Shot Blast Inputs

Shot Blast provides the following setup options:

Shot Blast Media

This setup option affects Shot Blast Feasibility and Additional Direct Costs.

This specifies the media used to shot blast the part in the blast chamber. By default, aPriori selects a media type that is compatible with the selected material. This may be defined in either of the following ways:

  • The shotBlastInstances lookup table. This is empty in starting point Digital Factories but can be populated with shot media types for each shot blast instance (see Abrasive Shot Blast Routing).

  • The default Shot Blast media. This is the feasible media with the lowest Cost Per Mass in the Digital Factory tool shop materials table (under Surface Treatment > Processes > Shot Blast > Tool Shops > Default).

With this setup option, users can override the default on a per-part basis by selecting an alternative from the drop-down list of media. The available materials in the drop-down list are filtered to show only media types that are compatible with the selected material, as defined in the tblShotBlast table.

Number of Parts in the Batch

This setup option affects cycle time and Additional Direct Costs.

This specifies the number of parts in a batch loaded into the blast chamber. By default, aPriori calculates this based on the part batch size, the maximum batch weight of parts the machine can support, and the maximum number of parts that can fit on a hanger. With this setup option, users can override the default on a per-part basis. The number must be between 1 and 60. Note that this can force a change in machine selection.

The calculations for default hanger limits draw on the values of the following cost model variables (starting point Digital Factory defaults are shown in parentheses):

  • defaultHangerHeightAllowance: The default spacing of a hanger between top and bottom of the blast chamber (300 mm).

  • defaultHangerLayerNestingAllowance: The default spacing between layers of parts on a hanger (50 mm).

  • defaultHangerWidthAllowance: The default spacing of a hanger from the walls of the blast chamber (300 mm).

See Default Number of Parts in the Batch for Shot Blasting (below) for more information.

By default, the number of parts in a batch is the lowest of the following three values:

1. Batch Size: This is the size of a production batch, as specified in the Production Scenario tab of the Cost Guide.

2. Maximum Number of Parts Batch Weight: This is the maximum number of parts the machine can support based on the part mass. It is calculated as: the Weight Capacity machine property / the mass of the part.

3. Carousel Hanger Batch Size: This is the maximum number of parts that can fit on a hanger in a carousel orientation. It is calculated as Number Of Layers * Number Of Parts Per Layer (see below).

  • Number Of Layers (the number of layers on a hanger based on part dimensions) is calculated as: (Chamber Height - (2 * Hanger Height Allowance)) / (Maximum Part Dimension + Layer Nesting Allowance):

    • Chamber Height: This is specified by the Chamber Height machine property.

    • Hanger Height Allowance: This is the default spacing of a hanger between the top and bottom of the blast chamber, as specified by the defaultHangerHeightAllowance cost model variable (300 mm in starting point Digital Factories).

    • Maximum Part Dimension: This is whichever is the largest: the part’s length, width, or height.

    • Layer Nesting Allowance: This is the default spacing between layers of parts on a hanger, as specified by the defaultHangerLayerNestingAllowance cost model variable (50 mm in starting point Digital Factories).

  • Number Of Parts Per Layer (the number of parts per layer on the hanger) is calculated as the largest of either:

    • (360 / ang2): In the ang2 formula (described below), Mid Part Dimension = ‘Part Dimension A’, and Minimum Part Dimension = ‘Part Dimension B’.

    • (360 / ang2): In the ang2 formula (described below), Mid Part Dimension = ‘Part Dimension B’, and Minimum Part Dimension = ‘Part Dimension A’.

      • Mid Part Dimension: This is calculated as (Part Length * Part Width * Part Height) / (Maximum Part Dimension * Minimum Part Dimension):

        • Maximum Part Dimension: This is whichever is the largest: the part’s length, width, or height.

        • Minimum Part Dimension: This is whichever is the smallest: the part’s length, width, or height.

      • Minimum Part Dimension: As described above.

      • ang2: This is calculated as (ang1 * 2):

        • ang1: This is calculated as the arctangent of (a/b):

          • a: This is calculated as ‘Part Dimension A’ / 2.

          • b: This is the Hanger Radius, calculated as: Hanger Diameter / 2 (see below).

            Hanger Diameter is calculated as: Chamber Width - (2 * Hanger Width Allowance) - (2 * ‘Part Dimension B’)

          • Chamber Width: This is specified by the Chamber Width machine property.

          • Hanger Width Allowance: This is the default spacing of a hanger from the walls of the blast chamber, as specified by the defaultHangerWidthAllowance cost model variable (300 mm in starting point Digital Factories).