Shot Peen Formulas

Cycle Time = Process Time * Adjustment Factor

Cycle time is the product of the following:

• Process time (see formula below)

• Adjustment factor (specified by the cost model variable cycleTimeAdjustmentFactor). This factor is 1 in aPriori starting point VPEs. VPE administrators can modify cycleTimeAdjustmentFactor in order to adjust cycle times across processes within the current VPE.

Process Time = Shot Peen Area * Surface Area Allowance

Process time is the product of the following:

• Shot peen area: by default in starting point VPEs, this is half the surface area of the part or assembly. Administrators can customize the default, and specify the percentage of the total area to be shot peened, by using the cost model variable defaultShotPeenArea (50% in starting point VPEs). Users can override the default on a per-part basis with the setup option Percentage of Part/Assembly Surface Area to be Shot Peened.

• Surface area allowance: this is the time per unit surface area required to perform the process. It is specified in sec/m2 by the machine property Surface Area Allowance.

Note that shot peen area is converted to square meters for use in this formula.

Additional Direct Costs =

(Total Media Cost * Additional Shot Peen Weight) / Final Yield

Additional direct costs depend on the following:

• Total media cost: by default, this is looked up by Material for Shot Peen Media in the tool shop Tool Materials. Users can override the default with the setup option Cost of Media.

Note that the default media material is specified by the cost model variable defaultShotPeenMediaType (iron silicate in starting point VPEs). Users can override the media material on a per-part basis with the setup option Material for Shot Peen Media.

• Additional shot peen weight (see formula)

• Final Yield (see Surface Treatment Yield Calculations)

Additional Shot Peen Weight =

Application Rate * Cycle Time * Fraction Non-Recyclable

This is the mass of media consumed per part in one machine cycle. It is the product of the following:

• Application rate: specified in kg/min by the machine property Application Rate.

• Cycle time (see formula)

• Fraction non-recyclable: this is the fraction of used shot that cannot be recycled (and is thus consumed). By default this is 0.2. Administrators can customize the default, and specify the percentage of shot that can be recycled, with the cost model variable percentRecycledShot (80% in starting point VPEs). Users can override the default on a per-part basis with the setup option Percentage of Media Recycled from 1 Part.

Note that application rate is converted to kg/sec for use in this formula.

Amortized Batch Setup =

(Setup Time * (Labor Rate + Direct Overhead Rate)) / Batch Size

Amortized batch setup depends on the following:

• Setup time (specified as the machine property Setup Time)

• Labor rate (specified by the machine property Labor Rate)

• Direct overhead rate (see Direct and Indirect Overhead)

• Batch size (specified in the Production Scenario screen of the Cost Guide)