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New equipment for lower-cost RIM.

New Equipment for Lower-Cost RIM

A new and growing category of smaller RIM dispensing equipment is exemplified by the first offerings from the recently formed RIM div. of Gusmer in Lakewood, N.J. While these machines do not have the high output rates required to produce large parts quickly, they are priced low enough to attract additional processors to the RIM business, according to the company. Gusmer has introduced three lines of RIM machinery: the RimCell, DeltaRim, and k-RIM models, at prices ranging from $28,400 to $65,580.

All of the new machines operate at dispensing pressures up to 3000 psi. Open design facilitates access. Standard equipment includes a shot controller with 50 programmable settings based on either time or material volume. An automatic sequence of different shots can also be programmed. A novel temperature-control system brings the RIM material in direct contact with fluorocarbon heat exchangers, without using water as an intermediate medium or additional pumps. Low-pressure recirculation prevents stationary chilling.

In-line flow meters are used to calibrate the machines internally, rather than pouring and measuring material externally. Direct readout is provided of A-side and B-side flow rates and ratio during dispensing. Non-solvent flushing of the mix heads is handled by a plunger that also serves to shut off the flow of material. In addition, a small lance pump provides impulse flow of liquid plasticizer to the metering-pump shaft-seal cavity in order to flush the isocyanate approx. every 15 sec.

Still another unusual feature is a 3.5-gal air reservoir fed by shop air, which ensures an adequate reserve to maintain blanket pressure and seat-valve operation in case of a brief interruption in flow from the compressor. A built-in air dryer is standard.

FOR LOW-VISCOSITY SYSTEMS

RimCell machines come in two configurations, with outputs of either 100 or 240 lb/min. These units have two variable-ratio axial piston pumps that are manually adjustable by handwheels. Intended for processing non-abrasive, non-corrosive, and unfilled systems with viscosities up to 3000 cp, the RimCell machines operate under closed-loop digital control and can attain infinitely variable ratios from 1:5 to 5:1. A reportedly unique feature of these machines is the use of a gear pump to feed the piston metering pump. This tandem arrangement helps with the higher-viscosity materials and ensures that the metering pump always "sees" the same inlet pressure, regardless of viscosity. Because the feed pump operates at a slightly higher flow rate than the metering pump, the excess flow is used to cool the pump casing.

Control consoles on these units rotate 270[degrees] for operator convenience. Optional equipment includes pneumatic booms, tank-level monitor, and agitators. A variety of hydraulic mix heads are available.

The RimCell 100 requires 26 kw of power and costs $54,480, while the RimCell 240 requires 52 kw and costs $65,580. Both machines measure 76 in. long X 95 in. wide X 82 in. high. Gusmer reports that Hercules, Wilmington, Del., has just purchased a RimCell 240 to use in developmental work with its Metton DCPD liquid-molding resins. (CIRCLE 2)

UNLIMITED SHOT SIZE

A distinguishing feature of the DeltaRim machines is the use of double-acting, hydraulically driven piston pumps that can process high-viscosity materials (up to at least 18,000 cp), filled and abrasive systems, polyurea, and other multiple-component systems. The line currently includes models with outputs of 40 and 80 lb/min, while a 160-lb/min model will be introduced soon. The machines have a variable pump ratio of 1:4 to 4:1 and can accommodate either a hydraulic or pneumatic mix head, or an optional spray head.

The double-acting pump sequence results in a continuous flow of material, allowing for large-part production with an unlimited shot size. This uninterrupted dispensing is not attainable with a standard lance cylinder machine, which must stop and recycle before dispensing again.

The DeltaRim 40 requires 10 kw of power and costs $39,900 with a pneumatic head and $46,380 with a hydraulic head. The DeltaRim 80 requires 20 kw and costs $50,580. Both machines measure 57 in. long X 60 in. wide X 47 in. high. (CIRCLE 3)

FIXED-RATIO MODELS

Fixed-ratio k-RIM machines also use double-acting piston pumps to produce outputs of 40 or 60 lb/min, with unlimited shot size. They are said to process the same types of high-viscosity, filled, and abrasive materials as the DeltaRim machines.

The k-RIM 40 requires 8 kw of power and costs $28,400, while the k-RIM 60 requires 16 kw and costs $30,600. Both machines measure 55 in. long X 40 in. wide X 60 in. high. A spray conversion option is also available. (CIRCLE 4)
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Title Annotation:reaction injection molding
Author:Evans, Bill
Publication:Plastics Technology
Date:May 1, 1990
Words:775
Previous Article:New reclaim methods target PVC.
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