Surveillance and control of the yarn input tension on circular weft knitting machines: new approaches

The yarn input tension - YIT is one of the most important parameters in weft knitting industry. This parameter must be maintained between limits in order to produce knitted fabric without faults. However, YIT is not the only parameter to control and monitor for preventing faults. The knitting elements and the knitting machine itself should be monitored to improve productivity and quality. The monitoring of the YIT can be used to detect the faults and at the same time controlled inside tight limits to prevent machine´s premature stop due to yarn break. This paper presents the recent developments made for monitoring and control the YIT. A surveillance system is presented, a low cost force sensor is suggested to substitute the present industrial solutions, and a new actuator for control of the YIT is introduced.