I N D U S T R Y & B U S I N E S S

New Plastics Molding Method Lowers Costs Teamwork by Ford, Dow, and Detroit Plastic Products simplifies plastic auto parts output

Look for more auto parts to be made of plastics. A new injection molding technique developed by Dow Chemi­cal, Ford Motor, and Detroit Plastic Products, Mount Clemens, Mich., has cut the cost of an air vent assembly for 1962 Thunderbirds by 75 %. The vent assembly is made of Dow's Styron 440 high-heat, high-impact polystyrene. The new technique offers savings in time, material, and labor and gives a better part, the companies involved say. And both auto and plastics people see the technique opening the door to much wider use of plastics for large, complex auto parts.

Key to the new technique is a split-core mold. This design eliminates the use of cams, lets the operator remove the part from the mold in one move­ment. The only secondary operation is the molding of a plastic baffle, which is then fastened to the main assembly with one rivet.

Implications of the development could be far reaching. Auto makers use about 35 pounds of plastics per car. Current predictions indicate 50 pounds will be used per car by 1965. But these predictions are based more or less on the use of present-day materials and techniques, plus a strong sales ef­fort by the plastics industry. New techniques, such as the split-core mold, should greatly increase use of plastics, pushing it up to 300 pounds per car within the next 10 years, according to Harold Lenheiser, automotive sales en­gineer at Detroit Plastic Products.

Moving Core. The air vent as­sembly for Ford's Thunderbird fits di­rectly into the heater housing. Orig­inally made of metal, the part was changed to plastic starting with 1960 models. The plastic was vacuum-formed in two sections, and a steel baffle riveted to it. This vent had sev­eral shortcomings. Assembly, for in­stance, took time and material. The two sections plus the baffle required 12 rivets. In addition, the part tended to draw together, restricting air flow.

The new molding technique was the result of a team effort. Looking for

better design and lower costs, Ford engineers approached Ford production buyer Curtis H. Brindley with the problem. Mr. Brindley, in turn, brought Plastic Products' Mr. Len­heiser and J. D. Haines, Dow sales representative, among others, into the picture.

The usual plastics approach to mold­ing such a complex part would require an intricate cam system. "Originally, we anticipated having to design a mold with four cams—one of which would be a cam within a cam," Mr. Lenheiser says. But taking a harder look at the job, the team came up with a way to make the part without any cams. Their solution was the split-core de­sign.

According to Mr. Lenheiser, the trick was to build a moving core from which the operator could grasp the part and lift it off with a forward motion. To solve this problem, the

team split the core above the center line—keeping the bottom half sta­tionary and traveling the upper half. Since the split is above line and the core travels until the entire bottom por­tion of the molded part is clear, the operator can easily lift the part off of the traveling section with a forward pull.

Another advantage to the design is that the part can be molded in one solid piece, since there isn't any need to fold down the front flap. The plas­tic baffle is molded along with the part and attaching it is the only secondary operation.

Biggest advantage of the new tech­nique to Ford is the 757© slash in costs. But it permits numerous other im­provements in the part, too. These include:

• Better control of air flow. • Easier assembly; locating tabs re­

place screw holes in the previous part, simplify assembly.

• Better dimensional stability; Dow's Styron 440 has good impact and heat resistance characteristics.

• Lighter weight; the new part weighs 22.7% less than the old vacuum-formed one.

Tougher Sledding. Use of plastics in autos has grown rapidly over the past decade—especially for internal decorative trim. But their growth as

ONE-STEP MOLDING. Operator at Detroit Plastic Products removes polystyrene Thunderbird air vent assembly and baffle from press in a single operation by grasp­ing it from the back of the extended split core and pulling it forward off the traveling core section. Mold can produce 100 pieces an hour

A P R I L 2 3, 196 2 C & E N 27

Chemical Industry Assails Waterway Bill MCA joins fertilizer producers in opposing proposed repeal of bulk commodity exemption

structural materials hasn't been as great as some in the industry have hoped for. For one thing, auto makers feel that plastics haven't lived up to their rigid performance standards. Plastics often require intricate and dif­ficult fabrication techniques. And fre­quently auto makers end up with plas­tic parts that need the same amount of time-consuming handling as the metal parts they have replaced. So the em­phasis today is on high performance materials as well as on better fabrica­tion techniques.

To fill these needs, plastics makers have concentrated on tailoring mate­rials specifically for auto functional uses. Leading the way has been the development of new thermoplastics. Plastics with improved properties-greater strength, better resistance to distortion by heat—selling at costs com­petitive with metals have been the re­sult. Dow's Styron 444, for example, is a material similar to Styron 440 but designed specifically for auto use. Also gaining acceptance are new mate­rials, such as polycarbonates and poly-formaldehydes.

Better Methods. Meanwhile, fabri­cators have been evolving better fabri­cating techniques. With improved plastics now available, they can better tackle the problem of making parts easily and cheaply. They are using more intricate mold designs, better molding methods, and bigger presses.

A growing trend among fabricators is to design the mold around the part, tailoring the part to the end use. The new split-core injection molding tech­nique is an example of this.

Today, many parts require two or more manufacturing operations. The trend, though, is to combine two or more parts into one injection molded part. This means better designed and lower cost parts.

The new technique promises to pave the way for wider use of injection molding to make large and compli­cated auto parts. Ten or 15 years ago, for instance, Detroit Plastic Products just molded knobs and a few slightly larger items. Today, however, it is molding parts that measure 6 feet long and 2 feet wide. These are replacing from 10 to 15 metal parts that were stamped out and welded together.

Other parts which may offer oppor­tunities for cost savings and improve­ments are getting a hard look, too. These include glove compartments and doors, instrument panels, and heater distribution ducts.

A legislative proposal to repeal the water carrier dry bulk commodity ex­emption has run into stiff opposition from the chemical industry. The measure (H.R. 5595), now in com­mittee, would subject barge shipments of dry bulk commodities to rate regu­lation by the Interstate Commerce Commission.

And, according to the Manufactur­ing Chemists' Association, it would in­crease the chemical industry's cost of doing business (C&EN, April 16, page 27) . Hardest hit would be barge transport of basic chemical raw ma­terials—large volume, low unit cost commodities which are extremely sen­sitive to shipping costs. Earlier, the National Plant Food Institute also voiced strong opposition to the bill.

Under Section 303(b) of the Inter­state Commerce Act, inland water transportation of dry bulk commodities is free of ICC regulation, provided the carrier does not haul more than three commodities and doesn't mix bulk commodities with regulated ones. About 90% of U.S. inland waterways tonnage is now moved by carriers ex­empt from regulation.

Chemicals Would Suffer. In a state­ment to the House Interstate and Foreign Commerce Committee's Trans­portation and Aeronautics Subcom­mittee, Clinton H. Vescelius, chairman of MCA's waterway bulk commodity exemption committee, pointed out that many chemical companies have spent millions on waterfront plants and ma­rine facilities "in reliance upon the principle declared by Congress that bulk water transportation would be free from regulation and would, there­fore, remain a low-cost medium." If the bill goes through, these companies could suffer a loss of property values.

Regulated barge lines can and do compete for dry bulk cargoes without regulation on the same terms as their competitors, Mr. Vescelius points out. "But, for the most part, they prefer not to do so—instead they propose to have Congress extend federal regulations over their competitors," he says. This would eliminate the benefits of com­petition and result in higher rates to industry, he believes.

Mr. Vescelius, who is general trans­

portation manager of Olin Mathieson, believes that if dry bulk materials are subject to regulation, carriers may not be able to make contracts, advanta­geous to carrier and shipper alike, for long-term, tailor-made service. Com­panies who have sought and obtained low rates in return for long-term com­mitments would lose this advantage.

And, Mr. Vescelius adds, the bill would extend regulation on inland waters generally, but the Great Lakes and offshore trades would remain ex­empt. As a result, he believes, "there would be many a plant on the rivers or canals whose raw materials costs would rise out of proportion to those of its competitors."

In earlier testimony before the sub­committee, Robert V. Peabody, chair­man of NPFI's traffic committee, pointed out that the bill would repeal the exemption on bulk commodities moving in dry form, but those moving in liquid form would continue to be exempt from regulation. Many ferti­lizers and fertilizer materials can be transported by water in either dry or liquid form. H.R. 5595, Mr. Peabody stresses, would be a gross discrimina­tion against shippers and receivers of dry commodities as opposed to those shipping and receiving the same or competitive commodities in liquid form. If adopted, the measure would, he believes, disrupt the economic structure of the fertilizer industry.

Two Alternatives. Chances of en­actment of the measure are considered virtually nil by many observers. They feel that Congress will wait and re­view proposed legislation of this type in the light of President Kennedy's transportation message to Congress (C&EN, April 16, page 42).

The President calls for removal of what he calls the inequality in bulk commodity transport by either "ex­tending to all other carriers the exemp­tion from the approval or prescription of minimum rates" or by repealing the existing exemption. Mr. Kennedy favors his first alternative, under which ICC would continue to regulate the maximum rates of common carriers but not the minimum rates. But many feel that this approach would touch off a destructive price war among carriers.

28 C & E N A P R I L 2 3, 1962