Measurement-control and fit variation

Learning objectives

• Standardize garment measurement method before judging fit variation.
• Separate pattern, cutting, sewing and finishing contributions to dimensional variation.
• Use SPC only after stability and MSA are confirmed.

Problem and CTQ

Dimensions can drift by size, material, line and process stage. Lock method, conditioning, points, units and rounding before analysing capability.

DMAIC path

• Attribute or variables MSA for tape, table and appraiser.
• Analyse patterns, shrinkage, cutting, sewing method and finishing effects.
• Assess capability only after the process is stable.

Improvement choices

• Pattern/version control and measurement fixture.
• Method training and critical-operation controls.
• Shrinkage compensation and first-off approval.

Control plan

• Pass %, mean deviation, Cpk/Ppk by measurement/size, repeat MSA cadence, alteration/repair minutes and fit complaints.

Garment-factory example

A bottom-hem width on a chino at size 32 shows Cpk 0.71 with mean 0.4 cm above nominal. A pattern reduction of 0.3 cm plus a fixture at hem-close lifts Cpk to 1.24 with zero size-mix escape.

Common mistakes

• Pooling tolerances across sizes.
• Measuring garments before conditioning.