Quality

Cutting Rework Cost: Shrinking the Hidden Factory

Rework looks like work, which is why it survives. How to cost it in three layers, find the top offenders, and cut the bill 40 to 60 percent in a year.

Rework hides because it looks like work. Same operators, same stations, same badge swipes, but the units crossing the bench have already been paid for once. A cell reworking 60 units a day at 12 minutes each burns 12 labor hours daily; at $32 fully loaded that is $384 a day and roughly $96,000 a year, and it never shows on a purchase order. Add the machine time rework steals from good production, worth $75 to $150 per hour on constrained equipment, and rework is usually the largest quality cost nobody budgets. If it is not a line item, it is a leak.

Cost a rework run in three parts. Labor: units times minutes times loaded rate, so 200 units at 15 minutes and $30 per hour is $1,500. Materials: replacement components, consumables, repaint; at $4 per unit that adds $800. Lost capacity: if rework occupies a bottleneck machine for 20 hours that would have produced 50 sellable units at $35 contribution margin each, add $1,750. Total: $4,050 for the run, about $20 per unit reworked. The Rework Cost calculator stacks those three layers; the discipline is refusing to quote rework as labor only, which typically understates it by 50 to 150 percent.

Benchmarks: rework labor at 2 to 5 percent of direct labor hours is common in assembly plants, under 1 percent is strong, and above 8 percent means you are staffing a hidden factory. In fabrication and welding, expect 3 to 7 percent of hours; in electronics, touch-up and reflow rework often consumes 4 to 10 percent of test-area labor. As a share of sales, total rework cost typically runs 0.5 to 2 percent. Measure your own baseline for two weeks with a simple log of units, minutes, materials, and station before trusting any range, because plant-reported rework is undercounted almost everywhere.

The biggest lever is catching defects earlier. A defect fixed at the station costs 1x; caught at final test, 5 to 10x; caught by the customer, 30 to 100x. So move detection upstream with in-process checks at the three stations generating 70 percent of rework. Second lever, kill repeat offenders: if one connector orientation drives 40 percent of rework minutes, a $1,500 asymmetric fixture beats a year of touch-up labor. Third, cap the loop: units reworked more than twice pass at maybe 60 percent rates and should trigger scrap review, because the third attempt often costs more than the unit's margin.

Failure modes to watch. Informal rework: the 45 second fix nobody logs, which can hide half your true volume; audit by comparing component consumption against bill-of-material for a week, and the overage tells the truth. Rework as a career: dedicated rework technicians become permanent and the position outlives the problem, so sunset every rework station with a 90 day review. Costing at standard labor instead of loaded rates understates the bill 30 to 40 percent. And reworked units commonly fail downstream at 2 to 4 times the rate of first-pass units, so track them as a separate population.

Cadence: daily, log every rework event with unit, defect code, and minutes, and review yesterday's total minutes at the tier meeting next to first pass yield. Weekly, convert minutes to dollars and Pareto by defect code; the top item gets a countermeasure due within 10 working days. Monthly, report rework cost as one number to plant leadership, labor plus material plus lost capacity, trended over 13 weeks. Quarterly, walk the floor and physically count rework in process against the log; a gap above 15 percent means the daily layer is decaying and needs a reset before the numbers rot.

World-class plants hold rework under 1 percent of labor hours, log 95 percent plus of events, and treat any dedicated rework station as a temporary embarrassment with a closure date. They can quote rework cost per unit by product family from memory, and they reinvest the savings visibly: a cell that cut rework from $9,000 to $2,000 a month funds its own fixtures and gets faster approvals next time. Expect a serious program to cut rework cost 40 to 60 percent in the first year, mostly from the top three defect codes, then 10 to 20 percent a year once the easy money is gone.

Published 2026-07-02.