7 Tips about short molding in 2021
Short molding meaning: melt into the cavity after a filling is not complete, resulting in a lack of plastic parts.
7 Tips about short molding causes and solutions:
① Improper equipment selection:
In the selection of equipment, the machine’s melt volume must be greater than the amount of product melt. Injection molding machine parts can only account for the total amount of plastic melt 85%.
② Lack of supply:
Feeding port whether there is a “bridging” phenomenon may be appropriate to increase the screw injection stroke, increase the amount of feed.
③ Poor raw material flow:
Improve the stagnation of mold casting system defects, reasonable placement of plastic pouring position. Expand the gate, runner, and injection port size, and the use of larger nozzles. The appropriate increase in raw material temperature.
④ Pouring system design is unreasonable:
Design a pouring system, we should pay attention to the gate balance. The weight of each cavity plastic part and the gate is proportional to the size of the cavity. That can be filled at the same time. In the gate position to choose the original wall Parts, you can also use the sub-runner balance layout design.
⑤ Poor mold exhaust:
Check whether the cold material cavity or the location is correct. For the mold cavity darker, should be added in the injection of exhaust grooves and the exhaust vent in the clamping surface can be opened 0.02-0.04mm deep. 5-11mm wide exhaust slots, exhaust holes should be set in the final filling cavity. In addition, in terms of process operation, mold temperature can be increased. Injection speed can be reduced, casting system resistance can be reduced, and a mold clamping force can be reduced.
⑥ The mold temperature is too low:
Preheat the mold must be preheated to the process requirements of the temperature. If the mold temperature does not rise. Should check the mold design is not only a reasonable waterway.
⑦ Lack of injection pressure:
Injection pressure and the length of the die close to the proportional relationship. The injection pressure is too small, the filling length is short. The cavity filling dissatisfaction. Which can slow down the forward speed of the injection, the appropriate Ting long injection time?
Improve Injection pressure.
In addition to product short molding, there will be flash, shrinkage, and other issues.