Sustainability Data for Stock Machining

Note: See Sustainability Cost Model Overview for general information about the carbon information data that aPriori provides for all supported processes.

The Stock Machining cost model provides Sustainability data for the following processes:

Band Saw

The band Saw process cost model provides the following Sustainability outputs on the Part Details / Sustainability tab in aPriori:

  • Supports Sustainability: Yes.

  • Primary Material Carbon Factor: not applicable. aPriori leaves the cell blank.

  • Energy Carbon Factor, Logistics Carbon, Annual Carbon, and Total Carbon: the calculations for these variables are the same for all processes – see Sustainability Cost Model Overview.

  • Material Carbon: aPriori sets the Material Carbon value to zero. Although you can see the Material Carbon formula in the Formula Dependencies window, all the cells are blank other than the Final Yield percentage.

  • Process Carbon: see Process Carbon Calculation for Band Saw. Note that the Indirect Machine Power calculation included in the Process Carbon calculation is the same for all processes – see Indirect Machine Power Calculation. Also see Process Carbon in the Sustainability Cost Model Overview for some general points about the Electricity Process Carbon and Other Process Carbon calculations.

Process Carbon Calculation for Band Saw

Process Carbon = Electricity Process Carbon + Other Process Carbon

  • Electricity Process Carbon: the primary source of process carbon based on energy factors and energy consumption. Calculated as (Energy Carbon Factor * Energy Consumption ) / Final Yield:

    • Energy Carbon Factor: the CO2 equivalent factor for a unit of energy consumed. Specified by the top-level Digital Factory variable Electricity Carbon Factor (data provided by Ecoinvent). You can update the value in the Formula Dependencies or in the Digital Factory if you have a factor that you think is more representative of your selected location.

    • Energy Consumption: the energy consumption of the machine for the process, including direct and indirect energy consumption. See formula below.

    • Final Yield: the number of acceptable parts at the end of the entire part routing divided by the number of this process’ starting pieces including scrap. See Yields For Machining.

  • Other Process Carbon: (if applicable) any source of process carbon, including additional sources of carbon not related to electricity. If not applicable, this will have a value of 0.00.

Energy Consumption = (Direct Machine Energy Consumption + Indirect Machine Energy Consumption)

  • Direct Machine Energy Consumption: the direct energy consumption of the machine. By default, aPriori calculates this using the Calculated Energy Consumption calculation. However, if you override Cycle Time or an element of Cycle Time that is not in the powerProfileFactors table, aPriori uses the Cycle Time Energy Consumption calculation. (If you override an element of Cycle Time that is in the powerProfileFactors table, aPriori continues to use the Calculated Energy Consumption calculation.)

  • Indirect Machine Energy Consumption: the indirect energy consumption of the work center based on the overhead facility power usage. Calculated as (Indirect Machine Power * Cycle Time):

    • Indirect Machine Power: the indirect power of the work center based on the overhead facility power usage. The calculations are the same for all processes – see Sustainability Cost Model Overview.

    • Cycle Time: the time for one complete cycle of the applicable machine to make a single part. Includes the process times for each stage of the process. For details, see Process Cycle Time.

Calculated Energy Consumption

This is the calculated energy consumption of the machine based on cycle time stages and specific power profile factors. aPriori performs a lookup in the powerProfileFactors table, calculates (Machine Power * Power Factor * Process Step Time * Cycle Time Adjustment Factor) for each cycle stage in the process, sums the results, and displays the total energy consumption for each stage of the process (Process Step Energy Consumption):

  • Machine Power: the power requirement of the work center. This is specified by the machine property Machine Power.

  • Power Factor: the Power Factor for each cycle stage in the powerProfileFactors table. This is a researched value that is applied to the Machine Power to reduce it to the power requirement of the particular stage of the cycle.

  • Process Step Time: the time to complete each step of the Cycle Time calculation (specified by the Formula Name in the powerProfileFactors table).

  • Cycle Time Adjustment Factor: the value of the cost model variable cycleTimeAdjustmentFactor. This is set to 1 in starting point Digital Factories.

Cycle Time Energy Consumption

This is the energy consumption based on the cycle time and the maximum power profile factor. Calculated as: (Machine Power * Applied Power Factor) * Cycle Time:

  • Machine Power: specified by the machine property Machine Power.

  • Applied Power Factor: aPriori performs a lookup in the powerProfileFactors table and selects the maximum Power Factor for the process.

  • Cycle Time: the time for one complete cycle of the applicable machine to make a single part. Includes the process times for each stage of the process. For details, see Process Cycle Time.

Material Stock

The Material Stock cost model provides the following Sustainability outputs on the Part Details / Sustainability tab in aPriori:

  • Supports Sustainability: Yes.

  • Primary Material Carbon Factor: the CO2 equivalent factor for a given mass of the selected material for the utilization process in the routing. By default, this is specified by the selected material’s Carbon Emissions Factor as specified in the Material Selection table. If you select a baseline material stock from your Digital Factory, aPriori uses the property Material Stock Carbon Emissions Factor. If virtual stock is used, aPriori uses the material property Carbon Emissions Factor.

  • Energy Carbon Factor, Logistics Carbon, Annual Carbon, and Total Carbon: the calculations for these variables are the same for all processes – see Sustainability Cost Model Overview.

  • Material Carbon: see Material Carbon Calculation for Material Stock.

  • Process Carbon: not applicable. aPriori sets the Process Carbon value to zero. The Material Stock process has no cycle time associated with it in aPriori and is used primarily for Sustainability error handling purposes.

Material Carbon Calculation for Material Stock

Material Carbon = (Rough Mass * Primary Material Carbon Factor) / Final Yield

  • Rough Mass: the mass of the workpiece prior to production (shown on the Part Summary tab). aPriori calculates this as (Finish Mass / Utilization):

    • Finish Mass: the mass of a single part after processing is complete. It is the product of part Volume and material Density.

    • Utilization: the fraction of the mass the workpiece’s raw material that remains after all operations are complete. This is calculated by the aPriori cost engine and is a function of Finish Mass, Stock Mass, and Number of Parts Per Stock.

  • Primary Material Carbon Factor: the CO2 equivalent factor for a given mass of the selected material for the utilization process in the routing. By default, this is specified by the selected material’s Carbon Emissions Factor as specified in the Material Selection table. If you select a baseline material stock from your Digital Factory, aPriori uses the property Material Stock Carbon Emissions Factor. If virtual stock is used, aPriori uses the material property Carbon Emissions Factor.

  • Final Yield: as described above.