One of the most astounding displays at this year’s Fakuma international trade fair in Germany was Netstal’s demonstration of injection compression molding on a stack mold. The results may have seemed quite ordinary: a simple polypropylene margarine container. However, the 15-ounce container weighed in at a mere 10.7 grams. In addition, Netstal claimed its advancement on injection compression molding technology cut material costs by an impressive 20%. While Netstal may have made history with the world’s first injection compression mold on a stack mold, the actual process of merging compression and injection molding techniques has been in play for some time, often with gorgeous results.
An Overview of the Procedure
Injection compression molding differs immediately from standard injection molding at the outset of the process in that the mold is left slightly ajar during the filling procedure. The compression clamp is activated once the molten plastic has partly filled the mold. Therefore, the compression process is instrumental in fully filling the mold with the injected molten plastic material. While standard injection molding practices can result in warping and substandard pattern transfers, injection compression molding largely bypasses such flaws.
The Unique Appeal of Injection Compression Molding
The reasons a plastic manufacturer may turn to injection compression molding techniques are manifold, but an even distribution of resin is a primary benefit. A general decrease in the ratio of flow distance to thickness, heightened reproduction of micro-surface details, and better hold pressure result in a molding process that’s ideal for products that require ornate detail orientation. Since the pressure associated with the injection process is reduced when combined with compression molding, injection compression molding is ideal for manufacturing fragile commodities as well. It’s commonly used in the manufacturing of products with optical attributes such as DVDs. Likewise, any products that require a thin wall with minimal warping rely heavily on combining compression and injection molding process. This makes injection compression molding popular in the production of televisions; the thinner the model, the more vital the injection compression process. In addition, the molding cycle is generally faster when the compression and injection molding processes are combined than when injection molding is executed alone.
When the Process Goes Wrong
While injection compression molding merges heightened detail with structural strength in the completed commodity, the process can go awry lending to less-desirable results. For example, jumping the gun on the compression process can result in a consequence called “short shot”; an inadequate filling of the mold. Likewise, a delayed compression brings its own headaches with the melt compromising the parting line, at times resulting in overfilling. In order to get the optimum benefits of injection compression molding, the compression must be timed just right.
Injection compression molding remains a specialty service when compared to classic injection molding processes. Its specialized ability to create nuanced, detailed products with initially fragile structures finds it the method of choice for several commodities. With comparatively less stress than standard injection molding techniques, the finessed hybrid of injection and compression procedures offers unique benefits integral to optical commodities, thin-walled components, and insulated parts.