Plastic Molding Enhancement

Faster Computation of Part Thickness (GCD Extraction)

aPriori 2023 R1 SP1 includes faster GCD extraction algorithms for measuring the thickness of molded parts when running aPriori on machines with multiple cores.

In the Plastic Molding process group, aPriori measures and stores part thickness values at many points across a part. This thickness determination can be time-consuming for complex parts and comprise a significant percentage of the total GCD extraction time.

In aPriori 2023 R1 SP1, aPriori improved the speed of these thickness determination algorithms. GCD extraction will be faster for many parts analyzed in these process groups, without sacrificing the accuracy of these thickness measurements. The amount of time by which the thickness determination is reduced depends on the complexity of the part geometry and also on the configuration of the computer on which aPriori is running. For computers with multiple cores (including for aPriori’s cloud solutions), thickness determination may be three times faster or more. For complex parts, this can result in savings of multiple minutes during the initial analysis of a part, and also whenever GCDs are re-extracted. For single-core machines, little decrease in thickness determination time was expected or observed.

• The previous release aPriori 2023 R1 introduced a problem in the calculation of nominal wall thickness for Injection Molding parts. Some parts that should have been classified as High Aspect Ratio instead were erroneously classified as Low Thickness Deviation or Medium Thickness Deviation. The classification affects aPriori's estimate of nominal wall thickness, cool time, and required machine clamp force. This release fixes the problem and correctly classifies all parts. The custom output Nominal Wall Thickness Profile indicates how a part is classified.

  As a result of this change, estimated cool time increases for some parts now correctly classified as High Aspect Ratio, compared to the previous release. In a set of test parts, cool time generally increased by around 10% for parts classified as High Aspect Ratio, although increases of up to around 50% were observed. In rare cases, a higher-overhead machine might be selected for such a part. Tooling costs might also change slightly in some cases. The affected parts are those for which both the following conditions apply:

  • Part does not have high thickness variation. A part is considered to have a high amount of thickness variation if the geometric property Thickness Std Dev is greater than the value of the cost model variable medThicknessDevThreshold (0.50 mm in starting point Digital Factories).

  • Part has a height-to-length ratio greater than or equal to the value of the cost model variable highAspectRatioThreshold (0.50 in starting point Digital Factories) and less than the value of the cost model variable cmHighAspectRatioThreshold (3.0 in starting point Digital Factories). Note that the part height is measured in the draw direction, for plastic molding process groups.

  The problem affects only cost model version 220, introduced in aPriori 2023 R1. Earlier cost model versions are not affected, unless they have been customized to import the library libFunctionsUtils.csl.

• aPriori Professional 2023 R1 SP1 corrects some minor display issues in the Design Guidance tab and secondary dialogs, related to Material selection for Plastic Molding parts. Previously if a part failed to cost, the Relative Cooling Time(s) field displayed a range of null to zero, and the % Cooling Time Change field displayed a very large value. Now these fields will display dashes (-) to indicate these computations are not valid when a part has failed to cost.