Garment Line Efficiency Drop After Style Change
A garment factory runs a sewing line of 32 operators producing a basic T-shirt at a standard minute value (SMV) of 8.0 minutes per garment. The line previously achieved 78% efficiency at a target of 600 pieces per shift of 8 hours. After switching to a polo shirt with a placket, collar, and button stand, the SMV was re-set to 14.5 minutes. The line still has 32 operators but only 6 have prior polo experience. Output has fallen to 290 pieces per shift and efficiency is reported as 52%. The production manager wants to add 8 operators to recover output. The customer's order is 18,000 pieces with a 25-day delivery window, and the factory works one shift per day with 6 working days per week.
1. Calculate the theoretical output at the new SMV and assess whether adding operators is the right first response.
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Theoretical capacity at 100% efficiency: 32 operators x 480 minutes / 14.5 SMV = 1,059 pieces per shift. At 78% efficiency, expected output would be about 826 pieces per shift. Actual output is 290 pieces, so efficiency is 290 x 14.5 / (32 x 480) = 4,205 / 15,360 = 27.4%, not 52%. The reported 52% is likely computed on the old SMV or old output basis and should be corrected.
Adding 8 operators is premature. The gap between 27% and a realistic 70-78% is a learning-curve and method problem, not a headcount problem. With only 6 experienced operators, the line is bottlenecked at the placket, collar, and button stand operations, and untrained operators create rework and idle time downstream. Adding operators to a poorly balanced line increases work-in-progress and congestion rather than output.
2. Propose a line-balancing and ramp-up plan, and check whether the order can be met.
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Plan: identify the bottleneck operations (placket, collar attach, button stand) and allocate the most experienced operators there. Pair each experienced operator with one or two learners for on-the-job training. Re-balance the line by operation time rather than equal headcount, and use a skills matrix to track competence. Introduce a ramp-up curve with weekly efficiency targets, for example 45%, 60%, 70%, then 78%, and review daily output against the curve. Add operators only if a genuine capacity shortfall remains after balance is achieved.
Order check: available working days = 25 calendar days, at 6 days/week approximately 21 working days. Required output = 18,000 / 21 = 857 pieces per day. At 78% efficiency the line can make about 826 pieces per shift, marginally short. At 70% it makes about 741 pieces, short by about 116 per day. The factory should plan overtime, a second shift for part of the period, or negotiate a phased delivery. Adding a small number of operators (for example 4) after balance is achieved may close the gap, but not 8 at the outset.