Stock Trim GCD

StockTrim GCDs represent material allowances added to the finished part's dimensions in order to arrive at the dimensions of the raw stock from which the part is machined.

With Rectangular Bar, Square Bar, Plate, and Hex stock, aPriori extracts multiple StockTrim GCDs for most parts. Material removal calculations use a Rough Milling operation that takes into account the approach direction as well as the appropriate tool size and cut depth for each StockTrim.

With other stock forms, aPriori extracts a single StockTrim GCD for each part. Material-removal calculations use the Bulk Milling algorithm, which uses a single, volumetric-removal rate regardless of feature sizes and orientations.

With Rectangular Bar or Square Bar stock, aPriori extracts the following the following six StockTrim GCDs for a given part:

  • LENGTH_A and LENGTH_B: These two StockTrims provide length allowance. Each one's dimension along the part height includes the height allowance and each one's dimension along the part width includes the width allowance.

  • HEIGHT_A and HEIGHT_B: These two StockTrims provide height allowance. Each one's dimension along part length does not include the length allowance and each one's dimension along part width does include the width allowance.

  • WIDTH_A and WIDTH_B: These two StockTrims provide width allowance. Each one's dimension along part length does not include the length allowance and each one's dimension along part height does not include the height allowance.

With Plate stock, aPriori extracts six StockTrim GCDs for a given part:

  • LENGTH_A and LENGTH_B: These two StockTrims provide length allowance. Each one's dimension along the part height does not include the height allowance and each one's dimension along the part width does include the width allowance. (The _A and _B suffixes are assigned arbitrarily to the two StockTrim GCDs.)

  • HEIGHT_A and HEIGHT_B: These two StockTrims provide height allowance. Each one's dimension along part length does include the length allowance and each one's dimension along part width does include the width allowance.

  • WIDTH_A and WIDTH_B: These two StockTrims provide width allowance. Each one's dimension along part length does not include the length allowance and each one's dimension along part height does not include the height allowance.

With Hex stock, aPriori extracts one, two, or three StockTrim GCDs for a given part.

If the setup option Stock Width Across Flats Dimension is not 0, aPriori extracts the following three StockTrims:

  • END_A and END_B: These StockTrims provide length allowance. Their width-across-flats dimension includes the allowance provided by MIDDLE_OD.

  • MIDDLE_OD: This StockTrim wraps around the part, encompassing the six rectangular faces. It provides allowance across the flats. Its dimension along part length does not include the length allowance.

If the setup option Stock Width Across Flats Dimension is 0, and a bar-feed lathe routing is not selected, aPriori extracts just two StockTrims: END_A and END_B.

If the setup option Stock Width Across Flats Dimension is 0, and a bar-feed lathe routing is selected, aPriori extracts just one StockTrim: END_A (since the margin that would be provided by END_B is removed the part-off operation on the previous part).

The following are among the key StockTrim geometric properties:

  • Length Outer: dimension of the StockTrim aligned with part Length.

  • Height Outer: dimension of the StockTrim aligned with part Height.

  • Width Outer: dimension of the StockTrim aligned with part Width.

  • Stock Trim Type: one of the following values (see above):

    • LENGTH_A

    • LENGTH_B

    • HEIGHT_A

    • HEIGHT_B

    • WIDTH_A

    • WIDTH_B

    • END_A

    • END_B

    • MIDDLE_OD

Note: To direct aPriori to extract a single, aggregate StockTrim GCD for each part regardless of stock type, set the site variable enableMultipleStockTrims to false. In this case, material-removal calculations for the StockTrim will use the Bulk Milling algorithm.