Sponsored By

March 5, 2003

17 Min Read
RIM is growing, and not just in cars

feature7.jpg

Electronics and sensor encapsulation while still in the mold is shown in this photo from Hi-Tech Engineering.

The mood in the RIM business is more upbeat than in most other sectors of the plastics business.

When the Alliance for the Polyurethanes Industry (API) met in Salt Lake City last November, the lead item was the growth in polyurethane (PUR) applications in the automotive industry using reaction injection molding (RIM). Seat cushions and console panels were singled out as hot segments. ?We?ve become economically competitive, but that?s not enough,? said Hermann Schaller of the Belgian multinational Recticel. ?We?re looking to go further.?

RIM already has gone further, by capturing other applications, and continues to look healthy?no small achievement, given the current economy. Automotive is still the leading attention getter, but many industry specialists with whom PM&A spoke were quick to point out new RIM applications in other fields. Overall, the picture is positive.

Otto Huiber, for example, of Hi-Tech Engineering?which supplies a wide range of RIM production systems from its base in Grand Rapids, MI?says the scope of the RIM business is broadening. The auto industry is good but slowed by the economy and currently beset with more capacity than demand. Another oft-mentioned segment, insulation panels, is holding steady, and applications such as seating and refrigerator insulation are on hold awaiting regulatory approval for blowing agents. When the overall economy recovers, prospects are good for all these segments.

feature8.jpg

Hi-Tech Engineering developed the high-pressure Eco-RIM system that eliminates solvent flush as a higher-precision alternative to low-pressure systems while still holding to the low-pressure price point. Eco-RIM will generate low- or high-density, rigid, integral skin, flexible foam, and cold-cure elastomer products.

Meanwhile, there is some vitality in gasketing, encapsulation, and sealing for a range of industries, particularly electronics. Huiber notes that components of both consumer and industrial products are becoming not only smaller but also more fragile. Low-pressure, low-temperature RIM processing has a real advantage. Plus, the mechanical properties and surface quality suit the finished products.

Compared to thermoplastics, RIM polyurethane offers lower tooling costs thanks to low-pressure molds and the elimination of material waste from runners. Multiple cavities have become the norm for these products, four and six being most common, and some products are going to 12 cavities to cut costs. Material cost is usually higher than thermoplastics, but Huiber says the overall cost equation definitely favors RIM-PUR.

Huiber says processing machinery improvements are supporting the growth. His company, Hi-Tech Engineering, has been busy improving its control systems, making them more powerful and precise process managers, as well as easier to operate, via simplified graphical interfaces and touchscreens.

Huiber says OEMs calling for shorter runs and more color changes are driving processors toward more versatility. In response, Hi-Tech?s machines have become more flexible. With a typical traditional machine, changeover from a seat cushion to a door panel could take half a day. Huiber says that time now can be as little as half an hour. Moreover, the material used?that is to say, wasted?during the change has gone from 20 or 30 gal to 2 or 3 gal. Huiber says this comes from simplifying machine design such that far less testing and calibration is needed during both setup and operation. Hi-Tech found that simplicity appeals to processors, the proof being that the company is seeing less interest in elaborate machines vs. simplified systems.

feature9.jpg

The high-quality surfaces produced with Krauss-Maffei?s Clear Coat Molding (CCM) system result from a new transfer-mixing head and the latest RIM-Star 8/8 machine. Insulated tanks, lines, and pumps, plus heated pipes and hoses ensure constant high processing temperatures from daytank to mixing head.

Multimarket, Multiregional Growth
Michael Mölzer of machinery supplier Krauss-Maffei (Munich, Germany/Krauss-Maffei USA, Florence, KY) sees RIM growing 3 to 5 percent annually, depending on the market segment. Future expectations, though a bit guarded because of the slow world economy, are positive. He says the auto industry?s ever-shortening product life cycles necessitate shorter development cycles. Add to this the desire for more model customizing and the result is smaller overall volume per mold and fewer production orders. OEM product changes that formerly occured every 6 to 7 years now happen every 3 to 4 years, and even that will likely become shorter. It is still easier, cheaper, and faster to tool up for RIM production than for metal.

Automakers speak openly of giving customers more choice, and of creating appeal for a model through special features, colors, and design packages, often in a limited series. This points to a decrease in the average number of vehicles per model and/or design series, but it does not contradict the trend to common vehicle platforms. What is put on those platforms will be varied, not the platforms themselves. Since both exteriors and interiors figure into the automakers? plans, it portends well for plastic materials in general and for RIM-PUR in particular. Mölzer says other smaller but still substantial segments where RIM should thrive include large and small appliances, technical products, enclosures for electrical and electronic devices, and medical devices.

feature10.jpgOne molder, two different awards

GI Plastek took two awards at the 2002 SPI Structural Plastics Div. parts competition. Both were for what could be called ?value-added? services beyond simply molding the parts, but they are very different from each other. One award was for GI Plastek?s two-stage ProTek inmold clear coat, which provides weathering resistance and appearance retention to components of Caterpillar?s (Peoria, IL) Challenger Tractor (above, center). Having used RIM elastomer fenders in a previous model, Caterpillar added a heating/ventilating/air conditioning (HVAC) cover and outer roof for the new series. The outer roof is RIM structural foam coated in yellow with a white base coat. Core pulls in the nickel shell mold allow production of both a U.S. version with light openings and an EU version without. The HVAC cover and fenders are elastomeric RIM and core pulls are also used in the fender molds for versions with and without holes for mud flaps.

Caterpillar wanted to clearcoat all exterior trim pieces, metal and plastic, and wanted to stay with inmold coating for the plastic parts. OEM and molder together developed a two-stage inmold coating (IMC) process in which a specially formulated clear coating is applied to the open mold cavity, followed by the pigmented coating. Color and gloss retention are comparable to post-applied basecoat/clearcoat systems and better than single stage post-paint. The results exceed the OEM?s one-year accelerated weathering performance requirements for color retention and gloss retention?even after the equivalent of three years? exposure.

feature11.jpgThe second award was SPI Structural Plastics Div.?s environmental honor, given for the use of a soybean-based feedstock to RIM process an access door for a John Deere Harvester Combine (right). The material is a special formulation of Bayer?s Baydur HD foam RIM PUR incorporating soybean feedstock. Weighing 35 lb and measuring 52 by 28 inches, the door uses about 14 lb of soybeans. For comparison, a bushel of soybeans weights 60 lb. Although it is strong, the door weighs 25 percent less than steel, and is coated with GI Plastek?s ProTek to retain good appearance characteristics.

Because soybean oils and fats are chemically similar to the triglycerides in petroleum, beans can be processed into polyol components for PUR formulations. In the U.S., soybeans offer a source that is renewable, not import-dependent, and abundant. Grown in 29 states, soybeans are the second largest U.S. cash crop and the number one export crop. The United Soybean Board says a conservative estimate indicates soybean demand for plastics could exceed 7 million bushels annually.


On another front entirely, Mölzer says pipe insulation holds much promise for RIM-PUR. Eastern Europe illustrates the point. For example, Russia has an estimated 800 km (460 miles) of heating pipes, 70-80 percent of which are old, leaking, and uninsulated. While all the refitting won?t happen overnight, it offers a good prospect for the next 10 years, particularly with the predicted increase in energy costs. The markets for insulation and other panels for construction and remodeling can be expected to respond similarly, says Mölzer, probably in the mid-term.

Growth potential includes Eastern Europe and then China, Mölzer says. Figures from the VDMA, the German plastics machinery makers association, as well as Krauss-Maffei?s own numbers, point to continuing growth in China. There, too, it will not happen overnight, says Mölzer, but given China?s economic growth rate, increasing numbers of people will want and be able to afford more consumer items. Autos and appliances always top the shopping list.

Mölzer says that, contrary to popular belief, processors in China are not all using old equipment and outdated technology in antiquated buildings. Many plants use state-of-the-art equipment and are clean and logistically well-organized. With the low cost of labor there, you find noticeably less automation than in Europe, but the rest of the RIM plants?mold carriers, process controls, and mix heads?are about the same.

In the automotive market, Mölzer sees much activity for RIM in roof modules, both interior and exterior, and notes that some very creative thinking has already put many new ideas into play. For example, obtaining a Class A surface by RIM backmolding onto an inserted surface foil is on the upswing. The roof module of Smart Car?s new models will be made with a Class A finish on newly supplied Krauss-Maffei RIM-PUR equipment. Mölzer says reduced equipment cost on both the dry and wet sides is a strong factor in selecting RIM-PUR for these parts.

Krauss-Maffei?s recently introduced Clear Coat Molding (CCM) system offers yet more proof that RIM-PUR versatility is catching on. It is an in-the-mold coating solution for pieces such as auto interior decorative trim made of wood or wood veneer, and other molded pieces. Time-consuming multilayer coating operations?and their environmental issues?are history. With CCM, the article is inserted in a mold with a cavity allowing for the coating thickness. The mold closes and the gap between article and mold wall is filled at high pressure with two-component PUR. Mixing and metering is precise, repeatable, and bubble-free. Since the finished surface reflects the cavity wall, no finishing is needed. The aliphatic PUR, which can be rigid or flexible, colored or clear, is nonfading, and bonds firmly with wood, metal, and various textiles.

In a touch of irony, the ProTek Class A surface has become so good that a client recently asked that an ?orange-peel? effect be added?so the PUR part would match adjacent vehicle components.

Besides internal and external vehicle components, items such as medical trays, petri dishes, and furniture components also call for a non-fading, scratch-resistant surface. The coating process currently used typically consists of a pre-treatment followed by up to ten or more coats. Each coat needs up to 20 minutes of gelling time. These intermediate layers usually need grinding and polishing. There is a final curing time of 48-72 hours, after which the top layer must be ground for uniform layer thickness and then polished. Processing is thus measured in days and environmental issues exist all along the way. Environmental issues are minimal with CCM as it is a mold-contained process, and the part, except for cooling time, is ready out of the mold. Any questions?

Krauss-Maffei?s CCM System is already in use, making auto components in Hungary and Belgium. A machine is going to China. One auto supplier who has been using a CCM system for several months will invest in five more shortly.

Market drives RIM Technology improvements
Michael Mölzer of Krauss-Maffei says we can expect to live with pump and piston machine technology for the next 10 years or so. But within that frame a lot is changing. Mölzer points to mixing head design as one area that had to change. Material suppliers have been working hard to produce formulations that reduce RIM cycle times toward the realm of thermoplastic processes.

When cycles shorten, curing time becomes an issue and the materials themselves are more sensitive due to their heightened reactivity, or to processing variables. The traditional position of the component nozzles in mixing heads has been facing each other squarely. Isocyanate and polyol come together directly and mix. Mölzer says learning that combining components at an angle improves mixing has led to new designs that considerably speed up the mixing process. The thinking now is to use each of the three axes and the resulting ?spin? effects. A new Krauss-Maffei mixing head design using angled mixing also includes improved controls and nozzle design to make it all work. A given product may need six or seven shots at about 0.5 seconds each. The nozzle must open and close very quickly, and advanced frequency controls are needed to change the pump speeds rapidly.

The need to increase product flexibility is also spurring Krauss-Maffei?s development on the dry side of the process. Fifteen years ago, the carousel was a big breakthrough, radically increasing productivity. Now the challenge is imposed by the need for frequent model and color changes. Mölzer says color change, in particular, is much more in demand. The mixing head designs his company showed at the K 2001 Show in Germany support clean shot-to-shot color change.

Another feature on the rise is robotic changing of mixing heads between shots. Mölzer says quick-change couplings make the process fast and secure enough that the change can be made during curing time, or possibly while a carousel turns for the next shot. The initial spark for this came from shoe sole makers and has found its way into many markets where customers ask for color and model variation while production batch quantity shrinks.

feature12.jpgRIM-DCPD is opening a new application zone

DCPDmolding material for RIM processing is not new. Developed in the late ?80s, it has been steadily finding its niche in the gamut of processes used to make large structural parts. That niche, based on a mix of part volume, complexity, cost, and performance factors, has turned out to be a fairly broad territory right in the midst of processes such as injection molding, hand layup or spray glass-fiber reinforced plastics molding (FRP), processing sheet molding compound (SMC), and resin-transfer processing (RTP).

Body panels for agricultural and construction vehicles and large trucks, where the demands for appearance and performance over time are high but the volumes are relatively low, are the largest application area so far.

With molders like GI Plastek and others in the U.S., LCM in England, Wayand in Germany, and several in Japan leading the way, the niche is expanding. Metton America, which was part of Hercules during the development and launch of DCPD, is now a leading supplier with production facilities in the U.S. and Japan. Its DCPD material goes under the tradename Metton LMR (liquid molding resin).

Garland Lee of Metton America says the two-component material works in normal low-pressure (15 to 30 psi) RIM systems used for urethane and is based on the same monomer as urethane. Performance and processing properties are quite different. One of the two low-viscosity DCPD components contains an activator and the other contains a catalyst. Joined using standard mixing heads (1:1 ratio) in a heated, closed mold, the exothermic reaction cures the material in about a minute?considerably less time than that required for PUR. Injection time is 15 to 20 seconds, and total cycle time is 4 to 6 minutes, depending on part size and complexity. Parts can be up to 120 sq ft or more using several hundred pounds of material. Sections can be up to 12 inches (30 cm) thick with thick-thin transitions. The low-pressure molds can be cast or machined aluminum, nickel shell, or Kirksite.

Just out of the mold, the surface of a DCPD part is like olefin in that virtually nothing will stick to it. However, the surface quickly oxidizes to become a very friendly site for paint and adhesives. High quality surface finishes, including Class A right from the mold, adorn many parts, and bonding the part to other components is relatively easy. Lee says a number of parts are being chrome plated, which requires a very high quality surface. In its performace properties, DCPD is more like an engineering thermoplastic than PUR. Toughness across a broad temperature range and impact strength, says Lee, are more like polycarbonate than PUR.

Garland Lee noted that DCPD also enjoys an advantage in its range of mold materials. If a part is not only big, but also has a deep draw, it is hard to find metal billets large enough to make mold halves. Plus, most of the metal is left on the machine shop floor. An illustration of this advantage would be water tanks for purification systems in Japan. One of them, says Lee, is made of two DCPD halves bolted together. Each half weighs 220 lb (100 kg).

Chart Source: SPI conference paper: A case study of the adaptation of a Kenworth Class 8 truck hood from fiberglass reinforced plastic to Metton.?Scott E. Weatherford, Kenworth Truck Co.


RIM as a Growth Engine
GI Plastek developed and recently improved a proprietary inmold painting/coating system yielding an Automotive Class A finish. The company regularly works with new and alternative materials (see sidebar, p. 21). RIM production went into a second location a few years ago, and it too is growing. GI Plastek does a lot of work for vehicles, but not for cars.

GI Plastek RIM molds components for snowmobiles and all-terrain vehicles (ATVs), medium and large trucks, lift trucks, and a variety of agricultural and construction vehicles such as tractors and combines. Steve Trapp, in charge of new business development at GI Plastek, says the company is also busy in medical equipment, electronics, and general industrial markets.

Many applications in these markets share one of the key factors that allow RIM to replace metal: low volume. Trapp says typical volume from a single mold ranges from 1000 to 10,000 pieces annually. Housings for industrial control electronics, enclosures for blood analysis devices, and electrical switching equipment often fall into that category. When volumes exceed 25,000, the cost of switching to standard injection molding tooling starts to become justifiable and practical. GI Plastek can provide that service since it?s also a sizable multilocation injection molder.

Trapp says GI Plastek is particularly interested these days in RIM-processed dicyclopentadiene (DCPD) material because it expands RIM?s range through higher performance (see sidebar, right). Historically, RIM has overwhelmingly used urethane: foamed, solid, or elastomer. DCPD is based on the same monomer, but it has different performance properties. Toughness, temperature resistance, and impact strength over a broad temperature range make it useful for applications such as airplane wheel chocks, where PUR cannot qualify.

Does this mean a move away from traditional PUR formulations at GI Plastek? Not at all, says Trapp. Alternate materials extend the company?s RIM offerings. GI Plastek earlier found new applications by developing ProTek, the proprietary inmold coating (IMC) process for Class A surfaces.

Previously, getting to Class A meant post-mold painting, with its higher costs and environmental protection requirements. ProTek, now in its second generation, has expanded to include two-color parts. In a touch of irony, the ProTek Class A surface has become so good that Trapp says a client recently asked that an ?orange-peel? effect be added so that the PUR part would match adjacent vehicle components. To meet the need, GI Plastek textured the mold.

GI Plastek is extending its geographic range, concentrating its production sites in zones of opportunity. Until a few years ago, almost all RIM processing was done in an acquired operation in Newburyport, MA. There are 12 RIM presses there as well as injection equipment. A new plant established in Dewitt, Iowa a few years ago is well located to support GIP clients such as Case, John Deere, and Caterpillar. Two DCPD presses operating there.

The Dewitt plant has grown with the acquisition of new business in that area (see photos) and is in the process of adding injection molding capability as well. GIP has concentrated on large part/short run applications that, since they are not efficient to ship, have not joined the migration of work off shore, generally meaning Asia. GIP is looking the other way. It is interested in bringing its technology to developing markets and licensing technology, like ProTek, if the situation is right.

Sign up for the PlasticsToday NewsFeed newsletter.

You May Also Like