Unusual machines, materials & tooling debut at SPE thermoforming expo.

One of the largest thermoforming exhibitions ever mounted, featuring displays from nearly 100 equipment and materials suppliers, accompanied the recent SPE Seventh Annual Thermoforming Conference in Atlanta. Among the more unusual displays were a linear three-station machine with a single traveling oven, a porous composite tooling material that needs no drilling of vacuum holes, and composite sheet materials that have been adapted for thermoforming from other processes.

THREE STATIONS SIDE BY SIDE

A new linearly arranged three-station machine from The Shuman Co., Charlotte, N.C., lets you conduct a mold change at one or two stations without disrupting the forming cycle at the third station. Model SPA 39 HxH has a single rail-mounted quartz top heater that serves all three stations. Sequence controls program movement of the oven from station to station, skipping a station if desired. Built-in platen rails accommodate 9 x 8.5 ft molds. It forms parts up to 36 in. deep and is intended for production of hot tubs and other large parts.

Alternate production of two different halves of a product (like a container and lid) on one machine is possible with the new HD SBS (side-by-side) series dual-station formers from ZMD International, Long Beach, Calif. The oven is mounted on linear bearings to move from station to station with computer control that permits you to set heating intensity and duration at each station. ZMD offers forming areas of 3 x 4 ft and up.

The new Tower single-station thermoformers from ZMD are said to have half the footprint of conventional units. Vertical movement of the top and bottom heaters is adjustable - within 48 in. on top, 15 in. on the bottom - which lets the operator keep sufficient heat on the part as it starts to sag but without getting material caught in the heater. The ceramic radiant heaters are blocked off with a shutter when forming is complete. The unit is available in sizes of 3 x 5 ft and up. The company says this design makes very large machines possible at an attractive price.

ZMD has also developed a three-axis CNC servo trimmer and router with 12 in. of daylight, as opposed to similar units that have only 3-4 in. of daylight.

UPGRADED OVENS & CONTROLS

Uniform heat distribution, faster start-up, and quicker temperature response are said to result with the new Infra-Cat catalytic gas heater from Vulcan Catalytic Systems Ltd., Portsmouth, R.I. A new gas-dispersion system reportedly delivers natural gas evenly across the surface of the catalyst, producing 35% shorter heat-up times. The heater takes 8 min to preheat to 350 F before gas is introduced, after which it takes only 2 min more to stabilize the heaters at full operating temperature up to 950 F. The entire heater surface reportedly can be adjusted from high to low fire or vice versa in only 15 sec, while other catalytic gas heaters can take 3-4 min to go from high to low fire and 1.5 min from low to high fire, Vulcan says. The new heater is offered in a standard 16 x 20 in. unit as well as custom sizes.

Operators of 36 x 48 in. Cam-form machines from Zed Industries Inc., Vandalia, Ohio, can monitor more process parameters and troubleshoot more easily with upgraded controls. The $20,000 upgrade package includes a new encoder that monitors all press parameters, including the stacker, and a diagnostic program with maintenance-scheduling functions. Operator interface is new Windows 95-based graphical color touchscreen.

New PLC controls and a flying-knife cutoff are improvements to the APM Intermediate Continuous Inline machine from American Plastic Machinery Corp., Great Bend, Kans. The machine can be roll or sheet fed and comes with forming areas of 24 in. square up to 32 x 48 in.

Dynaseal air-cooled, liquid-ring vacuum pumps from Travaini Pumps USA, Michigan City, Mich., have been redesigned to cost 20-30% less, making them more competitive with rotary pumps. Flexible hose connections rather than metal piping is the key change that results in the lower cost for these units of 5-10 hp.

As reported last month (p. 11), a new porous, air-permeable composite can be used for making thermoforming molds that don't need drilling of vacuum holes. Metapor, a combination of aluminum powder and epoxy, is available from both International Mold Steel Inc., Florence, Ky., and Edward D. Segen & Co. Inc., Milford, Conn.

FORMABLE COMPOSITE SHEET

Several new types of materials for thermoforming have emerged from the "Supersize" program at GE Plastics, Pittsfield, Mass., which is aimed at developing very large parts of engineering resins. As one example, GE's Azdel Inc. joint venture with PPG Industries in Shelby, N.C., has come up with developmental grades of Azdel long-glass-reinforced PP sheet that are specially tailored for thermoforming. (Normally, Azdel is compression molded.) Sheet with 22%, 30%, or 40% by weight of 0.5-in. chopped fibers has tensile and flexural moduli between 449,500 and 797,500 psi and notched Izod impact from 7 to 10 ft-lb/in. Sheet is made 0.085-0.155 in. thick and 52-in. wide, in either 8-ft-long pieces or in coils of up to 1000 ft. On standard, unmodified thermoforming equipment, Azdel sheet can be drawn up to 2 in. for grades based on continuous-strand glass mat and up to 20 in. with chopped fiber.

High stiffness-to-weight ratio and high heat, chemical, and damage resistance are claimed for a composite structure made with sheet of GE's Noryl GTX PPO/nylon blend that is first thermoformed and then bonded to a substrate of thermoset polyester and glass fiber through a resin-transfer-molding (RTM) process. The composite is targeted for structural parts in marine, automotive, truck, mass-transit, and agricultural-equipment markets. High HDT of the Noryl GTX sheet suits it to high-temperature bake ovens required for in-line automotive painting.

GE has also developed a thermoformable sheet of Enduran, a highly filled PBT typically used in injection molding. In kitchen and bath applications, Enduran sheet offers scratch resistance and a seamless solid-surface appearance. GE has also coextruded Enduran with its Cycolac ABS resin to help reduce cost and weight while boosting toughness and dimensional stability. Because this ABS is modified for compatibility with PBT, the coextruded structure can be recycled.

UV stability is improved with a new 3-mm coextruded three-layer version of Forex EPC, a closed-cell foamed polycarbonate sheet from Alusuisse Composites Inc., Benton, Ky. The skin-foam-skin structure comes in standard sizes of 48 x 120 in.

ABS resin provides the economy and acrylic provides the gloss and chemical resistance to new imitation-granite Kapstone coextruded sheet from Spartech Plastics, St. Louis. The uv-stabilized sheet comes in thicknesses up to 0.5 in. and is intended for hot tubs.

Spartech is also developing a urethane-foam-backed ABS sheet in 0.060-to 0.45-in. gauges for automotive interior products. The low-gloss, scuff-resistant product is uv stabilized and chemical and oil resistant.

Tru-Pearl is a new line of pearlescent HIPS sheet from custom extruder New Hampshire Plastics Inc., Manchester, N.H. It is made in a proprietary multilayer process that produces a "shimmering" effect. The sheet is offered in 24 standard colors.

Royalite Thermoplastics Div. of Uniroyal Technology Corp., Mishawaka, Ind., has two new sheet grades initially introduced at the NPE show in Chicago in June. Fire-rated R71/920 polycarbonate/ABS sheet reportedly meets UL 94V0 at 0.062 in. thickness. Notched Izod impact strength is 8 ft-lb/in. Tensile strength in the machine direction is 8000 psi and flex modulus is 330,000 psi. New general-purpose R910 PC/ABS sheet has a notched Izod value of 10 ft-lb/in.