Sewing Needle Temperature

The effect of various sewing conditions and needle characteristics on the temperature observed during high speed sewing has been studied. The maximum needle temperatures were determined by means of infrared (ir) flux measurements. A complete statistical experiment was used to show the effect of sewing speed, the use of thread as compared to no thread in testing, thread size, and needle diameter on the needle temperature. The temperature was found to increase with speed at a rate of about 0.08°F/rpm. The use of thread was found to decrease the observed temperatures by as much as 200°F and there was a significant thread-speed interaction. Thread size and needle diameter were not found to be significant. It was found possible to reduce the needle temperature by 10-15% by using a cyclic type of operation with short periods of sewing followed by short periods of idle time. The use of thread or cloth lubricants were found to have very little effect. The use of forced air cooling was found to be very effective in lowering the needle temperatures with reductions of 150-200°F being easily obtained. It is concluded that the application of all the factors shown to reduce needle temperatures could reduce the temperature of a chrome-plated needle sewing at 4000 rpm from 700°F to below 300°F for a Kooltorr® needle sewing at 3000 rpm on a machine equipped with an air cooling pump.