The Basic Formula
Start with strip consumption per part: pitch times strip width times gauge times material density gives weight per stroke, divided by parts per stroke. Multiply by price per pound for the coil as purchased, including gauge, width and coating extras, slitting charges and freight. Then subtract scrap credit on the weight that comes out as scrap.
098, so check the alloy rather than assuming. Pricing for steel is often index-based or carries a surcharge, so build a field for the price date, not a fixed number, and revisit quotes when contracts allow a pass-through.
- Weight per stroke = pitch x width x gauge x density
- Cost per part = weight per part x delivered coil price per pound
- Net material = cost per part minus scrap credit on engineered scrap
- Add slitting, edge condition, coating and freight to the coil price
Losses That Are Not in the Blank Weight
Utilization is finished part weight divided by strip weight consumed, and it usually falls below the layout number once real production starts. Coil starts and ends leave short scrap pieces that cannot feed. Setup and tryout consume strip before the first good part.
Reject and sort losses scale with scrap rate, and parts reworked or held for containment still consumed material. Edge wave, camber, and coil set variation in the incoming coil can force pitch adjustment or lost production. Finally, a heat or lot change mid-run can strand a partial coil.
A quote based on layout yield without a shop-floor allowance for these is optimistic on day one.
Scrap Credit Without Fooling Yourself
Scrap is sold, not free money. Engineered scrap (slugs, skeleton, trim) is typically segregated by material and sold at a price below what you paid, and the gap depends on the market, grade, cleanliness and volume. Mixed alloy or contaminated scrap sells for less, and coated steel or aluminum may have its own rules.
Many stampers credit scrap in the part price at the actual recent recovery rate, and some customers' contracts specify who owns the scrap. Do not credit scrap at purchase price; model it at the real resale, and update when your scrap hauler's pricing changes.
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Plate Nesting Utilization and Material Cost per Part Worksheet
Enter sheet size, thickness, density, part area and parts per nest to get sheet weight, utilization percent and material cost per part for each job.
Measuring Real Utilization From the Floor
The way to verify the estimate is to compare coil weight issued to a job against good-part weight produced and scrap weighed. That needs discipline at three points: coil weight at issue, the remaining weight returned, and good piece counts at the end of each run. In ERPs such as Epicor, Plex, DELMIAworks or SyteLine this means material issue transactions, return-to-stock, and scrap reporting with reason codes.
Where this is done by hand on paper, utilization data is usually thin or unreliable. Fixing the data capture is more valuable than any analysis built on weak numbers.
- Weigh or log coil at issue and the remaining coil on return
- Report scrap by reason code: setup, die, material, operator
- Compare actual utilization with quoted utilization by part number
When Precision Is Not Worth the Effort
For low-volume parts with cheap material, tracking coil to the pound may cost more than it saves. Focus your measurement on high-volume programs, expensive alloys such as stainless, copper or pre-plated strip, and customers who audit material. A mid-sized stamper with a hundred active part numbers might measure utilization monthly on the top twenty by material spend and review the rest quarterly.
AI can help by flagging jobs where actual weight consumed is out of line with history, but it cannot fix missing transactions.
Frequently asked questions
How do you calculate material yield in stamping?
Divide the finished part weight by the weight of strip consumed per good part. Strip weight uses pitch, width, gauge and density, and should be adjusted for coil-end losses, setup and tryout material, and reject losses. Layout yield from the die designer is the ceiling, and actual utilization from production is the number to quote with.
Should scrap credit be included in a stamping quote?
Yes, but at realistic resale value, not at the purchase price. Segregated engineered scrap sells at a discount to coil cost, and mixed or contaminated scrap fetches less. Check your customer contract too, since some customers claim scrap ownership or require a specific treatment.
How do steel price changes affect stamping quotes?
Because material is often the largest cost line, shops commonly use index-based pass-through clauses or surcharges agreed with customers, and update quotes when contracts allow. Without a clause, a price swing in coil can erase margin on long programs, so store the price date used in each quote.
Netray can build a read-only view over your ERP that compares quoted and actual coil utilization by part, press and material lot.