Injection molding.

As reported in our show preview (PT, May '94, p. 40), all-electric injection presses seemed to be popping up everywhere at NPE. There were also new developments in small machines and in coinjection models. In the CIM area, a new software package reportedly optimizes a process without the need to interrupt production for formal design-of-experiments (DOE) procedures.

ALL-ELECTRICS PROLIFERATE

Once the practically exclusive domain (in North America, at least) of Cincinnati Milacron, all-electric injection machines were featured by no less than eight suppliers at NPE '94. Despite the new competition, Milacron's U.S. Plastics Machinery Div., Batavia, Ohio, scored two firsts: It introduced the Elektra series as the first U.S.-built all-electric line and as the first machines of this type intended for general-purpose molding at prices comparable to standard hydraulic toggle machines. Milacron also showed off a new high-end Roboshot line as a successor to its ACT series.

Milacron won't be alone among domestic suppliers for long. At the show, HPM Corp., Mount Gilead, Ohio, announced that it is teaming up with an unnamed Swiss engineering firm (not an injection machine builder) to develop a line of a-c servo-electric injection presses, which HPM plans to manufacture and introduce by the middle of next year. HPM president and CEO William T. Flickinger says the electric presses will comprise a small part of HPM's product line-up and will not replace any of the company's current models. He estimates that the electric presses will be priced 15-20% above comparable hydraulic toggle machines.

The first vertical all-electric machine to be offered here is a 55-ton model built by Okuma, a Japanese machine-tool supplier, and marketed in North America by MC Machinery Systems, Wood Dale, Ill. The IM-50V, equipped with a-c servo motors, reportedly consumes 50-70% less energy than comparable hydraulic-clamp machines.

The vertical injection unit has closed-loop pressure control and is capable of injection speeds from 3.94 in./sec down to 0.004 in./sec. The four-tiebar vertical toggle clamp has 13.8-in. tiebar spacing and 18.5-in. max. daylight. The press has a small footprint (5 x 5.75 ft) and comes with a pull-out color CRT control panel. Approx. price is $100,000-110,000.

NEW CAPABILITIES

Milacron introduced new capabilities for its existing Vista press line. One is a convertible vertical/horizontal injection-unit option on the Vista Sentry line (33-85 tons). Changeover is straightforward and can be accomplished in about 15 min with the aid of a crane by undoing and then refastening four bolts along each guide rod. Cost of the option is around $3500-4000 on new Sentry machines.

Another new option from Milacron is coinjection capability for its Vista machines of any size. It requires dual injection units and a new manifold with a pin valve that opens either or both flow paths to permit simultaneous or sequential injection. Milacron recommends coinjection as a way to use regrind or recycled resins in the core of a part without affecting surface esthetics. It can also be used to combine a structural reinforced core with an unfilled surface layer for smooth appearance, or to save on expensive pigments and additives that are not needed in the core layer. The coinjection manifold utilizes standard components and is said to be both easier to purge and capable of faster injection speeds than other coinjection equipment on the market.

Note that a different coinjection technology, called Mono-Sandwich molding, is available on the Ferromatik Milacron press series acquired by Milacron from Klockner of Germany (PT, Oct. '93, p. 11).

PROCESS OPTIMIZATION 

A new software product marketed by Syscon International, South Bend, Ind., is said to help optimize a process during normal production without the need to perform time-consuming design-of-experiment routines. The DOS-based "Pro-T-coN" package, which was developed by GS Technology of the U.K., reportedly is applicable to almost any plastics process. Using statistical analysis, the software builds a mathematical model of the process. It automatically correlates the part-quality values with process parameters and determines how each parameter influences the product. Once that link is established, the program can indicate how to set up the process to achieve the best results it is capable of. If the process does go awry, the software can help pinpoint the cause and can predict what effect a corrective change in any variable will have on a particular product attribute.

Syscon says Pro-T-coN does not require much expertise to use and is simple enough to be useful for optimizing even relatively short-run jobs. PlantStar offers to use the software on a consulting basis for a fee of $5000 plus expenses. Or the software can be purchased for about $18,000.