Product bore eccentricity

(1) Definition of defect

Eccentricity of product bore refers to the phenomenon that after injection molding, the bore of the product will produce a difference in wall thickness from the design, with one side being thin and the other side being thick.

(2) Classification of causes

① Product design reasons

A. The product itself has the structure of designing long core, which causes the risk of congenital eccentricity defect.

B. The long core structure of the product does not take into account the structural design to prevent eccentricity.

② Mold causes

A. There is a large eccentricity in the processing of the long core of the mold, causing the product to deviate to one side.

B. The long core of the mold is not designed with a cooling system, and the high temperature during the production process causes the long core of the mold to deform to one side and become eccentric.

C. The strength of the long core insert is not enough to withstand the injection pressure.

③ Causes of injection process

A. The injection pressure is too high, and the long core insert of the mold is punched off.

B. The injection speed is too fast, so that the molten material is extruded to one side, and eccentricity is formed.

(3) Solution

① Product design countermeasures

A. Avoid the design of the long core structure of the product and use the structure of the insert instead.

B. Long core products to do touch through the structure to prevent eccentricity.

② Mold countermeasures

A. Improve the precision of mold processing, design the mold structure that can adjust the eccentricity of the long core.

B. Enhance the cooling effect of the mold long core inserts.

C. Mold long core insert design is relatively large to ensure the strength.

③ Injection molding process countermeasures

A. Low pressure injection.

B. Low-speed injection first, to ensure that the long core inserts are surrounded by materials before high-speed injection.

---- The above content is selected from the “injection molding use of technology”, thank you for your attention to Fomtec Machine!