There may be a variety of solutions, especially for some specific situations, but the general solutions include:

1 Use injection machines with large clamping force, wherein the rated clamping force must be higher than the tension of injection molds during filling, otherwise, mold expansion and flash will occur.

2 Check the clamping system of injection machine, especially whether the toggle unit is straight under clamping state; dispel such factors as unbalanced clamping and fluctuated clamping force of melt during the process of injection and filling.
3 Optimize gate position and achieve balanced mold-filling; avoid unbalanced clamping and partial over-dwell for melt in parts where filling has been completed.
4 Properly reduce injection pressure and dwell pressure and switch pressure in time.
5 Optimize prescription of plastic raw materials, properly reduce dosage of lubricating agent, keep the viscosity of plastics within a proper range; appropriately reduce temperature of barrel, nozzle and molds and injection rate, properly increase section dimension of gate and thereby optimizing the flow and filling state of melt.

6 Check the attaching degree of parting line for deformation or foreign matters (if any), and polish the part of parting line with flash; check the places that have gliding or insert fit with the molding parts for discrepancy of assembly or abrasion clearance (if any); check whether rigidity of mold plate is sufficient; when necessary, properly improve the design and manufacturing precision of clearance at moving or fixed part of molds.

7 Check whether exhausting slot is overlarge or overdeep and properly arrange the clearance dimension of mold exhausting channel.