Shrinkage of nylon 66 raw material
- Author：
- Source：
- Date：2017-12-13
Shrinkage of nylon 66 raw material
- Author：
- Source：
- Date：2017-12-13
Details
2017-12-13
Process shrinkage of nylon 66 raw materials
The process characteristics of nylon 66 raw materials are shown in many aspects, some are only related to its operation, while others affect the selection of molding methods and process characteristics.
In the melting state of nylon 66 raw material, its plastic melting, after molding cooling, the phenomenon of volume shrinkage, and people call this phenomenon shrinkage. How do you know the shrinkage? This is the rate of shrinkage.
Nylon 66 RAW material shrinkage principle: usually due to nylon 66 raw material thermal expansion and cold contraction, plastic deformation and demoulding elastic recovery and other reasons. But not only this form, it may also be due to the shape of plastic parts, material flow direction and molding process parameters caused by different shrinkage. Product shrinkage will affect the quality and accuracy of the final product. Therefore, to minimize shrinkage, we should first understand the causes of shrinkage before solving the problem:
1) Nylon 66 raw material plastic varieties: different plastics, its characteristics are different, shrinkage rate is also different. The increase of filler and other substances will also cause the shrinkage of the same material is different
2) nylon 66 raw material product structure: the shape of the product itself, wall thickness, size and so on will also have an impact on the plastic shrinkage rate. The shrinkage rate of the products with complex shape, thin wall and large number of embedded parts is small.
3) Nylon 66 raw material molding process conditions. Nylon 66 raw material mold temperature is high, melt cooling slow, density, shrinkage. For crystalline materials, high crystallinity, large volume change, so the shrinkage rate is greater. The shrinkage rate of nylon 66 is actually smaller than that of crystal: the shrinkage rate of nylon 66 was 1.5-2.2 originally, but when 30% glass fiber was added, the shrinkage rate became 1.2-2.0. Why did the shrinkage rate become smaller after adding glass fiber? This is what I said in the first point, the same material, but with some excipients, its shrinkage rate will change.
Mold temperature affects shrinkage rate: that is, mold temperature and plastic parts inside and outside cooling and density uniformity directly affect the size and direction of shrinkage of each part.
Molding pressure and pressure holding time also have an impact on the shrinkage rate: high pressure, long time, shrink, but directionality; The material temperature is high, the shrinkage is large, but the directionality is small. Therefore, when molding to adjust the mold temperature, pressure, injection speed and cooling time and other factors, may affect the shrinkage of plastic parts.
Process shrinkage of nylon 66 raw materials
The process characteristics of nylon 66 raw materials are shown in many aspects, some are only related to its operation, while others affect the selection of molding methods and process characteristics.
In the melting state of nylon 66 raw material, its plastic melting, after molding cooling, the phenomenon of volume shrinkage, and people call this phenomenon shrinkage. How do you know the shrinkage? This is the rate of shrinkage.
Nylon 66 RAW material shrinkage principle: usually due to nylon 66 raw material thermal expansion and cold contraction, plastic deformation and demoulding elastic recovery and other reasons. But not only this form, it may also be due to the shape of plastic parts, material flow direction and molding process parameters caused by different shrinkage. Product shrinkage will affect the quality and accuracy of the final product. Therefore, to minimize shrinkage, we should first understand the causes of shrinkage before solving the problem:
1) Nylon 66 raw material plastic varieties: different plastics, its characteristics are different, shrinkage rate is also different. The increase of filler and other substances will also cause the shrinkage of the same material is different
2) nylon 66 raw material product structure: the shape of the product itself, wall thickness, size and so on will also have an impact on the plastic shrinkage rate. The shrinkage rate of the products with complex shape, thin wall and large number of embedded parts is small.
3) Nylon 66 raw material molding process conditions. Nylon 66 raw material mold temperature is high, melt cooling slow, density, shrinkage. For crystalline materials, high crystallinity, large volume change, so the shrinkage rate is greater. The shrinkage rate of nylon 66 is actually smaller than that of crystal: the shrinkage rate of nylon 66 was 1.5-2.2 originally, but when 30% glass fiber was added, the shrinkage rate became 1.2-2.0. Why did the shrinkage rate become smaller after adding glass fiber? This is what I said in the first point, the same material, but with some excipients, its shrinkage rate will change.
Mold temperature affects shrinkage rate: that is, mold temperature and plastic parts inside and outside cooling and density uniformity directly affect the size and direction of shrinkage of each part.
Molding pressure and pressure holding time also have an impact on the shrinkage rate: high pressure, long time, shrink, but directionality; The material temperature is high, the shrinkage is large, but the directionality is small. Therefore, when molding to adjust the mold temperature, pressure, injection speed and cooling time and other factors, may affect the shrinkage of plastic parts.
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