How do you calculate coating reject rate?

Divide the number of rejected or reworked parts by the total parts coated. With 8 rejects out of 250 parts, that is 8/250 = 3.2%.

What is a good first-pass yield for thermal spray?

Mature production coating lines often run first-pass yields of 95% or better, meaning a reject rate at or below 5%. The 3.2% in the example clears a 95% target comfortably.

How does the gap to target work here?

The calculator subtracts the measured rate from your reference target. With a 95 target and a 3.2% measured rate the reported gap is 91.8 points, a large positive gap that signals the batch beat the threshold; a small or negative gap flags a batch that needs attention.

What causes high thermal spray reject rates?

Common drivers are poor surface prep (contaminated or under-blasted substrate), wrong standoff or spray angle, thermal shock and spallation, thickness out of tolerance, and overspray bleeding onto masked critical features.

Should I count reworkable parts as rejects?

Include them if you are measuring first-pass yield, since a part that needs a strip-and-recoat consumed capacity and material. Track scrap-only separately if you also need a true scrap rate for costing.

Reject rate vs. overspray loss of material, are they the same?

No. This measures parts that failed inspection. Material overspray, the powder or wire that misses the part, is captured by transfer efficiency in the powder and wire consumption calculators.

Thermal Spray, Hardfacing & Wear Coatings calculator

Overspray Loss Calculator

This calculator measures the reject rate on a thermal spray batch, the share of coated parts that fail inspection for defects like poor adhesion, spallation, out-of-spec thickness, or excessive overspray on masked features. Quality engineers and shop supervisors use it to track coating yield, spot process drift, and decide whether a run needs corrective action before the next batch. In a business where a rejected carbide-coated part carries the full cost of powder, gas, labor, and a grinding allowance, even a few points of reject rate erodes margin fast. The tool returns the measured rate and the gap to your first-pass yield target so you know at a glance whether the batch met standard.

What this calculator does

This calculator measures the reject rate on a thermal spray batch, the share of coated parts that fail inspection for defects like poor adhesion, spallation, out-of-spec thickness, or excessive overspray on masked features.
Use it when overspray loss in thermal spray, hardfacing and wear coatings needs a clean rate and gap-to-target you can put on a tier board.
It computes the fraction of coated parts that were rejected or reworked in a batch and compares that yield against your target.

Formula used

Overspray Loss rate = affected amount ÷ total amount
Gap to target = target rate - calculated rate

Inputs explained

Rejected or reworked coated parts:
Total parts coated in the batch:
Target first-pass yield:

How to use the result

Use it at batch close-out or during a process capability review to trend coating quality and flag runs that miss the yield target.
It counts parts, not defect severity or root cause; a batch dominated by one bad fixture reads the same as one with scattered failures, so pair it with defect Pareto data.

Current U.S. benchmarks

Industrial electricity averages 8.66 cents per kWh across the U.S. (EIA, Apr 2026), up 5.5% from a year earlier. Energy-intensive steps carry this directly into unit cost.
The producer price index for industrial chemicals stands at 344.336 (BLS, May 2026), up 16.1% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 14,543 chemical manufacturing establishments employing about 911,245 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate coating reject rate? Divide the number of rejected or reworked parts by the total parts coated. With 8 rejects out of 250 parts, that is 8/250 = 3.2%.
What is a good first-pass yield for thermal spray? Mature production coating lines often run first-pass yields of 95% or better, meaning a reject rate at or below 5%. The 3.2% in the example clears a 95% target comfortably.
How does the gap to target work here? The calculator subtracts the measured rate from your reference target. With a 95 target and a 3.2% measured rate the reported gap is 91.8 points, a large positive gap that signals the batch beat the threshold; a small or negative gap flags a batch that needs attention.
What causes high thermal spray reject rates? Common drivers are poor surface prep (contaminated or under-blasted substrate), wrong standoff or spray angle, thermal shock and spallation, thickness out of tolerance, and overspray bleeding onto masked critical features.
Should I count reworkable parts as rejects? Include them if you are measuring first-pass yield, since a part that needs a strip-and-recoat consumed capacity and material. Track scrap-only separately if you also need a true scrap rate for costing.

Last reviewed 2026-05-12.