I. Equipment
Poor plasticization and uneven melt temperature can extend the molding cycle to make plasticization more complete. If necessary, replace the machine with a large plasticization capacity.
II. Mold
(1) The mold temperature is too low. The mold temperature should be appropriately increased or the local temperature at the weld seam should be purposefully increased.
(2) The flow channel is small, too narrow or too shallow, and the cold well is small. The size of the flow channel should be increased to improve the flow channel efficiency and increase the volume of the cold well.
(3) Enlarge or reduce the gate cross section and change the gate position. When opening the gate, try to avoid the melt flowing around the inserts and holes. If the gate is filled with injection, try to correct, move or add a block to buffer it. Try not to use or use as few gates as possible.
(4) Poor exhaust or no exhaust holes. The exhaust channel should be opened, expanded or unblocked, including exhausting through the gaps of inserts and ejector pins.
III. Process
(1) Increase the injection pressure and extend the injection time.
(2) Adjust the injection speed: high speed can make the molten material reach the confluence before it has time to cool down, and low speed can allow time for the air in the cavity to be discharged.
(3) Adjust the temperature of the barrel and nozzle: high temperature makes the viscosity of the plastic small, the flow is smooth, and the weld mark becomes thinner; low temperature reduces the decomposition of gaseous substances.
(4) Release agents should be used as little as possible, especially silicone release agents, otherwise the material flow will not be able to merge.
(5) Reduce the clamping force to facilitate exhaust.
(6) Increase the screw speed to reduce the viscosity of the plastic; increase the back pressure to increase the density of the plastic.
IV. Raw materials
(1) The raw materials should be dry and the liquid additives in the formula should be minimized.
(2) Lubricants and stabilizers should be added appropriately to plastics with poor fluidity or high heat sensitivity. If necessary, plastics with good fluidity or high heat resistance should be used instead.
V. Product design
(1) If the wall thickness is small, the part should be thickened to avoid premature solidification.
(2) If the insert position is improper, it should be adjusted.
