The Orientation at top skin result is generated at the end of a Fill analysis using Midplane analysis technology, and shows the flow direction at the plastic/metal interface for the top side when plastic fills an element.
Without rigorous Fiber orientation analysis, skin and core orientations provide a good indication of how molecules will be aligned in non-fiber filled materials. This result shows how fibers will be oriented at the skin when using a fiber-filled material.
The magnitudes of these vectors are normalized to one and are displayed multiplied by the given scale factor. Skin orientation is determined by the velocity direction when the melt front first reaches a given location.
Skin orientation is useful for estimating the mechanical properties of a part. For example, the impact strength is typically much higher in the direction of skin orientation. When using fiber-filled polymers, the tensile strength is also higher in the direction of skin orientation, because the fibers on the surface are aligned in that direction. Skin orientation generally represents the direction of strength. For plastic parts that must withstand high impact or force, the gate location can be designed to give a skin orientation in the direction of the impact or force.
The linear shrinkage of a part also depends on the skin orientation. For unfilled polymers, the shrinkage in the direction of skin (flow) orientation is greater than in the direction of core (transverse) orientation. However, this situation may be reversed when using fiber-filled polymers, because of the low shrinkage and stiffness of the fibers in the direction of skin orientation.
There are exceptions to the fiber orientation described above. For example, in the area of radial flow near a gate, polymer melt stretches in the transverse direction. Fibers are then more likely to be oriented in the transverse direction in both the skin and core.