How do you calculate green body scrap rate?

Divide rejected green bodies by total green bodies inspected and multiply by 100. With 38 rejects out of 850 inspected, that is 38 ÷ 850 × 100 = 4.47% green scrap.

What is a good green scrap rate for technical ceramics?

It depends on the part and forming route, but many dry-pressed alumina and zirconia lines target 2-4% green scrap. The 4.47% in the example sits just above a 3% allowance, so it is a yellow flag rather than a crisis.

What does a negative scrap gap mean?

A negative gap means you are under your allowance. Here the gap is -1.47 percentage points, meaning the actual 4.47% rate is... above the 3% allowance, so the gap is positive in magnitude; a truly negative value would indicate you beat target.

Why track green scrap separately from fired scrap?

Green rejects cost only powder and press time, while fired rejects carry the full kiln and grinding cost. Catching defects green is where most of your scrap savings live.

Green scrap vs fired scrap — which matters more for cost?

Per part, fired scrap is far more expensive because it has absorbed firing energy and machining. But high green scrap is the earlier, more actionable signal that pressing or binder chemistry needs attention.

Does green scrap rate predict final yield?

Partly. Rising green scrap often precedes rising fired defects from the same root cause, but some defects (overfiring, thermal cracks) appear only after sintering, so use both metrics together.

Advanced Technical Ceramics calculator

Green Body Scrap Rate Calculator

Green body scrap rate measures the percentage of pressed or cast ceramic parts that fail inspection before they ever reach the kiln. Process engineers in technical ceramics plants watch this number because green-stage rejects — chips, laminations, low green density, cracks from ejection — are the cheapest defects to catch and the loudest signal that pressing, binder, or handling is drifting. A part scrapped green costs only the powder and the press cycle; the same defect that survives to post-sinter inspection costs the full firing and grinding bill. Tracking green scrap against an agreed allowance tells you whether forming is in control before you commit kiln time.

What this calculator does

Calculate green ceramic body scrap from rejected unfired parts, total green parts handled, and the allowed scrap target.
a process engineer needs to quantify unfired scrap before sending a batch of technical ceramic parts to the kiln
It computes the share of inspected green bodies that were rejected and the gap between that rate and your allowed green scrap target.

Formula used

Green body scrap rate = rejected green bodies ÷ total green bodies inspected × 100
Scrap gap to allowance = green body scrap rate - allowed green scrap rate

Inputs explained

Rejected green bodies:
Total green bodies inspected:
Allowed green scrap rate:

How to use the result

Use it at the forming and pre-fire inspection station, per press shift, batch, or tool, to flag forming drift before firing.
It only counts defects caught at green inspection — a clean green scrap rate says nothing about cracks or warpage that only appear after sintering.

Current U.S. benchmarks

Steel mill PPI stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. New factory orders are up 2.3% year over year (Census).

Common questions

How do you calculate green body scrap rate? Divide rejected green bodies by total green bodies inspected and multiply by 100. With 38 rejects out of 850 inspected, that is 38 ÷ 850 × 100 = 4.47% green scrap.
What is a good green scrap rate for technical ceramics? It depends on the part and forming route, but many dry-pressed alumina and zirconia lines target 2-4% green scrap. The 4.47% in the example sits just above a 3% allowance, so it is a yellow flag rather than a crisis.
What does a negative scrap gap mean? A negative gap means you are under your allowance. Here the gap is -1.47 percentage points, meaning the actual 4.47% rate is... above the 3% allowance, so the gap is positive in magnitude; a truly negative value would indicate you beat target.
Why track green scrap separately from fired scrap? Green rejects cost only powder and press time, while fired rejects carry the full kiln and grinding cost. Catching defects green is where most of your scrap savings live.
Green scrap vs fired scrap — which matters more for cost? Per part, fired scrap is far more expensive because it has absorbed firing energy and machining. But high green scrap is the earlier, more actionable signal that pressing or binder chemistry needs attention.

Last reviewed 2026-05-12.