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.

Causes and remedies of short shot in moulded products

In Pursuit Of The Perfect Injection Moulded Part - Short Shot

The most common cause of short shots is flow restriction resulting from narrow or blocked gates. Sometimes the material is too viscous or the mould is too cold to allow the molten material to completely fill the mould before cooling. And other times trapped air pockets may be hindering proper flow or injection pressure may be inadequate. Consider the following steps to prevent short shot:

  • Redesign the mould with wider channels or gates for better flow
  • Increase injection speed or pressure or choose a thinner base material to improve flow
  • Increase mould temperature to prevent material from cooling too rapidly
  • Add additional air vents or enlarge existing vents in the mould to allow trapped air to escape

Patterson & Rothwell are a Plastic Injection Moulding Company based in the North West of England, UK producing goods for many business sectors. Our ethos is to offer our customers a professional yet flexible approach and of course provide attention to detail at every stage. Please contact us if you wish to discuss any Plastic Injection Moulding Project.