TECHNOLOGY
Cold-stamped plastics challenge metals Plastic parts can be formed directly from billet and sheet stock at metal-forming speeds Mass production of plastics parts directly from sheet or billets instead of through injection-molding steps is fast becoming a commercial reality. Marbon Chemical is now cold-forming garden sprayer parts from acrylonitrilebutadiene-styrene (ABS) sheet stock using conventional metalworking equipment. Marbon and others are pushing development work for large potential markets such as the automobile industry. Indeed, small coldstamped ABS trim pieces may show up on 1968 models late in the model year. At its Centaur Engineering Center outside Detroit, Marbon has facilities for demonstrating to auto makers that complete auto bodies can be thermoformed in a few minutes from sheet ABS. High-density polyethylene is also getting considerable play. Celanese is now getting reactions from some U.S. auto makers on prototype parts warmformed from high-density polyethylene. It reports cutting forming time in half (from about 20 seconds down to 8 to 10 seconds) by use of a specially built hydraulic stamping press. These activities presage a quiet revolution in the handling of plastics: use of metal-forming techniques and, often, metal-forming equipment to make plastic parts at metal-forming speeds. Such high-speed production of plastic parts, instead of producing them by relatively slow methods such as injection molding, has long been the dream of plastics makers. It is no wonder that the companies involved in development efforts represent a who's who among major plastic makers.
ABS producers Uniroyal, Monsanto, and Union Carbide, in addition to Marbon, are all interested in cold- and warm-formed plastics. ( Cold-forming is a room temperature process, warm-forming requires heating the plastic to temperatures near its crystalline melting point.) Uniroyal, for example, has a cold-forming ABS, Kralastic CF, on the market. Marbon introduced two grades last spring— Cycolac ABS 155 designed for food applications and Cycolac MS for appliance, auto, and other uses. Allied, Du Pont, and Phillips, highdensity polyethylene makers all, confirm the applicability of the plastic to cold- and warm-forming processes and have development efforts under way. Though use of ABS parts in autos could be responsible for adding luster to an already bright market picture for the plastic, the auto industry itself claims little involvement in development work. Of the big three only General Motors admits that it is looking into the new processes. GM considers the area an embryonic one. Greatly reduced forming times put a new perspective on the troublesome economics of plastic parts. Though often roughly four times as expensive, pound for pound, as the metals they would likely replace, the much less dense plastics compare more favorably on a volume basis. When formed by high-speed metal-handling techniques plastic parts drop in cost again. Add the traditional declining price curve for plastics as against the rising curve for most metals and the picture looks even brighter.
Celanese process cuts forming time in half Water chiller Regrind
Scrap grinder Reject Billets
Extrude
Cut off
Convey & condition
Auto weighing
Flake
56 C&EN NOV. 13, 1967
Feedback loop
Forge
Auto-eject Cool in air
In addition, both Marbon and Celanese say warm-forming offers potential savings in equipment costs. Based on its experience with ABS car bodies at its Centaur Engineering Center, Marbon figures thermoforming equipment costs a bare 2% of metal tooling costs and only 10% of costs for equipment to make glass-fiber-reinforced plastic bodies. The economic cincher could well be, as Marbon contends, that regular metal-stamping machinery can be used for ABS at normal metal stamping speeds. Its manager of cold-formed products, Conrad Larson, says that the room-temperature operation may require subtle modifications such as reduced holding force on the blank in the press, but that fabricators will need no additional equipment. When Marbon placed its first two grades of Cycolac ABS designed for cold-forming on the market last April (C&EN, April 17, page 20), they estimated 1970 markets at about 55 million pounds, mostly for small parts such as food and other containers. The company now has in production its first cold-formed part, a small sleeve which is being made by Root-Lowell Corp., Lowell, Mich., for its Atomist electric garden sprayer. From such small beginnings the trend is toward much larger parts. At its Washington, W.Va., site, Marbon has cold-stamped parts up to 18 feet by 24 feet from ABS sheet up to a quarter inch thick. Depth of contours in the largest item is about six inches. Marbon's stamped ABS, as well as having uniform thickness from center to edge (variations can occur in metal stamping), shows increased tensile strength over injection-molded varieties. Uniroyal has also concentrated on small parts in its search for markets. However, the company declares that the economic advantages of cold-forming over injection molding often increase with the size of the part being made. Thus, most of Uniroyal's R&D effort is geared to applying what it has learned with small parts to larger products such as auto fender wells. Celanese also reports increases in tensile strength for high-density polyethylene formed by its warm-forming
EASTMAN Organic Chemicals
EASTMAN Organ
Need compounds between bench-top and tank-car quantities?
The EASTMAN Organics people can scale up fast PLASTIC BODY. Specialty products like Beehoo's Amphi-cat, where steel is not entrenched, offer attractive markets for direct-formed plastics
process. Using a specially made stamping press, Celanese feeds powdered polyethylene which is extruded, cut into billets, weighed automatically, conditioned by heating to the crystalline melting point of 275° F., and stamped. The hydraulic forge shapes the billet efficiently with no flash. The resulting material shows tensile strengths of 5000 to 6400 p.s.i. depending on forge pressure. Injection-molded material has a tensile strength of about 3500 p.s.i. Celanese has its sights on specialty automotive areas rather than the huge body and fender market eyed by ABS makers. They are emphasizing parts no larger than two feet in their greatest dimension. With the expansion this year of thermoformed ABS to use as the body shell of passenger vehicles such as Travel Industry's camper and Beehoo Industry's Amphi-cat, Marbon feels the plastic has bridged the gap from parts to structures. The large body shells ,are formed by preheating ABS sheet and vacuum-drawing it into molds. Marbon states that molding time for such large unit pieces ranges from five minutes up. Marbon aside, present expectations for plastics as structural shells are being couched in conservative terms. Steel is entrenched, plastics are new on the scene. Outpourings from the many R&D efforts under way must therefore be awaited before even the companies involved have firm estimates of the future demand for plastic car bodies and other structural applications. How deep the penetration goes will ultimately hang on the technology chemical companies are developing to adapt plastics to what have been largely metal processes.
The organic compounds for which we are famous in laboratory amounts can be made in much larger quantities. Tell us what you need. Even if it isn't in our catalog, try us anyway. Distillation Products Industries, Rochester, N.Y. 14603, phone 716458-4080 (Division of Eastman Kodak Company).
HP.
Kodak
EASTMAN Organic Chemicals
|URETY GLOVE CASE HISTORY REPORT From Gas Meter Manufacturer:
"We get a third more wear with SURETY GLOVES" Surety Gloves receive a hard, abrasive pounding in this gas meter manufacturing plant. In addition to snagging, tearing action from the handling of heavy metal components, the gloves take a bath in such corrosive chemicals as Lektrosol, methyl ethyl ketone, and alcohol at various stages of the workday. Surety couldn't be more pleased having this user testify to one-third more service
than from a previous type. Surety Gloves can furnish superior performance as readily for you. The first step is to see your Surety Distributor.
THE SURETY RUBBER COMPANY Box97-U-ll f Carrollton, Ohio 44615, U.S.A. Export Division: 1007 Temple Bar Building Cincinnati, Ohio 45202 In Canada: Safety Supply Company, Toronto
NOV. 13, 1967 C&EN
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