Reasons and solutions for sink marks in plastic molds


Author: MULAN -Plastic Molding Manufacturer

This phenomenon in injection molded plastic parts is usually associated with face marks (voids), which are formed when the plastic shrinks away from the surface of the mold. The following editor from Xingye, an injection molding factory, will introduce the reasons and solutions for plastic molds with sink marks: Reasons for plastic molds with sink marks: (1) The melting temperature during injection molding is either too high or too low. (2) The plastic in the inner cavity of the injection mold is not enough.

(3) The surface in contact with the plastic is overheated during the cooling process. (4) The diversion channel is unreasonable, and the gate section is too small. (5) Whether the mold temperature is suitable for the properties of the plastic.

(6) The product structure is unreasonable (reinforcement is too high, too thick, and the thickness is obviously uneven); (7) The cooling is poor, and the product continues to shrink after demoulding. The solution to the sink mark defect of the plastic mold: (1) Adjust the temperature of the nozzle. (2) Adjust the screw speed to make the screw surface speed correct.

(3) Increase the injection volume. (4) Make sure to use the correct liner; increase the screw forward time; increase the injection pressure; increase the injection speed. (5) Check whether the stop valve is installed correctly, because abnormal operation will cause pressure loss.

(6) Reduce the mold surface temperature. (7) Adjust the flow path to avoid excessive pressure loss; according to actual needs, appropriately increase the cross-sectional size. (8) Properly control the mold temperature according to the nature of the plastic used and the product structure.

(9) Improve the product structure according to the license. (10) Try to keep the product fully cooled. For more information about plastic molds, please visit Xingye's official website:

Just tell us your requirements, we can do more than you can imagine.
    Send your inquiry

    Send your inquiry

      Choose a different language
      Current language:English