Plastics Design Principles: Balancing with Flow Leaders & Flow Deflectors

By Jay Shoemaker

Related links: Moldflow Plastics Design Guide | Moldflow Communicator™ | Moldflow Design Guide: A Resource for Plastics Engineers

Flow leaders are local increases in the nominal wall thickness, whereas flow deflectors are local decreases in thickness. Many times a part cannot be balanced by gate placement alone. It can be useful to slightly change the wall thickness to enhance or retard the flow in a certain direction. This will allow the filling of the part to be balanced, even though the flow lengths from the gate to the extremities of the part are not equal (see Figure 11: Flow leaders). Generally it is better from a material saving point of view to decrease the wall thickness. This may not always be possible, however, due to structural requirements of the part.

Figure 11: Flow Leaders

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