Sheet Plastic Enhancements

Updated Part Spacing and Material Utilization Estimates

aPriori 2023 R1 SP2 includes more conservative part-spacing estimates for thermoformed parts made with positive forming tools. This updated logic reduces estimates of material utilization and increases estimates of material and tooling cost, compared to the previous release of aPriori.

In 2023R1 SP2, when using positive forming tools, the part spacing logic was updated to dynamically calculate part-to-part and part-to-sheet-edge (clamp) spacing based on the height of the part being formed. The updated logic better simulates the physical restrictions imposed by forming material over a positive tool, since increased spacing may be required to prevent bridging of the material during the thermoforming process

The dynamic part spacing is calculated by multiplying the part height by the cost model variable partSpacingMultiplierPositiveTool (set to 1.0 in the starting point Digital Factories). The minimum part spacing used by aPriori is the larger of the new dynamic part spacing calculation and the static value in the cost model variable partSpacingPositiveTool (set to 10.15mm in the starting point Digital Factories).

This enhancement affects only parts formed using a positive tool, not those formed with a negative tool. For parts formed with a positive tool, sheet sizes, material, and tooling costs will increase compared to the previous release of aPriori. In a set of test parts, material cost increased on average by 33% with a maximum increase of 156%. Fully burdened cost increased on average by 14% with a maximum increase of 66%.

Inclusion of a Vertical Band Saw process for separating multiple parts

The Sheet Plastic manufacturing process now includes a vertical Band Saw process to account for separating multiple parts formed from a single sheet, resulting in a more accurate and complete representation of the manufacturing process within the baseline cost models.

In 2023R1 SP2 the Sheet Plastic routing provides an optional manual Vertical Band Saw process after the Thermoforming Station and before the Router process . The Vertical Band Saw is included automatically when multiple parts are formed from a single sheet of plastic (controlled by the process setup option Number of Parts Per Sheet). This represents the process of roughly cutting the molded sheet into its individual parts before the Router is used to perform fine trimming of the part perimeters and any cutouts.

Four new Vertical Band Saw machines were added to the Regional Data Libraries with Throat Depth and Working Height limits dictating the size of part that can pass through the band saw. The aPriori cycle time logic accounts for the loading and unloading time, the operator-controlled material federate during cutting, and the number and lengths of cuts required to separate the parts. The material feed rate for the process is defined using the cost model variable verticalBandSawMaxHumanFeedRate . The number and lengths of cuts are calculated using intelligent logic that takes the part size, part spacing, and machine limitations into account. For more detail, please see the aP Pro Cost Model Guide.

This enhancement will have no cost impact for baseline behavior as the Number of Parts Per Sheet is set to 1. If a user increases this value, the Vertical Band Saw process will be included automatically and the cost estimate per part will increase significantly.

In a set of test parts in which Number of Parts Per Sheet was set to 2, the addition of the vertical bandsaw process resulted in an average increase in cycle time of 53% mainly due to the inclusion of the process, but also due to the increased handling due to the updated part spacing resulting in a larger sheet size.

The updated part spacing and addition of Vertical Band Saw results in an average increase in fully burdened cost of 43% and a maximum increase of 103%.

Including Material Scrap Credit

The Sheet Plastic manufacturing process model now optionally accounts for Scrap Material Credit and Scrap Part Credit, resulting in a more flexible and complete accounting of material costs aligned with customer cost accounting practices.

aPriori 2023 R1 SP2 provides the ability to discount a thermoformed 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. This is consistent with existing Material Cost accounting logic in most other aPriori process groups. Note that by default, the calculation of scrap credit is not enabled in the baseline cost models.

Two new process setup options, Enable Scrap Material Credit and Enable Scrap Part Credit, now are available in the Sheet Plastic model. These options are unchecked (not selected) by default. When the options are selected, calculated material cost will be reduced to account for the sale of the scrap material.

• Enable Scrap Material Credit accounts for the sale of scrap mass produced during the manufacture of the part.

• Enable Scrap Part Credit accounts for the sale of scrap parts as result of the good part yield.

To include scrap buyback credit by default for all Sheet Plastic parts, a Digital Factory Administrator should set the cost model variables enableScrapMaterialCredit and enableScrapPartCredit to true.