Formulas and calculations used by the Printing process are described in the following sections:

Batch setup cost per part depends on the following:

Cycle time is the product of the following:

Process time is the sum of the following:

Build time depends on the following:

The number of swipes required to build a layer-thick cross-section of the part depends on the following:

The height of the part in layers depends on the following:

This is the number of parts that are built at one time. By default, this is the maximum number of parts that can fit on the build plate. Users can override the default and specify this number with the setup option Number of Parts per Build Plate.

To calculate the default value, aPriori uses either true-part-shape or rectangular nesting calculations. The cost model assumes a border all around each part whose size, by default, is specified by the cost model variable nestingAllowance (5mm in starting point VPEs). Users can override the default with the setup option Nesting Allowance. aPriori assumes true-part-shape nesting by default, but rectangular nesting is used if you select an option other than True-Part Shape Nesting in the Material Utilization dialog.

With true-part-shape nesting, the cost engine uses an internal algorithm that considers multiple candidate nesting arrangements using a variety of part orientations. By default, the various orientations differ by an angle specified by the cost model variable defaultUtilizationStepAngle (90° in starting point VPEs). With the setup option Step Angle for True-Part Shape Nesting, users can specify a step angle for the cost engine to use in order to generate additional candidate orientations—smaller step angles result in the consideration of a greater number of candidate nesting arrangements (which increases costing time but may result in more efficient nesting). The algorithm chooses the optimal nesting arrangement from among the considered candidates.

With rectangular nesting, the cost model uses the steps below in order to determine the number of parts that can fit on the build plate.

Material Cost includes the cost for the material used for the part. The cost of material used for support structures is included in Additional Direct Costs—see Additional Direct Costs—Support Structures for Printing.

Material cost depends on the following:

Geometry extraction creates a number of GCDs to represent support structures, which support overhanging geometries, and provide a base that separates the part from the build platform.

The cost of support structures is accounted for as an additional direct cost. The material for support structures is different from the part material. Support material density and cost are determined as described for the Support Cost formula below. The cost model assumes that support structures include the following:

Geometry extraction attempts to choose the height dimension of the part so as to minimize the volume of supports. The cost model assumes that the part is oriented with the height direction normal to the build plate. Users can override the choice of height dimension with the Build Direction tool—see Using the Build Direction Tool to Orient the Part.

If a user considers a particular support structure unnecessary, they can manually assign the GCD to the No Cost operation: right-click on the GCD in the Manufacturing Process pane or Geometric Cost Drivers pane, and select Edit Operation….

Then click No Cost operation in the Operation Sequence Selection dialog, and click OK.

In this case, costs associated with the support structure GCD will not be included.

Additional direct costs depends on the following:

Support volume depends on the following: