Formulas and calculations used by the Resin Curing 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 depends on the following:

Part time is the time to build all the parts on the build platform, not including time to build the support base (see the formula for Support Time), and including the time spent between layers (including layers of the support base) to move the build platform in preparation for the next layer. It also includes time after each layer to apply a fresh layer of resin. It depends on the following:

This is the time to build one part (not including the support base). It depends on the following:

Solidification rate is the volume per unit time created by the sintering process. It is the product of the following:

Layer delay is the time spent between layers moving the build platform in preparation for a new layer. This is the time spent for all the parts on the build platform. The total layer delay depends on the following:

This is the distance in layers from the platform to the top of the part, that is, the number of layers in one vertical cross-section of the sintered material (the part together with the buffer of material between platform and part). It depends on the following:

This is the time apply fresh layers of resin for all the parts on the build platform. Wipe time depends on the following:

This is the time to build the bases that separate the parts from the build platform. It depends on the following:

Support volume depends on the following:

Solidification rate is the volume per unit time created by the sintering process. It is the product of 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 for Resin Curing.

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.

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.

In particular, the 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.

The structures are made with the same material as the part, but the layer thickness can differ (see the formula for Support Solidification Rate in Cycle Time Formulas for Resin Curing). Support structure material is not recoverable.

If the 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, 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.

Material Cost includes the cost for the material used for the part.

Material cost depends on the following:

Utilization depends on the following:

Rough mass depends on the following:

Additional direct costs depend on the following:

Laser cost depends on the following:

Note that aPriori converts the times to hours for use in this formula.