The impact of shrinkage on plastic processing


1. Shrinkage after processing:


The shrinkage after processing is the shrinkage of the products after a period of time after demolding, and the post-shrinkage is generally small compared to the molding shrinkage.

The first cause of post-contraction is the relaxation of the internal stress of the article. For polymers with a rigid molecular chain, the post-contraction of the product is relatively large; this is mainly because the rigid molecular chain moves slowly, and its molecular chain changes from one state to another, requiring a long realignment process.

Therefore, the post-shrinkage time is relatively long, and the post-shrinkage rate is relatively large. On the other hand, rigid molecular chains tend to generate internal stress, and slowly stress relaxation occurs after molding. The second cause of post-contraction is the continued crystallization. For the complete crystallization, and the crystallization can continue at normal temperature, thereby causing a slight shrinkage of the product.

2. Average shrinkage rate:

Since the shrinkage size of plastic processing is greatly affected by the molding conditions, the shrinkage rate is not a fixed value, but a range. In the specific processing process, various processing conditions can increase the molding shrinkage rate, and 4% can be selected.

For specific shrinkage, if the specific molding conditions are favorable for the reduction of molding shrinkage, then 2.5% can be selected as the specific shrinkage. Of course, the latter method is more difficult.

About JasonMould Industrial Company Limited


Person: James Yuan
Company: JasonMould Industrial Company Limited
Tel: 86-752-6682869
Email: [email protected]


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