Injection molding machine conventional nozzle

With backpressure the process is performed in conventional injection molding machines (IMMs) (Chapter 4). The cover stock is inserted and located in an open mold. A shear edge mold permits draw-in of the cover stock during the closing cycle to avoid wrinkles and damage by stretching of the fabric. Molds require special attention. They generally use a hot runner system with its shut-off nozzle(s). All mold elements such as ejector, core pulls, and slides have to be on the injection side mold half. 

The SCORIM process employs a unique hardware component that is retrofitted to a conventional injection molding machine. Located between the injection nozzle and the mold, this unit contains a pair of pistons that exert pressure on the melt after it is injected... 

Polyliner n A perforated, longitudinally ribbed sleeve that fitted snugly inside the cylinder of a ram-type injection-molding machine, replacing the conventional torpedo. It improved the heat transfer, plastifying rate, and uniformity of melt temperature at the nozzle. 

One advantage over conventional systems is the minimized control complexity for multi-cavity applications. Only one control point per manifold is needed. These systems are suitable for processing polyolefin, styrene, and acetal. Applications for other plastics may also be possible after consultation with the manufacturer. Basically, shot weights are possible from 0.05 to 2 g per nozzle tip. The product made from polyacetal, which is shown in Figure 2.61,hasaproductweightofonly0.1 gand is produced in a four-cavity mold on a mini-injection molding machine babyplast . 

Injection Molding. Matched metal molds are used in the fabrication of plastic closures, specialty packages, and botde preforms. In conventional injection mol ding the plastic resin is melted in an extmder which forces a measured quantity or shot into a precision-machined chilled mold after which the nozzle of the extmder is withdrawn. 

Injection Molding The processing and equipment for injection molding of thermosetting polymers differs slightly from the conventional injection machines used for thermoplastics. Reasons are (i) the thermosetting formulation must have a short residence time in the barrel or nozzle and (ii) the injection pressure is reduced after the mold is filled. 

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