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Mold Analysis Terminology
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Flow Analysis
Flow Front Temperature - The mid-stream temperature when the flow front reaches each point. This result is used to identify appropriate fill speed, as well as determine areas of excessive shear heating or excessive cooling in thin areas. Ideal result shows a uniform temperature distribution.
Melt Front Advancement - The position of the flow front at regular intervals as the cavity fills. Each color contour represents the parts of the mold that were being filled at the same time. At the start of injection, the result shows red, and the last places to fill are dark blue. If the part is a short shot, the section that did not fill has no color. In a part with a good fill time result, the flow pattern is balanced.
Pressure at Switchover - The injection pressure when the flow analysis algorithm changed from the velocity control to pressure control. This results is used to determine how well the flow is balanced, and whether or not the part will fill easily enough.
Shear Rate - The rate of shear strain in the cavity at the end of fill. The shear rate should be less than the maximum recommended for the material. Regions above the limit could be subject to material degradation, embrittlement and poor surface finish. Used primarily to size gates and runners.
Shear Stress - The tendency for the moving layers of polymer melt to drag along slower or frozen layers. It is directly related to the viscosity and shear rate of the material, and should be less than the maximum recommended for the material. It can also be considered a measure of the level of material orientation locked into the part. Filling speed, wall thickness, and melt temperature are major factors.
Weld Lines – Indicated by colored lines, they are areas where two flow fronts have converged. The presence of weld lines may indicate a structural weakness and/or a surface blemish.
Air Traps – Indicated by red circles or purple dots, they are empty areas in the cavity surrounded by melt fronts. These areas are potential areas of burning or voiding and should be vented if possible, or eliminated by part modification or gate relocation.