Induction Tempering Gains Popularity in Production Systems
May 1, 2008
Induction tempering systems have been designed and built by Ajax TOCCO Magnethermic Corporation for pipe, tube, ball screw, shaft and bar applications for several decades. Recent customer demands for tempering within production cells have resulted in a number of new concepts, machine designs and installations. The major advantage of induction tempering is that it reduces the number of parts in process to just a few versus over 100 parts with conventional temper furnaces. Other advantages include precise control of power, monitoring of the final temperature of each part, reduced part handling, reduced floor space and improved operator environment. Options can include tracking of parts through the harden and temper stations and cool down of the tempered parts prior to exiting the system.
The part configuration, production rate and heat-treat requirements will dictate the type of induction system re-quired for harden and temper. Some parts such as large sprockets and workpieces can use the residual heat from hardening to temper the part. In other cases, such as statically heating a transmission race or scanning a shaft, the same equipment can be used for hardening followed by tempering. The tempering adds time to the cycle and thus the pro- duction rate is lower than hardening only. If a single machine can meet the production requirements, naturally this is ideal. However, if additional production is required, doubling the equipment (a lift rotate or scanner) is one possibility that adds both productivity and production flexibility. In many recent installations, separate induction temper station(s) or a separate system have been considered to maintain the short harden cycle and allow a long temper cycle.
Temper stations can be added to new machines by providing an additional station or two on a pick & place, turntable or conveyor fixture. Temper stations can also be added to existing induction hardening systems using a separate pick & place fixture or conveyor system. The design generally selected is based on the number of parts (stations) required to meet the metallurgical requirements. Temper inductor(s) are furnished with a separate power supply to provide precise control. These automated systems include quality monitoring of part temperature, energy and time in process to assure that all parts exiting the system are within the operating parameters.IH