Lean manufacturing is a way of running production that focuses on what the customer is paying for and removes everything else. In a garment factory that means fewer bundles waiting between operations, less walking and searching, fewer repairs, shorter changeovers and a steady flow of finished garments.
Lean is not a single tool. It is a set of habits: see the waste, fix the cause, standardise the fix, repeat.
Value and waste#
Value-adding work changes the product in a way the customer pays for: cutting a panel, sewing a seam, pressing a finished garment.
Waste is everything else that consumes time, space or material. Some waste is needed today (moving bundles to the next operation) but can be reduced; some can be removed completely.
The eight wastes in a garment factory#
| Waste | What it looks like on the floor |
|---|---|
| Overproduction | Cutting far ahead of sewing; sewing sizes the line does not need yet |
| Waiting | Operators waiting for bundles, trims, a mechanic or a decision |
| Transport | Bundles carried long distances, between floors or back and forth |
| Over-processing | Extra trimming, double checking, pressing that the product does not need |
| Inventory | Large WIP between operations, full cutting racks, piles of finished goods |
| Motion | Operators reaching, turning and searching; tools out of reach |
| Defects | Repairs, re-cuts, rework after inspection |
| Unused skills | Operator ideas ignored; people doing work below their skill |
A common memory aid is TIMWOODS (transport, inventory, motion, waiting, overproduction, over-processing, defects, skills).
Lean tools that work in garment production#
5S#
Sort, set in order, shine, standardise, sustain. A clean, organised workplace where everything has a place is the base for everything else. See 5S in garment factories.
Value stream mapping#
Draw the flow of one product from fabric receipt to shipment, with the time material spends waiting at each step. In most factories, fabric and garments spend far longer waiting than being worked on. The map shows where.
Takt time and line balancing#
Set the line's pace from customer demand (takt time), then balance work so every station can meet it (line balancing).
Small bundles and WIP limits#
Large bundles hide defects and create long waiting times. Smaller bundles, or single-piece flow in cells for suitable styles, reduce WIP and show problems quickly. See WIP control.
Standard work#
A written and demonstrated best method for each operation: pick-up and aside positions, sequence of motions, quality checks. Standard work is the baseline for training and for improvement.
Quick changeover#
Style changes cost days of efficiency. Preparing machines, attachments, trims and operator training before the old style finishes shortens the changeover and the learning curve.
Built-in quality#
Inline checks at the operation, simple error-proofing devices (guides, folders, stops), and stopping to fix a problem rather than passing it on. See inline inspection.
Visual management#
Hourly boards showing target and actual, WIP limits marked on the floor, andon lights or flags when a line needs help.
Kaizen#
Many small improvements made by the people doing the work, tested and standardised. See kaizen.
A realistic order to start#
- Pick one line as a pilot, not the whole factory.
- Do 5S on that line and its supply area.
- Measure the baseline: efficiency, WIP between operations, DHU, throughput time.
- Balance the line to takt and set WIP limits.
- Write standard work for the bottleneck operations first.
- Hold short daily meetings at the line board to deal with problems.
- Standardise what works, then extend to the next line.
Measuring progress#
Track a few numbers before and after: line efficiency, WIP pieces, throughput time (cut to pack), DHU or RFT, and changeover losses. Improvements that do not show in these numbers are probably not improvements.
Common pitfalls#
- Treating lean as a project with an end date instead of a way of working.
- Copying tools without the thinking, such as painting floor lines without setting WIP limits.
- Cutting WIP before fixing balance and machines, which just stops the line.
- Ignoring operators' ideas, which wastes the most useful knowledge in the factory.
The takt time calculator and line efficiency calculator help set targets and track results.