Material Cost and Utilization

aPriori provides three options for calculating utilization, which the user can choose from in the Material Selection dialog.

• Computed (see below)

• Machine Default (determined by the machine property Avg Utilization)

• Override (fixed percent value entered by user)

aPriori assumes the part is nested along the length of a stock piece. The rough mass is equal to the total mass of the stock divided by the number of parts nested on the stock. In some cases where the part may require a secondary trim operation after forming (for example, if a bend is very close to one end), nesting will automatically account for this required trim.

The current nesting pattern on the currently selected stock is viewable in the Viewer using the Analysis menu. The stock can be changed via the Material Selection dialog.

Material Cost = Raw Material Cost – Scrap Material Credit – Scrap Part Credit

Material Cost depends on the following:

• Raw material cost: see formula

• Scrap material credit: see formula.

• Scrap part credit: see formula.

Raw Material Cost = (Material Cost Per Mass * Rough Mass) / Final Yield

Raw material cost is the cost of material for one part, including the cost of scrap produced during manufacture of the part, as well as the amortized cost of scrapped parts. It depends on the following:

• Material cost per mass: specified by the material property Cost per KG.

• Rough mass: see formula.

• Final yield: see Yields for Bar & Tube Fabrication.

Rough Mass = Finish Mass / Utilization

Rough mass depends on the following:

• Finish mass: product of part Volume and material Density.

• Utilization: see formula.

Utilization = (Number of Parts Per Stock * Finish Mass) / Stock Mass

Utilization depends on the following:

• Number of parts per stock: based on linear nesting and trim allowance (if needed).

• Finish mass: product of part Volume and material Density.

• Stock Mass: product of stock length, part cross-sectional area, and material density.

Scrap Material Credit = Material Cost Per Mass * Scrap Cost Percent * Scrap Mass

Scrap material credit is the product of the following:

• Material cost per mass: specified by the material property Cost per KG.

• Scrap cost percent: this is 0 if the setup option Enable Scrap Material Credit is un-checked (the default in starting point VPEs). Otherwise, it is specified as a percentage by the material property Scrap Cost Percent.

• Scrap mass: see formula.

Scrap Mass = Rough Mass – Finish Mass

Scrap mass depends on the following:

• Rough mass: see formula.

• Finish mass: product of part Volume and material Density.

Scrap Part Credit =

(Material Cost per Kg * Scrap Cost Fraction) *

((Number of Scrap Parts + Number of Scrap Parts Down Stream) *

Rough Mass) /

Total Production Volume

Scrap part credit is 0 if the setup option Enable Scrap Part Credit is set to false. Otherwise, it is the product of the following:

• Material cost per mass: specified by the material property Cost per KG.

• Scrap cost fraction: this is 0 if the setup option is un-checked (the default in starting point VPEs). Otherwise, it is specified as a percentage by the material property Scrap Cost Percent.

• Number of scrap parts: number of parts discarded as scrap by this process. See Yields for Bar & Tube Fabrication.

• Number of scrap parts down stream: number of parts discarded as scrap by downstream processes. See Yields for Bar & Tube Fabrication.

• Rough mass: see formula

• Total production volume: specified in the Production Scenario tab of the Cost Guide.