How do you calculate ramp scrap exposure hours?

Divide the at-risk unit count by the screening rate for base hours, then multiply by one plus the allowance. 120 units at 12 units / hr is 10 base hours, and a 10% allowance yields 11 hours.

What is 'at-risk' volume during a ramp?

The parts made before the process is proven capable, typically 100% inspected because scrap and rework rates are elevated. The 120-unit default reflects a containment lot pulled from early-ramp output.

Why include a containment allowance?

Sorting isn't clean cycle time. You lose hours to segregation, re-inspection, documentation, and rework routing. The 10% allowance adds one hour to a 10-hour base to cover that overhead.

How is this different from a scrap-cost calculator?

This sizes the labor-hours to handle a known at-risk population, not the dollar value of scrapped material. Use it to staff the sort; use a scrap-cost tool to value what you throw away.

What's a realistic screening rate?

It depends on inspection complexity, a quick go/no-go gauge runs fast, while functional test or teardown is slow. The 12 units / hr default fits a straightforward visual or gauge screen.

Base hours vs required hours, which do I staff to?

Staff to required hours (11 here), not base (10). If you plan only base hours, containment runs short and either escapes slip through or the sort spills into the next shift.

Production Ramp, Scale-Up & Launch Readiness calculator

Ramp Scrap Exposure Calculator

Ramp scrap exposure estimates the labor-hours needed to screen, sort, and rework the units that a line produces while yield is still climbing during early production. Quality and launch teams use it to staff containment during the riskiest weeks of a ramp, when process capability hasn't stabilized and defect rates run well above steady-state. It turns a population of at-risk parts and a demonstrated screening rate into the hours you must plan for sorting and rework. Sized correctly, containment protects the customer without swamping your team; sized wrong, escapes reach the field or your sort labor explodes.

What this calculator does

Estimate ramp scrap exposure for production ramp, scale-up and launch readiness using production-ready inputs so teams can plan labor hours, schedule the work, or check whether the job fits the available shift time.
Use it when ramp scrap exposure in production ramp, scale-up and launch readiness needs a defensible run time before a quote goes out.
It converts a volume of at-risk ramp units and a screening/rework throughput into the base labor-hours, then inflates that by an allowance for sorting, containment, and rework overhead.

Formula used

Base ramp scrap exposure time = ramp scrap exposure workload ÷ ramp scrap exposure completion rate
Required ramp scrap exposure time = base ramp scrap exposure time × allowance factor

Inputs explained

Ramp units at elevated scrap risk:
Ramp screening and rework rate:
Sorting, containment, and rework allowance:

How to use the result

Use it during the ramp phase to staff containment and sort activities before the process reaches stable Cpk and normal AQL sampling.
It assumes a steady screening rate; in practice screening slows when defect complexity varies, and it doesn't tell you the scrap rate itself, only the hours to handle a known at-risk population.

Common questions

How do you calculate ramp scrap exposure hours? Divide the at-risk unit count by the screening rate for base hours, then multiply by one plus the allowance. 120 units at 12 units / hr is 10 base hours, and a 10% allowance yields 11 hours.
What is 'at-risk' volume during a ramp? The parts made before the process is proven capable, typically 100% inspected because scrap and rework rates are elevated. The 120-unit default reflects a containment lot pulled from early-ramp output.
Why include a containment allowance? Sorting isn't clean cycle time. You lose hours to segregation, re-inspection, documentation, and rework routing. The 10% allowance adds one hour to a 10-hour base to cover that overhead.
How is this different from a scrap-cost calculator? This sizes the labor-hours to handle a known at-risk population, not the dollar value of scrapped material. Use it to staff the sort; use a scrap-cost tool to value what you throw away.
What's a realistic screening rate? It depends on inspection complexity, a quick go/no-go gauge runs fast, while functional test or teardown is slow. The 12 units / hr default fits a straightforward visual or gauge screen.
Base hours vs required hours, which do I staff to? Staff to required hours (11 here), not base (10). If you plan only base hours, containment runs short and either escapes slip through or the sort spills into the next shift.

Last reviewed 2026-08-12.