Page 10 - Moldex3d training Manual

In the scenario above, the thin feature is by-passed and is not attempted to fill out until the thicker section
is filled out completely. Once the material reaches the main end of fill, the pressure attempts to push the
melt front forward in the thin section, but is has been already frozen at this point, causing a short shot to
occur.
Placing thin features closer to the main end of fill will help to fill the part completely and avoid this
hesitation problem.
Leading occurs when a there is a major variation of thickness in the part, where the melt will trend to fill
out faster along certain regions over others.

In the example above, the upper rails are thicker than the features towards the bottom, causing an
imbalance of flow in the different regions.
In extreme cases, leading can cause a “backfill”, or and internal void, to occur in the part. The example
below shows a part that is thicker around the outside and thinner towards the middle.

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