Wear in Injection Molds, To Float or Not to Float

Here is a throwback to a principle that removes stress by incorporating designs that allow components to move in the mold.


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If components are moving inside an injection mold, then the probability of wear of the moving components is very high. In this example, the most probable components that will see wear are component A, the bubbler core, component B, the ejector sleeve and component C, the B side.

The bubbler core A may see wear on the outside diameter due to the ejector sleve B rubbing on the bubbler core. The ejector sleeve B may see wear on the inside diameter as it rubs against the bubbler core. Also, the outside diameter of the ejector sleeve B may see wear due to it rubbing against the inside diamater of the B side core C. Lastly, the insider diameter of the B side core may see were due to the rubbing from the outside diameter of the ejector sleeve C.

Recommendations: Design the components so each component floats or more specifically, each component can move slightly to reduce or eliminate stress between components. The component that is moving against the other two is the ejector sleeve. Designing this component so it can move as needed to reduce stress during the ejector stroke will significantly reduce wear. It is also possible to design component C, the B side core, to also float slightly, creating a belt and suspenders fix to reduce the probability of wear.

Click here to read this 2008 article by contributor David Caldwell, explaining the "floating concept".