How to adjust the injection molding machine, how to solve the shrinkage of injection molding products?
The reasons for design and improvement measures are shown in the following table:1, head of cross section is too small to increase head cross section2, head is too long to shorten the head3, the nozzle hole is too small to increase the diameter of the nozzle4, head office will open in the thin head positioning in the thick wall5, excessive accumulation of materials to avoid material accumulation6, the wall / tendon section is not reasonable, providing a reasonable ratio of the wall / tendon sectionTo sum up, from the aspects of processing parameters, first consider the injection molding machine to maintain pressure.
The reasons for the machining parameters and the improvement measures are shown in the following table:1, keep the pressure too low, increase the dwell pressure2, the holding time is too short to extend the holding time3, die wall temperature is too high, reduce mold wall temperature4, melting material temperature is too high, reduce melting material temperature, reduce the barrel temperature
Shrinkage (Sink, marks, or shrinkage) is one of the defects in injection molding.ApparentThere is a dent in the accumulation area of the surface material of the plastic parts. The shrinkage occurs mainly in the thick part of the plastic wall or in the change of the wall thickness.Physical reasonsWhen the product is cooled, shrinkage (decrease in volume, shrinkage) occurs at the time where the outer wall of the die is frozen first, and the inner center of the work product forms an internal stress. If the stress is too high, it will cause plastic deformation of the outer plastic. In other words, the outer layer will sag inwards. If the shrinkage occurs and the deformation of the outer wall is not stable (as it has not cooled), the pressure shall not be added to the melt and the mold will settle between the die wall and the solidified outer layer of the product.These settlements are usually seen as shrinkage. If the product has a thick cross section, this shrinkage may also occur after demoulding. This is because there is still heat inside, and it passes through the outer layer and heats up the outer layer. The tensile stress produced in the product causes the thermal outer layer to settle inward, forming shrinkage during this process.
