Solutions to common problems of extrusion blow molding machine production

I The longitudinal wall thickness of blow molded products is uneven.

Cause:

1. The weight of the parison is severely drooping

2. The diameter of the two longitudinal cross-sections of the blow molded product is too different

Solution:

1. Reduce the melt temperature of the parison, increase the extrusion speed of the parison, replace the resin with a lower melt flow rate, and adjust the parison control device

2. Appropriately change the design of the product and adopt the bottom blowing method to form

II The lateral wall thickness of blow molded products is uneven

Cause:

1. The parison extrusion is skewed

2. The temperature difference between the inside and outside of the mold sleeve and the mold core is large

3. The shape of the product is asymmetrical

4. The inflation ratio of the parison is too large

Solution:

1. Adjust the gap width deviation of the die to make the wall thickness of the parison uniform; before closing the die, the straightened shape is broken

2. Increase or reduce the heating temperature of the die sleeve to improve the temperature deviation between the inside and outside of the die

3. Before closing the mold, pre-clamp and pre-expand the parison to make the parison shift to the thin-walled direction appropriately

4. Reduce the inflation ratio of the parison

III Orange peel-like patterns or pits appear on the surface of blow molded products

Cause:

1. Poor mold exhaust

2. Mold leakage or condensation in the mold cavity

3. Poor plasticization of the parison and melt fracture of the parison

4. Insufficient inflation pressure

5. Slow inflation speed

6. The inflation ratio is too small

Solution:

1. The mold parison is sandblasted, and vent holes are added

2. Repair the mold and adjust the mold cooling temperature to above the "dew point"

3. Reduce the screw speed and increase the heating temperature of the extruder

4. Raise high inflation air pressure

5. Clean the compressed air channel and check if the blowing rod is leaking

6. Replace the mold sleeve and core to increase the inflation ratio of the parison