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Articles from 2002 In March


IMMC's Plant Tour: Molding magnesium's future

Many new molding machines have been added to MGP since we last visited in 1999, including five new 220-tonners, yet there still seems to be plenty of room.

Three years ago in the first issue of IMMC we introduced you to the world's first mass-production TXM plant, MG Precision Co. Ltd. (MGP). MGP is a wholly owned subsidiary of The Japan Steel Works Ltd., the world's first TXM injection molding machine builder. JSW originally created MGP in 1996 to convince potential customers that TXM was a viable process for making consumer electronics parts. Increasing demand for the parts MGP was molding convinced JSW to spin its offspring off as a separate profit center. Its decision has paid off-not just for JSW, but for the entire global TXM community.

That's because in addition to producing the key components used in many of today's leading-edge mobile consumer electronic products-everything from digital cameras to third-generation, Web-capable mobile phones with color video displays-MGP also serves as a testing ground for the latest types of TXM production systems JSW develops to reduce materials, molding, and labor costs, while improving good parts yield.

Working as one with JSW's Technology Development Center, MGP today is proving out many of the systems that will improve the productivity of its TXM customers tomorrow. Hot runner TXM, automated power lubricant dispensing, induction heating of barrels, and recycling are among the latest systems MGP is fine tuning. Meanwhile, by putting these newer technologies to work, MGP helps fund JSW's TXM R&D, as it continues to grow its own business.
MGP is remodeling its plant layout to improve flow and reduce waste. Secondary operations like tumbling, shot blasting, and machining have been moved away from the press.
As JSW's subsidiary magnesium custom molding operation, MGP proves out many of the new productivity-improving systems developed at JSW's Technology Development Center. Attendees of Thixomat's International Magnesium Conference toured MGP last year.


The attendees of Thixomat's 2001 International Magnesium Conference in Hiroshima were treated to a tour of MGP. IMM tagged along. Of course, there have been a few new changes at MGP since last summer. Let's tour.

Hot Running Mg

MGP is right next door to JSW's Technology Development Center, which is a good place to begin our tour. The center is used for plastics molding R&D, as well as magnesium molding. It's a glimpse of what's to come.

There is a Model JLM 220-MG JSW for instance, a 220-metric-ton TXM double toggle, demonstrating the application of hot runner tooling. As previously reported in IMMC, JSW has worked with Ju-Oh Inc. (Kanagawa-Ken, Japan) to make runnerless, magnesium alloy molding a reality.

Hot runners can speed cycle times in magnesium molding, just like they can in plastics molding. What's more, they have a significant impact on reducing the volume of costly material wasted in those huge magnesium sprues. Hot runners also can widen the projected areas of parts and allow for molds with higher cavitation, further improving productivity.


MG Precision Co., Hiroshima-City, Japan
Square footage: 21,528 (2000 sq m)
Annual sales: 1.6 billion Yen (approximately $11.9 million)
Markets served: Mobile electronics (mobile phones, video cameras, digital cameras, LCD projectors)
Parts produced: 300,000 parts/month
Materials used: AZ91D Mg alloy
No. of employees: 68, including part-time employees
Shifts worked: One shift/day, five days/week
Molding machines: 14, 75 to 850 tons, JSW
Secondary operations: CNC machining, shot blasting, tumbling, belt sanding, finishing, inspection
Internal moldmaking: Yes
Quality: ISO 14002, ISO 9002
The JLM220-MG in the testing area is running a two-cavity hot runner tool molding mobile phone housings with a shot weight of 43g. It would have weighed 125g if a conventional cold runner was used. With the hot runner the machine cycles at 18 seconds vs. 24 seconds running a cold runner tool.

Inmold Lube Job

Next we see a Model JLM450E-C5, an older-model JSW press. In fact, it was the first production TXM machine JSW ever built. It is seven years old and still runs well. The press is molding a 480g automotive oil pump body in 60-second cycles. It is also demonstrating JSW's new automated powder lubricant system, developed by JSW in conjunction with Hanano Corp. (Tokyo, Japan).

Lubricant (mold release in plastics molding lingo) must be applied to TXM mold faces after every shot, what with magnesium being as sticky as it is. Lubricants have traditionally been silicone liquids sprayed into open molds. JSW's new system dispenses dry powder lubricant on the cavity surface while the mold is closed. It is primarily for large, flat TXM parts because it would be difficult for the powder to be applied in small, intricately configured cavities.

Flash is reduced because there is no accumulation of the lubricant on the parting line. Cycle times are faster and gas emissions from the lubricant are reduced for a better working environment. Mold temperatures also are more consistent, and the powders eliminate misting and waste water.

Induction Heater Bands

The final magnesium molding demo in the Technology Development Center is of a new induction heating (IH) system designed to super-heat the barrel and thereby speed cycle time. A Model JLM650-MG, a 650-metric-tonner, is molding a laptop PC enclosure out of AZ91D. With a 540g shot for a product weighing in at 275g, the press is cycling at 28 seconds. Normally, with only conventional electric heaters, these parts would cycle at anywhere from 40 to 60 seconds.



IH uses an induction current in an alternating magnetic field to heat an electrically conductive material. In doing so, IH systems provide a higher power density and heat efficiency, and a more uniform heating profile than conventional electric barrel heaters. The hot runner system JSW developed with Ju-Oh is based on IH technology.

JSW is still testing its IH barrel heating system in hopes of increasing shot weights on parts run in smaller machines. Sources say IH heating will better stabilize magnesium alloy melting and metering in the barrel and extend heater life, while also reducing cycle times. No date has been announced for commercialization.
MGP, the first mass-production TXM molding facility, now runs the world's first mass-production TXM hot runner molds. This photo was taken when the plant was running mobile phone housings in two-cavity cold runner tooling. Material costs have been reduced by 50 percent using hot runners.
MGP has plans to further automate and isolate secondaries (shown in these four images) off the main shop floor, including degating, machining, tumbling, and shot blasting.


Mobile Phone Cell

Approaching MGP's building, it looks much the same as it did when we visited in 1999. Yet, inside, under its 3.4- to 5m-high ceiling with surrounding skylights and bright halogen lamps, it's a brand-new factory.

The plant itself is evolving into a lean manufacturing cell. There have been expansions in its molding capacity and the general layout of the shop floor has been altered to improve material and product flow while reducing waste. Among MGP's latest additions are five 220-tonners and one 150-ton machine. Most of its materials handling auxiliaries are from Matsui.

All secondaries will eventually be off the main floor in their own enclosed areas, so product can flow even more smoothly. Today, many of the secondary machining, shot blasting, and tumbling procedures have been moved away from the primaries, but some secondaries are still being carried out beside the press.

One of MGP's big 850-metric-ton JSWs is the first machine we see. It is running housings for an LCD projector in a single-cavity tool. Shot weight is 604.2g with a product weight of 315.8g. The press cycles at 56 seconds. It is impressive, but the next product family manufacturing cell we see blows us out of the water. It is the shape of things to come.

The molding machines in this area are mass-producing TXM mobile phone housings with the help of two floor-mounted, five-axis, articulated-arm robots. During the Thixomat-sponsored tour last year, cold runner molds were being used. Things have changed since then. Today, the 220-metric-ton molding machines in this area are running hot runner molds. This is the first TXM manufacturing system anywhere mass-producing parts with hot runner molds.

The robots remove the parts and automatically transfer them to a trimming press nearby. There are four 220-tonners in the cell. Today, three of them are robotized. The cell produces 3000 mobile phone enclosures every 18 hours.

These parts are buffed, polished, and CNC drilled before moving on to inspection. Since the conversion to hot runner molds, material costs have been reduced by 50 percent and molding costs by 22 percent. These molds, like all the molds at the factory, are produced by MGP at a separate facility in Hiroshima. Kazuo Kitamura, gm of JSW's Magnesium Process Equipment & Products Div., tells us the company is already thinking of building four-cavity hot runner molds.

Direct Recycling

Kitamura says JSW has already built its 230th TXM press and he is elated by the company making its first inroads into mainland China. He says the Chinese government is actively supporting the developments of magnesium mobile phone manufacturing, and JSW already has signed contracts with two companies there to deliver full production lines, including everything from molding presses to painting systems.

Fifteen molding machines were involved in the first round of orders late last year, from 220 to 850 tons, and 15 more are now being supplied. What's more, one customer plans to double its press capacity later this year. The new systems being developed by JSW and proven out in production by MGP will be part of the packages.

Leaving MGP, we can't help but notice drums of magnesium alloy chips sporting a label that reads JSW Thixalloy. As previously reported in IMMC, JSW has begun supplying its own materials, even to MGP.

Next to these drums are recycled AZ91D chips. MGP and JSW work closely with Nihon Sahmo, a materials supplier located in the Okayama prefecture, in its direct scrap recycling efforts.

Contact information
The Japan Steel Works Ltd.
Tokyo, Japan
Kazuo Kitamura
+81 (3) 3501 6164
www.jsw.co.jp/mg_f/mg_indexe.htm

A television powerhouse tunes in to TXM

By: Carl Kirkland

Yukio Nishikawa is the senior staff engineer in the materials and processing R&D group of the corporate production engineering division at Matsushita Electric Industrial Co. Ltd. of Osaka, Japan, better known in the U.S. as National/Panasonic. Though he admits that much work lies ahead in improving the productivity of the process, he is confident that magnesium TXM has a bright future in the markets Matsushita serves.

In fact, he and his colleagues have produced a 36-inch magnesium TV cabinet on a Model JLM1600-IU850, a 1600-metric-ton JSW TXM machine, the world's largest, which is in their lab.

Unlike a similarly sized plastic TV frame, the magnesium cabinet is strong enough to support the weight of the entire TV—90 kg—all on its own. What's more, it is inherently EMI shielded, thermally conductive, and doesn't need to be painted. Nishikawa also reports that Matsushita has built a new captive and custom TXM plant near Tokyo.

Environmental concerns in the Japanese electronic home appliance market are one of the major reasons why Nishikawa says Matsushita is tuning in to TXM. Stringent new laws proposed in April 2000 are now in full effect in Japan. They stress the source reduction, reuse, and recycling of home appliances such as TVs, washing machines, air conditioners, and refrigerators. Consumers now bear the recycling costs for these items.


In 1998, Matsushita successfully molded a 21-inch magnesium TV cabinet. Last year, it molded this 36-inch cabinet, which can support the entire weight of the TV. 


Nishikawa says the recycling ratio of plastics is only about 20 percent today. What is not recycled is burned in Japan, which reportedly releases environmentally harmful dioxins.

"From a hardware supplier's perspective, newer products must be smaller, thinner, and lighter; they must be mobile and safe; and they must be more ecologically friendly," he says.

Greener Than Plastics

Matsushita's production engineering lab has been actively investigating magnesium as an alternative to plastics since 1996. It has researched the diecasting of magnesium, as well as TXM. Nishikawa says Matsushita has found that TXM has a number of important advantages over diecasting.

He says TXM is safer and cleaner because it's a more closed process. There's no generation of ozone-depleting gases that some say are produced during die-casting. And he says the semisolid nature of the melt in the TXM process produces higher-quality finished products.

TXM products are lightweight and rigid. The superior heat conductivity of magnesium enables Matsushita to eliminate the radiation apertures on its products, a plus in big TVs. Magnesium, which is available in abundance, is inherently EMI shielded—EMI radiation is considered to be a serious health risk in Japan. And, as far as the environment goes, Nishikawa says Mg products have an 80-plus percent recycling ratio.

TXM products have a high-quality appearance and feel. The cost of the parts is going to be equivalent to plastic parts, according to Nishikawa, and large quantities can be delivered quickly and easily—100,000 pieces/month. Also, Mg parts will have a comfortably short development cycle. Adding up all these pluses, Nishikawa expects that the market for magnesium TXM parts could grow by more than 200 percent per year. Still, he says there is much development work that needs to be done, particularly in manufacturing.

Manufacturing R&D

"TXM has a small material cost ratio," he says. "There needs to be fewer postmolding processes involved to reduce WIP and inventory. Cycle times have to be reduced, as do the amount of labor involved and the capital equipment costs."

Nishikawa and his associates have discovered that control over solidification time, injection time, and flow have the most significant impact on part quality. Mold temperature, injection velocity, and mold design have been found to be extremely influential factors in controlling the molding process. Control over all of these variables is key to improving TXM productivity at Matsushita.

Nishikawa also has found it best to use water as a modeling material when running flow analyses since he says magnesium, like water, splashes into a mold cavity.

He has found there to be no differences whatsoever when running either new or recycled magnesium chips in regard to the molding process, part mechanical properties, or part corrosion resistance. AZ91D magnesium alloy is most used at Matsushita. However, there are economical concerns in other areas when it comes to taking advantage of magnesium's recyclability, especially the costs involved in recovery of painted parts.

Contact information
Thixomat Inc.
Ann Arbor, MI
Herb Pritzker
(734) 995-5558
www.thixomat.com
 

MIM filling and packing dynamics

Edited by: Michelle Maniscalco

Editor's note: At last year's PIM2TEC, a group presented the following excerpted paper that details an investigation into the filling and packing behavior of metal injection molding. The work reported here is part of a U.S. Dept. of Commerce Advanced Technology program for furthering MIM technology, which is supported by Honeywell, Ingersoll Rand, Polymer Technologies, CM Furnaces, CompAS Controls, and Penn State University. Authors of the paper include James Stevenson, Richard Roser, and Alexander Kozlov of Honeywell; and Abdessalem Derdouri and Florin Ilinca of the National Research Council of Canada.


Figure 1. In this experiment, the nozzle and mold cavity were set up with the indicated transducers to record data.


After several decades of research, the dynamics of plastics injection molding are admittedly well understood. For metal injection molding, however, a firm grasp of material behavior during the injection molding process is still developing. An experimental effort toward this goal, using an instrumented plate mold and a specific MIM material, produced results that agreed with a 3-D finite-element simulation.

First, pressure profiles measured at three locations in the mold and at two material temperature levels showed that the pressure necessary for moldfilling, as with plastics, increases sharply with increasing fill time. Second, the experiment helped to develop a procedure to determine minimum packing time.

Experimental Details

To conduct MIM molding tests, the team used a 55-ton Arburg with a 140-cu-cm shot size. The mold designed and produced for these tests featured a rectangular plate cavity 225 mm long and 25 mm wide with an adjustable thickness of 3, 4, or 5 mm. The 5-mm cavity contained removable obstacles such as a cylinder and a triangle. The mold also included a full-length knockout plate to remove parts.

As in Figure 1, the nozzle was instrumented with a Dynisco strain gauge pressure transducer and a Nanmac fast response thermocouple that extended into the melt stream. Pressure transducers located just inside the gate and at the end of the cavity were spaced 210 mm apart. The MIM compound used in the tests was PowderFlo 17-4PH U, based on gas-atomized powder with an aqueous gel binder.

Figure 2. Simulation of temperature distribution on the part surface at the instant of fill for the longest part fill time, 16.2 seconds. Cooled regions at the side and high temperatures at the end of fill are caused by fountain flow.


Filling Facts

The time required to fill the entire plate mold cavity—sprue, runner, and plate—was roughly 2.5 seconds. Once the tool was filled, a profiled pack pressure was maintained for 8 seconds, followed by 10 seconds of cooling. Also, the mold was filled in a series of runs at seven injection rates that covered the machine's limits and at two temperature setpoints—74C and 96C. Injection rates ranged from 1.6 cu cm/sec to 128 cu cm/sec.

Pressure data were collected from each of the transducers in the mold. The pressure profiles generally showed an expected minimum in injection pressure at intermediate fill times of 2 seconds (plate fill) and 3.5 seconds (cavity fill) with an injection rate of about 8 cu cm/sec.

Interestingly, this same trend has been observed for plastics as well. As fill times become shorter, the flowing material has little time to cool, so higher pressures are needed to maintain higher flow rates. At longer fill times, the increasing viscosity of the cooling material requires a higher pressure even though the flow rate is slower. This minimum pressure region is considered the optimal operating window.

Simulating MIM

The researchers simulated moldfilling for the 3-mm plate tool using a 3-D finite-element code developed by the National Research Council of Canada. For this simulation, rheological properties of the material were characterized by Datapoint Labs (Ithaca, NY).

Figure 3. Simulation of velocity distribution at the midplane for the longest part fill time. Again, areas along the side are cool, and velocity down the center of the plate is high, especially in the runner and gate areas.
Figure 4. Simulation of temperature distribution on the part surface at the instant of fill for the shortest part fill time, .2 second. Shear heating causes the hot areas in the center of the plate.


The software predicted temperature distribution for the 74C setpoint and for highest part fill times (16.2 seconds), including the sprue and runner (Figure 2). For this long fill time, the material cooled (blue layer) and stopped flowing along the outside edge of the cavity. However, flow at the center of the cavity continued at a relatively higher rate (Figure 3). The team examined sintered parts molded with long fill times, and they showed flow defects consistent with this predicted flow pattern.

For the shortest fill time (.2 second), the software predicted higher surface temperatures (Figure 4). As expected, longer fill times have lower surface temperatures (28 to 76C), while the shorter fill times create higher temperatures (65 to 90C).

Minimum Pack Time

The gate-freeze method for determining pack time for plastics doesn't translate well to MIM parts. One main reason is that for MIM compounds based on aqueous gel binders, the melt becomes an elastic gel rather than a frozen solid. So the team attempted to determine minimum pack time by observing the time at which pressure inside the gate was not influenced by nozzle pressure.

To do this, the researchers held pack pressure at a 4000-psi setpoint for 2 to 64 seconds, and then dropped the setpoint to 1000 psi. They then plotted pressure at the nozzle and gate vs. time. Data indicated that after 20 seconds of pack time, nozzle pressure no longer influenced gate pressure.

This result is specific to this material and mold. However, the same type of tests could be run on other material/mold combinations to determine minimum pack time.

Contact information
Honeywell, Morristown, NJ
(973) 455-2000
www.honeywell.com
 

Materials Update

High-temp resins boost turbo performance

  • Project: CAC end tanks for Ford diesel pickups   
  • Award: 2001 SPE Automotive Innovation, Powertrain category   
  • Molder/Moldmaker: Carlisle Engineering Products   
  • Resin: Grivory/Amodel/Zytel HTN
By: Michelle Maniscalco

Underhood automotive applications flourished when the first high-temperature nylons were introduced decades ago. Air intake manifolds and engine covers seemed to transform overnight from cast aluminum to injection molded plastic. In bringing these products to the auto market, designers and resin suppliers made huge technological leaps to meet performance, cost, and weight goals.

Today's automotive designers are reaping the benefits of this intensive development, and many examples can be found in the 2001 winners of SPE's Automotive Div.'s Innovation Awards. One such winning application, charge-air-cooler (CAC) end tanks for Ford F-250 through F-550 diesel pickup trucks, showcases the flexibility and performance options now available with high-temperature polyamide resins.

Let's first start with some background: A charge air cooler is also known as an intercooler. It is an air-to-air heat exchanger that cools hot, compressed air coming from a turbocharger's compressor. Before the air gets to the intake manifold, the CAC cools it to increase density.

Interestingly, the CAC end tanks were cospecified (by molder Carlisle Engineering Products and its customer Valeo Engine Cooling) in three high-temperature and dimensionally stable polyamides: DuPont Zytel HTN, Solvay Amodel, and Ems-Chemie Grivory. Each resin is a 45 percent glass-filled grade that is injection moldable in water-cooled molds. According to Larry Butterfield, vp of advanced engineering for Carlisle, each of the three resins was chosen for its ability to withstand temperature spike requirements of more than 400F and pressures of up to 40 psi. "These parts withstand repeated high pressure-temperature cycles without fatigue failure at lower cost and weight than aluminum," he says.

The CAC end tanks replaced cast aluminum versions for a weight savings of 40 percent (4 lb) per vehicle. As the first application of its kind to switch to plastics, however, the tanks received rigorous endurance testing to ensure they would perform as well or better than aluminum.

Perhaps the most dramatic change in switching to plastic tanks was found in the assembly phase. The new tanks eliminated a significant step: welding the aluminum end tanks to the CAC cooling core. At volumes of 300,000 sets per year, eliminating this step offered substantial cost savings.

To mold these highly filled resins, Carlisle built tools with multiple wear resistance coatings and custom designed sprue bushings. A specialized ejection system allows for fully robotic molding.

One of the biggest challenges in this winning application involved meeting Ford Motor's requirements in a short time frame. In fact, the project moved from concept to production in less than 12 months. To speed up the process, Carlisle used its rapid prototyping and finite-element analysis resources. "We were able to innovate without sacrificing quality or end-use performance," Butterfield says.


Contact information
Carlisle Engineered Products
Livonia, MI; (734) 542-8200
www.cepcarlisle.com

Virtual design team speeds product to very real market

During an online collaboration session at Harbec Plastics, all key players on a project meet to discuss a new design. Harbec estimates that online collaboration may cut three to four days from a typical mold development project.
What sets an innovator apart from the pack? The innovator is never satisfied with business-as-usual. Twenty-five years ago, when Bob Bechtold founded Harbec Plastics as a contract tool and die maker, he wasn't interested in doing business the same old way. He believed new technologies would transform the industry, and he wanted to be on that leading edge. As an early adopter of CNC and CAD/CAM technologies, Harbec has seen the benefits of offering its customers a better and more competitive approach to plastics part manufacturing and tooling design.

A generation later, Harbec offers a complete solution from initial concept modeling and advanced production tooling to low- or high-volume-production injection molding and secondary manufacturing and assembly processes.

Harbec is also leading its competitors in another important new technology area: online collaboration. "Collaboration is proving critical to our ability to provide customers with the best solution to their modelmaking, toolmaking, and plastic injection molding needs, and the quickest way to market," Bechtold says.

He says collaboration helps Harbec find the best and most innovative solutions for its customers by bringing together key players on a project—the designer, model- or moldmaker, and project manager from Harbec, along with the customer. Using OneSpace software from CoCreate, the various players are able to meet online in a virtual conference room.

Though physically separated, the team members communicate as if gathered around the same table. Team members explore alternative design approaches and build on one another's ideas until the team not only agrees on its next steps, but in many cases, reaches a solution that no single person had envisioned before the meeting started.

"Everybody knows the importance of getting to market first. But it does you no good to get to market with a product that won't serve the customer well. You need to get to market first with the correct product," says Bechtold.


Here are the original two parts of a fuel system product, one plastic and one metal (foreground). Harbec was able to use online collaboration and its Quick Manufacturing Solutions to create the tool in the background. Designers developed a one-piece solution (center) for the Detroit-based customer that reduces assembly time, cost, and leak potential.
Improving Speed to Market
Harbec is well known to its customers for being fast and accurate. One way that this molder cuts the turnaround time for projects is with its Quick Manufacturing Solutions (QMS) process. This system enables Harbec to produce exact engineering models, using the same materials and processes that will ultimately be used in mass production. The process works for lot quantities as small as one piece.

With QMS, project turnaround time is reduced to two to four weeks vs. the typical eight to 12 weeks of more traditional shops. Customers get an exact representation of a new product design that they can test for fit and performance, and are assured of functionality before mass production. With the shorter lead times, Harbec can fine-tune the product within the same window of time normally needed to build a single model.

Collaboration contributes to the process by ensuring that projects continue to move forward without the delays required to schedule and hold physical meetings with team members. They meet in the virtual conference room with no business travel required.

Because collaboration sessions allow team members to explore all the feasible alternatives very early in the process, when 70 percent of a project's costs are defined, they reduce or eliminate potentially costly changes later in the process. "It prevents us from wasting a lot of effort, having to rework tooling and produce scrap," says Bechtold. "That speeds project completion and cuts costs for our customers."

Overall, Bechtold estimates that online collaboration may cut three to five days off a typical mold development project, accounting for up to a 20 percent savings in turnaround time. Avoiding tooling rework late in the process can save the customer anywhere from a few thousand dollars to upwards of $100,000 or more, depending on the required changes.


Real-life Collaboration
How is collaboration likely to affect an individual project? Bechtold is happy to share a couple of examples.

Harbec works with customers on product design when customer requirements fall outside its core competencies. One such project was a test stand for a germ-sensing device involving nanotechnology. Harbec designers worked with the customer to develop the test stand while collaborating on aspects of the moldmaking and injection molding processes in order to provide an easily manufacturable solution at a reasonable cost.

"In this example, collaboration with our customer allowed an improved understanding of design and tooling choices—a critical aspect for a project of
These are examples of another potential of Harbec's QMS system. They are nylon parts produced by a DTM Sinterstation. The parts are functional and accurate and were produced within two days.
this scale, since interferences and incompatibilities in the tooling could take weeks to solve and cost tens of thousands of dollars," says Bechtold.

In another example, working with a Detroit-based company that manufactures fuel delivery systems, Harbec cut a week from the time required for review and approval of a design change. The client's existing product had a fuel bowl positioned over a filter and held onto the body of the filter by a metal ring and gasket. Harbec engineers eliminated the metal part and gasket, replacing the assembly with a single injection molded part. The new part reduces assembly time and cuts component costs, while eliminating the potential for a leak.

"We initiated a OneSpace session to review the proposed design change, and within 20 minutes had approval to proceed," says Bechtold. "Without online collaboration, it would have taken a week to schedule an onsite meeting and get that approval. We also saved the cost of travel."


Competitive Edge
Ultimately, customers care about the quality of Harbec's work and the speed with which it completes projects. But many potential customers are interested first in learning about the process a molding company will use. Harbec shares its online collaboration and QMS programs with customers who want an insider's perspective.

"You're always looking for something that will interest a potential customer and make you stand out from the competition. The ability to collaborate is helping us to differentiate ourselves to that customer," Bechtold says. "It shows that we're the kind of company that will be able to do parts faster, cheaper, and with less risk."

     
During an online session (right) at Harbec, the project manager (pointing at the screen), the model shop manager (with the calendar), the tool designer (far left) and the toolmaker are in real-time conversation with an engineer and a project manager from the fuel system customer's company. They discussed the proposed one-piece design and reached agreement in roughly 15 to 20 minutes. Below, two tool designers and one project manager in an online session with the customer in Detroit discuss an additional design detail.


Meeting online
In an online session, each team member loads the CAD model onto his or her computer, regardless of the CAD software used. Each participant can see the same model being manipulated by other team members. It can be rotated, changed, and annotated. Team members have the potential to take control of the model at any time in the meeting and suggest ideas while manipulating the model.

One of the most powerful features of Harbec's online collaboration capability, Bechtold says, is CAD neutrality. "I've been involved in an effort to find real-time collaboration solutions for years. Among large companies involved in that search, the general mentality has always been that we were waiting for the ultimate translator—a neutral language—to bridge the gap between different CAD systems. Some people thought IGES was that ultimate translator, others thought STEP would be it."

Although CoCreate didn't find a universal language, it solved the problem by enabling all of the existing ones to be used. "They have native adapters for every contemporary CAD system out there, so we don't worry about what CAD system the customer has. We know he can work in his system, and we can work in ours, and OneSpace brings us together seamlessly online. We can even bring models from different CAD systems together. This is very powerful as we are able to identify possible interferences and validate the best final solution for the final tooling and assembly process."

Before the company began using the software, Bechtold says, Harbec had developed a collection of CAD viewers that it supplied to its customers in an attempt to achieve the same result. "We dealt with firewall problems and other issues as best we could, but the solution was never as elegant or powerful as we thought it could be."


Contact information
Harbec Plastics Inc., Ontario, NY
Bob Bechtold
(716) 265-0100
www.harbec.com

CoCreate Software Inc.
Fort Collins, CO
(888) 262-7328
www.cocreate.com

Plastic to MIM: A natural evolution

By: Clare Goldsberry

Moving into MIM seemed a natural evolution for custom plastic injection molder Trenco Products Inc. (San Diego, CA). The process allows the company to broaden the services and capabilities it offers to its customers in the medical device, telecommunications, textile machinery, and hardware end markets.

"We're flexible in trying to meet customer requirements in any area they want us to, and we saw MIM as a real growth area," says Mark Jahn, director of marketing for Trenco.



MIM is used by Trenco to service a variety of industries. Gun barrels for the firearms industry, for instance, require no subsequent machining, and golf putter heads of surprising thickness are being produced from a variety of metals, including steel, titanium, stainless steel, and other blends. 


Jahn explains that Trenco was sometimes frustrated trying to meet its customers' needs with only thermoplastic injection molding materials and processes. "Many times our customers needed better properties than plastics alone could offer, even though we were aware of the higher-performing engineering thermoplastics like PEEK," he says. "When we first found out about MIM we got very excited about it, and the board of directors made the decision to move in this direction. It allows us to offer more in the way of customer support across the breadth of manufacturing the product."

Complete Solutions

Trenco started in the custom injection molding business in San Diego in 1987. Since then, the company has added a second plant in the U.S. and two operations in Asia. It was at its Taiwan plant in 1996 that Trenco broke into metal injection molding. Last year, demand for MIM prompted the company to begin offering the process at its Los Angeles area facility.

MIM has allowed Trenco to broaden its services and capabilities, often enabling it to provide complete solutions like this nail gun. Trenco molds the plastic components, makes the MIM components, heat treats the anvil, does the necessary secondary work, and assembles, tests, packages, and ships this nail gun to its customer as a finished product. 


Jahn is reluctant to specify the company's market niches because applications for MIM run the gamut of all industries. But, at the recent MD&M West trade show in Anaheim, Trenco displayed some of the many parts it has made, including barrels for firearms, golf putter heads, and a variety of components for industrial products such as the nail gun pictured at right. Jahn says people are often surprised at the large size of the components Trenco is capable of producing, such as the thick-walled pistol barrel.

"We do much larger parts and more complex parts than a lot of others," says Jahn. "People are amazed that you can mold parts as large as a gun barrel, finish it and blue it, and basically use it as molded with no subsequent machining, except for the rifling in the barrel."

Jahn says the forte of the company is its ability to manufacture and assemble complete products, which it does by offering a broad range of secondary operations. For one product—the aforementioned nail gun—Trenco molds the plastic housings and other plastic components, makes the MIM components, heat treats the anvil, does the secondary work, assembles the product (complete with the motor installation), tests the units, packages them, and ships them to the customer, finished.

"We're very vertically integrated in what we can do from design for manufacturability and moldmaking on the front end through to finished products at the back," says Jahn.

Customer Know-how

Marketing MIM is made somewhat difficult for Trenco because many of its customers consider the use of MIM in their products to be proprietary. "A lot of the parts we do for customers we're not allowed to show because people want to use us as their competitive advantage," Jahn explains. "That's why many people say they have never heard of us. We've been a well-kept secret, but that's because our customers didn't want us known."

Kirk Takvorian, senior applications/sales engineer (left), Ted Hou, president (middle), and Mark Jahn, marketing director, discuss a MIM gun barrel part that must meet stringent tolerance requirements. 


However, it's getting harder to keep the secret. MIM is becoming more well known and accepted as a viable process for many applications across industries. "It used to be that I'd have to explain MIM to everyone, but we do a lot less of that now," he says. "About a third of the customers we come into contact with still need an education, but the vast majority know exactly what the process is all about, how to use it, and what it can do for them as far as eliminating costs to manufacture, particularly on complex components, over the cost to machine parts. The more complex the part, the more cost reduction the customer can expect to see."

Jahn adds, however, that "cost reduction for simple parts can be very cost-effective as well." In fact, the company regularly produces tooling and makes parts in quantities of just a few thousand.

About 40 percent of the company's MIM customer base is in the U.S., 25 percent in Europe, another 25 percent in Asia, and the balance from other regions. To Jahn, MIM appears to be more widely known and used in the U.S. "We have worldwide customers," he says. "It just seems there are more MIM-savvy designers and engineers here in the states, or a greater concentration of them, so most of our work comes out of the U.S." 
Contact information
Trenco Products Inc.
San Diego, CA
Mark Jahn
(858) 587-9681
www.trencoproducts.com
 

Smart molding meets smart molds

Curt Watkins, vp and chief technology officer, Plastics Molding Corp. (far left); Dennis W. Richmond, regional sales manager, Ferromatik Milacron (center); and Kirby Johnson, business development manager, Dynamic Feed Synventive Molding Solutions (right) are shown here with the Dynamic Feed control system, which is helping PMC dramatically reduce tool construction time.
Plastic Moldings Corp. LLC (PMC) of Cincinnati, OH dramatically reduced tool construction troubleshooting time on six very complex multicavity family molds for mobile phone cases and was able to go from art to part in less than five weeks. What's more, its molds produced Six Sigma-quality parts regardless of which molding machine they were run on. One secret of PMC's success was Smart Molding hot runner technology, also known as Dynamic Feed, from Synventive Molding Solutions (Peabody, MA).

As previously detailed (see July 1998 IMM, p. 61), Dynamic Feed is a melt delivery system designed to control the plastic going into the mold through independent, real-time, closed loop process control at each gate. Each nozzle has a hydraulically powered flow control pin that automatically controls injection and pack pressure to balance each cavity accurately.

The other secret of PMC's time-to-market success was its own Modutech rapid tooling process. Its Modutech tools match mold inserts, Dynamic Feed hot runner systems, and premachined core and cavity sets to individual customer applications. The slides and lifters are integrated into these fully hardened production tools.

Maybe you saw a PMC Modutech mobile phone mold running in Chicago at NPE 2000.


PMC is able to mold complex, thin-wall, Six Sigma-quality mobile phone housings in multicavity family molds that it built in record time thanks to the Dynamic Feed inmold process control system.
Smart Molding, Lean Thinking
Way back then, a two-cavity Modutech/Dynamic Feed mold in the mobile phone project was run at the Ferromatik Milacron booth in a Ferromatik Milacron Europe K-TEC 155, an accumulator-assisted racer (for more, see September NPE Showcase 2000 IMM, p. 68). PMC runs more than 50 presses in Cincinnati, ranging from 28 to 400 tons. Most of them are from Ferromatik Milacron.

Tom Hennings, PMC's president, says the mobile phone molds are run with zero inventory in a lean, robotized, single-piece workcell on four K-TEC 155 machines. "The parts are molded, packaged, and that's it, we're finished. We only have a couple of products with any sort of work being done on the parts outside of our cells. Virtually everything we do is done in single-piece flow."

Hennings continues, "We were a beta site for Dynamic Feed. As a matter of fact, we went to Synventive when we first heard about it. We're all on board with it now and the ship has left the dock. It offers tremendous competitive opportunities in both of the industries we serve today—telecommunications and automotive—especially with our Modutech molds."

Time, Hennings says, is of the essence. "Time has always been a big issue, but it's become a bigger one today. Typically, hot runner systems take anywhere from six to 19 weeks to develop, depending on what you're looking for. We had this job running in just over four weeks, but we've done some others in three."


Contact information
Plastic Moldings Corp. LLC
Cincinnati, OH
Tom Hennings
(513) 557-5210
www.plasticmoldings.com

Synventive Molding
Solutions
Peabody, MA
(978) 750-8065
www.synventive.com

What makes for a successful PIM component?

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

Figure 1. The concept of effective density is based on looking at the component mass divided by original volume that would be required if it was machined. This component has an effective density of 1.8 g/cu cm.
Powder injection molding (PIM) relies on a thermoplastic polymer blend filled with about 60 percent by volume of a small metal or ceramic powder. This mixture of polymer and powder is injection molded to form a complex shape. Once molding is completed, the polymer (binder) is extracted and the small powder is sintered. Sintering is a high-temperature heat treatment designed to induce densification of the particles. Accordingly, the final product is typically 15 percent smaller than the tooling, but densified to a level where the mechanical and physical properties rival wrought materials.

Although many complex geometries can be fabricated via PIM, only certain component characteristics prove cost-effective. The small powders are more expensive than wrought materials, so there is an initial material cost penalty. Early identification of designs that match well with the PIM technology helps ensure economic success. Typical considerations involve material, properties, component size and shape, tolerances, production cost, production quantity, and design features. For example, PIM excels at forming shapes with dead-ended holes, dovetails, slots, threads, or curved surfaces.

As a starting point in considering PIM, Table 1 summarizes the typical, minimum, and maximum attributes. Some explanation is in order. In practice, there are many technology variants--powder types, binder formulations, debinding techniques, and sintering furnaces. Such variation affects what is possible in terms of each company's capabilities. Accordingly there are significant producer-to-producer differences, largely dependent on the age of the equipment.


Capabilities of PIM
Complex net-shape components are the main target for PIM. A gauge of the advantage over competitive technologies is the number of call-outs or dimensions on the engineering drawing. A simple shape has only a few features, while a microcomputer circuit has millions of features; both would be poor applications for PIM. Common PIM successes involve several dimensions--a wristwatch case is one example--that matches well with the technology. The most challenging components in production involve up to approximately 130 dimensional specifications.

A simple way to introduce the geometric design window for PIM is to start with a very simple characteristic, a parameter known as the effective density. Density is defined as mass over volume, and usually is given in g/cu cm (water is 1 g/cu cm and most steels are just less than 8 g/cu cm).

For this discussion, let's contrast PIM with machining. The final component is characterized by its geometric aspects, including largest dimension, holes, slots, and other specifications that might include wall thickness. For many PIM parts, the wall thickness is usually small, and might be less than 10 percent of the largest dimension. However, components with aspect ratios (largest dimension divided by the smallest wall thickness) might range up to 120 or more. The blades of scissors are an example where the length is much greater than the thickness, and the thickness is not highly variable. In PIM it is the wall thickness that determines debinding time (time needed to extract the polymer while leaving the particles intact), and is the slow step.

Consider the PIM component shown in Figure 1, which has a mass of 27.4g. If we put an outer box around the component, then we define the volume of starting material that would be required for machining. The final mass divided by the initial volume gives the effective density. In this case, the effective density is 1.8 g/cu cm (27.4g divided by a box of 2.9 by 2.1 by 2.5 cm).

Even this is an underestimate of the starting volume, since it presumes that ideal-sized blocks of steel will be available. In reality there will be more waste and less-than-ideal feed for a machining process. Using this concept of mass divided by the outer envelope volume leads to the bar chart shown in Figure 2, taken from several PIM steel and stainless steel products. Note the high population of components in the 1.5 to 2.0 g/cu cm range (reflecting about 20 percent material utilization).

Figure 3. This scatter plot shows how the effective density clusters against the maximum component dimension, with the bulk of current production being smaller objects if the effective density is high.
Another view of the same components can be given as a scatter plot (Figure 3), which shows the characteristic mass and longest dimension for the same samples. The larger components have lower effective densities. These simple plots show that components with many undercuts, holes, slots, and other features requiring mass removal, such as by machining, are ideal targets for PIM. These considerations illustrate how PIM is best suited f
or components with sufficient shape complexity that machining is unattractive.

Today, typical PIM component mass is generally low, in part because the small powders are expensive. Economic justification is strongest when alternative technologies waste time and material. The general production limit for precise components is 250g (.25 lb), although several special processes have evolved to produce precise components of more than 1 kg (2.2 lb), and current production ranges up to 17 kg (37 lb).

The criteria for early identification of PIM candidate components are summarized here in terms of a few key considerations. Several should be familiar to plastics injection molders:

  • Mass/volume. Seek a low effective density, indicating high material loss in machining and possible gains in productivity via PIM. A target would be about 20 percent of theoretical density.

  • Quantity. Tooling and setup costs are not justified for low production quantities. Seek production quantities from 5000 or more a year, preferably at least 20,000 per year.

  • Material. PIM is easier to justify for materials that are hard to machine.

  • Complexity. Seek components that require multiple axes for indexing during machining.

  • Performance. If performance is important, then the properties attained via full density sintering are justified.

  • Surface finish. At no additional cost PIM can deliver relatively smooth surfaces, so use this advantage when possible.

  • Assembly. Look for opportunities to consolidate several parts into a single piece to save on inventory and assembly costs.

  • Novel compositions. Use material combinations that are difficult via traditional processes. For example, wear-resistant stainless steels are possible by adding a small proportion of ceramic particles to the feedstock.

For more information about injection molding powdered metals and ceramics, check out the latest copy of IMMC. Look for more articles on this topic to come in future issues of IMM.

Contact information
Center for Innovative Sintered
Products, Penn State University
University Park, PA
Randall M. German; (814) 863-8025
www.cisp.psu.edu
[email protected]
aIMM Infolink 287

Industry Watch

TXM design guide 
Design engineers and others interested in unlocking the secrets of how to design parts that best exploit the benefits of the TXM process now have a new asset. Thixomat Inc. (Ann Arbor, MI) has completed a CD-ROM design manual for the company's patented TXM process.

Nearly one year in the making, the new design guide details all the steps involved in taking a TXM product from art to part. It includes information on properties, part configurations, dimensional tolerances, prototyping, and tooling. Part finishing, joining and fastening, and defect prevention guidelines also are included, as are illustrated examples of TXM parts, tables, and case histories.

Steve LeBeau, Thixomat's vp of sales and marketing, says he is very pleased with the feedback he's already received. "I called one design firm out in the western U.S. to find out if they liked it," LeBeau said. "They told me they'd already burned over a dozen copies to distribute to their engineers. Our marketing is primarily an education process, and the design disk is not copyrighted, so people who receive one are free to burn as many copies as they want."

Each TXM licensee will receive a free CD-ROM. For others, the cost is $20. However, in lieu of payment to Thixomat, company officials would prefer purchasers make a donation to the charity of their choice, or to Child Hope International (1703 Columbine Rd., Colorado Springs, CO 80907; [email protected]). For more information about the design guide, go to www.thixomat.com.


Feedstocks attain a newer, roomier latitude

The MIM business infrastructure has recently experienced a major change, one that has the potential to further accelerate the growth and acceptance of this technology. Latitude Mfg. Technology (Hackettstown, NJ) has obtained all the intellectual property rights and licensing privileges to make


Latitude Mfg. Technology has obtained rights to make and sell PowderFlo MIM feedstocks. Metal parts molded from PowderFlo were displayed prominently at NPE 2000.
and sell PowderFlo MIM feedstocks formerly supplied by Honeywell (Honeywell has retained its CIM materials). In addition, Latitude is partnering with RTP Co. (Winona, MN), a leading compounder of advanced injection molding materials, to make its PowderFlo MIM feedstocks.

Paul Stepanoff, Latitude's president and ceo, plans to transform the PowderFlo supply business model to make MIM more attractive to plastics injection molders. A former vp of engineering at a major plastics molder himself, Stepanoff says Latitude will provide free development licenses to injection molders and cut by about half the commercial license fees Honeywell had tagged on to its PowderFlo feedstocks. Technical support services will be bundled with the materials to help newcomers to MIM.

"Over a period of, say, a couple of years, Latitude will provide a licensee fee structure proportional to the yearly feedstock usage of the licensee, one that will include our technical support," Stepanoff says. "Why should molders new to MIM have to do it all on their own and pay for it all by themselves, especially when it comes to understanding powder metallurgy, debinding, and sintering?" Stepanoff asks. "We also plan to ally ourselves with toll sintering houses that we can recommend to customers. This would help get them into production faster, before they have to decide on bringing sintering furnaces in-house," Stepanoff says.

Additionally, Latitude will cut the cost of PowderFlo MIM pellets in half, bringing the cost of PowderFlo stainless steel feedstocks, for instance, to approximately $10/lb, according to Stepanoff. PowderFlo features an environmentally friendly aqueous-gel binder based on agar, which, when combined with water, allows the feedstock to run at relatively low temperatures and pressures, much like a low-viscosity commodity thermoplastic. After the green parts are dried, they can be debound and sintered in the same process, speeding overall cycle times. (For more technical details, see December 1999 IMMC, pp. 21-22).

Timing right for system manufacturer to expand
An industry-wide trend favoring full systems rather than individual components and MIM parts over machined steel has spurred BorgWarner Morse TEC to expand its engine timing system business. The company moved its engine timing operations to a 133,300 sq-ft former industrial facility in Cortland, NY. The plant was renovated to meet BorgWarner's needs. The Cortland operation currently employs 120, but an additional 70 workers will be needed to meet growing customer demand, according to the company. BorgWarner is a global producer of chain systems and components for engine timing, automatic transmissions, and four-wheel drive applications. Clients include Ford, DaimlerChrysler, GM, Toyota, and Volkswagen.


MIMA can help you get started 
Are you a metal or ceramics injection molder, a moldmaker, a supplier of feedstocks or powder materials, or a supplier of primary processing machinery interested in selling to the high-growth MIM marketplace? If so, representatives of the Metal Injection Molding Assn. (MIMA) say a good place to start is membership in its international trade association.

MIMA is one of six trade associations in the Metal Powder Industries Federation (MPIF). MIMA develops technical materials, test method standards, statistics, and survey data. The association also performs public relations and market development services, as well as providing sales leads and management information to its members.

Through the MPIF, MIMA sponsors design seminars for the marketplace, industry-related short courses, and produces educational videos, technical brochures, and product directories. It also supports Internet services and government relations as well as coordinates its standards activities with ASTM and ISO.

MIMA convenes two membership meetings each year and is instrumental in organizing state-of-the-art technical sessions for the MPIF's annual technical conference. Annual corporate membership fees are $3020.

For more information or to find out if you're qualified to join, contact the MPIF (Princeton, NJ) at (609) 452-7700 or sign onto www.mpif.org.


All things PIM on the Web 
ComplexShape.net is a new online resource for designers, engineers, and business professionals who have an interest in powder injection molding. The site offers visitors PIM background information, including frequently asked questions. PIM industry contacts for processing, supplies, and design are also given. Questions can be referred to a group of online PIM experts, and a calendar lists upcoming seminars for the technology. Sample products and applications can also be viewed. The site, which covers metal and ceramic injection molding, is sponsored by the International Powder Injection Molding Alliance.


TXM conference goes for three 
The Third International TXM Magnesium Conference will be held next month, May 22-24, at the Wyndham Bristol Place Hotel in Toronto, ON. In addition to attending presentations on TXM technology and market opportunities with displays of TXM parts, conference attendees also will visit the global HQ of Husky Injection Molding Systems Ltd. in Bolton, ON. Husky, one of Thixomat's licensed machine builders, plans to formally introduce its first commercial TXM press, a 500-tonner, to attendees. Last year's conference was held in Hiroshima, Japan. You can read about a presentation given there by National/Panasonic on p. 6. For more information go to www.thixomat.com

Simulating PIM in true 3-D


Using Sigmasoft's true 3-D volume elements, designers can analyze thick and thin areas, model flow phenomena such as jetting, and use the program's fully coupled thermal and fluid flow calculation.


By: Michelle Maniscalco

A new simulation code that uses 3-D volume elements is now available. Based on software developed for metal castings, Sigmasoft uses its 3-D feature to model thick and thin sections while looking at all dimensions. This development is a big asset for PIM part design.

According to Lothar Kallien, head of Sigma Engineering GmbH (Aachen, Germany), the use of these elements in injection molding simulation has many advantages. "Flow simulations are normally done in 21/2 dimensions using midplane collapsed sections. The Sigmasoft simulation program includes true 3-D elements," Kallien explains. The key to simulating PIM properly lies in being able to accurately model thickness changes. "For example," he says, "thermal effects at the base of ribs can only be detected by 3-D models. Key areas such as thickness changes or the area of a rib really need true 3-D. Assuming planar flow, true 3-D can look at all dimensions."

Sigmasoft can also calculate the speed of heat transfer and depict the core and cavity around a part. Inserts and the tool are part of the model, and both are calculated in 3-D. "The program can read all components down to the date stamp of the tool in order to visualize thermal reactivity of the tool for many cycles," he adds.


Benefits of using 3-D volume elements in Sigmasoft include the ability to simulate water flow and postmold cooling in room temperature. The software also has a module to simulate thermal transfer during sintering.


Other benefits of the 3-D elements include the ability to simulate the kinetic effect of fluid flow and postmold cooling to room temperature. It can track air pressure in the tool to indicate areas that need venting.

Automatic meshing capabilities are standard with the software and typically create a controlled-volume mesh in minutes. Models can be sliced in all three dimensions to zoom in on an area of interest.

Kallien plans to work with PIM expert Randall German of Penn State to further develop Sigma's software in collaboration with MIM molder Advanced Materials Technology. He has also done 3-D fiber orientation simulation in thermoplastics using Sigmasoft to determine fiber warpage.

With Sigmasoft, designers can see the surface of the flow front as well as the thickness. Designs can be imported from most major CAD systems. Sigma is represented in the U.S. by Torsten Kruse and his firm Kruse Analysis, which also provides analysis services.

Contact information
Sigma Engineering GmbH
Aachen, Germany
Lothar Kallien
+49 (241) 89 495 0
www.sigmasoft.de

Kruse Analysis LLC
East Haddam, CT
Torsten Kruse
(860) 873-2960
www.kruseanalysis.com
[email protected]