Traffic Light System for Quality Inspection in Garment Manufacturing

Like other quality inspection tools, the traffic light inspection system is widely used in garment quality inspection. This system is used to stop producing defect at the source. This is a random inspection system. Traffic light system is more effective in controlling shop floor quality than other quality tools because of its visual communication. At the same time, it measures operator’s performance level in quality. No operators like be presented themselves as lower quality makers. They concentrate on quality aspect during stitching garments.

The format used for displaying as well as recording audit report. The format is very simple to use and to understand. The format is printed on a slightly thick A4 sheet and hanged on the sewing machine. In this system quality auditor visit operator’s workplace 4 times in a day (considering 8 hours shift day) and inspects stitched garments and fill circles with color according to the inspection result. In the initial stage when this format had been introduced by JC Penny for their supplier, they instructed to inspect 7 pieces from the stitch garments and if auditor found any defective piece respective circle to be filled by RED color. If red color is marked on the inspection sheet, all stitched pieces must be checked by an auditor. And operator needs to be explained about the quality expected from him/her and how to get that expected quality. In some case, operators need more practice to get right quality pieces.

Factory QAs later modified sample size, the rating criteria and added yellow color keeping purpose right. The sample size is reduced as a quality auditor does not get 7 pieces at a time of inspection at most of the workstations. This happens due to low work in process (WIP) in between two workstation. 

I have recently visited a factory in Delhi and found that factory uses Traffic Light System. Inspection formats in the floor were spread over to all machines. The criteria set by that factory have been shown in the following image (Copy of the format).

Standard Sample Size: 5 pieces. Garment Inspection to be done after every two hours. 
Color marking procedures: Circles will be filled with color 

  • GREEN: If found No defect 
  • YELLOW: If found 1 defect 
  • RED: If found 2 defects

Image: Traffic Light System Format

How to fill/use the format: 

The above format is used for a single operator or workstation. A single sheet will keep the record for the whole month for an operator. As a quality auditor, on the first day of the month, you have to fill details such as Operator name, Operation name, Line number, Floor number, and the name of the Month. Inspection instructions have been given on the format itself with rating procedures. The format is displayed in two sections to cover 31 days (whole month). Write the date in the cells of the top row. Each column contains 4 circles, represents four inspections in a day.

After inspection fill the respective circle (date and number of inspection of the day) according to the rating criteria. At the end of the day quality auditor has to sign the report on below the circles.  

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