How do you calculate foundry rework rate?

Divide reworked parts by total inspected parts and multiply by 100. With 16 reworked out of 420 inspected, the rework rate is 3.81 percent.

What is a good rework rate for a foundry?

It varies by alloy and complexity, but many production foundries target 2 to 4 percent for established parts. At 3.81 percent against a 3 percent target, this lot is 0.81 points over the ceiling.

What is the difference between rework and scrap?

Rework parts are salvageable through repair operations and ship after correction; scrap parts are unrecoverable and lost. Tracking both separately shows how much defect cost you are recovering versus writing off.

Why is my rework rate trending up?

Common drivers are mold or core degradation, gating issues, alloy chemistry drift, die wear in forging, or tightened inspection. Compare the trend against pattern age and chemistry logs to isolate the cause.

Does rework rate include scrap?

No. This metric counts only parts routed to a repair operation. Add a separate scrap-rate calculation to capture parts that fail beyond repair.

How does rework rate relate to first-pass yield?

First-pass yield is roughly 100 percent minus rework minus scrap. A 3.81 percent rework rate alone caps first-pass yield at about 96 percent before scrap is subtracted.

Foundry & Forging calculator

Foundry Rework Rate Calculator

Foundry Rework Rate is the share of inspected castings or forgings that need rework (weld repair, regrinding, straightening, re-impregnation) rather than passing first time. It is a core quality KPI in casting and forging plants because rework consumes labor and energy on parts you have already made, eroding throughput and margin. Quality engineers and shift supervisors track it to gate process changes, qualify new patterns or dies, and hold suppliers to spec. Watched alongside scrap rate, it separates recoverable defects from total losses.

What this calculator does

Calculate the rework rate for castings, forgings, molds, cores, heats, or machined cast products.
Use it when defects require weld repair, grinding, straightening, heat-treat rework, dimensional correction, or retest.
It computes rework as a percentage of total inspected output and shows how far that percentage sits from your target ceiling.

Formula used

Foundry Rework Rate rate = reworked castings or forgings ÷ total inspected output × 100
Foundry Rework Rate gap to target = calculated rate - target maximum rework rate

Inputs explained

Reworked castings or forgings:
Total inspected castings or forgings:
Target maximum rework rate:

How to use the result

Use it at end of shift, lot close, or in a quality review to monitor first-pass yield and trigger corrective action.
It treats every reworked part the same; a quick deburr and a full weld-and-stress-relieve repair count equally, so cost impact can differ greatly at the same rate.

Current U.S. benchmarks

The producer price index for steel mill products stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 3,569 primary metal manufacturing establishments employing about 354,911 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate foundry rework rate? Divide reworked parts by total inspected parts and multiply by 100. With 16 reworked out of 420 inspected, the rework rate is 3.81 percent.
What is a good rework rate for a foundry? It varies by alloy and complexity, but many production foundries target 2 to 4 percent for established parts. At 3.81 percent against a 3 percent target, this lot is 0.81 points over the ceiling.
What is the difference between rework and scrap? Rework parts are salvageable through repair operations and ship after correction; scrap parts are unrecoverable and lost. Tracking both separately shows how much defect cost you are recovering versus writing off.
Why is my rework rate trending up? Common drivers are mold or core degradation, gating issues, alloy chemistry drift, die wear in forging, or tightened inspection. Compare the trend against pattern age and chemistry logs to isolate the cause.
Does rework rate include scrap? No. This metric counts only parts routed to a repair operation. Add a separate scrap-rate calculation to capture parts that fail beyond repair.

Last reviewed 2026-05-12.