TPE, TPR products appear (shot pattern, flow pattern, wave pattern) the solution to defects

  • Time of issue:2022-09-21
  • Views:554

TPE, TPR products appear (shot pattern, flow pattern, wave pattern) the solution to defects

  • Categories:Elastomer knowledge
  • Author:SPP
  • Time of issue:2022-09-21
  • Views:554

  For TPE products surface irregularities, affecting the quality of product appearance, I think it is commonplace, TPE products surface texture defects, according to its causes, briefly divided into the following two situations: 1.

  1. Shot pattern

  The shooting pattern is fundamentally caused by the gas in the mold cavity injection speed is too fast, the material tube or the air in the mold cavity can not be discharged in a timely manner, in the mold cavity to produce a large gas pressure, and the product surface friction shear, and finally formed on the surface of the product sheet shooting pattern.

  Solution: Reduce the injection speed appropriately. In addition, if the molding temperature is too high, the material will decompose and produce gas, which will also lead to the formation of shot pattern; solution: control the molding temperature. If the material contains water, when molding at high temperature, the water will evaporate and form gas, which will also lead to the emergence of shot pattern, and if the molding temperature is low, it will also form a lack of glossy pockmark. Solution: Bake the material before molding.

  2. Rhyolite

  It is mainly affected by material fluidity, plasticization degree, mold temperature and gate temperature, mold and runner structure, poor material fluidity, easy melt filling, if not completed quickly, the melt temperature decreases, the flow rate decreases, easy to form flow lines on the surface of the product.

  Solution: Replace the TPE material with better flowability.

  Mold temperature and gate temperature is too low, will strengthen the friction shear between the melt and the mold surface, which will lead to the flow pattern.

  Solution: Increase the mold temperature and mold gate temperature appropriately. Insufficient plasticization of the material and poor melting will easily lead to obvious flow lines on the surface of the product; Solution: Properly increase the injection temperature and screw speed to strengthen plasticization.

  3. Wave pattern

  In the process of melt filling, the new melt flow is constantly pressed out from the inner layer, pushing the front wave stagnant flow to move, while the front wave edge is constantly stretched, due to the resistance to flow, the melt pressure rises later and flattens the front wave pattern just formed, resulting in the accumulation of stagnant flow, thus forming the product surface wavy pattern.


  ① Change the process conditions. The use of high pressure and low speed injection, can maintain the stability of the melt mass melt flow, thereby preventing the appearance of wavy lines.

  ② Increase the mold temperature. As the mold temperature increases, the melt flow increases, and for crystalline polymers, a higher temperature is beneficial. The higher temperature is good for the crystalline polymer. It is good for the uniformity of crystallization, thus reducing the appearance of wavy patterns.

  ③ Change the structure of the mold cavity. The structure of the mold can also cause wavy patterns on the surface of the product. For example, if the angles of the mold core are more prominent, the melt flow resistance is higher, which will cause the melt flow instability, thus forming wave pattern. Therefore, changing the corners of the mold core to make a buffer transition and keep the melt flow stable can prevent the appearance of wavy patterns.

  ④Change the thickness of the product. Uneven thickness of the product will make the melt flow resistance sometimes large and sometimes small, resulting in unstable melt flow, so try to design the thickness of the product as uniform thickness, which can also prevent the appearance of wavy lines.


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