Molding parameters affect cooling time and shrinkage Mo […]
Molding parameters affect cooling time and shrinkage
Molding parameters have a significant impact on the performance of injection molded parts. Machining conditions that affect part geometry include temperature, filling parameters, cooling time and injection speed. Each of these conditions plays an important role in how the material solidifies and how long it takes to cool down to meet part specifications. Processors should work closely with mold designers to design molds based on molding conditions.
Materials have a direct effect on cooling and shrinkage, as each material has specific properties, and molding conditions can also have a significant impact on the material properties of any product design. Two important parameters that affect cooling time and shrinkage of a material are melt temperature and mold temperature.
Mold Design and Cooling Time
The chair mould design, or rather the geometry of the part itself, will affect how the part cools in the mold. When the part begins to cool, it is from the outside to the inside. If a part contains areas of non-uniform wall thickness, stresses may develop during the cooling phase, where thinner sections solidify faster than thicker sections, potentially causing part warpage.
A skilled design engineer will understand how the part cools in the mold based on the part geometry, resin used and processing parameters, and design the cooling system accordingly. The cooling system consists of water passages through the mold to properly cool the part. The mold designer must be careful so that the cooling lines do not interfere with the clamping system or tie rods of the molding press.