Process Requirements of PA Materials in Injection Molding Plants

Table of Contents

PA (polyamide) is a thermoplastic commonly used for injection molding. It is made of diamine and dibasic acid through polycondensation. PA has strong tensile, compressive and wear resistance, but it also has disadvantages such as strong water absorption, large shrinkage and poor stability. Therefore, when using PA materials, injection molding plants need to fully consider its advantages and disadvantages, take advantage of its advantages, and meet processing requirements by adding other materials or using specific equipment.

Inspection of material dryness and wetness

Before using PA materials, injection molding plants will check their dryness and wetness. If PA has too much moisture, it will have a negative impact on the processing process, reduce the melt viscosity, and cause defects such as bubbles and silver streaks on the surface of the product. In severe cases, it will also affect the mechanical properties of the product. Therefore, injection molding plants usually dry PA. Since PA is easily oxidized, vacuum drying is usually used. It should be noted that PA should be used in time after drying to prevent it from absorbing excessive moisture again.

Selection of injection pressure

When processing PA, injection molding plants need to carefully select injection pressure. PA is less sensitive to injection pressure, so the injection pressure should be reasonably controlled according to factors such as injection molding machine type, product shape, size, mold structure, injection speed, injection time and holding time.

Reasonableness of injection speed

In addition, the china custom plastic molding supplier must also maintain rationality when selecting the injection speed of PA. The injection speed should be associated with factors such as product wall thickness, melt temperature and gate size. For thin-walled products, the injection molding plant will use a faster injection speed, while for thick-walled products, a slower injection speed should be used. When a higher melt temperature and a slower injection speed are combined with a smaller gate size, the injection speed should not be too fast to avoid excessive shearing, resulting in excessive melt temperature and degradation, which will cause discoloration and decreased mechanical properties. If the injection speed is too fast, the product may have defects such as bubbles and carbonization.