Home » Injection Moulding 101 » Cracks of Injection Molded Parts

Cracks of Injection Molded Parts

Causes of molded parts cracks
  • Residual stress caused by forming condition (satiety mould)
  • Residual stress occurs when stripping
  • Stress concentration caused by the shape of injection moulded parts
  • Error caused by insert thermal expansion
  • Materials deterioration
Associate knowledge of cracks
The residual stress within the product. Moulding conditions should be set towards to elimination of stress. That is to increase cylinder and mould temperature, and when the flow ability of the material becomes a good state, the injection pressure should not be too high.
Injection molded parts crack
Pre-heated metal insert can ease the residual stress during injection moulding. In the same principle, annealing after forming the insert is also a method.

When setting the moulding condition, reduce the injection pressure is the most effective.
If the ejector pins are balanced, release more force when demoulding.

Solutions
Instant: Increase cylinder temperature, reduce injection pressure and release rate.
Short-term: Improve the smooth finish of the injection mould cavity.
Long-term: Stripping slope should be sufficient, release pin should be balance distribution, the product design should not have acute angle, as well as to try to avoid thickness differences of the injection molded parts.

Differences in materials
Pay attention that the PC, PVC and other materials are tends to stick to the mould chrome layer, especially in the corners.
PC material prone to produce crack in the mould insert, it is better to add some reinforced glass fiber.

References
Due to solvent, oil and medicine adhesion, the injection molded parts may have cracks (stress cracking). A little oil may cause a lot of cracks.

Post a Comment:

    
Plz Calculate (8 - 1) =
(Your comment will show after approved.)

You may also like:


Online tour of our plastic injection mould making factory in Shenzhen China.
Featured Articles
Plastic Injection Mould Making in China Why choose us as your partner in mould making & injection moulding? We provide one-stop service of plastic injection mould ...
China Plastic Injection Mould ... ACO Mold - plastic injection moulding manufacturer located in Shenzhen, China, established in 2000, mainly develops, designs and ...
How to Make Plastic Die Sinking ... Under the circumstance of without drawing, plastic injection moulding company can provide the product copy data service to make ...
Mould Maker, Injection Mould Making ... Mould Maker, Injection Mould Making Company Selection TipsIt is very easy to find an injection mould maker, the most simple and effective way is to participate in relevant exhibitions. ...
10 Factors Influence Injection Mould ... 10 Factors Influence Injection Mould QualitySteel is a decisive factor of mould quality, a reasonable choice of steel is the most important. Steel selection criteria are: ...