How do you calculate scrap and rework cost in rotomolding?

Multiply the scrap quantity by the per-part cost and by the unrecovered-cost factor, then add fixed rework cost. With 100 parts at $45, an 80% capture factor, and $250 fixed, total cost is $3,850, or $38.50 per piece.

What should the capture factor represent?

It's the fraction of each part's cost you can't get back. At 80% you recover 20% of value (typically as regrind), so $3,600 of the $4,500 gross part value is captured as loss before the $250 fixed cost.

Why include a fixed cost in scrap calculations?

Rework and disposal carry setup, sorting, and handling charges that don't scale with quantity, like granulator setup or a QA hold. Here that's $250, which alone adds $2.50 per piece across 100 parts.

What is a good scrap rate for rotational molding?

Well-run rotomolding lines target 2 to 5% scrap. Complex multi-layer or foamed parts run higher. The dollar figure matters more than the percent: 100 scrapped tanks at $38.50 each is $3,850 whether that's 2% or 8% of volume.

How does regrind recovery lower scrap cost?

Reclaimable resin drops the capture factor. If you recover more material and reprocess it, set a lower factor so less of each part's cost counts as pure loss. Parts that can't be reground stay near 100%.

Scrap cost vs. rework cost, what's the difference?

Scrap is unrecoverable loss of the part; rework is added cost to salvage it. This tool blends both: the capture factor handles scrap loss, and the fixed cost captures the setup side of rework and handling.

Rotational Molding calculator

Scrap/Rework Cost Calculator

Scrap and rework cost captures the real money lost when rotomolded parts come out with pinholes, warpage, bridging, or short shots and either hit the regrind bin or go back through finishing. In rotomolding the sunk cost is high because each part has already absorbed a full oven cycle of energy, cycle time, and labor before defects show up at demold. Plant managers and cost accountants use this figure to decide whether a defect mode is worth a tooling fix or process change. Because rotomolded resin can only be partially reclaimed as regrind, the number is usually larger than operators expect.

What this calculator does

Scrap and rework cost captures the real money lost when rotomolded parts come out with pinholes, warpage, bridging, or short shots and either hit the regrind bin or go back through finishing.
Use it when scrap/rework cost in rotational molding is being put through a rotational molding weighted-cost review.
It computes the total and per-piece cost of scrap and rework for a run, weighting each part's cost by the share that can't be recovered and adding a fixed rework charge.

Formula used

Scrap/Rework Cost cost = quantity × rate × capture factor + fixed cost
Per-unit scrap/rework cost = total cost ÷ quantity

Inputs explained

Scrapped or reworked parts in the run:
Fully burdened cost per scrapped part:
Share of cost not recovered as regrind:
Fixed rework setup and handling cost:

How to use the result

Use it when reviewing a defect spike, building a business case for a mold repair, or reporting cost of poor quality for a molding line.
The capture factor is an estimate of unrecoverable cost, not a precise scrap valuation; it doesn't distinguish scrap that becomes usable regrind from parts that must be landfilled.

Current U.S. benchmarks

The producer price index for plastic resins and materials stands at 319.371 (BLS, May 2026), up 19.5% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 9,635 plastics product manufacturing establishments employing about 677,302 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate scrap and rework cost in rotomolding? Multiply the scrap quantity by the per-part cost and by the unrecovered-cost factor, then add fixed rework cost. With 100 parts at $45, an 80% capture factor, and $250 fixed, total cost is $3,850, or $38.50 per piece.
What should the capture factor represent? It's the fraction of each part's cost you can't get back. At 80% you recover 20% of value (typically as regrind), so $3,600 of the $4,500 gross part value is captured as loss before the $250 fixed cost.
Why include a fixed cost in scrap calculations? Rework and disposal carry setup, sorting, and handling charges that don't scale with quantity, like granulator setup or a QA hold. Here that's $250, which alone adds $2.50 per piece across 100 parts.
What is a good scrap rate for rotational molding? Well-run rotomolding lines target 2 to 5% scrap. Complex multi-layer or foamed parts run higher. The dollar figure matters more than the percent: 100 scrapped tanks at $38.50 each is $3,850 whether that's 2% or 8% of volume.
How does regrind recovery lower scrap cost? Reclaimable resin drops the capture factor. If you recover more material and reprocess it, set a lower factor so less of each part's cost counts as pure loss. Parts that can't be reground stay near 100%.

Last reviewed 2026-05-12.