The 2-Model Machining process group enables you to more accurately cost a part if you have:

By comparing the two models, aPriori can automatically identify machined features and the amount of material removed, providing a highly accurate determination of the machining operations and cycle times required.

For example, you could have a model of a raw or unfinished part that is created from a casting or forging process, and which just provides the basic shape of the part, without small holes or finished surfaces or other details:

The finished model might include drilled holes and machined surfaces:

This makes the separately-licensed 2-Model Machining process group somewhat different than the other process groups in aPriori, since you are not costing a part from raw material through to final product. Rather, you are comparing two parts and determining the cost of getting from one to the other. aPriori creates GCDs based on differences between the finished and source models.

aPriori guides you through this costing process with the Cost Guide (see the "Initial costing: the Cost Guide" section of the aPriori User Guide). There are multiple ways you can approach this procedure. Typically, you will cost the source model, and then cost the finished model, using the source model as input. However, it is possible that you might start with the finished model and not have the casting or forged model until later in the project. Or you may have a number of intermediate models (casting model, first machining model, second machining model, finished machining model). The examples below assume the typical case (costing the source model and then costing the finished machined model), though other approaches are also discussed.

Note that you must be CAD-file connected to both the source and finished CAD models in order to extract GCDs. If you change the source scenario specified in the Production Scenario tab of the Cost Guide, both the new source scenario and the current finished scenario should be CAD-file connected; if either is not, aPriori disables Save for the current finished scenario, and any subsequent costing relies on GCDs extracted using the old source scenario.