Competition brings out top engineering for winners

The Society of the Plastics Industry used to call this the Structural Foam Conference, then the Structural Plastics Conference. Now it's known as the Applied Plastics Technology & Design Conference and New Product Design Competition. No matter. The name's changed, but the concept is the same. The heart of this three-day gathering is the parts competition, featuring products from molders, designers, and OEMs from around the world.

This conference always features parts manufactured with a cornucopia of processes--everything from straight injection molding to injection-compression to structural foam. What made this year's competition particularly interesting was the combination of processes used to mold different parts for a single product.

Take, for instance, the top award winner, a digital copier that is made using low-pressure structural foam and straight injection. Or check out the hospital bed. It uses gas assist, conventional injection, extrusion blowmolding, and thermoforming. The rear view mirror assembly uses gas assist and coinjection, the latter of which allows the molding of an unpainted weatherable plastic skin. The front bumper fascia for the Ford Contour uses coinjection and sequential gating to inject a virgin TPO skin over a painted TPO reyclate.

Descriptions and photos of the winners of this year's competition that benefit from injection molding follow.

Conference Award/Computer and Business Equipment

Digital copier. Molded for Xerox by Mack Molding in Arlington, VT, this high-resolution copier is a monument to the potential injection molding continues to wield in manufacturing. Mack uses low-pressure structural foam and straight injection molding to process PPO/PPE, PC, PC with a 20- to 30-percent glass filler, and ABS. The materials chosen are highly conductive, dimensionally stable under high temperatures, and molded to tight tolerances, eliminating the normal sheet metal and mechanical requirements.

Judges' Award

TotalCare Hospital Bed. This represents possibly the largest use of plastics in a hospital bed. Materials include PPO/ PPE, PP, PE, PUR, and acetal, processed by gas-assist injection molding, injection molding, extrusion blowmolding, and thermoforming. Original equipment manufacturer Hill-Rom, based in Batesville, IN, designed the bed to take advantage of plastic's strength-to-weight ratio, aesthetics, flame retardant features, and ease of assembly. The intermediate siderail on the bed is molded via gas assist and replaced 13 steel components that were cut, formed, and welded. The combination of gas-formed tubes and thin-wall design resulted in major improvements in cleanability and infection control. All of the tools used to produce parts for this bed are textured, and all of the parts leave the mold finished.

Building and Construction

Niche panel of the systematic bathroom. Based on brochures floating about the conference, it appears this bathroom panel is designed for Japanese bathrooms, which are notoriously cramped. The idea is to incorporate into one product a mirror and storage space for the usual assortment of toiletries. This polystyrene part used to be made via vacuum forming. Molder Kyowa Molding Co. in Japan was looking for a new design and an opportunity to reduce costs. It wound up converting the panel to injection-compression molding, producing this part on a 3000-ton press, where conventional molding would have required 5000 tons. The panel has a molded-in marble-like appearance and uses structural ribs to strengthen the part. As a result, costs were reduced by 15 percent. The injection-compression unit also produces less warp and fewer sink marks. The machine that produced the panel is not devoted to injection-compression molding. Kyowa used a new injection-compression unit from Idemitsu Petrochemical Corp. that retrofits onto conventional injection molding machines. Dubbed the IPM unit, it fits between the machine platen and the mold and provides a relatively inexpensive way to get into injection-compression without heavy up-front investment or any
major machine modifications.

Consumer ElectronicsScreen phone.

What makes this screen phone an award winner is the awe-inspiring detail found on the hidden surfaces of the unit. This would explain why the part was entered into the competition by the moldmaker Minco Tool & Mold, based in Dayton, OH. Underneath every part of the phone is found some combination of ribs, supports, bosses, ridges, undercuts, and holes. Texture is molded in for aesthetics, and ABS is used for its favorable performance-to-cost ratio. The designer, OEM, and molder is Philips Consumer Communications.

Medical and Scientific/Single Part

i2000 instrument structure and skins/i2000 baseplate. The i2000 is a fluid analyzer used to perform clinical diagnostics, a device apparently perfectly suited for structural foam molding. The instrument structure and skins won the best-part award in the medical and scientific category. The baseplate from the unit won the award for best single part. The structure and skins include some 30 structural foam parts reinforced with structural metal and sheet metal. The assembly uses the structural foam parts to provide design flexibility
to integrate features, reducing part count, product cost, and assembly time. The structure and skins can be reconfigured to link instruments together to meet customer needs.

Most impressive is the baseplate, which provides support for about 20 subassemblies that perform diagnostic assays on blood and other fluids. It consolidates the functions of more than 100 parts if made via conventional methods. The part is loaded with ultrasonically installed inserts that provide the subassembly support. Precision and stability on this project are a must. The baseplate incorporates an insulated chamber for refrigerated chemical storage and spill containment for hazardous chemicals. The material, chosen for strength, processibility, and chemical resistance, is a PPO/PPE, molded by FM Corp., based in Rogers, AR. The OEM is Abbott Diagnostics Div. in Irving, TX.

Retail Hardware

Millenia hot drink center. Gas-assist and solid-wall injection molding were used to make the trim panels and dispensing covers for this snack and refreshment center. Gas assist was used to eliminate potential sink marks from thick ribbing in the panel trim parts and to reduce tonnage requirements of the large cover parts. All exterior panels have molded-in texture and color.

The mold uses interchangeable inserts to produce three different size/configuration dispensing parts for different machines, depending upon the product being vended. The material used is polycarbonate. The designer and OEM is Crane National Vendors, based in Bridgeton, MO. The moldmaker is Majestic Tool & Mold located in Oldcastle, ON, and the molder is Pulsar Plastics, in Carlyle, IL.

Transportation

Exterior rear view mirror. Combining two processes that by themselves can drive a molder to drink won injection molder Siegel-Robert the transportation award. The part is the housing and assembly for an exterior rear view mirror. Why did it win? The short answer is this: It's molded using gas assist and coinjection and requires no painting or finishing. The long answer is this: The weatherable skin of the mirror--injected first--consists of a PC/PET alloy. Color, gloss, and texture are molded in, eliminating pricey postmold painting. The core is a 30 percent glass-filled ABS that is molded using gas assist to impart strength and stiffness to the fold-away mirror. As a result, Siegel-Robert eliminated the use of metal mounting brackets required by traditional designs. Siegel-Robert, based in St. Louis, created the design and does the molding. Laser Die & Engineering (Kentwood, MI) made the two-cavity tool. The mirror is currently used on GM vehicles, including the 1998 Chevy Venture, the Oldsmobile Silhouette, and the Pontiac Trans Port.

These charts show the processes and materials used to produce the parts entered in this year's New Product Design Competition. The total exceeds the number of parts submitted as some products used multiple processes and materials.

Ford Contour bumper fascia takes environmental award

In a rare combination of processes, the Advanced Injection Molding Dept. of Visteon Automotive Systems presented a bumper fascia for the 1998 Ford Contour that's molded using sequential gating and coinjection. While such a combination is notable and relatively rare, the part won the environmental award because of the material it uses.

Gary Whitlark is a process development engineer at Visteon's Milan, MI facility who helped develop the process and coauthored a paper on the bumper presented at the conference. He says the skin of the fascia uses a virgin TPO. The core of the part is recycled, painted TPO and constitutes 21 to 23 percent of the bumper. The product at the conference clearly shows the location of the darker, painted recyclate under the opaque, virgin TPO (in production, the virgin TPO is pigmented and does not show the recyclate core). This allows Visteon to reuse much of its TPO recyclate, while still producing a structurally sound fascia cost effectively.

The bumper has four gates. The two in the center (one top, one bottom) open simultaneously at the start of injection. The two other gates are located near the top of the fascia, directly above the round, cored-out holes on each side of the bumper. When the flow front passes them, the secondary gates open to finish filling the part. Weld line regions are filled only with skin material as the process requires that the flow fronts be free of core material; when flow fronts meet, core material is displaced.

The heart of the system, says Whitlark, is the hot runner system, which uses independently operated valve gates in a single-cavity mold. The hot runner system, one each provided by Incoe and Kona/Dynisco, allows three-position valve actuation. A portion of the skin is injected first, followed by the simultaneous injection of core and skin. After the core material is injected, skin is injected again to complete packing of the mold and to seal the core material.

Whitlark says the bumper is molded on a 4000-ton Ube and a 4000-ton Engel. The Ube was modified by adding a second screw and enhancing controller and hydraulic capabilities. The Engel was purchased as a coinjection unit. Whitlark reports that Visteon is currently investigating the use of postconsumer recyclate in this and other applications. Dale Moore, manager of Advanced Injection Molding at Visteon, coauthored the paper with Whitlark.