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Articles from 2002 In September


A quick guide to candidate components for PIM production

Editor’s note: A recognized expert in powder injection molding (PIM), Randall German is Brush Chair professor in materials at Penn State University. This column is part of an occasional series on understanding and applying PIM.

Figure 1. A simple decision tree suggests how to perform a first screening of candidate components with respect to matches with powder injection molding.
How do you know a good candidate for powder injection molding? It is a waste of resources to investigate poor candidates, so a quick means to screen components for early identification of successes is valuable.

As a first pass, consider the schematic decision tree shown in Figure 1. One thing to consider is the annual production quantity. Powder injection molding has historically best matched with industrial needs at production quantities from 5000 to 100 million parts/year. These parts range from specialty firearm sights to cellular telephone vibrator weights. If the target production rates are in that range, then it is appropriate to continue with consideration of PIM.

The next factor relates to the engineering specification. Powder injection molding works best where there are at least 10 specifications (dimensions, locations, surface finish, and such) on the engineering drawing or definition. But the process struggles when the complexity and constrictions exceed more than 100 callouts. Further, it struggles when tolerances become too tight (±.1 percent) on more than a few dimensions. Components are in production by PIM outside this window, but they are the exceptions. For example, one crash avoidance sensor mount for luxury automobiles is in production using PIM with 130 dimensional specifications. In other cases, critical dimensions are machined after sintering.

Figure 2. A Venn diagram suggests some of the current justifications for PIM based on high production quantities, high performance, and shape complexity, with various PIM products shown in each of the intersections with these three concerns. Cemented carbide sandblast nozzles and water jet cutting nozzles or other wear-resistant, complex shapes are an idealized convergence of these three concerns.
Next is consideration of the materials. It is most important that the material is available as a small powder, and that the powder is easily sintered. Many, but not all, of the common engineering materials are available as small powders, but the powders are more expensive than bulk materials. Since the small powders used in PIM are expensive, good candidates for powder injection molding have high component manufacturing costs when compared to the material cost. A survey across the industry shows that up to 40 percent of the manufacturing cost is powder.

If a small powder is available (diameter smaller than 20 µm), then sintering becomes the next concern. In many cases, small powders can be sinter densified without extraordinary processing cycles, but many require compositional shifts for easier sintering. For ceramics, this usually means small concentrations of additives to enhance sintering. A common example is the addition of .1 percent magnesia (MgO) to alumina (Al2O3).

For metals, sinterability usually means the powders have low contents of ingredients that prove reactive, especially the strong oxide formers, reactive metals, volatile elements, and toxic materials. This usually means PIM compositions avoid beryllium (toxic and easily oxidized), mercury (toxic and volatile), lead (toxic and volatile), manganese (strong oxide former and both the metal and oxide are volatile), zinc (volatile), sodium (reactive), magnesium (reactive and strong oxide former), aluminum (strong oxide former), tantalum (reactive), diamond (unstable during sintering), oxides of metals such as indium and tin (unstable during sintering), and titanium (reactive and strong oxide former).

This is not to say these are impossible to process by PIM, since several have been processed successfully. But the problems that arise with these ingredients are usually best avoided by using more inert compositions.

Another problem is with lower-melting-temperature materials, where other technologies are very effective. Generally, materials that melt at temperatures greater than 1000C (1832F) are more successful by PIM. One reason for this is that lower-melting materials prove easier to process using diecasting, machining, or other fabrication routes where there is adequate tooling for low-temperature forming. But as the melting temperature increases, then problems with technologies geared to lower-temperature materials increase, creating more interest in PIM. Consequently, even though PIM aluminum (melting temperature of 660C or 1220F) and other lower-melting-temperature alloys such as brass have been demonstrated, they still are not commercially successful.

Figure 3. Machining is relatively inexpensive for rough surfaces and setup dominates cost, while for smooth surfaces cost is dominated by the machining time. For PIM to compete against machining, it is important to seek smooth surfaces and situations in which there is considerable mass removal needed to generate the final shape.
The Cost Factor
If all of these simple tests are passed, then probably the component is a candidate for PIM, except for one final barrier: How much does it cost? In simple terms, the application dictates how much can be paid for a component. It is widely recognized that consumer products tend to migrate toward the low cost of plastics. Conversely, PIM is a favorite for higher-performance metallic and ceramic products used in medical or dental devices, defense and aerospace systems, sporting goods, appliance and industrial components, hand tools, business machines, watches, sensors, cutting tools, automotive engines, electronic packaging, or marine equipment.

These applications share similar requirements: good performance (as measured by resistance to high service stresses); resistance to wear, corrosion, and high temperatures; good thermal and electrical conductivity; high density; or excellent magnetic response.

Although these criteria might seem constrictive, PIM has succeeded in thousands of applications. As indicated in Figure 2, success comes from the coincidental concerns over shape complexity, production quantities, and performance. To help realize the applications, this Venn diagram indicates some PIM applications that intersect with each of these areas. In addition, surface finish and final properties are often cited as reasons for using PIM. Hard materials prove difficult and expensive to grind or machine, so applications that require materials with poor machinability or applications that require difficult-to-machine geometries are better candidates for PIM.

Surface Finish
Other factors that impact the identification of good candidates include tolerances and surface finish. For rough surfaces, the machining cost is dominated by setup, but for smooth surfaces machining costs associated with the longer time of machining dominate, as illustrated in Figure 3. Thus, from the perspective of machinability, the following attributes provide an incentive to use PIM:

  • Designs that require hard materials.   
  • Designs that seek good, but not polished, surface finishes.   
  • Materials that resist machining.   
  • Mixed-phase microstructures.   
  • Component designs that hinder coolant access during machining.   
  • Component designs that would require considerable mass removal in machining.

    Today, most common engineering materials are available via PIM. Although a wide range of materials can be processed, in the end a few dominate the field because of widespread use and low raw material cost:

  • Ferrous alloys (steel, stainless steel, and tool steel).   
  • Oxide ceramics (silica, alumina-based ceramics, zirconia).

    For these materials, there is an ample supply of powders, the powder cost is relatively low, and sintering is well established.

    Contact information
    Center for Innovative Sintered
      Products, Penn State University
    University Park, PA
    Randall M. German
    (814) 863-8025; [email protected]

  • This molder speaks the language of medicine

    It looks and smells like an OEM shop, but it’s not. This molder has put product design, FEMA, prototyping, mold design, molding, assembly, and packaging services under one roof.

    Wilden worked with Roche Diagnostics to make its new Softclix blood monitoring device more compact and easier to use. The number, complexity, and precision of the parts show the expertise required in design
    and manufacturing.

    Within the walls of Wilden Medical Plastics Systems in Pfreimd, Germany, you find what appears to be a modern medical and pharmaceutical systems company—an OEM. All the required disciplines are there: product concept and design, development, testing, GMP conformance, cleanroom manufacturing, assembly, packaging, and above all, market knowledge and expertise. Appearances in this case are deceiving, but only a little.

    Wilden is not a medical/pharmaceutical OEM. It is the successful and growing production partner of many of the largest and best-known OEMs in the field—AstraZeneca, Boehringer Ingelheim, Roche Diagnostics, Becton Dickinson, and Novartis, to name a few. The visible investments combined with the group’s medical/pharmaceutical expertise have earned it this position, but there is something more making Wilden a formidable player in medical/pharmaceutical. (For a report on Wilden’s cleanroom operations, see “The Ideal Cleanroom: Build It and They Will Come,” March 2001 IMM, pp. 106-110.)

    In addition to making the Softclix device used by diabetics for blood monitoring, Wilden also makes the disposable lancets that pierce the skin and collect the tiny sample.
    Synergizing Plastics, Medical, and More
    Wilden Medical Systems is part of Wilden AG (Regensburg, Germany), which, with its 2001 turnover of 190 million euros ($186.5 million), is one of the largest plastics molders in Europe. More than 1000 employees work in 11 plants and
    subsidiaries in Germany, Switzerland, the Czech Republic, Sweden, Italy, and the U.S. The medical/pharmaceutical market is not the company’s only specialty, though it is a major one. Of Wilden’s 323,000 sq ft of production space, 91,500 sq ft is in cleanrooms ranging from Class 100,000 to Class 10,000. Class 100 sterile production using laminar flow tents is also available.

    Wilden’s other markets include automotive, communication and information technology, and electronics. Far from diluting Wilden’s medical/pharmaceutical effort, this broad base provides a palette of resources that are consciously synergized, most notably by means of Wilden’s Technical Center.

    In addition to design, engineering, and processing expertise, the Center constantly updates a comprehensive technical database that serves all groups in the company including Medical Systems, naturally. Another estimable resource for Wilden’s Medical Systems unit is a subsidiary moldmaking and automation systems company in Wackersdorf, Germany, which serves the needs of both in-house and external customers.

    Wilden's product development program is based on many years of experience with a wide variety of medical and pharmaceutical projects. True to its role as working partner, Wilden lets clients customize the steps based on their own capabilities.

    Wilden thus is able to offer the medical market its overall strength in plastics molding, virtually all of which is highly technical, integrated with its broad expertise in medical and pharmaceutical technology. It is that expertise, and in particular its all-inclusiveness, that causes Wilden Medical to resemble an OEM—and this is no coincidence. The company’s strategy is based on a knowledge of the entire medical process chain, to the patient using the device. Only then can it be a full production partner for its customers from product idea through distribution. A couple of recently introduced products illustrate how that competence is used.

    Wilden has more than 90,000 sq ft of working cleanrooms from Class 100,000 to Class 10,000. Sterile Class 100 production under laminar flow 
    tents is also available.
    The First Refillable Powder Inhaler
    Wilden’s discussion of the Novolizer powder inhaler it makes for Viatris (formerly Sofotec) does not begin with materials, molds, processes, or even product design. It starts by pointing out that an asthma attack can be life-threatening, and the person suffering the attack can be highly stressed. Therefore, the solution must be reflexively easy to use, as well as provide the exact dose needed. The Viatris Novolizer, which was the first refillable powder inhaler on the market, is designed to do just that. It is a completely mechanical device that consists of 14 molded plastic parts and three steel springs. The cartridge for the active ingredients consists of three parts. Wilden was involved in the design and conception of the Novolizer and cartridge virtually from the start.

    To avoid errors in use, the Novolizer has two signals—one visual and one audible. When the release button is pressed, the drug is dispensed, and the color in the transparent window goes from red to green. If the powder is inhaled correctly, a click is heard, and the window again shows red. If the inhalation is not correct, further dosage is blocked to prevent an overdose. An integrated counter shows both the previous and remaining doses as a control.

    Wilden spent a great deal of effort in materials selection and performs extensive receiving inspections on everything, including the purchased springs. Documentation of this and every phase of production is extremely detailed. Recyclate is never used. The components of the critical dosage mechanism are molded of PBT and POM.

    The molds for the Softclix components were designed and built by Wilden's moldmaking and automation systems subsidiary in Wackersdorf, Germany, as were the automated assembly systems.
    The drug powder’s tendency toward “bridging” makes it difficult to proportion precisely, so several mechanical processes are used to ensure exact dosing. A slide on the underside of the cartridge transports the exact quantity into the cyclone chamber, while a striker released by the dosing button counteracts the bridging. A lever then positions the powder for application and, together with the respiratory flow of the user, triggers the release by a valve flap.

    The 14 molded parts of the Novolizer are made in a Class 100,000 cleanroom and are assembled manually, along with the three purchased springs. Every inhaler is 100 percent performance tested. The cartridge components—lid, body, and proportioning slide—are molded in ABS and assembled in a Class 10,000 cleanroom.

    Wilden has an in-house pharmaceutical laboratory and is licensed to produce powder mixtures and to do filling and packaging. Although in this case the client performs those operations, the lab is another investment that lets Wilden differentiate itself from other injection molders.

    Simulation software, including Moldflow, was used to detect critical issues in advance for the Softclix lancing device and to optimize the
    multicavity mold design.
    Take Something Good, Make it Better
    Wilden’s objective with Softclix, a lancing device for blood glucose monitoring by diabetics from Roche Diagnostics, was to transport the excellent performance characteristics of a previous system into a design that was smaller and easier to operate. As Wilden points out, monitoring blood glucose several times a day is tiresome for diabetics. New analysis methods have minimized the amount of blood needed, but until needle-free measuring becomes reality, it is still necessary to lance a fingertip or ear lobe. The right system can at least make this necessity virtually painless.

    A particular requirement for this project was to bring it to market as soon as possible. Wilden made extensive use of Moldflow and other simulation software to save time. Once the concept was defined, 3-D CAD was used to develop the necessary components. Prototypes, another Wilden in-house service, followed quickly and subsequently became the basis for the production molds. Wilden now produces two versions of the Softclix, one for home use and the other for medical professionals; it also makes the disposable lancets used in each test.

    Perhaps the most critical role in making the lancing device uncomplicated and as painless as possible is played by the actuating sleeve that creates a gentle skin penetration. Wilden’s designers say this sleeve transmits the torque of a tension spring in an axial movement—the lancing movement.

    The entire energy of the spring acts on an integral clip that is the release element for the lancing process. Pressing the release button is what triggers the lancing movement, but while the device is under tension, the spring’s energy has to be absorbed by the clip of the actuating sleeve. To ensure the precise functioning of the actuating sleeve, it was necessary to build a prototype mold and thoroughly test the parts. Only after thorough modification was it possible to release that part to production.

    These are but a few examples of the many Wilden medical products being made or under development. Customer focus breeds success, and Wilden has gone beyond mere focus to become a part of the medical industry; in fact, its highly experienced engineering and product development group is full of medical specialists. When Burkhard Stolz, Wilden’s head of engineering, says, “We speak the language of our customers,” he is referring not to German or English but to medical-ese. In Wilden’s case, there is no foreign accent.

    The overall 60-station assembly system built by Wilden and used by Dade Behring in Marburg, Germany to assemble critical blood platelet measuring cells used by doctors to determine bleed time.
    Medical automation to go
    One of Wilden’s main assets in the medical market is its moldmaking and automation subsidiary located in Wackersdorf, Germany. However, its products are not always used in Wilden’s medical production plants in Pfreimd, Germany and Zug, Switzerland. A good example is the extensive automation system that Wilden created for Dade Behring of Deerfield, IL—60 stations covering 55 sq m (600 sq ft). Currently operating in Dade Behring’s Marburg, Germany plant, this fully automatic system produces blood platelet cells used in the often-critical process of measuring bleed time.

    These special measuring cells enable doctors to simulate a blood vessel injury and determine the bleed time critical to beginning the correct treatment. The cells are very small, and their design dictates stringent assembly requirements under cleanroom conditions. In the Wilden-built system, the three components of each 5g measuring cell are assembled and furnished with various reagents.

    Visual inspection systems are used at virtually every stage of this assembly, such as this one checking that the specified one microliter of reagent has been added to the cell.
    Central to the cell is a fiber membrane into which a 150-µm-diameter hole is punched, and the diameter verified by a camera equipped with a microscope lens. The membrane is transferred with vacuum assistance to the floor of the cup and ultrasonically welded in place. Weld quality is camera checked before a microdosing pump applies 1 µl of reagent onto the fiber. The dosing is then camera checked, and the parts go to a drying line.

    When the fluid has penetrated the fiber membrane, it turns gray, which is controlled by a color sensor. If no change took place, the cell is sorted out as a reject. At the next station, a second fluid is applied, and the 1 µl volume is verified again. Following a reaction period, the cell blank is dried for about 30 minutes at a precise temperature and air velocity. Reagents are kept cooled to 4C in tanks containing a magnetic stirrer that prevents sedimentation of the molecule chain in the suspension.

    Since the hole punched in this fiber web must measure precisely 150 micrometers, it is verified by a camera fitted with a microscope lens.
    A conveyor takes the cups to an assembly station where a capillary is ultrasonically welded in place. A camera system checks for correct positioning of the capillary needles. A gripper then inserts each cup with its capillary into a molded plastic housing and presses it into a holding device. The housings are sealed by a bottom sheet previously verified leakproof, and the assemblies are again sensor-checked. The housing is sealed by aluminum foil, batch numbered, and taken from the system. Stored data documents every phase of the assembly, and batch numbers permit tracing an individual cell at any time.

    Contact information
    Wilden AG, Regensburg, Germany
    Karin Strasser; +49 (941) 7058 140
    www.wilden.com
    [email protected]

    Colors, screws, and changes


    The 1000 or so standardized colors used by Silhouette in making eyeglass frames are cataloged in sliding wall racks. Besides reducing color change times, Engel’s Marathon screws reduce the risk of nonhomogenous distribution of mica- and aluminum-based special-effect pigments.
    Sometimes new products do not follow the exact route envisioned by their creators. Users of the product often surprise the maker. Though this could be a problem, that is certainly not the case with Engel’s Marathon Screw.

    IMM remembers the introduction of the Marathon screw line in 2000 when Engel stressed the longer service life to be expected with these carbide-coated screws. Other benefits of the Marathon screws mentioned at the time included plasticating capacity 5 to 8 percent greater than hardened steel screws, reduced torque requirements for plastication, the ability to reduce melt temperature by about 5 deg C, and a narrowing of the residence time profile. These benefits were mostly attributed to a more slippery surface, which provides a low level of friction resistance as the material moves through the barrel.

    One of the other benefits of this new screw design was faster color changeover times, which stood to reason if the material slid through faster. As those who frequently change color know, it involves a lot more than flipping a switch, especially in terms of time. If the Marathon screw could indeed save color change time, it would be a real benefit to those companies that make many and/or frequent color changes. A couple of Engel’s customers in Austria who fit that description put it to the test.

    Quality Up, Time Down
    Eyeglass frame manufacturer Silhouette has a product range broad enough to call for molding 25 different materials, mostly varieties of nylon, in about 1000 colors. The coloring primarily is done via powder masterbatches. Because of the variety of colors and the widely varying and ever-shifting demands of the fashion market, the company normally deals with batch sizes of 50 pieces and sometimes fewer. One of Silhouette’s production units, comprising nine molding machines, performs an average of 20 color changes per shift. That means about 60 color changes in 24 hours, not to mention two or three changes of material.

    The screw in back is an Engel Marathon model after the carbide coating has been applied by a flame-spraying process. The screw in the front is also a Marathon, which, after finishing, looks much like a standard hardened metal unit.
    Silhouette started testing the Marathon screw on one of those machines using a 25-mm unit. Because the initial results after three months were so positive, the company then equipped all nine machines with Marathon screws ranging from 18 to 25 mm. After nine months of use on all of the machines, Silhouette was saving about 30 percent on both time and material for each color change, or the capacity equivalent of an additional 2.7 injection machines.

    In addition to the time savings, Silhouette found that the screws helped with quality when using the mica- and aluminum-based pigments that create special effects in the company’s sunglasses. Prolonged residence time raises the risk of nonhomogenous mixing of the pigment particles. The Marathon screw reduced that risk notably, which cut the need for costly visual control and allowed for a higher degree of process automation.

    Manufacturing Uptime
    Trodat is the Austrian market leader in rubber stamp and marking systems. Processing mainly ABS, PS, POM, and TPE, the company has to cope with about 2500 color changes annually on its 45 injection molding machines. The reason here, too, is small batch sizes. Trodat made a systematic study of the material feeding systems and all the individual components involved in the plastication process.

    Peter Baldinger (left), development manager for plasticating units at Engel and Karl Ebenberger, works manager of Trodat, are shown next to some of the latter's many stamping products. Changing screw type and some other processing parameters helped reduce color change time by 30 percent.
    After a series of tests, the company determined the optimum combination of screw profile, mixing torpedo, and shutoff system. Plastication components such as the cylinder flange and the nozzle were redesigned to improve melt flow, in addition to switching to the Marathon screws. The result is that Trodat dropped its average color change time from 40 to 25 minutes. Multiply the 15-minute time savings by the 2500 color changes, and that means Trodat now enjoys an additional 625 hours of uptime per year.

    Engel is currently making Marathon screws in diameters up to 105 mm, although its Steyr, Austria facility has the machinery to make screws as large as 170 mm in diameter and 5m long. More than 1000 Marathon screws are already in use and Engel says they can be used on any injection machine.

    Contact information
    Engel, Guelph, ON; (519) 836-0220
    www.engelmachinery.com

    IMM Plant Tour: Molding above and beyond

    Believe it or not, all of these parts were injection molded at EnviroTech Molded Products. A modified two-stage injection process called bulk injection molding makes it possible to routinely produce parts with 5-inch-thick walls that weigh up to 400 lb.
    Perhaps you think you’ve seen or heard it all in the IM industry . . . until you happen upon a custom molder producing parts considered impossible for this process. Would you believe a part with walls 5 inches thick weighing 400 lb could emerge from an injection molding press? At EnviroTech Molded Products, these are among the kinds of parts they make. Every day.

    Of course, to radically diverge from accepted guidelines, adjustments must be made to the molding machine. EnviroTech, a privately held company, devised a way to modify existing molding equipment and processes using a custom-designed accumulator that stores the huge amounts of melted resin needed for each shot. According to Forrest Day, director of technology and product development, the two-stage process uses an extruder to fill the accumulator and a company-designed injection unit to fill the mold.

    Called bulk injection molding, the proprietary process was invented in 1963 by Steve Davis, a member of EnviroTech’s earliest incarnation as an operating unit of Eimco Corp. At the time, Davis was looking for a way to make large, heavy-wall (150-lb, 1-inch-thick) parts for big rotary drum vacuum filters for the chemical processing industry. After seeing the bulk IM process succeed, the group spun  off from Eimco as a stand-alone company. It is now the world leader in large, heavy-wall IM parts, and was recently acquired by the Klinkau Group (Germany), a global supplier of molded filter plates.

    An interrupted thread design on this valve cover improves safety for the chemical processing industry and was designed by EnviroTech.
    Living Large
    In going where most molders have never gone before, EnviroTech works with a unique set of challenges. Its products compete not only with metal castings, but also with plastics machined or fabricated from sheet stock. Cycle times are longer than conventional injection molding processes (the company declines to say how long), and mold temperature and process control are critical to success.

    On the flip side, molding large, thick parts does have its benefits. Because of the thickness, polymer chains have a greater freedom and, thus, a more random orientation. This, in turn, provides more uniform material properties throughout. Low injection pressures (about 10,000 psi) contribute to lower molded-in stress and greater dimensional stability. Controlled and continuous packing phases ensure that voids, sinks, and porosity are eliminated or reduced to specified levels.

    Bulk IM accommodates parts up to 400 lb with wall sections up to 5 inches thick on a routine basis. “Resin suppliers tell us we can’t do the things we’re doing,” says Day, “but we consistently prove them wrong. We’ve made wall sections up to 13 inches thick, but only on special occasions.”

    EnviroTech helps its customers design every part for moldability and strength. Pumps, for example, require additional design engineering for conversion from metal to plastic.
    Because of its specialty, EnviroTech is the single-source supplier for many of its OEM customers. “We provide technical expertise, quality parts, reliable delivery, and responsible pricing,” says Day, “and our customers tell us that no one else can mold the size and quality of parts that we do.”

    In addition to its custom molding operations, which account for 70 percent of sales, the company also produces a line of proprietary recess and membrane filter plates. These are sold under the EnviroTech name, and are also made for OEMs to be sold under each one’s brand name. “This is a product that we manufacture, market, and sell for end users and OEMs,” he says, “in which we own the tooling.”

    To control the bulk IM process, a custom process controller had to be built for the machines with special software packages programmed to monitor and control equipment parameters. Other quality equipment, including ultrasonic inspection to uncover voids, needed modification so that it would work with thick parts.

    EnviroTech Molded Products, Salt Lake City, UT

    Square footage: 76,000

    Markets served: Filtration, fluids handling, pulp and paper, electrochemical, electroplating, pump and valve, food processing equipment, pipe fittings, mining, equipment components, and aerospace

    Materials processed: Mainly PP, PE, PVDF, and nylon; also PC, PPS, PEEK, PEI, PPO, acrylic, fluoropolymers, polyethersulfone, polysulfone, TPU, and TPE

    Resin consumption:
    3 million lb/year

    No.of employees: 75

    Shifts worked: Three

    Molding machines: 24 bulk and modified conventional injection molding machines (various makes) from 300 to 2500 tons, most converted to bulk injection molding process

    Molding technology: Bulk injection molding

    Secondary operations: Machining, assembly, bonding, hot stamping, welding

    Internal moldmaking: No

    Size and Substance
    During a recent IMM tour of the Salt Lake City operation (a second facility is located near Milan, Italy), Day pointed out the reasons why large molded parts are in such great demand by customers in industrial and even aerospace markets. “Plastics offer better chemical and corrosion resistance than stainless steel or cast metals at 20 percent of the weight and usually a significant reduction in cost.”

    The process can also handle complex configurations and molded-in inserts. Parts can be produced in minutes rather than days or weeks. Molded-in, flanged inserts rather than post-installed inserts improve pullout and torque resistance for industrial applications. “Even when the price of a molded part exceeds that of a casting or machined plastic part, customers often prefer the molding for its ability to withstand operating conditions without failure,” he says.

    Production quantities tend to be on the low to medium side, typically from 50 to 50,000 pieces per year, although EnviroTech is capable of high-quantity production when required. “One high-speed, thin-wall part that we are molding represents an unusual volume for us,” says Day. The OEM customer makes exercise equipment, and the part is being produced in HIPS (.150-inch wall) at a rate of several hundred thousand per year.

    Relatively smaller parts (up to 35 lb and 3-inch wall thickness) can be produced economically using conventional molding machines modified to produce large, heavy-wall parts, including what EnviroTech calls “intrusion” molding. Here, the machine injects and extrudes material simultaneously. Again, a proprietary arrangement prevents full details, but the process is similar to bulk injection.

    With such unique processes, the company realizes, it must provide customers with the benefit of its expertise in design, materials, and secondary operations. “We’ve been designing for this process for 40 years, so no one knows it better. As a result, we offer single-source supply, including part design, design for manufacturability, material selection, and post-molding operations,” Day says.

    EnviroTech has three mold designers on staff who specify much of the tool and part design and work with moldmakers in Salt Lake City, Chicago, and elsewhere. Sales engineers are also experienced product designers. “Often, we’re converting metal to plastic, so our experience in molding, design, and materials makes the conversion easier.”

    Above-average Applications
    While OEMs from industrial markets such as filtration, pump and valve, electrochemical, pulp and paper, pipe fittings, and equipment components are the majority of EnviroTech’s customer base, it also serves high-end aerospace applications. Recently, the company finished a developmental project for the F-22 and Joint Strike Fighter, both jet fighter programs for the U.S. Air Force.

     
    Calvin Mills and Alan Nielson in the drum assembly area. Rotary drum filters, the company’s first product, are still produced at this facility.


    Two prototype canopies for jet fighters molded in PC passed every test for light transmission, optical clarity, and bird strike impact.
     
    Molding in an aluminum or titanium attachment on the canopy means greater stealth for the planes and faster changeovers during combat.
     
    Relatively small pumps are boxed up at the press, while larger items are stored prior to shipping.

    Clear canopies used on jet fighters are traditionally made by drape-forming a thick sheet of acrylic. This process takes up to six weeks and has a 20 to 30 percent reject rate, in part because the forming method produces variations in thickness that make it impossible to polish the canopy so that it is optically correct.

    EnviroTech began working on a monolithic PC canopy molded in one shot. With the Air Force, it designed the mold for a canopy that duplicated the front section of the F-16 fighter. Dow Plastics supplied the material. The scaled-down prototypes also included aluminum or titanium attachment devices that were insert molded at the edges of the canopy. These 78-lb, 2-inch-thick parts were produced in minutes vs. weeks for drape forming, and did not require polishing for optical correctness.

    The objectives of the Lockheed/Air Force development program were to determine moldability and produce a small quantity of bulk injection canopies to verify optical characteristics, impact properties, and the improved attaching method for the frameless transparency program. Parts were tested for light transmittance, optical clarity, and bird strike impact strength. In all categories, the PC canopies met or exceeded requirements.

    The molded-in attaching hardware was designed to improve the stealth characteristics of the fighter and allows technicians to replace damaged canopies in hours vs. days using the traditional method, one that requires bolting. This would save time and equipment in combat situations. Currently, the project is on hold while suppliers determine if a full-size mold (three times larger than the prototype) that is also optically correct can, in fact, be produced.

    On the other end of the spectrum, a high level of engineering goes into industrial pumps as well. In fact, Day considers the company to be one of the premier molders of large pumps, both centrifugal and double diaphragm. “There are 13 different pump manufacturers among our customers, and we have been molding and designing these products since 1963.”

    In papermaking, the molded-part applications range from cyclone cleaners to distribution manifolds. For instance, EnviroTech produces a nylon cyclone cleaner that replaces a cast-iron version at a 70 percent weight savings and 50 percent cost savings. In electrochemical applications, glass-filled PP copolymer replaces wood frames in nickel production plants because the wood absorbs chemicals and disintegrates over time.

     
    In addition to its custom work, EnviroTech produces a proprietary line of filter plates, shown here being removed from a horizontal mold.


    Molded parts for industrial markets such as chemical processing and papermaking replace cast metal or machined plastics at less weight and cost.
     
    Valves and pipe fittings for various industrial markets must be free of voids greater than .015 inch. Ultrasonic inspection ensures that parts meet the spec.
     
    Bruce Robinson, quality control manager, measures a diaphragm pump part on the coordinate measuring machine.

    Shop-floor Specifics
    Due to the proprietary nature of this process, several equipment and plant layout details were omitted in this article at the molder’s request. However, the process of bulk injection is relatively straightforward, with most large, flat parts being produced in horizontal mold units. Because of the size, most parts are removed manually, and then stored in cooling racks prior to shipping.

    Large areas of the shop floor are set aside to hold the current day’s production before it is sent to a finishing or shipping area. Relatively small parts, such as pumps and valves, are boxed up at the press. Material usage is high at several million lb/year, so the plant has several PP silos and a pneumatic materials handling system, custom-built with Conair components.

    For smaller (2- to 30-lb) pump parts, the plant uses four JSW machines modified to do heavy-wall parts up to 3 inches thick. These presses were selected for superior platen stiffness, and run mostly multicavity molds for thick-wall parts with molded-in inserts.

    Another area of the plant is set aside for assembly of EnviroTech’s first product—rotary drum vacuum filters for the chemical processing industry. Here, molded plates are bonded together to form large drum filters ranging in size from 3 to 10 inches in diameter and up to 16 inches long.

    Contact information
    EnviroTech Molded Products
    Salt Lake City, UT
    Forrest Day; (801) 323-2905
    www.empslc.com; [email protected]

    Parting Shots

    Stink
    We all know molders are busy people, but the exchange of ideas among peers through online forums has led to positive communication and networking relationships among those in the IM industry. It’s also a great way to blow off steam. We noticed this thread on IMM’s Networking Forum and thought readers deserved a laugh. This thread was started by Brent Borgerson, process engineering manager for Matrix Tooling Inc./Matrix Plastic Products in Wood Dale, IL.

    Please note:
    The opinions expressed by users of the online Forum do not necessarily reflect those of IMM.


    Brent: I would like to start a new thread. I would like to poll molders as to which resin odor they dislike the most. There would be two categories:
    1. Resin at its normal processing temperature.
    2. Resin that is degraded (other than PVC).
    My vote is for PBT in both categories. Let’s hear from you molders on this!

    respondent 1: Other than PVC (which, by the way, would win), I would have to say acrylic, especially at higher temps. The acetals can be nasty but, other than making you cry and sucking the oxygen out of your lungs, the smell is probably not that bad, if you could stand it long enough to smell it.

    respondent 2:  I have to agree with acrylic. Even under normal processing conditions this stuff turns my stomach! We mold enough of this to make certain days less than desirable in the molding area.

    respondent 3: Most definitely Noryl during processing. I would have to say most definitely that acetal would take the cake in regards to degraded material.

    respondent 4: I always thought PPO (Noryl and the like) smelled kind of funky.

    respondent 5: PPO and PBT may be foul, but I love the smell of acrylic in the morning. Cast my vote for filled PPA. A truly God-awful stench.

    respondent 6: I know you said other than PVC. How about CPVC? That extra chlorine molecule stinks and rusts tools.

    respondent 7: Noryl is my all-time funky-smelling, nose-dripping, lung-burning, eye-watering, teeth-grinding material.

    Brent: Yeah, almost forgot Noryl! Thanks for reminding me. We have a Noryl job coming up Thursday—got to find my nose plugs.

    Brent: Wait! Noryl is a PPO nylon blend. So what stinks? I say the PPO. I don’t know anybody who dislikes nylon odor.

    respondent 8: I vote with the guys who mentioned Noryl. I am not an actual molder but was working a tradeshow booth with an injection molding machine that was processing Noryl. I will never forget that smell. Consider my nose was that of an amateur and just imagine how much I suffered!

    respondent 9: I just ran a sample out of this stinky smelling stuff. MSDS. Very, very nasty—Grilamid TR 55 LX clear (polyamide 12).

    Brent: That’s a new one! Can you tell us what it smells like?

    respondent 9: Well, it’s worse than exploding ABS. Kind of like what I would imagine rotting human flesh to smell like. “Funk” is a good word to describe it. I think I’m gonna go burn up some acetal so when I become old and decrepit like the darn ABS was, I will hopefully avoid the comments I received the day of the sample. Has anyone seen degraded ABS “instantly” rust steel?

    respondent 10: I vote for an old product. It may be better now—I just won’t give it another chance. Has anyone ever experienced a resin called Geolast? I’ll admit there may have been some ignorance in processing; I wasn’t there personally until the smell permeated the offices 500 ft from the machine. Once molded, the parts stunk up my office for days (I made the mistake of leaving them on my desk over the weekend).

    The smell was complained about for a week throughout the plant and all nonprotected steel rusted in a 100-ft radius of the molding vicinity. I mean no malice towards the manufacturer, just that people should be warned of smell and degradation.

    respondent 11: Delrin left cooking for a short while has put tears in my eyes and burned the hair in my nose.

    respondent 12: Has no one ever used a product called Barex? When it is degraded you will leave that day smelling like it. People have gotten sick to their stomachs by the smell. There is no comparison. It makes acrylic smell like a bed of roses.

    respondent 13: I always found that acetal sitting in a hot runner for over an hour and then exploding out of the gates and back through the bushing was a good one. Someone left a mold sitting open in my plant once, failed to turn the hot runner off, and whammo! The thing blew degraded acetal all over the place. Luckily no one was in the area. Nothing like formaldehyde to start your day.

    Brent: Clears the sinuses, doesn’t it?

    Submissions to Parting Shots are welcome. We’re looking for stories about molding ingenuity or mystery parts for our What Is It? series. Send yours in and if we run it in this section, we’ll give you a check for $25. Direct them to Amie Chitwood, managing editor, fax (303) 321-3552, or e-mail [email protected].

    Curing the disposable screw syndrome

    At Dinesol Plastics, a workcell running 50 percent glass-filled nylon produced this type of screw wear every four months.
    Dinesol Plastics’ general manager Buddy Greathouse had a problem that reared its ugly head all too often at the high-volume, 24/7 molding facility. Roughly three times a year, one of the presses at the 150,000-sq-ft plant in Niles, OH needed a screw and barrel replacement. Each time, Greathouse noticed that not only were the flights on the screw eaten away, but the compression area of the barrel was also worn.

    It didn’t help that the 300-ton press was running an eight-cavity mold using 50 percent glass-filled nylon for two weeks out of every month. Before switching materials, of course, the screw had to be pulled so that a significant amount of charred material could be cleaned off. “Some of the screws were so bad,” recalls Greathouse, “we needed a grinder to get all of the degraded material off. At the time, we were using 9V screws and 10V liners.”

    General Plastex worked with Dinesol as a beta site customer for its Pro-Tex wear package. A screw with hard facing applied via PTA welding, shown here, awaits final machining and carbide coating steps.
    He estimates that in one year, Dinesol spent more than $19,000 on replacement screws and barrels. It was time for a change. “We decided to work with General Plastex as a beta site customer for its Pro-Tex wear package. They created a custom system, including screw and barrel, that we installed in 1998. Today, there are still no visible signs of wear, and we haven’t had to pull the screw for cleaning in two years because we can now clean the screw thoroughly by purging.”

    According to Oscar Toris, GM at General Plastex, the Pro-Tex system is based on a combination of commercially available bimetallic lining materials, a carbide coating, and welding materials, including a .050- to .060-inch hard facing. “It is a proprietary blend of material and process that we call full encapsulation, with the hard facing applied first via plasma transfer arc welding, and then a carbide coating applied on top.”

    Switching to a wear-resistant screw and barrel from General Plastex reduced costs at Dinesol by $19,000 per year and cut downtime by 500 hours annually.
    Today, Greathouse runs primarily glass-filled nylon and Ultem  PEI in the same press without having to pull screws or replace them. He estimates that the company has saved about 2000 hours in downtime over the four-year period. He has also been able to redirect several maintenance personnel to operations positions because the screw no longer needs to be pulled on a regular basis.

    Customers of the Pro-Tex package receive a guarantee (on new and rebuilt screws) that wear on both screw and barrel will not exceed .005 inch for 36 months. The guarantee is limited to materials with 50 percent filler and less, and operating temperatures of less than 800F. According to Toris, the package is not applicable to fluoropolymers, powdered metals, or extrusion.

    Contact information
    General Plastex Inc.
    Barberton, OH
    Dave Mantilla
    (330) 745-7775
    www.gplastex.com

    Mini hot runner systems explore new applications

    A smaller footprint, cost savings, and greater control over material delivery are reigning in more toolmakers to the mini hot runner stable.   System users and makers share their ideas.

    This double nozzle was developed by Günther for a switch application using insert technology. A 64-cavity hot runner system was specified, so Günther provided 32 of these nozzles for the .8g, glass-filled PPS part.

    The advantages of hot runner systems are generally well known. The last few years, however, have seen the introduction of several lines of mini or micro hot runner systems, developed to conserve space in the mold and to meet micromolding application requirements.

    Mini hot runner systems do have some quirks of design and application that designers and moldmakers should be aware of. IMM spoke with some experts to get their thoughts on how best to use mini and multitip systems.

    Gates and Runners
    Parts that require unusual gating, either for cosmetic reasons or for unique insert molding applications, are good candidates for mini hot runner systems. Ron Pleasant, president of Pleasant Precision Inc. (Kenton, OH), notes that the very small probes offer an optimal method to gate down into a deep-draw part, such as a lipstick tube cover. In this instance, the gate is placed on the inside of the part due to cosmetic requirements.

    “Spacing is not a big deal in these situations, but you have a confined area to get down in there with a small part, so the probe has to be small,” Pleasant explains. “Also, it can’t conduct heat into that core, which is one of the challenges—to get the probe in there with enough clearance that it avoids contact with side walls of the cores; and it must do this without compromising the integrity of the core walls. Sometimes you have to circulate water around the probe, which contacts the probe and the inside of the core. It takes a special probe to allow water to run around the outside of it.”

    A Stellar micro hot runner system from D-M-E enabled moldmaker Electroform to put 16 cavities in a 10x12 mold base and charge its customer half the cost of competing mold shops offering a standard 16-drop hot runner.

    Robert C. (Chuck) Massie of Cavaform, based in St. Petersburg, FL,  builds molds primarily for medical applications using commodity resins such as polypropylene and polystyrene. “We build very high-cavitation molds, 64 to 120 cavities, so to cut costs we design a multitip application,” says Massie. “It serves us well, particularly in the commodity resins. Engineering resins usually require a separate zone for each probe.”

    Massie says that Cavaform uses a multitip, multiprobe system to gate very small parts such as needle hubs and catheter tips—parts that are fractions of an inch long. He can typically direct-gate four parts off a single probe. “It’s not a mini system per se, but you get a fairly small mold footprint,” he adds. 

    Cavaform also uses a proprietary angle-tip nozzle based on a Mold-Masters system. The probe itself comes in at a 45° angle, explains Massie, to allow a gate on the side of a very short part. In a needle hub mold, for example, he can land the gate on a rib and direct-gate a cluster of four to six parts from one drop while keeping a close center line.

    Another consideration in small-part applications is the amount of material consumed by a runner system. Dirk Vander Noot, VP of Günther Hot Runner Systems Inc. (Buffalo Grove, IL), explains that in applications where small parts don’t require a large mold, but a large mold is needed to accommodate the runner, a mini hot runner system “allows you to reduce the size of the mold by eliminating the runner, which is especially cost effective in applications where regrind can’t be used.”

    Designing for mini-micro hot runner systems requires consideration of the mold base, waterlines, and machine type.

    Insert Possibilities
    Pleasant says that another good application for mini hot runner systems is insert molds in which the part has plastic details molded on various locations of the insert. In some cases, Pleasant points out, the mold has slides or other mechanical devices in the same area. “You have to build a manifold that’s balanced to deliver material in a specific spot,” he explains, “and small probes let you tuck these in next to these mechanisms. This is a good place for minis. Some of these have 90° gates, and those are very handy for these various tight places.”

    However, Pleasant adds, “those are a real trick to get installed in the mold itself—trying to tuck this probe into a blind hole. You have to do some special mold design techniques to get it in there.”

    Another advantage of the mini systems is cost competitiveness. Wade Clark, president of moldmaking firm Electroform Co. Inc. (Rockford, IL), recently won a job to build a 16-cavity washer mold. Clark credits his success with the decision to design the mold using a Stellar micro hot runner system from D-M-E. This allowed him to put 16 cavities in a 10x12 mold base and reduce the cost of the mold by about half of what his competitors quoted using a standard 16-drop hot runner.

    Clark noted that most of the challenge of designing for the system was negated by a readily available design from D-M-E. The pre-engineered system design guidelines were accessible online, plus the appropriate CAD files were e-mailed to the designer to plug into the mold design, making it easy to incorporate the Stellar system.

    With competitive issues at the forefront of the moldmaking industry, mini or micro systems are proving to be an advantage, as in Electroform’s case. “If I can save my customer half on a hot runner system, I’ll do that wherever I can,” says Clark.

    • Melt channel design. Thermal degradation of the melt as a result of excessive residence time can cause changes in the molded part’s physical properties or lead to burning and black streaks. 
    • Mold base integrity. Mold design for small parts inherently includes tight cavity spacing and large pockets cut into the mold base relative to its size. Mold base integrity to resist clamp and plastic pressures must be considered. 
    • Mold cooling. Cavity spacing of small parts can limit waterline access to the cavity and gate area. Consideration for the proximity and size of waterlines is critical for molding parts with minimal gate vestige and optimum cycle time. 
    • Gate access for direct gating. Direct gating of small parts is generally accomplished with the use of small-diameter thermal gates or edge gating systems. Valve gate nozzles that require a valve stem in addition to the melt channel at the molding surface require more space for access. 
    • Manifold thermal profile. Small-part molding relies on heat input from the manifold heaters for melt uniformity. Heater layout and thermal losses must be considered in manifold design to achieve minimal temperature variation across the manifold. 
    • Machine selection. The molding machine used for small-part molding must be carefully selected. Barrel size and screw type can have a large impact on shot-to-shot repeatability.

    Contact information
    Husky Injection Molding
      Systems Inc., Milton, VT
    (800) 516-9590; www.husky.ca

    Pleasant Precision Inc., Kenton, OH
    Ron Pleasant; (419) 675-3334
    www.roundmate.com
    aIMM Infolink 314

    Mold-Masters Ltd., Georgetown, ON
    Neil Dewat; (905) 877-0185
    www.moldmasters.com
    aIMM Infolink 315

    Günther Hot Runner Systems Inc.
    Buffalo Grove, IL
    Dirk Vander Noot; (847) 215-7874
    www.guenther-hotrunner.com
    aIMM Infolink 316

    D-M-E Co., Madison Heights, MI
    Ken Kurtz; (248) 398-6000
    www.dme.net

    Materials Update

    Syringes used to inject radioactive isotopes are being tested with Ecomass. The heavy-weight composite material is said to provide isotope shielding to both technician and patient. Below is the carrying case for the syringe, also made of Ecomass.

    Replacing metal with plastic in thousands of applications over the past several decades has provided opportunities for many products. Now, after several years of R&D, it appears that a replacement for lead has become a reality in the marketplace as heavy-weight composite materials—tradenamed Ecomass—are beginning to appear.

    Ecomass compound consists of a polymeric binder such as nylon, PE, PPS, PEEK, or TPE with a filler—tungsten, copper, iron, or stainless steel. A technology transfer company, Ideas to Market (I2M, Austin, TX), in 1997 acquired the patent for the compound and subsequently granted PolyOne an exclusive worldwide license to manufacture and sell the compound through a joint venture.

    The potential to provide a replacement for lead in a variety of applications promises some long-term gains for OEMs and molders that master the processing of this material. But it’s not without its challenges. Ecomass is 96 percent tungsten by weight and 50 percent plastic by volume. It is physically heavy—a 1-gal pail of Ecomass weighs 35 lb, with composite densities ranging from 6.0 to 11.0 g/cu cm, which makes many molders want to avoid it.

    Upcoming Applications
    Atlas Precision Inc. (Arden, NC) is one custom injection molder that’s not afraid of looking for materials and products that promise unique niches and growth potential. Ecomass is one of the materials Atlas is working with to help customers mold new products.

    Two products, currently in clinical trials, include a syringe shield and carrying case invented by William Patton McDonald, chairman and chief scientific director for Molecular Diagnostics of America Inc. (Birmingham, AL). The syringes are used to inject patients with radioactive isotopes for use in positron emission topography (PET) imaging.

    PET, a nonsurgical, computer-aided imaging technique, is used for diagnosing coronary artery disease, cancer, and other disease states by taking a 3-D picture of metabolism on a molecular level. The syringe shield, along with a carrying case for transporting the syringes, will reportedly offer protection to both the technician and the patient from the radioactive isotopes by eliminating gamma radiation leakage. It also negates needle stick injuries of health care workers.

    Additionally, the newly designed syringe shield is more ergonomically friendly and cost efficient to produce than current syringes, which use clamps machined of tungsten or steel.

    Such shielding has traditionally fallen in the realm of lead, but long-term exposure poses a health threat, and its use in paint and gasoline has been banned for many years. As a result, more industries are looking for replacement materials. A radiation shielding grade, Ecomass RS, is said to provide full and partial radiation shielding without the hazards associated with lead. It’s made with a combination of tungsten powder and barium sulfate.

    Tooling, Molding Considerations
    Tooling for Ecomass requires high precision for the entire mold—not just core and cavities, explains Robert Bulla, marketing and sales manager for Atlas. Tolerances are critical and wear is a concern, especially in gate areas. “A valve-gated hot runner system needs to be used because you’re trying to eliminate a lot of wear areas in the tool. Erosion can be an issue,” he says.

    It’s recommended that any project considered for Ecomass be prototyped first. “Because they’ve not dealt with these densities before, customers might not know what they’re up against,” advises Bulla. “For example, there can be no sharp corners in the part design.”

    However, Jack Turner, PolyOne’s market development manager for Ecomass, notes that the material has considerable design flexibility in the selection of metal powders and choices of substrates for increased functionality such as temperature range, application environment, impact, and post-molding finishing, including plating, painting, or powder coating.

    In the molding process, the wear on the screw, barrel, and tips is reportedly comparable to other aggressive compounds such as glass-reinforced nylon and PP. Conventional metals and surface treatments for these materials are also effective with Ecomass.

    Handling the material is another consideration from a safety standpoint. As the material is very heavy (bulk densities up to 350 lb/cu ft), care must be taken moving it from the pallet into the hopper, and then from the hopper to the feedthroat. “The average loader can’t pick up one pellet,” says Bulla.

    Also, you can’t use a hopper that holds 600 lb of ABS and fill it with Ecomass. “It won’t hold up, obviously,” cautions Bulla, adding that drying the material is also a challenge.

    Atlas has invested considerable time in the processing of Ecomass. “It processes fairly well, but you have to take into consideration that you’re dealing with a very heavily loaded material that has the ability to wick heat out of the barrel,” says Bulla.

    Turner adds that the material is still basically a thermoplastic. “Even in its uniqueness, it still flows, reacts to shear, and shrinks like plastic,” he says.

    Contact information
    Atlas Precision Corp., Arden, NC
    Robert Bulla; (828) 687-9900
    PolyOne Corp., Cleveland, OH
    (216) 589-4000; www.polyone.com

    Shifting to 3-D mold design

    Still designing tools the old-fashioned way—with a two-dimensional software package? Mold designers share their experiences leaving this method behind and embracing 3-D models. The payoff: faster results, smoother interoperability, and boosted productivity.

    For a single-cavity mold design, Kreutzberger used several components created previously and stored in the MoldWorks library, speeding design time.

    Computer-aided mold design (CAMD) is a field that is finally coming into its own, as software providers begin to differentiate products specifically for the tool designer. One example in this category of products, MoldWorks by R&B Mold & Die Design Solutions (Yokneam, Israel), is a 3-D solids application that offers features specific to the injection molding industry and works with SolidWorks, a popular CAD package.

    IMM asked three mold designers using the SolidWorks/MoldWorks combination to detail their experiences in changing to a 3-D design environment: John Kreutzberger, owner of JK Mold Design (Sacramento, CA); Gregory Brown, designer with Burco Precision Products Inc. (Denton, TX), a moldmaker; and mold designer Curt Westgate of Cool Polymers Inc. (Warwick, RI).

    Customer-focused Contract Design
    John Kreutzberger became a contract injection mold designer in 1984. At that time, he used a drafting table to create mold designs and eventually migrated to computer-aided 2-D (CADkey), and then to a CADkey add-on product that brought him into the 3-D world.

    He shifted to a full-blown 3-D environment four years ago in an attempt to keep up with time pressures. “My customers are mainly small, California-based mold shops, and my biggest challenges are meeting ever-decreasing lead time requirements and maintaining quality with projects that vary greatly. I can’t limit myself to the size or scope of a mold design, so I create small molds such as unit inserts, mold bases that are typically found in standard catalogs, and large custom mold bases.

    “Using this software combination [SolidWorks/MoldWorks] allows me to provide customers with usable 3-D models for CNC production capabilities. I have to be able to generate accurate drawings that my clients can show their customers as well as 3-D data for use on the shop floor. Also, 3-D software allows me to quickly incorporate components from a great number of different suppliers. To date, every CNC platform that my different customers use has been able to import my data.”

     
    MoldWorks allows users to select the size and manufacturer for ejector pins and specify the bearing length of the pin. Total pin length can be extracted from models. The oversize tab is used to specify clearances.
     
    This is the dialogue box used for changing the size of a mold base.
    Faster Models
    Burco Precision Products, a division of Triple S Technologies LP, designs and manufactures injection molds for consumer products, defense, telecommunications, electronics, and the automotive industry.

    Burco went from 2-D AutoCAD to solids-based design more than three years ago. Brown says, “We identified several areas that would help improve our upfront modeling time—designing complex cavity core splits and creating mold bases using standard mold components.”

    Designers at Burco start with the part, add shrink, and then build up the cavity, core, and any side action that may be required. They create a cavity and core assembly using the CAD software, and then devise a parting line intuitively or using an automated module called SplitWorks (a companion product to MoldWorks). To select an initial mold base and modify any dimensions as needed, Brown uses MoldWorks, which also takes care of mates, ensures that all plate sizes are correct, and verifies that all assembly screws are in the correct location.

    The software allows Brown to add standard ejector pins from PCS, National, or Hasco. MoldWorks then automatically puts the ejector pinholes in the core insert, B plate, and support plate. It also counter-bores the ejector retainer plate. Brown adds, “I prefer to use one sketch for each unique pin diameter.”

    From Resin to Mold
    Cool Polymers manufactures thermally conductive plastics and heat transfer solutions, supplying both pellets and injection molded parts produced from these resins. It assists in the design, modeling, testing, prototyping, and tooling of customer applications, which include electronics, automotive, appliance, heating/cooling/refrigeration, lighting, medical, food, and sporting goods.

    Prior to implementing 3-D CAMD, Cool Polymers was using a 2-D mold base software package as well as design tables to create mold base components. “It took a long time to design a mold because for each new mold design, components such as waterlines, knockout pins, and inserts had to be individually added,” says Westgate. “And if there was a change, each component had to be individually moved.”

    With the move to 3-D, all knockout pins, inserts, and waterlines are easily added and parametrically tied to the assembly. They can be moved or adjusted with a few menu selections. Design time has improved, tooling delivery time has improved, and in turn, projects are completed sooner.

    “The switch has increased our productivity by enabling us to create a mold base assembly in one week or less,” Westgate adds. Formerly, a typical mold base assembly would take from 21¼2 to 31¼2 weeks to complete. “This also includes all necessary drawings required for vendors and/or toolrooms as well as the exploded assembly drawing with part tabulation,” he says.

    Contact information
    Neuvotec Inc.,
      distributor of MoldWorks
    Cave Creek, AZ
    (480) 473-0840; www.neuvotec.com

    Rapid product developer is developing rapidly

    A medical device used for monitoring patients at home for sleep disorders is shown in two components and assembled. The design was engineered, two molds built, and parts were in hand in 15 days.
    A product just can't come to market fast enough anymore, so one firm is blazing a speedy trail through the development cycle with tools built for production parts in just days.

    OEM companies that used to measure development cycles in months or even years are now measuring in weeks and in some cases, days. They are starting to think in terms of hours. The resulting markets for rapid technology, despite the poor economy, are bustling: rapid engineering, rapid design, rapid prototyping, rapid tooling, rapid production. Using any or all of these technologies is giving OEMs what they really want: rapid product development (RPD).

    Seeing a market opportunity where many saw merely a trend, Catalyst PDG set up shop four years ago in Indianapolis to reduce development cycles for OEMs. PDG stands for Product Development Group, and since its founding, Catalyst has grown rapidly by slashing development time for its clients—often dramatically. When VP Earl Dunlap talks about how the company has taken big or even small chunks of time from development cycles, he bubbles over with excitement. “This is all about time to market,” says Dunlap. “The word is out among manufacturers about how it works. They want it, and, fortunately, it is still improving.”

    By now, it is generally accepted among marketers that being first to bring a product to the customer generates much more income and profit than being second or third. Though this has been generally associated with go-go markets such as computers, consumer electronics, and automobiles, Dunlap says the idea is now working its way into virtually every industry and market. Compressing development time, he says, is something every company needs and wants. Therefore, the groundswell of activity seen in rapid engineering and design, rapid prototyping, rapid tooling, and rapid short-run manufacturing is no surprise.

    Products developed by Catalyst surround the company’s founders: Jack Lawson, president (left); Dennis Turner, VP (center); and Earl Dunlap, VP.
    Catalyst PDG, which now employs about 30, has been attacking RPD in a number of ways. It has strong front-end design skills with up-to-date CAD systems. Twelve of its people are in plastics tooling, or more properly, rapid tooling. A good indication of the fast pace of this business is their productivity: 35 to 40 tools per month, all of them made fast. Rapid prototyping is an in-house specialty with prototypes available in virtually any material, including wood and metals. There is also an in-house plastics molding operation to speed up that stage of the cycle. Capabilities extend to making first working prototypes of electromechanical components.

    Wanting to take a leadership role in rapid development rather than simply participating, Catalyst developed proprietary technology in-house. For instance, the company created a material-process combination to make SLA prototypes with about 12 times normal impact, tensile, and torque strengths. One significant development is a system for creating a rapid tool that allows normal molding of high-quantity parts in the production material or nearly any other material the client wants in days, not weeks.

    A STAT tool built with a clear textured finish molded this translucent light cover for an office divider system. Mold build time was 10 days.
    STAT—As in Right Now
    Catalyst PDG is currently beginning to license a proprietary process for rapid toolmaking called STAT (Sample Time Acceleration Technology) that is a hybrid of composite and traditional tooling technologies. The company has been using it in-house for several years with excellent results. The bottom line, says Dunlap, is that the client can have plastic parts molded in the resin of choice in days, as opposed to weeks or even months, and the quality is very high.

    Catalyst’s STAT Process produces molds that can do the following:

  • Yield 1500 or more pieces, depending on the material.      
  • Produce parts microsized or as large as 6 by 18 by 20 inches.      
  • Use the customer’s material of choice.      
  • Allow high polish and texturing.      
  • Hold tolerances of ±.005 inch.      
  • Include multiple slides, undercuts.

    How rapidly will that happen? Turnaround time—art to parts—using STAT technology is quoted by Catalyst as seven days. Dunlap says it’s often faster, depending on the complexity of the part, and larger parts can take a few days longer. He says holding tolerances of ±.005 inch, or even tighter, and producing parts in the production material at a quality normally associated only with aluminum or steel tools is what sets the STAT process apart in the RT field. Not surprisingly, the process is patented; Catalyst will not disclose many details and will show photos only of the molded parts, not the molds themselves.

    The key to the technology is a trademarked tempering process, RP Tempering, which, when applied to composite materials, allows them to withstand the heat and pressure inside an injection molding clamp. The tempering is a four-step process, and the technology is still undergoing development. Currently, tools are made using a mix of STAT composite material and traditional metal; however, in the future, they will consist almost entirely of composites. The material will be formed in spherical shapes for uniformity.

    A special resin flow orifice regulator (RFOR) developed for the STAT tooling and molding process prolongs the life of the tool, especially where the STAT composites come into play. Upfront engineering accounts for the tempering process so tolerances can be held. The part file is adjusted for the thickness variation caused by tempering, process tolerances, and resin properties during the mold split and design.

    Containing more than 100 details, these paper path document imaging parts were made with the STAT process. Tolerances were held to ±.003 inch.
    Catalyst Catalyzes its Own Development
    Besides OEMs such as Kodak, HP Invent (Hewlett-Packard), Motorola, Cosco, Fleetguard, Amway, automakers, and a list of other household names, Dunlap says the client list also includes many project-responsible molders and moldmakers. What is of paramount importance to each Catalyst client, he says, is sheer speed. “They each want to be first. The return on investment is there.” Conversely, time lost translates directly into lost revenue and profit.

    In addition to product development, engineering, and prototyping, Dunlap says product testing has been a critical component of Catalyst’s total service. On the front end, Catalyst offers finite-element analysis (FEA) of the product design and Moldflow analysis of the mold configuration. On the back end of the cycle, it provides services such as life cycle analysis, impact, overall performance testing, and more. It also tests materials stringently. The current range of materials used includes PP, PE, nylon, PC, ABS, blends, and even phenolics. Fillers and reinforcements such as glass and carbon are routine.

    Supporting the rapid turnaround cycle near the back end are four molding machines that include a 10-ton Morgan system and JSWs in 50, 165, and 500 tons. That range and the related possible mold sizes, says Dunlap, position Catalyst to handle the vast majority of part sizes and designs of its clients. They also position the company to do short-run production for clients. That area has been growing fast and proving itself so busy and profitable that Catalyst may spin it off as a separate operation.

    Speaking of other operations, Catalyst is opening a second location in Irvine, CA in November 2002 to keep up with the workload, and, more importantly, to ensure fast turnarounds. Dunlap says current planning envisions up to four more sites in strategic locations at dates still to be determined, but not far off. At that point, he adds, the firm will be adding sales/client contact people—something it has not had until this point. The need for rapid product development was and still is urgent enough, says Dunlap, that once it began delivering high-quality rapid development engineering, prototypes, and molded products, word of mouth filled the order slots.

    Contact information
    Catalyst Product Development
      Group Inc., Indianapolis, IN
    Earl Dunlap
    (317) 786-4444; www.catalystpdg.com