Needle Heat
Needle heat is the phenomenon in which a sewing machine needle becomes hot due to friction between the needle and the fabric and sewing thread during high-speed machine sewing, and it is a condition that can lead to sewing defects such as thread breakage and fabric damage.
Contents6 sections
Definition and mechanism of occurrence
Needle heat is the phenomenon in which the temperature of a sewing machine needle rises due to friction when the needle repeatedly penetrates the fabric, as well as friction with the sewing thread passing through the needle eye. The higher the sewing speed and the longer the continuous sewing time, the more likely it is to occur.
Needle heat is not a term for the material name or thickness of the thread itself, but a heat-related problem that occurs during sewing. The needle surface condition, needle size, needle type, sewing conditions, and the combination of fabric and thread all affect one another.
Relationship with materials and thread structure
In synthetic fibers with thermoplastic properties, if needle heat becomes excessive, the sewing thread or fabric fibers may soften or melt, leading to thread breakage, skipped stitches, and gloss or hardening around the needle holes. In particular, high-density fabrics with high friction require attention.
Friction between the sewing thread and the needle varies not only with the fiber material but also with thickness, twist, fuzz, and whether or not a lubricant is present. In general, a sewing thread with a smooth surface and appropriate lubricity is an option for reducing friction heat.
- Thread for preventing needle heat is used for the purpose of reducing heat generated by friction and making it easier for heat to dissipate.
- Thread selection should not be based on material alone; it should be evaluated together with the fabric, needle, sewing speed, and stitch specifications.
Gauge indication and how to view needle heat
There is no specific gauge or nominal size for needle heat. The gauge of sewing thread indicates thread thickness, and the gauge of a sewing machine needle indicates needle thickness, so each should be combined according to the fabric and sewing specifications.
Using a needle or thread that is too fine on heavy or high-density materials may increase friction and load. On the other hand, a needle that is unnecessarily thick may make the needle holes more noticeable, so do not change the gauge for needle heat countermeasures alone; confirm through test sewing.
Countermeasures and checks during sewing
For countermeasures, select the proper needle type and needle size, and replace needles that are worn or bent. The basics are to review sewing speed, adjust thread tension properly, and use a sewing thread that matches the fabric. If necessary, consider thread with heat-dissipation or lubricating properties.
Before mass production, conduct a continuous sewing test using the actual fabric and check for thread breakage, skipped stitches, discoloration or gloss around the needle holes, and the appearance of the seams. Since the results can also change depending on the sewing equipment and factory conditions, it is important to share the test conditions and acceptance criteria in the specification sheet.
Differences from similar terms
Sewability refers to the overall property of fabric or materials being sewn stably. Needle heat is one of the factors that reduces sewability. Skipped stitches are a defect in which stitches are not formed, and in some cases can be caused by thread damage due to needle heat.
Needle marks are line-like scratches or marks that appear on the fabric surface due to needle penetration or sewing. Although needle heat may make the area around the needle holes more noticeable, needle marks are checked separately in terms of cause and appearance.
Frequently asked questions
In what kinds of fabric does needle heat occur more easily?
Attention is needed when sewing continuously at high speed, with high-density fabrics that are difficult for the needle to penetrate, or with fabrics containing synthetic fibers that are easily affected by heat through friction. However, the degree of occurrence is not determined by the fabric alone; it varies depending on the combination of needle, thread, sewing speed, and sewing specifications.
What should be checked to prevent thread breakage caused by needle heat?
First, check needle wear, bending, and whether the needle type and needle size are appropriate. Next, review the thread size for the fabric, thread tension, and sewing speed. Conduct continuous test sewing under multiple conditions, including thread for countermeasures, and check not only thread breakage but also seam appearance and fabric damage.
