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High-speed Sewing Machine Upper Line Occasional Broken Line Empty Needle Debugging Method
- Oct 29, 2018 -

When we operate a high-speed lockstitch machine, we often encounter situations where the upper thread sometimes breaks or becomes empty for 1 or 2 stitches, and then continues to work. For the debugging method of this kind of problem, we only need to deal with the cooperation relationship between the needle and the wire, and adjust the stroke and tension of the thread take-up spring to be suitable.

First check if the needle-to-line relationship matches, and if the needle and needle hole sizes are appropriate. Do not use thin needles for thin materials, use needle plates with large needle holes, or use thick needles with small needle needle plates. There is also the quality problem of the suture itself, the synchronization relationship between the needle and the hook, and the gap size are also checked. Sometimes due to the quality, elasticity, and twist of the suture, the formation of the needle thread loop needs to increase the line balance to achieve the desired effect. The needle bar height can be appropriately lowered or the hook line time can be adjusted later.

Secondly, check if the thread take-up spring stroke is too large and the tension is too strong. The problem is random, the state is unstable, and it is good or bad. According to the author's judgment, it is likely that the stroke and tension of the thread take-up spring are not adjusted. Because the stroke and tension of the thread take-up spring are not adjusted well, it is easy to cause the supply line to be unstable during sewing, causing wire breakage, or the needle may not be supplied by the needle thread, sometimes returning to normal, and the adaptability to sewing conditions is poor. 

The normal thread take-up spring tension is generally around 25g, and its swing range is from 7mm to 10mm (this value varies with different sewing machines and different sewing conditions). When sewing a particularly thin sewing material (small stitch code), the tension of the thread take-up spring is weakened and the swing range is relaxed; the sewing of a particularly thick sewing material (large stitch code) is reversed.

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