The second case: the screw of the injection molding machine can reach the set melt stroke, but it can not reach the set injection stroke (the amount of residual glue). This means that there is melt glue in the barrel, but the injection does not enter the mold. Possible causes of the cavity:
1. The fluidity of the melt adhesive is not enough. The fluidity of the melt adhesive is insufficient, and the flow resistance is large. It is difficult for the colloid to be filled into the mold. This may be caused by the following reasons. :
(1) The raw material itself has poor fluidity;
(2) The processing temperature of the barrel is set too low or the temperature does not reach the set value, such as the temperature display is not true.
(3) The mold temperature is low. Although the colloidal fluidity in the barrel is good, after flowing into the mold flow path, the temperature is too fast, and the fluidity in the mold cavity in the mold flow path is poor, resulting in dissatisfaction of filling.
2. The injection molding process parameters are not set properly.
The injection pressure is low, the colloid can not overcome the filling resistance; the injection speed is low, the melting time of the glue is long when filling, the fluidity is reduced, resulting in a large filling resistance; the injection holding time is short, the filling is stopped before the product is filled, etc. Causes the product to be less than glue.