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REPRINTED FROM MODERN PLASTICS - June 2000
Industry weighs in on promising microcellular foam technologyProcess benefits and license model may speed market acceptance of process. Trexel Corp. is convinced that it has in its MuCell microcellular foam process a sound technology for reducing the weight and cost of molded parts. For a new technology to catch on in global molding, however, more than a promising concept is needed, declares David Bernstein, president and CEO of the Woburn, MA venture capital company. The other key ingredient, is a model for commercializing the process that gets it in the hands of pioneering molders and end-users through a licensing program that is timely and cost -effective. Further, the licensor must offer support technologies, and spur advances that reduce risks and troubleshoot the problems that inevitably arise when novel processes are applied. Trexel has taken the innovative step of licensing the process to six machine OEM's, in an effort to make the technology available to the largest number of users in the shortest time. NPE this month will be the formal debut of this process on multiple stands. Usually, proprietary technology is licensed to processors on an individual basis, slowing its market penetration. The extent of Trexel's success in meeting these goals will be visible on the show floor at NPE, where three molding presses, each adapted under license to the MuCell process, will run parts. The machines involved are a 66-ton vertical press by Arburg, Newington CT, a 310-ton wide-platen toggle unit from Ferromatik Milacron, in Cincinnati, OH, and a 1000-ton, two-platen machine built and adopted by Engel, in Schwertberg, Austria. All units have been sold, and will be shipped direct from the show. What Trexel's process does is embed an atmospheric gas, usually nitrogen, evenly in molded parts in the form of millions of minuscule (under 50-microndia) voids. Demonstrations at NPE will show that the outcome is part lightweighting and improved processability. Trexel is eyeing potential in large automotive parts, thinwall business machines, appliance and consumer goods housings, thin-wall food packaging, and the encapsulation of electrical/electronic devices. "The process is in its infancy in molding," says Brian Bishop, sales vp. at Engel. Trexel offers separate licenses for machine builders and end-users. Bishop, in a conservative assessment, estimates that at least 10% of global molding stands to gain. He says about 10 MuCell-capable (mostly small-tonnage) presses have been sold, and trialing time at Engel's applications facilities is booked beyond September. John Adamowicz, Arburg's engineering manager for MuCell, envisions up to 30% of global molding potentially benefiting from the technology. More immediately, he stresses its potential as "problem solver" or "fixer" in tackling some intractable molding challenges. Equipment suppliers affirm that Trexel's process looks promising, but cite uncertainties: the extent of properties losses incurred, cosmetic deficits, and stability during high-output production. Peter Mooney, a consultant in Advance, NC, and author of a study of new technologies emerging in molding, observes that "signs of creative destruction brought by new process technologies are everywhere, as are venture capital models for bringing them to market. "The track record in plastics is disappointing, Mooney adds, citing the case of gas-assisted molding. He says legal disputes, relatively high-licensing fees, and overlooked process limits have led to "a far slower pace" of advance for that technology than appears to be warranted. When asked to access MuCell, Mooney voices what he terms the critical issue. He asks how much the technology will cost, how quick the payback will be, and what risks exist for processors. Potential of new process to be shown at NPE 2000 The concept of putting nitrogen into the plastics is by no means new in molding. Gas-assist molding concentrates nitrogen in part cores. Coralfoam, Petworth, West Sussex, England, has its Gas-in-Mold (GIM) system for feeding gas into moldings. Structural foam molding commonly makes use of chemical blowing agents in a conventional press to create lightweight parts. Reedy International, Keyport, NJ, has patented a variant that blends blowing agents and gas in molding. Aspects of Trexel's process, however, make it distinctive. One is the introduction of gas into machines as a supercritical fluid (i.e. under intense heat and pressure). As melt is injected into the mold, nitrogen reverts to gas, creating the myriad of voids. This method is said to create highly consistent structures as compared to other methods. Trexel claims it can mold thin-section parts and keep the appearance of parts being solid. The process enhances productivity first because the voids reduce part weight, usually by around 10% to 30% or higher. Also, when the melt enters a mold cavity, released gas acts as a highly efficient processing aid, reducing melt viscosity and thus shortening cycle times, filling long flow paths, and making parts with dimensional stability. Finally, the release of gas significantly reduces melt pressure, so that clamp tonnage needed to fill any particular mold is far less than for a conventionally operated machine . For molders, this means lower investment in new machinery and considerable energy savings. Benefits will be shown in the following NPE demonstrations:
Meanwhile, interest in the process has been heightened in recent months by moves by equipment suppliers to take licenses to adapt their machinery. They are, in addition to the three mentioned, Husky Injection Molding Systems, Bolton, ON, Battenfeld GmbH, Meinerzhagen, Germany, and JSW Machinery, Tokyo. The biggest unknown in microcellular molding is the nature and extent of property tradeoffs incurred at various levels of gas use. Indeed, Kaysun's initial goal is to "draw a map" of what happens to the properties of engineering resins when using the process, reports Bruce Wendt, Kaysun's president. "About 25% of our product mix is amenable to this process, and the OEM's we serve want us to investigate its use," Wendt says, speaking of business machine, medical, automotive, and telecommunication makers. "We plan to be experts on property tradeoffs," he says, portraying that as a platform for forging a competitive edge in new product design in non-cosmetic parts. DuPont is already well advanced in the systematic testing of PBT, nylon 66, and its other materials when used in the process. In an initial, and cautious assessment, Boyer reports that DuPont's materials, processes by MuCell, behave in "relatively repeatable and controllable ways." Essentially, as more gas is used and density is reduced, properties fall off, but in a fairly linear relationship. Boyer notes that current data is short-term, with long-term dimensional stability results, for instance, still far from confirmed. Testing by DuPont is anticipated, creating a database that will allow designers to use the technology in appropriate ways to cut part cost. Engel's Kai Jacobsen says that testing suggests that tradeoffs in physical properties are heavily influenced by part and tool design, as well as by specific material used. Increasingly, designers in the future will be able to minimize properties tradeoffs associated with use of the process. A second current deficit in microcellular foam is surface cosmetics. Class-A, high-gloss finishes are not feasible, because some gas does break the surface, creating swirl effects. But cosmetic properties are often "good enough" for a broad spectrum of parts. Longer-term, the Battenfeld Group views conjection as a promising way to tackle this deficit. In June, it expects to convert a coinjection machine to MuCell. Coinjection promises to offer benefits of a microcellular core structure, along with prime cosmetic quality in solid skin layers. A process closely comparable to that of Trexel is Coralfoam's gas-in-mold, a system that delivers nitrogen into the front section of the barrel. Reports Peter Clarke, the company's head of engineering. He claims that similar processing and lightweighting benefits occur, through the microcellular structure is different. In GIM, a skin is created on parts, and variable density foam achieved in the core. Until now, PP has been the material of choice. "The Achilles heel of Trexel's process in thinwall packaging is cycle time," Clarke says. He cites the one current commercial application for GIM: cutlery made by a U.S. molder. GIM gets a 3.2-sec cycle time. In items that are 0.375 in thick., Clarke claims. He argues that this result far exceeds reported cycle time performances typical for the Trexel process. Shortly, a thin wall soup cup made with the GIM process will be commercialized in Europe. In addition, a thin, wire-replacement coathanger, made of PP is being considered for conversion to GIM. Coralfoam is making progress in using the process with styremic resins, and in new markets from meat trays to industrial crates. A license for GIM involves a flat fee, and a 6% royalty on raw materials used. Broad accessibility at a predictable cost In five years, Trexel has poured $20 million into a viable model for getting MuCell into commercial markets. The linchpin is issuing separate licenses to the machine makers (OEM licenses) and those who use machines (end-use licenses). OEM licenses grant machine builders access to Trexel's patented technology, e.g. special barrel and screw design. The licensees estimate the price tag for a MuCell-capable injection unit at between 30% and 50% higher than for standard machines. Converted units continue to be capable of running in the conventional mode. End-user licenses are for a specified machine and involve annual fees over typical seven-year amortization periods for processes, with no royalties. The annual fee on a 200-ton press is $15,000/yr. Fees rise as machine size increases, says Dan Szczurko, vp of business development. In addition, Trexel supplies the supercritical fluid unit and control needed to feed gases into the press, at a cost of $70,000 for the first unit. Trexel's Bernstein emphasizes the firm's commitment to providing predictability to end user licensees in terms of licensing conditions, access to know-how, and intellectual property rights protection. Trexel lays claim to a strong patent position, and process-related advances made by end user licensees are retained by Trexel to keep them readily accessible. "Using new technologies is always a calculated risk, and the outcome depends on how one uses it," says Brian Worthington, R&D director at Hanson, a custom molder and tool builder in Ludlow, MA. The company has converted a 400-ton Engel machine to MuCell with a view to using it as a "differentiation tool." Worthington says conversion costs and fees are considerable, but he expects new markets to be created. Hanson is a part of the United Plastics Group, Bensenville, IL. In general, Worthington says, Trexel's process lends itself well to existing tooling, with minor modifications. In one recent case, Hanson was asked to modify an existing tool for a long, flat part, which failed due to dimensional stability deficits. Now, the tool is being run successfully, after minor modification, in microcellular foam. Meanwhile, the entry of Husky and other new equipment suppliers in offering adapted units is likely to greatly broaden the reach of the process. Husky plans to explore the technology across its entire line (from 65-to-8800-ton sizes), and in segments from autos to thin wall packaging. In packaging, one limit may be clarity, which can be disrupted by the voids. Willi Meyer, Husky project manager, says a 175 ton S-series unit has been converted to do customer tests at the firm's applications development center in Bolton, ON. "The S-series lends itself well to exploiting MuCell's productivity advantages," comments Meyer. Meyer says the goal is to explore the applicability of MuCell in various applications, and gain understanding in optimizing Husky equipment for its use. He emphasizes one requirement in using hot-runner systems with the process: to maintain the specified pressure on the melt needed to keep gas in solution, it is essential for all hot-runners to be valve-gated. JSW says it will be first to adapt an electric-hybrid class unit (the J200EL III) for microcellular molding. The unit, designed for high-speed thinwalling, is all-electric except for the hydraulic injection portion. "There have been dozens of inquiries about MuCell molding from Japan in recent months," says Jerry Johnson, vp of operations at JSW's technical center in Elk Grove Village, IL. The initial MuCell-capable J200EL III will be in place at the center by July. Technical support will be supplied by the Sanpho Group, Yokohama, Japan, and Boston, MA. "This is a dream technology for Japan, with many trends favoring its adoption there," remarks Yasuhide Sunamura, Sanpho's CEO. Regulation tends to favor nitrogen and CO2 use rather than emissions-producing foaming agents in Japan, he explains. Another driver is energy efficiency. Finally, interest in the cost-reducing benefits has been "early and intense" among Japan's manufacturers in automotive, telecommunications, and construction (e.g. mobile home panels). A problem solver and differentiator One of Trexel's earliest alliances was with the Mar-Lee Companies, Leominster, MA, which in mid 1999 established a technology center, with microcellular foam as one core area of interest. Mar-Lee builds tools specifically for the MuCell process. Indeed, Mar-Lee is the first to announce a commercial part using the process. This is a gate cover for a child's safety gate made by Safety 1st, an OEM in Canton, MA. John Gravelle, Mar-Lee's president, adds that this project also laid to rest a doubt about process stability and control. That was driven home in a recent five-day, 24-hour per day run of the Safety 1st part, implemented without major interruptions of glitches. Gravelle reports that around 25 customer programs are underway at Mar-Lee and anticipates typical return-on-investment results of less than a year. Another Mar-Lee thrust is to build molds that address deficits of the microcellular foam. Gravelle says the texturing of existing mold surfaces is often affective in getting a "cosmetically acceptable" part. Texturing works best in lighter colors (white, off-white, gray). Polymer Concepts, in Randleman, NC, reports heavy demand for machine time on its adapted Engel 200-ton tiebarless machine by OEM customers seeking to evaluate the new process on existing tools. "We find clamp force requirements are reduced by around 100%," says Larry Draughn, president of the startup firm. Draughn says interest in parts made of engineering resins is high, since a typical 25% weight savings quickly translates into a big cost savings. Yet Draughn says his first commercial MuCell parts, rear and front protective plates for motors used in electric carts and forklift trucks, are made of PP. Injectronics, in Clinton, MA, is an early user of a 200-ton tiebarless Engel press, and expects initial MuCell non-cosmetic parts to appear in 2001 model U.S. vehicles. Neal Elli, president of Empire Precision Plastics, buyer of an Arburg press, portrays it as a "problem solver" in existing and new applications where the encapsulation of sensitive parts is required. One promising example is a precise sensor float used to monitor critical fluid levels in some industrial equipment. The parts function effectively when density is even in all directions and tolerances are tight. Worthington of Hanson says his goal is to understand the process better and "push it to its limits." He remarks that steps towards controlling the process, and recognizing the benefits it brings in each application, are just beginning. Nevertheless, "cost structures in molding are being redefined as we speak." Worthington concludes that exploring new and accessible technologies is more essential today than ever. Return to Top | Return to Magazine Articles 00-01 |
