Enhanced Manufacturing Process Cost Model Overview
aPriori Professional 2019 R2 includes updates to various manufacturing process cost models. Updates which affect many process groups in common are described in this Overview section. Updates which are specific to individual process groups are described in separate sections below. Note that customers must use aPriori 2019 R2 starting point VPEs or upgrade the cost model versions for their own VPEs to take advantage of these updates.
aPriori 2019 R2 contained two enhancements which impact many different processes in many different process groups:
• aPriori 2019 R2 provides the ability to discount a part’s Material Cost, by assuming a Scrap Material Credit is achieved by selling scrap material and/or scrapped parts at a fraction of the original raw material cost. The scrap material credit logic now is available in following Process Groups: Bar & Tube Fab, Forging, Sheet Metal, Sheet Metal – Hydroforming, Sheet Metal – Stretch Forming, Sheet Metal – Transfer Die, and Stock Machining. (Note that the Casting-Sand, Casting-Die, Plastic Molding and Assembly Molding process groups already provided logic for re-melting and reuse of scrap material, so those process groups were not modified).
Scrap material buyback rates now are specified for each material composition in the baseline Regional Data Libraries. They are stored in the new Material field “Scrap Cost Percent” and are expressed as a percentage of raw material unit cost. The Scrap Material Credit value is determined by applying the buy-back rate to the Scrap Mass of the part. The Scrap Part Credit value is determined by applying the buy-back rate to the Rough Mass and Number of Scrapped Parts. The part’s Material Cost then is determined by subtracting the scrap buy-back value from the Raw Material Cost. The final Material Cost, Raw Material Cost, Scrap Material Credit and Scrap Part Credit calculations all can be reviewed in the Formula Dependencies dialog as shown below.
Note that by default, the calculation of scrap credit is not enabled in the baseline cost models. Users may enable the scrap credit for a specific part by using the process setup options Enable Scrap Material Credit and Enable Scrap Part Credit located at the top-level node in the routing. To include scrap buyback credit by default for all parts in a given process group, a VPE Administrator should use the plant variables enableScrapMaterialCredit and enableScrapPartCredit.
When Scrap Material Credit is enabled, the Material Cost of a part will be slightly reduced, depending on the specific part geometry, process group, and scrap buyback rate applied. In a set of test parts, material costs were reduced on the order of 2%. The impact of enabling Scrap Part Credit is more variable due to the difference in Good Part Yield specified for each process.
• In aPriori 2019 R2, tooling cost calculations for many processes were enhanced to determine tool life and the number of tools required to manufacture the specified production volume. The tool life calculations determine the number of parts which can be produced with a given tool before it wears to the point it needs replacing. The following processes now account for tool life:
o Bar & Tube Fabrication – Extrusion
o Die Casting - Gravity Die Casting, High Pressure Die Casting & Trim
o Forging - Hammer, Press & Trim
o Sheet Metal - Generic Press, Standard Press, Tandem Press & Progressive Die
o Sheet Metal Transfer Die - Transfer Die & Offline Blanking
o Sheet Metal Hydroforming - Hydroform & Offline Blanking
o Sheet Metal Stretch Forming - Stretch Form Cycles, Router & Bench Operation
o Sheet Plastic - 2 Cavities Drape Forming, 2 Cavities Vacuum Forming, 4 Cavities Drape Forming, 4 Cavities Vacuum Forming, Single Cavity Drape Forming, Single Cavity Vacuum Forming
o Roto & Blow Molding - Extrusion Blow Mold, Rotational Mold
o Plastic Molding - Injection Molding, Reaction Injection Molding, Structural Foam Molding
o Assembly Molding - Insert Injection Molding
o Powder Metal - Compaction Pressing
For most of these processes, tool life estimates are determined by considering the part material, the tool material, and the tool coating type. The part material is used to determine a starting number of hits or shots which then is adjusted based on the tool material and coating type, since some tool materials wear more quickly than others and some coatings provide more protection against wear than others.
Sheet Metal Stretch Forming uses an alternate approach in which the number of tools required is derived from a process setup option input. This process is unlikely to be involved with production volumes that will wear tools out so much that more than one tool is required. Extra tooling may be required for meeting a specific production rate though, so the process setup option provides for this scenario. The Forging cost model continues to make use of plant variables to specify the number of parts which can be made with the Hammer, Press, and Trim Die processes before the respective tools must be replaced.
The estimates of Tool Life and resulting Number of Tools can be viewed by using the Formula Dependencies dialog and/or in the Investments tab.
Note that as part of this effort, the 2019-10 aPriori Regional Data Libraries were updated to provide a larger set of tool materials and tool coating types for the processes listed above, and to provide up-to-date unit costs for these items. For example, Plastic Molding now provides tool material choices of Aluminum and Epoxy in addition to various Carbon and Stainless-Steel alloys. There are 40 unique tool material choices available across the set of processes mentioned above (though only a subset of these are available in any given process). 12 tool coatings are available for all the processes listed above. Process setup options for specifying the desired tool material and tool coating were added to the processes listed above (if not already available).
Due to the inclusion of these tool life calculations and updated tool material and coating costs in aPriori 2019 R2, tooling cost estimates will change somewhat compared to those in a previous release of aPriori. Cost increases will occur if production volumes are such that multiple tools are required. As a trend, as production volumes increase the Hard Tooling costs increase significantly, but Fully Burdened Cost is not expected to increase significantly as the extra tool cost is amortized across a larger number of parts. Additionally, even if multiple tools are not required, costs may change somewhat due to the updated data for tool material and tool coating unit costs. Across a set of test parts and manufacturing processes, hard tooling cost increases on the order of ~1.5% were observed due to these data updates.