How do you calculate fettling labor load?

Divide the castings needing fettling by the completion rate, then multiply by the allowance factor. With 160 parts at 18 parts/hr and a 20% allowance, base time is 8.89 hr and required load is 10.67 hr.

What is fettling in a foundry?

Fettling is the cleaning operation after knockout: removing runners, risers, gates, flash and adhered sand, then grinding and dressing the casting surface so it meets dimensional and cosmetic spec before machining or shipping.

Why add an allowance to fettling time?

Manual grinding involves fatigue, abrasive belt and disc changes, PPE breaks and rework on missed flash. A 15-25% allowance reflects that an operator is not productively cutting metal for every minute on shift.

What is a good fettling completion rate?

It depends entirely on part size and gating, but small-to-medium iron castings commonly run 12-25 parts/hr per grinder. The 18 parts/hr default sits mid-range; track your own bay to set a realistic figure.

How many fettlers do I need for a shift?

Divide the required labor load by available productive hours per operator. A 10.67 hr load fits inside roughly 1.5 operator-shifts, or one operator plus a few hours of overtime.

Does this include shot blasting?

No. This models manual fettling labor only. Shot blast, tumbling and automated deflashing run on separate equipment cycles and should be costed separately from grinder hours.

Foundry & Forging calculator

Fettling Labor Load Calculator

Fettling labor load is the number of grinding-room labor hours needed to clean, deburr and dress a batch of castings or forgings before they leave the foundry. Cleaning-room supervisors and production planners use it to staff the fettling bay, schedule shifts against a melt program, and quote the finishing cost that is easy to underprice. Because fettling is manual abrasive work with high fatigue and PPE downtime, the raw division of parts by rate always understates reality, which is why an allowance factor is built in. Getting this number right keeps castings flowing to inspection instead of piling up at the grinding stations.

What this calculator does

Estimate fettling labor hours for cutoff, chipping, grinding, riser removal, flash removal, and final dressing.
Use it when finishing labor must be scheduled or quoted for castings and forgings.
It computes the labor hours required to fettle a given quantity of castings or forgings at a known completion rate, inflated by a percentage allowance.

Formula used

Base fettling labor load = castings or forgings needing fettling ÷ fettling completion rate
Required fettling labor load = base time × allowance factor

Inputs explained

Castings or forgings needing fettling:
Fettling completion rate:
Fettling allowance:

How to use the result

Use it when planning fettling-bay staffing for a pour schedule, quoting finishing cost on a casting job, or sizing overtime to clear a backlog of as-cast parts.
The single completion rate assumes a consistent part mix; a batch with heavy gates, large flash or hard-to-reach pockets fettles far slower than the average rate suggests.

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 fettling labor load? Divide the castings needing fettling by the completion rate, then multiply by the allowance factor. With 160 parts at 18 parts/hr and a 20% allowance, base time is 8.89 hr and required load is 10.67 hr.
What is fettling in a foundry? Fettling is the cleaning operation after knockout: removing runners, risers, gates, flash and adhered sand, then grinding and dressing the casting surface so it meets dimensional and cosmetic spec before machining or shipping.
Why add an allowance to fettling time? Manual grinding involves fatigue, abrasive belt and disc changes, PPE breaks and rework on missed flash. A 15-25% allowance reflects that an operator is not productively cutting metal for every minute on shift.
What is a good fettling completion rate? It depends entirely on part size and gating, but small-to-medium iron castings commonly run 12-25 parts/hr per grinder. The 18 parts/hr default sits mid-range; track your own bay to set a realistic figure.
How many fettlers do I need for a shift? Divide the required labor load by available productive hours per operator. A 10.67 hr load fits inside roughly 1.5 operator-shifts, or one operator plus a few hours of overtime.

Last reviewed 2026-05-12.