High-tech solutions, new materials highlight thermoforming meeting.

News in materials, equipment, and processing technology drew record-breaking international crowds for the third year in a row to the annual conference and parts competition of SPE's Thermoforming Div. The Sixth Annual Thermoforming Conference, held last month in Fort Mitchell, Ky., drew 741 attendees versus 688 last year and 627 the year before that.

Recent conferences have pointed to increasing technological sophistication in thermoforming. One notable example this year was the presentation of new Windows-based PC software for simulating the stretching, thinning, and cooling of sheet during the forming process. Another was the announcement by a NASA spokesman of the agency's intention to offer technology solutions to plastics processors. Dale Webb, associate director of the NASA Mid-Continent Technology Transfer Center, located at Texas A&M University in College Station, Texas, said the agency has already helped a few processors - including at least one thermoformer - to solve manufacturing problems with technology originally developed by NASA for aerospace purposes. Further details were not available [TABULAR DATA OMITTED] at press time.

Other news at the SPE meeting included a new cooling approach to solve shrinkage problems in PP cut-in-place forming. In addition, several resin manufacturers and sheet makers announced new products at the meeting.

PREVIEW YOUR PROCESS

Computer-generated process simulation as a means to optimize thickness and temperatures distribution of a part in the mold is a promising new tool for theroformers (see PT, Sept. '96, p. 53). Up to now, the main commercial software packages available in North America have been C-Mold from AC Technology, Louisville, Ky., and T-Formcad from Polydynamics, Inc., Hamilton, Ont. A new entry on the scene is T-SIM from Accuform in the Czech Republic. The Windows package, available in Europe and Japan since 1992, is now available in the U.S. through T-SIM Inc., an office located at Sohner Plastic Technologies Inc. North Andover, Mass.

Sohner is a thermoformer and member of a new consortium of 11 firms that support T-SIM development. Other members are German forming machinery and tooling suppliers such as Illig, Gabler, Kiefel, Marbach, and Jacob.

Simulating the forming process step by step lets you test out product and tool designs before you cut steel, says T-SIM developer Karel Kouba. Windows point-and-click capability lets you check sheet temperature or thickness at any physical location and time step during the simulation. Movements of the mold or plug-assist tool can be simulated as well.

Heat transfer and friction of the sheet against the mold can be examined with the program, which has a rheology database containing 11 of the most common materials used in thermoforming. A CAD file of the tool design can be imported into the system, or a user can create a simple tool design in T-SIM using its built-in CAD module. T-SIM can also simulate the deformation of a preprinted image on a formed part, a feature useful for packagers.

T-SIM runs in Windows 96, Windows NT, or Windows 3.x. It requires a Pentium processor with at least 16 MB of RAM. T-SIM version 2.0 costs $18,000

COOLER TOOLING

Toolmaker Marbach Werkzeugbau of Heilbronn, Germany, says the key difficulties in thermoforming PP for food packaging, namely obtaining uniform cooling and part shrinkage, can be minimized with a new method it developed for cooling its trim-in-place molds. Traditional cooling-channel layouts direct water in a specified pattern past a number of cavities in succession. Since the cavities nearest the inlet are exposed to cooler water than the cavities near the outlet, nonuniform cooling - and therefore PP shrinkage - can easily result, says Marbach sales director Frank Biller.

Unlike this traditional "direct in/out" coolant flow, Marbach's new approach interconnects the cooling passageways so as to allow the water that is entering the tool to travel anywhere throughout the mold and around any cavity. The new design also reduces the impact of a clogged passage, which would ordinarily block cooling in one area of the tool. With the new design, cool and warm water can mix, leading to more uniform temperatures across the mold, Biller says.

Marbach is planning to establish U.S. representation in the Chicago area soon.

LOTS OF NEW MATERIALS

Four new HDPE resins for sheet extrusion and thermoforming from Mobil Polymers, Edison, N.J., are the first for these applications from that company and are also said to be the first of their type to be made by a gas-phase polymerization process (see table of properties on p. 21). Initially developed for blow molding, the new grades (HDA-026, HDA-027, HDA-303, and HFE-303) are said to have optimized rheology for a combination of easy extrudability and improved melt strength. One of the new grades (HFE-034) is said to be the first foamable HDPE sheet grade on the market. It is aimed at rigid packaging. In the future Mobil plans to introduce a foamable HDPE grade for injection molding applications.

Higher contact clarity is claimed for two new sheet extrusion and thermoforming grades of polypropylene being developed for food packaging by Amoco Polymers, Inc., Alpharetta, Ga. Amoco plans to upgrade its clarified homopolymer PP 6219 by the end of the year. And an experimental clarified random copolymer, PP 8249, exhibits what the company says is "ultra-high" clarity (see photo, p. 21) and good impact strength.

Making its entry into the North American market as a supplier of ABS resins is BASF Corp., Mount Olive, N.J., which is building a 300-million-lb/yr plant in Altamira, Mexico, that will start up in the second half of 1998. BASF has previously supplied its Terlux clear MABS (methacrylate ABS) in this country but now also offers two extrusion and five injection molding grades of standard Terluran ABS (see Technology Newsfocus for details). The two sheet grades are in the high-impact and very high-impact range.

A 30% mineral-filled extrusion-grade PBT polyester made initially for just one customer will be upgraded in melt strength and offered to the general extrusion/thermoforming market by GE Plastics, Pittsfield, Mass. GE says it will introduce the improved Enduran HV7322 grade within a month.

A new line of acrylic/PVC sheet products with a granite-like appearance was introduced at the SPE conference by Kleerdex Co., Mt. Laurel, N.J. The Kydex 130 series is available in gray, rose, red/black, green, navy, and black. The company offers sheet in thicknesses up to 0.375 in.