Design, Development and Productivity Improvement by Removing Secondary Operations and Fixturization

Abstract

Now a days all production industries are adapting automation by using various control systems such as hydraulic, pneumatic, electrical, electronic devices and computers, usually in combination for repetitive work to achieve high productivity. As a part of low cost automation fixtures are also widely used in the industries on assembly lines to improve productivity further. A Moulded Case Circuit Breaker (MCCB) is a mechanical switching device, capable of making, carrying and breaking currents under normal conditions, and breaking currents under specified abnormal circuit conditions, such as a short circuit and overload. The purpose of this project is to improve the productivity by reducing rejection of components. The improved processes leads to reduce operation cycle time. The press tool has also been designed for magnetic flapper part which is used in thermal magnetic release of 63-250 A rating circuit breaker. The developed press tool is used on hydro pneumatic press to make magnetic flappers. It has been found that by changing the bend angle of 17 degree to 11 degree magnetic calibration failure could be avoided. Another press tool is also designed and developed for insertion of a dowel pin into the lower contact of 63-250 A rating circuit breaker. The secondary operation of dowel pin insertion process is being eliminated and the dimensional consistency of lower contact has been also improved. As a part of this project work a fixture has been designed and developed for arc chute assembly. New arc chute assembly process has been developed and implemented including an innovative design of a toggle clamp fixture. This has eliminated a secondary operation and rejection of components with improved cycle time. The same idea is replicated for 250-500 A rating circuit breaker. A pneumatic set up is developed too for housing cover assembly of 20-125 A circuit breaker to reduce the cover gap between a housing cover and housing which further lead to reduction of rework carried out at quality check point. The all fixtures and set ups are designed in CAD Software CREO 2.0 and structural analysis has been carried out using FEA d in Ansys software.