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What is the reason why plastic products cannot completely fill the mold?

update:25-05-2019
abstract:

There are mainly the following reasons for the filling […]

There are mainly the following reasons for the filling of the product: 1. The temperature of the barrel and nozzle is low; 2. The temperature of the mold is too low; 3. The feeding amount is not enough; 4. The injection pressure is too low; 5. The injection speed is too slow; The gate is too small; 7, the injection time is too short; 8, the holding time is short; 9, the impurity blocking nozzle or the spring needle valve nozzle fails; 10, the quality or area of ​​the workpiece exceeds the maximum injection volume or the maximum injection area of ​​the injection molding machine ; 11, the cavity does not have a proper vent. All of the above are the reasons, but the main reason is the lack of material and injection pressure and speed (including the resistance caused by excessive pressure).

solution:

1. Machine side: 1 Due to the plasticizing amount of the machine or the instability of the heating power, the machine with large plasticizing amount and heating power should be selected; 2 the wear or damage of the screw and the barrel or the rubber head will cause The actual filling amount is not found when returning the material; 3 the actual temperature of the barrel caused by the failure of the heating system such as thermocouple or heating ring is too low, which will bring some dissatisfaction to the filling of the plastic product; 4 sealing element of the injection cylinder Wear and tear cause oil leakage or backflow, but can not reach the required injection pressure; 5 the nozzle hole is too small or the nozzle center degree is improperly adjusted to cause excessive resistance and pressure consumption.

2. Mold: 1 The temperature of the mold is too low or the whole is too low, which makes it difficult to feed. The mold temperature should be increased appropriately. Of course, if there is a mold temperature machine, these problems can be solved very well. 2The cavity of the mold The distribution is not balanced. The wall thickness of the workpiece is too thin, resulting in excessive pressure consumption and poor filling. The entire part or partial wall thickness should be increased or an auxiliary flow or gate solution should be provided in the vicinity of insufficient filling. 3 The flow path of the mold is too small to cause pressure loss; when it is too large, the glue will be weak; if it is too rough, the parts will be dissatisfied. The size of the flow channel should be properly set, and the appropriate arc transition should be applied to the transition between the main flow channel and the runner, the gate, or the turn itself. 4 The mold is poorly exhausted. The material entering the cavity is blocked by the pressure of the gas that is not exhausted, causing the filling to be dissatisfied. It is possible to make full use of the slit venting of the screw or to reduce the clamping force by using the parting surface to vent, and if necessary, to open the exhaust channel or the vent.

3. Reasons for repeated dissatisfaction of the parts: 1 When the granularity of the plastic raw materials is uneven, the amount of the added materials may be uncertain. 2 The excessive wear of the rubber head, the apron ring and the rubber gasket of the screw is too large, so that the melt may be dissatisfied by sliding and reflowing between the screw and the barrel. 3 The cooling system of the inlet is invalid, which makes the feeding amount unstable. 4 The amount of shots set by the barrel is insufficient, that is, if the cushion is too small, the parts will be dissatisfied when the material is shot for a long time.