Plastic product design compression molding

The Euler s formula developed by Leonard Euler (Swiss mathematician, 1707 to 1783) is used in product designs and also in designs using columns in molds and dies that process plastic. Euler s formula assumes that the failure of a column is due solely to the stresses induced by sidewise bending. This assumption is not true for short columns that fidl mainly by direct compression, nor is it true for columns of medium length. The failure in such cases is by a combination of direct compression and bending. 

Compression molding is a relatively simple and inexpensive procedure for the manufacture of moderate piece counts. For the production of bipolar plates compression molds with surface structured inserts were designed and manufactured. For the molding, the granulate can directly be molded in a heated mold under high pressure. Another way is the direct extmsion of a profile (semifinished material) into the structured mold, forming the plates from this plasticized polymer. In this variant the tool temperature is kept constant. With a multicavity-mold the cycle time can accordingly be shortened, and the output quantity of plates per cycle increased (Fig. 12). 

Proper venting is essential for the successful molding of plastics parts. Air is eliminated by breathing a compression mold. Since venting may influence the product design, it is desirable to consider its requirement. 

The mold is an important cost factor in the calculation of a plastic product. Mold modifications are usually associated with high costs and big risks. For proper functioning of compression molds, it is important that a technical drawing suitable for production be made before designing the mold. In some cases, it may be necessary to investigate and prove the manufacturability of a part with a prototype mold before manufacturing the production mold. 

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