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How to reduce shrinkage in plastic mold processing


Therefore, various technologies have been developed to minimize shrinkage and improve product quality. Shrinkage is a stubborn disease. Premature cooling at the gate reduces the fill time in the cavity, which increases the chance of shrink marks. In the thicker position of the plastic mold parts of the Huangjiang, such as the ribs or protrusions, the shrinkage is more serious than the adjacent position, because the cooling rate of the thicker area is much slower than the surrounding area.How to reduce shrinkage in plastic mold processing


How to reduce shrinkage in plastic mold processing? Shrinkage is the enemy of plastic mold processors, especially for large-scale home appliance precision plastic mold products with high surface quality requirements. There may be one or more reasons for the formation of shrink marks, including processing methods, component geometries, material selection, and mold design. Too short a filling phase will result in increased shrinkage and eventually more or larger shrinkage marks. After the part is filled, the excess material continues to fill the cavity to compensate for the shrinkage of the material. The difference in cooling rate causes a depression at the joint surface, which is a familiar shrinkage mark. This kind of defect severely limits the design and molding of precision plastic mold products for home appliances, especially large-scale thick-walled products such as the bevel case and display case of TV sets. For example, small gates such as tubular gates cool much faster than tapered gates. In addition, the gas-assisted method is also worth a try..


A simple solution is to modify the conventional air cooler mould factory core hole, but this method cannot be expected to be suitable for all resins. In fact, for the demanding products such as household electrical appliances, the shrinkage marks must be eliminated, and for products such as toys that have low surface quality requirements, shrinkage marks are allowed. The geometry and material selection are usually determined by the raw material supplier and are not easily changed. Filling pressure and time significantly affect shrinkage. This method may not reduce the shrinkage marks to a satisfactory level by itself, but the molder can adjust the filling conditions to improve the shrinkage marks. Another method is to modify the mold. But moldmakers still have a lot of factors about mold design that can affect shrinkage. For molding workers, adjusting the processing conditions is one way to solve the shrinkage problem. Cooling runner design, gate type, gate size can have multiple effects