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New equipment for RTM, SMC at Dusseldorf Show.

The mammoth K'92 exhibition late last year in Dusseldorf, Germany, was big enough to contain something for everyone, even a little news in equipment for reinforced plastics/composites. Two sophisticated metering units for RTM as well as robotic loading and unloading devices for SMC compression molding constituted pretty much all the major news in this area.

RTM PUMPING UNITS

The Cannon Group of Italy (parent of Cannon USA, Mars, Pa.) introduced its first RTM unit, called CompoMet. It's a high-pressure metering system for polyesters, epoxies, thermosetting acrylics (ICI's Modar) and other resins. Based on Cannon's urethane RIM technology, CompoMet uses a high-pressure impingement mixing in a self-cleaning mixhead that requires no solvent purge. Metering is via dual hydraulic pumps and dual, independently controlled piston cylinders for A and B sides. The latter are said to easily handle abrasive filled systems. Cylinders are sized to the application, able to deliver up to 110 lb/sec max.

Controls can range from simple manual type to closed-loop. Standard ratio adjustment is by vernier with manual calibration. Flow transducers can be added for automatic ratio control. The largest system could cost around $50,000.

The Swedish firm Aplicator AB (represented by Euromer Polymers Inc., Grand-Mere, Quebec) introduced its RI-10 RTM machine, developed in cooperation with Owens-Corning Fiberglas Corp. It has a single-stroke hydraulic pump and two hydraulic delivery cylinders for resin and catalyst. This system fills the mold in one continuous stroke, eliminating the pulsing and pressure fluctuations that can cause surface waviness. Cylinders of 10, 20 or 40 liters are sized to the application. A cam with an adjustable angle mechanically links the catalyst and resin cylinders, providing consistent ratio control. A special inlet valve and mix-head connect the pump directly to the mold; the pneumatic valve is used for solvent flushing into a sealed drum with no exposure of fumes to the air.

PLC control with a small CRT screen allows programming the injection sequence in up to 300 steps. Injection can be programmed in volumetric increments so as to achieve uniform flow-front advancement, especially in filling intricate cavities. Alternatively, filling can be programmed in pressure steps to permit fastest possible filling, limited only by the mold clamping force or "fiber washing" tendency of the reinforcement. Accuracy is said to be to 10 cc or |+ or -~ 3 g/kg. The PLC can store filling programs for up to 20 different tools. This system, said to run all types of resins, costs around $94,000 for a 10-liter system. One system is used by Sotira in Laval, France, to mold spoilers for Citroen and Ford Escort cars. A one-pack low-profile resin is molded in a two-cavity tool at 185 F in approx. 3-min cycles. That yields 15 cycles/hr and 300 parts/day from one tool.

AUTO PRESS LOAD/UNLOAD

Aplicator also showed an innovative system for loading SMC charges into a compression press without using any form of grippers. (It was described in a paper at last month's SPI Composites Institute conference in Cincinnati.) The Ergomatic 2000 is a large box-shaped device on wheels with a pedestal-mounted PLC control. The loader is positioned in front of the press. The operator stands at the back and manually places the charges (up to 44 lb) on an endless belt that is wrapped around a reciprocating table. Once the charges are in place, the cover is closed to prevent unnecessary exposure to fumes. For operator convenience, the loader can be programmed to elevate the table from a comfortable manual loading height up to press-loading height. On the operator's command, an automatic loading sequence starts. The table moves forward over the tool and then it retracts at the same time as the belt moves forward. These two precisely coordinated motions drop the charge into position with an accuracy of |+ or -~0.08 in., the company says. Up to 20 loading programs for different tools can be stored in the PLC. "Lead-through" or "teach-in" programming is used to create loading sequences.

Typical loading time is 5 sec. The low-profile unit requires minimal press opening to load charges. The system, costing around $125,000, is being used by Statoil in Sweden to mold 10.6-lb truck fenders in a two-cavity mold.

Also new is Aplicator's Ergomatic 2500 press unloader robot. This servo-driven device consists of a stationary pillar that stands at the back of the press, off to the side. Its horizontal arm can reach into the open mold, lift off a part, and retract from the mold in around 7 sec. As soon as the part is clear of the press, it can signal the charge loader to begin operating.

The new robot has quick-change vacuum grippers capable of a wrist motion, handles weights up to 110 lb, and boasts placement accuracy of |+ or -~0.04 in. The PLC control stores 20 unloading sequences and uses "teach-in" programming. Price is around $125,000.
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Title Annotation:RP/Composites; injection molding machinery exhibition
Author:Naitove, Matthew H.
Publication:Plastics Technology
Date:Mar 1, 1993
Words:816
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