How Are the Line Balancing and Assignment Problems Solved?
Line balancing (yamazumi) is, in lean thinking, the smooth and balanced sequencing of work steps so that the workload is shared in a levelled way. What makes it hard in apparel is how small the differences between operations are.
The problem: the invisible 0.2 minutes
In garment production, standard-time differences between operations fall to 0.1–0.2 minutes. Suppose one operator has a 0.9-minute operation and another a 0.7-minute one. Balanced to 0.9 minutes, the first operator's time is 100% loaded and the second's about 78%. Every piece carries a 0.2-minute wait, too short to give the operator extra work. In an irregular flow that wait goes unnoticed; everyone appears to work at the same pace.
Over a 540-minute day the second operator's load is 540 × 0.78 ≈ 420 minutes: roughly 2 hours less than the other operator, spent on work that adds no value. That is both unfair and inefficient. Without measurability the difference is never seen.
The solution: make the gap visible with bundles
In a regular flow, take a bundle of 40 pieces. The first operator finishes a bundle in 40 × 0.9 = 36 minutes, the second in 40 × 0.7 = 28. The 8-minute gap is enough to assign the operator another job. Once standard-time gaps are visible, balancing the workload becomes straightforward: instead of "help out for an unspecified quantity", an operator can be told 5 bundles of side seam and 3 bundles of sleeve attach per hour. No point of workload distribution on the floor is left undefined.
The assignment problem: who does which operation?
As important as balancing is the second question: which operator is assigned to which operation. argemas assignment optimization builds lines from operators' historical productivity and quality data, and re-plans on absenteeism and model changeover. In Arge Bilişim's lean transformation consultancy, line balancing and bottleneck management is one of 17 topics, alongside VSM and SMED.