The plastic mold is an abbreviation for a combined mold for compression molding, extrusion molding, injection molding, blow molding and low foam molding. Plastic mold injection molding is a processing method used in mass production of complex parts of certain shapes. The specific principle refers to: the plastic raw material melted by the heat is injected from the screw of the injection molding machine into the cavity of the plastic mold, and after cooling and solidifying, the plastic formed product is obtained.
When using plastic mold injection molding process to produce plastic formed products, there will be various problems due to equipment, process, technician experience, etc. For example, many plastic mold factories have warpage and deformation in the common products of plastic injection molding. A very difficult problem. This problem should be solved mainly from the design of plastic molds, and the adjustment effect of molding conditions is very limited. The causes and solutions for warpage and deformation can be referred to the following:
(1) When deformation is caused by residual stress caused by molding conditions, stress can be relieved by reducing the injection pressure, increasing the mold and making the mold temperature uniform, increasing the resin temperature, or annealing.
(2) When the stress is deformed due to poor mold release, it can be solved by increasing the number or area of the push rod and setting the draft angle.
(3) Since the cooling method is not suitable, and the cooling is not uniform or the cooling time is insufficient, the cooling method and the cooling time can be adjusted. For example, a cooling circuit can be placed as close as possible to the deformation.
(4) For the deformation caused by the molding shrinkage, it is necessary to correct the design of the mold. Among them, the most important thing is to make the wall thickness of the product consistent. Sometimes, in the case of a last resort, the mold must be trimmed in the opposite direction by measuring the deformation of the product. A resin with a large shrinkage ratio is generally a crystalline resin (such as polyacetal, nylon, polypropylene, polyethylene, and PET resin) than a non-crystalline resin (such as PMMA resin, polyvinyl chloride, polystyrene, ABS resin). And AS resin, etc.) have large deformation. In addition, since the glass fiber reinforced resin has fiber orientation, the deformation is also large.
In fact, plastic molds are not difficult. No matter how the plastic products change, for the molds that form the plastic products, as long as the control, design, manufacturing, production and other aspects of the molds are controlled, the final injection molded plastic products are not. There will be too many problems.
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