Topic
Sewing defects, their causes and fixes, plus the stitch, needle and thread choices that help prevent them.
10 notes
DHU counts defects per hundred garments checked. The formula, how it differs from defective percentage, a worked example from end-of-line checking, and how to turn DHU data into action on the line.
Inline inspection checks work at or near each operation while the line is running. How the traffic light system works, how to choose operations to check, sample sizes and frequency, and how to act on the results.
Broken needles stop production and, if fragments are lost, can end up in garments. Why needles break, how to troubleshoot them in a logical order, and how a broken needle policy protects the customer.
Repairing defects fixes garments; root cause analysis fixes the process. A step-by-step method for garment factories using defect data, the 5M categories, fishbone diagrams and 5 Why, with a worked example on open seams.
An overview of the sewing defects that cause most repairs and rejections, grouped by stitch, seam and assembly problems, with the usual causes and where to look first.
How to choose industrial sewing needles: needle systems, metric and Singer sizes, point types for knits and wovens, matching the needle to the thread, and how the wrong needle causes skipped stitches, needle cuts and thread breaks.
How to choose sewing thread for garments: core-spun, spun polyester, filament and textured threads, ticket numbers and sizes, matching thread to fabric, seam and needle, and the thread-related causes of seam failures.
Stitches per inch (SPI) or per centimeter affects seam strength, appearance, puckering and thread use. How to count stitch density correctly, typical ranges by fabric and seam, and what goes wrong when it is too high or too low.
The stitch classes used in garment making, how each is formed, where it is used and its strengths and weaknesses. Based on the ISO 4915 stitch classification, with the common stitch numbers you will see on spec sheets.
Frequent thread breaks stop operators, cause skipped and broken stitches and destroy line efficiency. A step-by-step way to find the cause in the needle, thread path, tension, timing, thread or fabric.