Part 2: Can Moldflow Validate the Quality of your Part?

In Part 2 we will continue our discussion of utilizing the Moldflow software to ensure the part does not fail in the field (Part 1: Can MoldFlow Validate the Quality of Your Part?)

Is the gate in the best location?

In many cases, the customer provides a part with a suggested gating location The gating location is sometimes determined during the part design process and is designed based on the assumed gate location However, the pre-determined gate location may not always be the best location for several reasons:

• The gate location may not provide a balanced filling pattern which can cause severe velocity changes to the flow front or an undercut scenario where the flow direction changes after the frozen layer on the wall has been established which causes tremendous shear within the part laminae Both of which can cause part deformation or even failure
• If the gate location creates an imbalanced filling pattern it can create a pressure spike which will also create a clamp tonnage spike Both of which lead to issues mentioned in aforementioned bullet
• The gate location may not be in the best location with regards to the material freezing back to the gate which is essential for proper part packing Some regions of the part may not be able to be packed due to a poorly selected gate location This can cause excessive volumetric shrinkage in isolated regions of the part which can lead to sink marks or even voids In the images below there is a wheel for a drawer carrier which is failing due to internal voids There is a cut-away showing the voids which are revealed in the analysis where the high volumetric shrinkage shows the regions where the voids can potentially occur:
  

  Has the tool design been verified?

  This may seem like a redundant question but there are times when the tool may undergo some design changes which may affect the outcome of the part design such as:

  • Cooling inserts added
  • Rerouting of cooling lines
  • Cavity orientation changes
  • Feed system changes (perhaps due to cavity orientation changes)
  • d possibly other tool design changes

  Many businesses integrate a final tool review before or at the initial trial run, so if this is not standard procedure it is highly recommended If anything HAS changed, the mold filling analyst will need to re-optimize the process based on those changes

  Has the material been qualified/verified? (Keep the material