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Is it important to control the cooling time of injection molding?

Update:22-04-2022
Summary:

In the injection molding process, the cooling time of i […]

In the injection molding process, the cooling time of injection molded parts accounts for about 80% of the entire injection cycle, which shows the importance of cooling time. If the cooling time is not in place, it will affect the warpage or insufficient surface, thus affecting the dimensional stability of the product. Proper scheduling of injection, pressure, and cooling times can improve product quality and productivity.

The cooling time of a part is usually the time from when the injection Auto Parts Mold cavity is filled with plastic melt until the part can be opened and taken out. The time standard for opening the mold and removing the part is usually based on the part being fully cured and having a certain strength and stiffness. No deformation or cracking when demoulding. Even when molding with the same plastic, the cooling time varies with wall thickness, molten plastic temperature, mold release temperature, and injection temperature. A formula that calculates the chilling time 100% correctly in all cases has not been published, only one that calculates on the basis of appropriate assumptions has been published. The formula also depends on the definition of cooling time.

The plastic in the cavity is in close contact with the cavity and will not separate due to shortened cooling time. There is no resistance to heat transfer and flow between the melt and the die wall. Upon contact, the temperature of the melt and the mold walls become the same. That is, when the plastic is filled into the mold cavity, the workpiece surface temperature is equal to the mold wall temperature; when the cavity temperature is equal to the mold wall temperature, the workpiece surface temperature is equal to the mold wall temperature.

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