Patterson & Rothwell


In Pursuit Of The Perfect Injection Moulded Part 11 – Flash


Flash is an excess of moulding material that appears as a thin lip or protrusion at the edge of a component. Flash appears because material has flowed outside of the intended flow channels and into the space between the tooling plates or at the injector. pin.

Flash is usually subtle but might be considered a major defect if particularly obvious on a product. The process for reworking a moulded product with flash often includes trimming the excess material. Continue reading

In Pursuit Of The Perfect Injection Moulded Part 10 – Short Shot

Short Shot

A short shot occurs when the flow of molten material doesn’t completely fill the cavities in a mould. The result is that the moulded component is incomplete after cooling. Short shot might appear as incomplete compartments in plastic shelves of a display or missing prongs on a plastic fork, for example. Short shots are typically classified as a major defect that can inhibit the function or appearance of the moulded part. Continue reading

In Pursuit Of The Perfect Injection Moulded Part 9 – Delamination


If you find thin layers on the surface of a moulded part are easily separating or peeling off the underlying material, you’re seeing a moulding defect called delamination. Delamination is a defect characterised by a flaking surface layer, similar to what you’d commonly find on flake mica. This is generally regarded as a relatively serious defect because it reduces the strength of the component. Continue reading

In Pursuit Of The Perfect Injection Moulded Part 7 – Jetting


Jetting refers to a kind of deformation in a moulded component that can occur when there’s an initial ‘jet’ of molten material injected into the mould cavity that starts to solidify before the cavity is filled. Jetting often appears as a squiggly line in the surface of the finished component, typically leading from the initial gate of injection. This visible flow pattern can result in part weakness. Continue reading