Production Systems, Productivity and Work Study Basics
This domain tests whether you can describe production systems, compute standard time and efficiency, and identify a bottleneck in a line.
Production systems
- Progressive bundle system: bundles move between operations; high WIP and handling.
- Unit production system: overhead hangers carry single pieces; less handling, better tracking.
- Modular or team system: small teams own a complete garment; short throughput time.
- One-piece flow and cellular layouts reduce WIP and expose bottlenecks.
- Lean tools: 5S, kaizen, kanban, poka-yoke, takt time.
Work measurement
Observe a cycle with a stopwatch, rate the operator against the standard pace, then add allowances. Basic time = observed time x rating / 100. SAM (standard allowed minute) = basic time x (1 + allowance factor). Efficiency = earned minutes / attended minutes x 100. Capacity = operators x available minutes / SAM. Line balancing sets pitch time = SAM / number of operators, and the slowest operation sets the line rate.
Worked example
Observed time 0.80 minute, rating 110%, allowance 20%. Basic time = 0.80 x 1.10 = 0.88 minute; SAM = 0.88 x 1.20 = 1.056, about 1.06 minutes. A 30-operator line working 480 minutes has capacity = 30 x 480 / 1.056 = about 13,636 pieces per shift. If actual output is 11,000, efficiency is (11,000 x 1.056) / (30 x 480) x 100 = about 81%.
Traps that cost marks
Adding allowances before applying the rating, using cycle time as if it were SAM, forgetting rework and machine downtime, and blaming the fastest operator instead of the bottleneck operation.