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Defects in the production of plastics

The production of plastics by the method of injection moulding is not without defects. In this article, I will tell you some of the most common defects that occur during the process and their possible causes.

Short shot It is a common defect that occurs when not enough molten plastic is injected into the mold. This can result in an incomplete or de-padded part in the manufactured product. can be caused by a number of factors including poor mold design, incorrect gate position (where the material enters) and incorrect machine set-up.


Flashing Flash occurs when molten plastic flows from the mold and solidifies along the parting line. This can be due to poor mold design, excessive pouring pressure or loose clamping between the two parts of the mold (tonnage) etc.



Occurs when the product inside the mold cools and shrinks unevenly, causing distortion. This can be caused by a number of factors, including incorrect gate position and incorrect cooling system design



They are marks that appear on the surface of the product due to uneven cooling. This can result in wall thinning and reduced dimensional stability in the product. Its also caused by improper machine settings, poor mold design and use of different materials (mix) with different shrinkage rates.


Burn marks

They are dark discoloration marks that appear on the surface of the object due to excessive heat. This can be caused by overheating of the molten plastic or by a very hot mold not cooling properly. Another important factor that can cause this is that the gases caused by the process are not allowed to escape outside of the mold resulting in signs of burning or degradation.

Delta plast & mould.

Article by: Dimitris Kakalidis


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