Page 8 - Moldex3d training Manual

2 Day 1 Level 1 - Achieving flow balance (Flow analysis)
2.1 Level 1 Theory (1/3) – Flow Balance
2.1.1 Objective of level 1 analysis
This analysis level is to ensure proper and acceptable flow balance of the part by deciding number and
locations of gates.
There are many different factors to consider when choosing the placement of the gate and when designing
the part:
- Gate Number
o Flow Length Distribution
- Gate Location
o Surface Defects
o Hesitation & Leading
2.1.1.1 Importance of flow balance
The most important factor to consider for a Level 1 analysis is the Flow Balance. The main goal of Flow
Balance is to have the outer most regions of the part fill at the same time.
Balancing the fill over the part will help to reduce the overall pressure requirement to fill the part and
protect from harmful pressure spikes during the fill. If one end of fill region is filled before the others,
then the momentum of the material must transition into filling the other regions of the part. If this
transition of pressure occurs through the gate, large pressure spikes will be observed.

The evenness of flow over the part can be optimized by calculating the Flow Length Ratio for each end of
fill region, which should be the same for each. This calculation is generalized and should consider the
effects of certain features on the part, such as holes, ribs and flow around the curvature of the part.
2.1.2 How to determine how many gates
The number of gates to be used on the part is typically determined by the Flow Length Ratio, which is
typically given by the linear flow divided by the nominal thickness.
An example of this calculation can be found below:

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