Multicavity injection molds

The use of multicavity injection molds together with a cold runner system. The objective of the cold runner system is to prevent the runner system in the mold from curing during the molding process. The result is that the elastomeric compound held in the run-... 

Balanced gating n. In multicavity injection molds, the objective is to fill all of the cavities simultaneously, to fill to the same final pressure, and then to have their gates freeze at the same time. Strong AB (2000)... 

Balanced runners n. In a multicavity injection mold, the runners are balanced when the injected melt reaches all the cavity gates at the same instant after the start of injection. In practice, with identical cavities whose shape, size, number, and layout permit, all runner branches are given equal cross sections and corresponding branch lengths are made equal. Uniform metal temperature throughout is assumed. 

C.-C. Lee and J. F. Stevenson, "Optimizing Runner System for Multicavity Injection Molds. Parti Runner Sizing," Polymer Engineering and Science, vol. 39, 1999. 

Beaumont J.P., Raltson J., Shuttleworth A. Troubleshooting Cavity to Cavity variations in Multicavity Injection Molds, ANTEC, 2000... 

Over the years the trend has been toward an increasing use of the more expensive elastomers. Concern has been expressed about the cost of waste compound when using a multicavity mold and injection molding, primarily due to the amount of elastomeric compound in the runner system. There are three approaches to overcome the problem ... 

SBC can also be molded into overcaps. These are injection molded clear caps that are often used on bottles for food and cosmetic packaging. Overcaps are typically made by injection molding in multicavity molds and designed for a snap fit. They must have high gloss and clarity and can often have a transparent color. 

Other stations can be included, such as decorating. Multicavity molds are used extensively. As is typical of injection molding and extrusion machines (Chapters 2 and 3), they can have sophisticated computer controls to ensure proper operation of all machine and material functions. 

Injection molding Low-viscosity resin Multicavity molds and parts with thin sections difficult to fill... 

Short shot n. In injection molding, failure to fill all cavities of the mold completely, caused by too low melt temperature, too low injection pressure, insufficient plasti-cation time, too constricted gates, too viscous resin, inadequate venting of cavities, etc. Short shots are often made deliberately when testing a new multicavity mold to reveal the pattern of runner flow and the sequence of cavity filling. 

Acetal parts can be manufactured by common thermoplastic processes. However, most parts are made by injection molding and extrusion. The resin s sharp crystalline melting point provides quality injection-molded parts. Often, small acetal parts can be injection molded in multicavity molds. 

M270-04 27.0 Highest flow. Superior moldability for hard to fill molds with somewhat less toughness than M90. Internally lubricated. High speed injection molding for multicavity parts. 

Flash Excessive injection pressure Excessive melt temperature Mold parting face faulty Insufiticient clamp force Foreign matter on mold parting face Flow restriction in one or more cavities of multicavity mold... 

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