How long can reject handlers step away before the bin fills?

For the bin cover time: bin capacity divided by rejects arriving per hour, times 60. At 120 rejects per hour a 150-unit bin lasts 75 minutes, so stagger breaks or add bin space if breaks run longer.

Should I size the station on average or worst-shift reject rate?

Worst shift. The average hides the hours when a bad batch or a drifting process raises rejects, and those hours decide whether the bin fills. Take the highest shift rate from your reject counter history.

Does this check whether the pusher or air blast is fast enough?

No. That is a timing check of the reject device's cycle against the gap between products at line speed. This page sizes the people or cells that clear and disposition rejects after the device diverts them.

What counts as one reject handling cycle?

Everything a position does per reject: pick it from the bin, re-inspect or re-weigh it, decide scrap, rework or release, log it and put it away. Time that whole sequence, not just the pick.

Conveyors calculator

Reject Station Capacity Calculator

Check whether reject handlers can clear rejects as fast as inspection diverts them, and how long the reject bin covers a stop. You need line rate, reject rate, positions, handling rate, uptime and bin capacity.

What this calculator does

Whether a reject station clears rejects as fast as inspection kicks them out, and how long its bin covers a stop.

Formula used

Rejects arriving = line rate × reject rate
Effective handling capacity = positions × reject cycles per position-hour × uptime
Utilization = rejects arriving ÷ capacity; spare capacity = capacity − rejects arriving
Positions needed = FLOOR(rejects arriving ÷ (cycles per position-hour × uptime)) + 1, the fewest keeping utilization below 100%
Bin cover time (min) = reject bin capacity ÷ rejects arriving × 60

Inputs explained

Line Rate Through Inspection: Units per hour through the inspection that feeds the reject station.
Reject Rate: Rejects ÷ units inspected from the reject counter; use your worst shift.
Active Reject Handling Positions: Operators, robots or cells clearing and dispositioning rejects in parallel.
Reject Cycles per Position-Hour: Rejects one position checks and dispositions per working hour, from time study.
Reject Station Uptime: Share of scheduled time staffed and able to clear rejects, from logs.
Reject Bin Capacity: Rejects the bin or reject conveyor holds before it must be emptied.

How to use the result

Best suited to planning breaks for reject handlers, sizing a reject bin or reject conveyor.
After a stop the bin drains only at the spare capacity rate, so back-to-back stops need more cover. Does not check the reject device's own speed against product spacing at line rate.

Current U.S. benchmarks

The U.S. has 21,668 machinery manufacturing establishments employing about 1,086,146 workers (Census County Business Patterns, 2023).

Common questions

How long can reject handlers step away before the bin fills? For the bin cover time: bin capacity divided by rejects arriving per hour, times 60. At 120 rejects per hour a 150-unit bin lasts 75 minutes, so stagger breaks or add bin space if breaks run longer.
Should I size the station on average or worst-shift reject rate? Worst shift. The average hides the hours when a bad batch or a drifting process raises rejects, and those hours decide whether the bin fills. Take the highest shift rate from your reject counter history.
Does this check whether the pusher or air blast is fast enough? No. That is a timing check of the reject device's cycle against the gap between products at line speed. This page sizes the people or cells that clear and disposition rejects after the device diverts them.
What counts as one reject handling cycle? Everything a position does per reject: pick it from the bin, re-inspect or re-weigh it, decide scrap, rework or release, log it and put it away. Time that whole sequence, not just the pick.

Last reviewed 2026-10-01.