Several common problems in Dongguan blow molding products?

Dongguan blow molding mainly refers to hollow blow molding (also known as blow molding), which is a method of expanding a hot melt parison closed in a mold to form a hollow product by means of gas pressure. It is a fast-growing plastic molding method. . The mold used for blow molding is only a female mold (concave mold). Compared with injection molding, blow molded products have lower equipment cost, stronger adaptability, good moldability (such as low stress), and can have complex undulating curves (shapes) ) Products.

First, the longitudinal wall thickness of the blown product is uneven:

cause:

①Sag phenomenon of parison's own weight is serious

② The difference between the two cross-sectional diameters of the longitudinal direction of the blown product is too large.

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

② Properly change product design and adopt bottom-blowing method

Second, the uneven wall thickness of blow molding products:

cause:

① Skewed parison extrusion

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

③ Asymmetric product shape

④ Excessive inflation ratio of parison

solution:

① Adjust the deviation of the die gap width to make the parison wall thickness uniform; before the mold is closed, the straightened shape is bad

② Raise or lower the heating temperature of the mold 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, so that the parison is properly shifted to the thin wall direction.

④ Reduce parison inflation ratio

3. Orange peel-like patterns or pits appear on the surface of blow molded products:

cause:

① Poor mold exhaust

② Water leakage in the mold or condensation in the mold cavity

③ Poor plastication of parison, melt fracture of parison ④ Insufficient inflation pressure

⑤ Slow inflation

⑥ The inflation ratio is too small

solution:

① The mold parison is sandblasted and additional 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 Lifting inflation pressure

⑤Clean the compressed air channel and check whether the blower is leaking

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