Topic
Sewing machines, stitches, needles and thread: how to choose them and what goes wrong when they are mismatched.
10 notes
A guide to the industrial sewing machines found on garment lines: lockstitch, overlock, flatlock, chainstitch, bartack, buttonhole, button sew, kansai and automatic units. What each does, where it is used and what to check.
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.
Seam strength tests measure the force needed to break a seam; seam slippage tests measure how far yarns pull away from a seam under load. Methods, how seams fail, and how thread, stitch density and seam design affect results.
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.
How to calculate sewing thread consumption per garment using seam lengths and measured thread-to-seam ratios for each stitch type, then convert it into cones per order by color and ticket.