Cost estimates
The cost estimates derived by Creo Elements/Direct Sheet Metal users are governed by a number of parameters derived from the 3D data model or held in the cost model itself.
This chapter discusses the following topics:
The Cost Model File
The cost model file derives the following information from the 3D model:
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partname
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Creo Elements/Direct Modeling name of the sheet metal part
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material
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Material ID
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thickness
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Material thickness
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bends
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Number of bends
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diff-bends
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Number of different bends
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hems
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Number of hems
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diff-hems
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Number of different hems
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flat-width
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Width of box enclosing flat
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flat-height
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Height of box enclosing flat
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body-width
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Width of box enclosing sheet metal body
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body-height
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Height of box enclosing sheet metal body
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body-depth
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Depth of box enclosing sheet metal body
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punches
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Number of punch features
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diff-punches
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Number of different punch features
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stamps
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Number of stamp features
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diff-stamps
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Number of different stamp features
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nibble-len
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Total length of non-feature elements
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contour-punches
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Number of non-straight non-feature elements
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The following information is held or calculated in the cost model itself:
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x y
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Size of the raw sheet supplied by the mill
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cost
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Unit cost of a single raw sheet
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punch-qty-x
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Number of flats that fit horizontally on a single raw sheet
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punch-qty-y
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Number of flats that fit vertically on a single raw sheet
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punch-qty
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Number of flats that can be produced from a single raw sheet
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punch-qty-rotated
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Number of flats rotated by 90 degrees that can be produced from a single raw sheet
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punch-runtime
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Punching machine time per part
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punch-setuptime
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Punching machine setup time
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punch-rate
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Cost of punching machine per time unit
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fold-runtime
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Folding machine time per part
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fold-setuptime
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Folding machine setup time
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fold-rate
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Cost of folding machine per time unit
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mat-costs
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Material costs depending on lotsize
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punch-costs
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Punch costs depending on lotsize
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fold-costs
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Fold costs depending on lotsize
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The cost model uses this information to calculate fabrication costs. For instance, the sha_costmodel.lsp file includes the following section specifying the dimensions of sheet metal supplied by a given steel or aluminum rolling mill:
((string= material "AA 5052" ) (setq x 1000) (setq y 1250) (setq cost 12.5))
((string= material "UST 1203") (setq x 750) (setq y 1000) (setq cost 17.5))
((setq x 750) (setq y 1000) (setq cost 17.5)))
;; default cost/size
((string= material "UST 1203") (setq x 750) (setq y 1000) (setq cost 17.5))
((setq x 750) (setq y 1000) (setq cost 17.5)))
;; default cost/size
This section implies the following:
• By default, the AA 5052 aluminium sheets measure 1000 mm by 1250 mm. The unit cost per sheet is 12.5 arbitrary currency units.
• By default, the UST 1203 steel sheets measure 750 mm by 1000 mm. The unit cost per sheet is 17.5 arbitrary currency units.
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Creo Elements/Direct Sheet Metal does not process any currency parameter. To account for any local currencies, you simply change the cost figures.
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Sheet Size
The sheet dimensions specified in the cost model file govern the following parameters:
• The maximum size of any sheet metal part (flat) which can be produced from this sheet;
• The yield (quantity) of sheet metal parts per sheet. The formula used by Creo Elements/Direct Sheet Metal to compute the yield is also included in the sha_costmodel.lsp file. Creo Elements/Direct Sheet Metal simply checks the horizontal and vertical dimensions of the flat against the size of the "raw" sheet stock.
Fabrication Process Times and Rates
The sha_costmodel.lsp file defines the following process times and rates for the punch, stamp, bend, hem, and offset processes:
• operation runtime
• setup time
• rate per machine hour
• rate per second
Lot Size
The following default lot sizes are specified in the sha_costmodel.lsp file:
• 1
• 5
• 10
• 50
• 100
• 500
• 1000
The costs are calculated for each of these lot sizes.
Creating and Applying a Customized Cost Model
By creating a working copy of the sha_costmodel.lsp file supplied with Creo Elements/Direct Sheet Metal and editing this copy, you can quickly and easily create your own (custom) cost model file.
Proceed as follows:
1. Copy the sha_costmodel.lsp file to a filename such as my_costmodel.lsp.
2. Use any text editor (such as vi) to open the my_costmodel.lsp file.
3. Add any custom materials (see Materials) to the new cost model file. Be sure to specify the as-supplied size and cost of any additional material.
4. Change any other parameters (such as runtimes, setup times, rates, etc) as appropriate.
5. Save the cost model file.
6. Unless you are using default paths, be sure to specify the full pathname of your new cost model file in sha_customize. See Implementing
Customized TDB Files for details.
You can repeat this procedure to create multiple cost files for different divisions of your organization.
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Please note that the cost model always applies to the latest flat.
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