging systems, and so forth. These are nice things to have, but they are also expensive. If you specialize in ultrahigh-volume runs with precision in an industry sector like medical, such equipment is the ante for playing the game. But, if you are making consumer products such as washing machine tubs, it's the size of your equipment that is the key determining factor. Your technology must fit your product line. Nobody is a custom molder. Everybody specializes. You only need to understand what you do well and sell that concept. To that end, your client base should match your expertise, not the other way around.   
  • Quality. I don't know of a buyer who doesn't want high Cps and CpKs. They want to order 10,000 parts and have them all defect free. This only happens if the part design and the quality expectations are reasonable. Only in the highly regulated industry sectors are "parts to print" the determining factor. Parts that work are really all anyone wants. This is a tough battle to win, but it is a reality that needs to be explained and reinforced to your client.   
  • Delivery. In all the measures of success of a customer-supplier relationship, delivery is the primary metric. It is an interesting exercise to point out to your buyer his need to pay for expedited freight and overtime costs when he absolutely has to have it. He'll also accept parts slightly not to print or even stall an engineering change so long as you keep shipping. His esteem for you goes up when he pushes back a delivery with you only doing a little complaining. This esteem really goes up when he is caught short, you whine about schedule bumping, and then ask for a premium (for your overtime costs) to run his rush job when you are actually shipping out of your secret just-in-time warehouse.   
  • Price. In the buyer's perfect world, you'd buy resin for $3.00/lb and sell parts for $3.01/lb. This myth is both silly and foolish. While scrap reduction is the highest source of improved profit to the molder, any time a buyer pays for anything additional to keep his production lines supplied he has just admitted price is not a determining factor.

Improving Your Odds
Now let's improve your odds of not being in the losing column. We'll use reverse auctions as an example. Sometimes you'll get a package with a whole stack of parts and prints with a letter that asks you to quote everything and telling you the job will be placed as a bundle. Bundling is a common technique now and is a thinly veiled way to trim the vendor list.

You have two options:
  1. Call the buyer and inform him that you want a purchase order for 1.5 hours per part multiplied by your engineering hourly rate ($150/hr). Bundling and auctions almost always mean you aren't bidding against two or three companies but against 10 or 20. If you are going to waste the time bidding, get paid for it. If the buyer won't pay, don't bid. You probably won't get the job anyway.   
  2. Sometimes (as a surprise) you'll see your own parts in the mix to bid. Here you can play hardball or softball.
  • Hardball. If you are already on the low end of your profit expectation, the buyer is really telling you he wants to pull the job. Remember, no matter what he says, he isn't offering you more business. Quietly call him and mention you don't take kindly to threats. If he wants to pull the job, you'll close all existing orders, stop molding, and await his decision on who the new molder will be.   
  • Softball. This is a modified version of hardball. Call the buyer before telling him/her you'll stop producing and ask if anyone else who is bidding has a performance record like yours in delivery and quality. If he says he's just benchmarking you to keep you honest, get indignant. You don't need a customer like this! (It's like asking your spouse if he/she was faithful to you today.) If he says everything you are doing is OK, tell him you will decline to bid and wish him well if he finds someone else who can keep his production lines up as well as you do. Try to communicate that consistent supply is better than low price. Let the buyer make the choice and then hope he can swallow (or choke on) it.

Choosing Not to Play
Threatening is really what auctions, vendor consolidation programs, and price reduction programs are all about. When molders are threatened they tend to panic. This "new" way of doing business is completely different from what they expected. While an effective purchasing technique, the only response to it is to threaten back. Never threaten directly; threaten implicitly. Point out some natural consequences to the buyer's actions. If he has threatened one job and you have others, bundle back: If you are going to be nailed on one project he can have all his jobs sent back when you lose one.

There is a word of caution here: While business
should never be based on threats and punishments, this is reality. Therefore, never bluff. If you make a threat, carry it through. If you can't, don't bluff in the first place.

Playing hardball or softball is an effective tool. Keep in the front of any discussions that the best sales tool isn't price, it's delivery performance—parts of sufficient quality, delivered consistently on time. The most profitable molders are the ones who get rid of feisty buyers/clients, turn down jobs they are not suited for, and don't take bundled jobs, but have a consistent reputation for quality and delivery. The guys who are currently going out of business play these price reduction games with their clients.

Greed is another problem. Too many molders look at a new job and only see the dollar sales. If the quote asks for pricing from lots of 5000 to 1 million pieces, two things will happen. First, the buyer will ask for the 1 million part price but order in lots of 5000. Second, the forecast is usually a pipe dream. A quote with this much of a spread is asking you to commit to capacity but not to sales. With times as they are you cannot reserve capacity for orders that don't materialize.

If you find out one of your clients is doing auctions, get rid of that customer. Just because you haven't been asked to bid doesn't mean your parts aren't being cross-quoted. If you mold the parts, you know all the problems. The other guys don't. If they pull the job, just ship the mold. Don't offer any help. If asked, sell your time for $1000/hr with a prepaid PO when the other molder is in trouble.

Remember how long it took to get the job qualified? Have you used a special hot tip, modified the venting, or put runner dams in the mold to balance the fill? This took time. Your buyer doesn't have time. If he threatens to pull the job if you don't drop the price, threaten back. Tell him you can have the job on his shipping dock tomorrow if he has the check. He'll have to scramble to find another qualified source, especially if you remove your special vents and tips and ship the mold as originally manufactured.

If you feel a buyer is trampling you, don't complain to him or go home and sniffle. Go up the food chain. Upper management never wants to hear about their supply lines being threatened. They'd rather pay a little more for the insurance of a continued supply of parts than the cost of lost production because of the lack of components. Besides, finding a new buyer is usually easier than finding a new supplier, and it's cheaper, too. Get a reputation for not being kicked around but also for playing fair, and your sales and profits will actually improve. Good luck.

Consultant Bill Tobin of WJT Assoc. is a regular contributor to IMM.

Contact information
WJT Assoc., Louisville, CO
(303) 604-9592
[email protected]

New tooling takes a beating, transfers heating

This mold has no cooling on the A side because the three-action movement makes it virtually impossible to incorporate pipe cooling into all of the moving steel. It was quoted at $15,240 to install cooling and improve the surface with CMT. Projected savings were calculated to be $10,900/month based on expected cycle reduction.
Composite Metal Tooling (CMT) is designed to do for a mold what no single material of construction can do. It features a core of a proprietary metal called Heat Transfer Metal (HTM), which reportedly is easily machined or formed to a desired shape, and combines it with salt bath heat treating of a through-hardened steel. The result is a tough, hard, and slick mold with a high degree of thermal conductivity, which speeds cycles and improves the consistency of either thermoset or thermoplastic molded parts.

The CMT approach also can be used to make screw and barrel assemblies. An agreement has been reached with New Castle Industries (New Castle, PA) to begin the development of this application. In addition, HTM can be used in channels where a mold's heat transfer medium flows—it is not subject to calcium plateout or oxidation—or anywhere optimum heat control is a must.

"When we consider that molds are nothing but high-pressure heat exchangers, we understand that materials other than tool steel would be able to provide better heat transfer, but for the problems of strength and wear," says Randy Lewis, president of P.R. Lewis (Dorado, Puerto Rico) and the inventor of the CMT process. "The molding industry has come to accept very poor heat transfer as the price for tool life."

"Basically," he continues, "this new composite method can through-harden an H-13 or S-7 cavity to 50 to 52 Rockwell C and passes the cavity through a heat treatment process that takes the surface hardness to 72 Rockwell C up to .020 inch deep. All the steel in the cavity not needed for strength is removed and is replaced with HTM, which improves heat transfer characteristics by two to five times."

Balanced Heat Flow
Lewis says his HTM mystery metal functions very much like a heat pipe. Both are not in direct contact with the melt and both are encased in steel. However, unlike heat pipes, he says HTM never needs replacing if the mold is accidentally overheated. Also, HTM can easily be machined or bent to fit intricate shapes. Heat pipes cannot.

He stresses that HTM is not meant to replace heat pipes. Heat pipes move more heat over a longer distance, but he says HTM can reduce the amount of steel through which the heat has to be moved.

"The ultimate goal in using HTM is not just to move heat faster, but to balance the heat flow in the mold so that cooling or heating is not limited by the properties of solid steel. Removing portions of the tool steel and replacing it with HTM can accomplish this."

Though easily shaped, HTM is strong enough to support 44 percent of what H-13 tool steel will bear. If, for example, 44 percent of the steel mass of a mold is replaced with HTM, Lewis says that the CMT mold will be just as thermally conductive as one made completely from beryllium copper. HTM has a coefficient of thermal conductivity that is reportedly more than nine times that of steel and twice that of aluminum.

Bathing In Salt
Various hardening methods were considered to increase the wear resistance and service life of the tooling, while reducing the coefficient of friction where the plastic contacts steel. Lewis chose through hardening with surface hardening. He says surface hardening steel that is not through hardened only increases the hardness of the steel by a few thousandths of an inch. Below this, the metal is at its original state.

"Conventional surface hardening leaves an extremely hard but brittle area in contact with the plastic," he says. If the mold is struck hard enough to dent the soft base steel, the hardened layer cracks and chips off. However, through hardening imparts hardening properties all the way through the mass of certain types of steel. Though Lewis admits that it can't achieve as great a hardening of the steel surface as surface hardening, it is not subject to surface chipping.

Through-hardened steel is often plated to achieve a desired surface hardness. But plating—hard chrome plating, for instance—is subject to chipping and other maintenance troubles as well. That's why Lewis says he opted for salt bath surface heat treatment. In this process, through-hardened steel is placed in a heated vat of salt under vacuum and the temperature is raised. The steel's surface is molecularly altered to a depth of .020 inch. There is nothing to chip off, as it is a part of the steel.

Worth Its Wait
Salt bathing raises surface hardness by 10 Rockwell C and increases the toughness of the base metal. Surfaces also become more slippery—more so than hard chrome—for easier mold release. And Lewis says they are more chemically resistant than stainless steel surfaces. HTM can be placed below the .020-inch hardened surface.

The cost of using CMT during initial construction or retrofitting depends on its application. But Lewis contends that the price is small when compared to the increased profitability generated by more thermally efficient manufacturing.

"In many cases, just the reduction in heat-up time can pay for the additional cost," he says.

Lewis has been issued a provisional patent on a method for using CMT to increase the heat transfer in tools for plastics. He also has entered into an agreement with Versatile Mold & Design Inc. (Rutledge, GA, www.versatilemd.com) for CMT's use in injection and compression mold cavities.

Contact information
P.R. Lewis, Dorado, Puerto Rico
Randy Lewis
(787) 270-4418
[email protected]

WEB EXCLUSIVE:Let's just call it AIM—Assisted Injection Molding

Measuring 78 by 36 inches, this gas-assist molded Volvo truck bunkboard supports the sleeper compartment's mattress. Gas assist helped consolidate various functional design components, resulting in a 20 percent part cost reduction vs. its pressed wood counterpart. It was designed by Richard Langhoff of Volvo and produced by Mack Molding Co. (headquartered in Arlington, VT).
As part of his presentation at Molding 2002 (March 4-6, New Orleans, LA), Terry C. Pearson, chairman of the recently consolidated Cinpres Gas Injection Ltd. (CGI, Cheshire, U.K. and Ann Arbor, MI) called on the molding community to consolidate its abbreviations. Whether molders are using gas assist, water assist, supercritical fluid assist, or combinations of these and more, he says that in spite of their differences they share a common bond. They all involve add-on systems to assist in improving processing and part designs. So, he asks, why not let them share a common name, namely, AIM (assisted injection molding)?

Time will tell whether or not Pearson's suggestion is adopted. Actually, the main topic of his presentation was the latest technological development in gas assist from CGI called the Plastic Expulsion Process, which we'll discuss later. In fact, there was a lot of other AIM news at this annual conference.

Jack Avery, manager of operational assets at GE Plastics (Pittsfield, MA), led the talks with his annual overview of the latest AIM trends. Avery says gas assist is no longer news. It has matured to the point where the technology itself is routinely being applied in product designs for most major markets, including appliance, building and construction, IT, materials handling, medical, sports and recreation, and transportation. Growth in the use of gas assist also has matured.

Citing published statistics, Avery says 48 percent of the largest 100 U.S. molders (in terms of sales) use gas assist to the greatest extent. On the whole, use of gas assist has remained unchanged for the past two years—about 14 percent of survey respondents, says Avery. The most active users are still automotive molders.

Supply-side News
On the business front, Avery says the biggest thing to happen last year was in July when BI Group Plc, the parent company of Cinpres, purchased Gas Injection Ltd. (www.gasinjection.com). "This is the first consolidation in the industry," says Avery, "and is a departure from what has been more typical—legal battles over patent infringement."

He doesn't think it will be the last. "In the current economic environment and with a larger number of suppliers of gas-assist injection molding technology vying for a limited amount of business, I will not be surprised if additional consolidation/contraction occurs."

At K 2001 Engel demonstrated its Watermelt water-assist system in molding this curved automotive coolant tube. There were three water injectors (WI): one at the mold gate (G) and two at the inlets of the two secondary overflow cavities (SC1 and SC2). Water assist reduced cycle time to 35 seconds.
OD: 25 mm
Wall thickness: 3-4 mm
Material: 30% glass-filled nylon 6/6


In fact, there was a change of hats at the conference. Factor Maschinen & Anlagentechnik GmbH (Hainburg, Germany), a European equipment supplier and sales rep, represented Gas Injection Ltd. at K 2001. Andreas Janisch, engineering and sales director for Factor, announced at Molding 2002 that it now represents Gain Technologies (Sterling Heights, MI, www.gaintechnologies.com).

Avery is upbeat about the M&A activities of AIM suppliers. He says, "The good news is that more energy and resources are being focused on technology, supporting customers, and developing new business, rather than on legal hassles."

Cool Technology
Rui Magalhaes, research fellow at the University of Warwick's Warwick Mfg. Group (WMG, Coventry, U.K.), discussed the results to date of a five-year research project. WMG wanted to determine whether cooling the gas prior to injecting it could further reduce cycle times vs. standard gas assist. It apparently does—by 40 to 60 percent, according to Magalhaes. WMG has trademarked its technology KoolGas.

KoolGas systems control the injection of cryogenically cooled nitrogen gas at temperatures from 0 to -196C. Electronic flow control of the super-cooled gas enhances heat transfer at the gas channel interface, resulting in faster cycles. The heart of the system is a proprietary cryogenic heat exchange unit installed inline with the gas injection system, downstream of the pressure regulation module, and as close as possible to the gas injection nozzle.

It does more than speed things up. Studies reportedly show that KoolGas allows the molding of parts with thinner walls. Tests also show that KoolGassed parts have gas channels with smoother bores throughout the gas channel than those molded with conventional gas assist. This can be a key point to consider when designing parts such as fluid conduits.

Magalhaes says the University has assigned its KoolGas intellectual property rights to a spin-off company, which will commercialize the process.

Control Over Overflow
As mentioned above, CGI's Pearson discussed his company's
Plastic Expulsion Process (PEP) in New Orleans this year. PEP provides a way to accurately control the amount of plastic injected into each cavity through the use of shutoff valves.

In one version, PEP 1 (see drawing, below), following the initial pressurization of the melt, a shutoff valve in each runner that connects the part cavity to a secondary overflow cavity is opened. The amount of material flowing to the secondary cavity is controlled both by the fixed volume of this secondary cavity and by the timing of the shutoff valves. The initial timing of gas injection is inconsequential to the volume of material expelled into the secondary cavity. A multicavity mold will use as many shutoffs and secondary cavities as are necessary.

In CGI's PEP 2 process an injection nozzle shutoff valve is used. Rather than expelling material into a secondary cavity, it is forced back into the injection cylinder by pushing back the injection screw against a controllable backpressure.

Pearson says both methods offer a number of benefits over conventional overflow techniques, including the elimination of hesitation marks and the elimination of the recovery and regrind of expelled material. CGI can provide all the necessary valves and controllers. Licensing will involve a one-time fee, he says, and will be competitively priced.

The amount of plastic expelled is controlled by the fixed volume of the secondary overflow cavity(ies) and by the timing of a shutoff valve in CGI's PEP 1 process. Part surface quality is improved, and since the initial timing of gas injection has no effect on the volume of plastic expelled, cycle times and part weight can be reduced through more gas core-out. Also, gate locations are less critical.
Water, Water Everywhere
The levee broke this year in New Orleans when it came to reports on water assist, adding to the flood of developmental activity that was so much in evidence for anyone wading through K 2001. GEP's Avery says that, since water is incompressible, when it is injected into the melt, a higher pressure can be generated than with gas. Water also has a greater heat exchange capacity than gas, and parts are cooled inside and out.

So larger, thick-walled parts—components with 1- to 3-inch-diameter channels and greater—can be molded in relatively fast cycles. Cycle time reductions of up to 75 percent have been achieved, according to Avery.

And, of equal importance in many applications, water improves the centricity and smooths the bore of the channel, reducing distortions, say, in an automotive intake manifold or cooling water pipes. Water also is easier to control than gas, while providing the part surface quality benefits of gas assist without the cost of nitrogen.

Avery cited a number of companies that have been very involved in developing water AIM, including Alliance Gas Systems (Chesterfield Twp., MI, www.gasassist.com), IKV (Aachen, Germany, www.rwth-aachen.de/ikv/), and Factor Gmbh. Battenfeld (Aquamold, www.battenfeld.com), Engel (Watermelt, www.engel.at), and Ferromatik Milacron Europe/North America (Aquapress, www.ferromatik.com) also are actively involved. Some even propose using water and gas injection combined. Most were at Molding 2002 and included mention of their water-assist systems in their presentations.

Ready to Take the Plunge?
Hermann Plank, managing director of Ferromatik Milacron Europe/North America, says that despite the commercialization of water-AIM systems, the technology is still in the red and has limited possibilities today that must be assessed on a case-by-case basis.

Plank, Factor's Janisch, GEP's Avery, and other speakers repeatedly stressed the fact that switching over from gas assist to water assist is anything but a drop-in process change. It's just too different. Specially designed injectors are required. Injectors designed for gas injection are not suitable for water. Injector sealoff is critical, as is sequence timing.

Then there's resin compatibility—will water assist work with resins like nylons, polycarbonates, and polyesters? Is there enough application-specific know-how around? And then there's the big question: What do you do with the water?

"Leakage is not a problem with gas-assist molding. With water, it's different," says Factor's Janisch. He says this is especially true when running water through a part in a water-cooled mold on an all-electric machine.

Other AIM News
Avery noted a few other intriguing developments in AIM.
For example, researchers at the University of Bradford in the U.K. are fine-tuning 3-D FEA and moldfilling analysis for gas assist. He also cited four University papers presented at the SPE's Antec 2001 in Dallas, TX that covered a wide range of topics—everything from optimizing processing conditions to the effect of liquid cooling of gas channels.

He also noted that IKV researchers have been applying gas-assist technology to PIM. In Aachen, gas assist has been found to reduce debinding time in large PIM parts with thick wall sections.

Editor's note: The complete Molding 2002 proceedings can be purchased from the conference's organizer, Executive Conference Management Inc. of Plymouth, MI, (734) 737-0507, www.executive-conference.com.



Water dissipates more heat than gas, so a high-viscosity membrane forms over the flow face, as in this Aquapress water-assist system from Ferromatik Milacron Europe/North America. The membrane has a greater displacement potential than gas, so more melt is moved in the direction of flow. Less is moved to the outer layer. Therefore, the remaining wall thickness is reduced and cavity centricity is improved.
The plastic expelled back into the injection cylinder in CGI's PEP 2 process can immediately be remolded in succeeding shots, with no recovery and regrinding. No trimming of the expelled plastic is required, and the cost of expulsion shutoff outlet valves is eliminated.

Analysis allows for perfect parts from day one

Figure 1. An ABS wheel cap for the GMC Tracker in its short-shot (left) and chrome-plated (right) stages. Filling analysis helped molder Hunjan Molded Products achieve zero scrap rates from the start of production.
Still not sold on the fact that moldfilling analysis works? Check out the following field report before you choose your final answer. Tom Peeler, Design Center manager at PolyOne Distribution, shares one of his recent projects with IMM to illustrate how tricky design problems can be solved via the virtual prototyping of moldfilling analysis.

Case Specifics
The subject of the field report was filling analysis of a wheel center cap for the GMC Tracker (Figure 1). The part is molded by Hunjan Molded Products (Waterloo) Ltd. (Waterloo, ON) for CAMI Automotive Inc. (Ingersoll, ON). The objective of the analysis was to determine if filling problems would occur in the cap using the side gate location. Designers were concerned about trapped air or a severe weldline opposite the gate. Additional objectives of the analysis were to minimize part stress to help achieve acceptable plating, to check gate orifice diameter and gate tab thickness, eliminate downtime, and to produce a part with no runout (see sidebar, below). The material to be used was Dow Magnum 3490 ABS. Molding conditions for part production include a melt temperature of 465F, a mold temperature of 150F, and a first-stage injection time of 1.5 seconds.

Runout defined

When a part is said to have no runout, what exactly does this mean? Peeler's answer: When looking at a part print at a certain view—let's say a side view of the wheel cap—there could be a datum line running along the straight (flat) edge of the cap from which all the dimensions in this view are referenced. The total deviation from this datum line in the molded part is the runout. In other words, the part has to be flat (no warpage) when laid on a flat surface; otherwise, it would cause the assembly to rattle and possibly come apart at the wheel's higher rotation levels. No runout (no warpage) is sometimes difficult when gating on the side of a part that ideally should be gated in the center.

Analysis Results
The analysis, performed with Moldflow Plastics Insight (MPI), showed that the material flows over the top of the cap sufficiently so that any trapped air is pushed to the vents at the parting line. This matched well with the actual short shots (Figure 2).

Designers selected various fill times and melt temperatures until the lowest stresses were achieved both near the gate and at the end of fill. Due to the low shear stress in actual molding, the parts plated well with no visual defects.

PolyOne also performed an iteration with a tab thickness of .080 inch, up from .060 inch, to see if any reduction in stress would result in the part. The software indicated no reduction in stress in the part itself, only in the tab. Therefore, the .060-inch tab thickness was deemed satisfactory and was used for moldbuilding. Also, with stress restricted to the tab and minimized in the part, optimum chrome plating could be ensured.

The only places that were slightly above the recommended shear stress were areas where the tab meets the part and at the end of fill. These were the lowest values that could be achieved in the analysis with this geometry, and they proved to be low enough to provide good plating (Figure 3).

The shear rate of 13,000 sec-1 in the .090-inch-diameter subgate was less than the recommended maximum value for this material; consequently, no excessive shearing occurred (see Figure 4).

Conclusion
Due to the OEM constraints on the start of production, Hunjan did not have time to make a prototype, nor did it have room for error. The company pays for every part it sends to the chrome plater, even if the part is subsequently scrapped.

Fortunately, as a result of the analysis, virtually no scrap was made. The chrome plater needed parts with extremely low stress, and proof of that came from virtually flawless plated parts. The plater also needed to rack (grab) the parts for plating, something that the tab provided. Confirmation from the filling analysis that gating into the tab would work gave the plater time to develop the rack during the toolbuilding stage.

The parts are high tolerance and almost no runout is allowed. This was a concern using the proposed side gate location, as the part could distort. Hunjan and CAMI needed a high degree of confidence that the parts would be flat and that no retooling would be required. In fact, the parts turned out to be extremely flat.

Figure 2 (upper left). At a simulated 95 percent fill, the Moldflow MPI results mirrored actual short shots.
Figure 3 (lower right). A shear stress simulation shows that stress is relatively constant and low across the entire part, an important parameter for successful chrome plating.


Figure 4. Shear rate simulation shows values less than the maximum for this material, predicting that there will be no excessive shearing in the part.


Contact information
PolyOne Distribution,
  Design Center
Suwanee, GA
Tom Peeler; (678) 546-6867
www.polyone.com
[email protected]

Parting Shots: Building plastic's future one Lego at a time

Benjamin Ciummo (left) and Thomas Gerhardt proudly display their handiwork from the NPCM's National Engineers Week program. Using one of the NPCM's computers, they were able to program their Lego Mindstorm kit.
Long seen as a catalyst for children's creative energies, officials at the National Plastics Center & Museum (NPCM), Leominster, MA, hope Lego toys and robot systems can ignite a lifelong passion in kids, prompting careers in engineering and design with plastics. "The aim of our robotics program was to help young people make two discoveries of importance to the future of the plastics industry and manufacturing in general," says Anne-Marie Arnold, the museum's education director. "The kids who took part learned that engineering can be a challenging and satisfying career and that plastics are essential materials of design." These lessons were learned at the NPCM's program for National Engineers Week. Drawing 315 students from sixth through 10th grade, the NPCM had participants construct robots and program their movements using Lego's Mindstorm robotics systems. Working collaboratively in teams of twos and threes, the children picked a design for their robot, specified a range of movements over set dimensions, and allowed the self-directed robots to complete their given tasks. For NPCM President David P. Hahn, the investment of time and money in the museum's outreach program should pay handsome dividends for the plastics industry in the future. "By helping young people discover the promise of engineering as a career," Hahn explains, "we are contributing to the future of the plastics industry."

From the American Northeast to the southern tip of Singapore, Lego toys' reach and capacity for invention extend to all corners of the globe. At the Mt. Faber cable car station in this south Asia city resides a full-size, functional Lego cable car. Proclaimed as the world's only Lego cable car, it is no doubt the byproduct of adults who never outgrew their childhood affinity for the small, molded building blocks.


Submissions to Parting Shots are welcome. If you have a favorite sign, saying, quote, or part that is used in this section, we'll send you a check for $25. For our What Is It? series, be sure to identify the part, material, manufacturer, and function. We're also looking for stories about molding ingenuity. Send your submission ideas to Amie Chitwood, managing editor, fax (303) 321-3552, or e-mail [email protected]