Optimization of Process Parameters of an Induction Furnace for Aluminium 6061 using Robust Design Approach

Abstract

Electric induction furnaces are extensively used in the foundry industries for the preparation of alloys and metal castings. The induction furnace works on the principal of electromagnetic induction. Some of the applications of induction heating include heat treatment, melting, surface treatment and in food industry. The detailed study about the working of an induction furnace was done. The induction furnace procured by mechanical department of our college is made by M/s EFD induction Ltd. and chiller is from M/s Werner Finly Ltd. The induction furnace with 10 coils works in the range of 4–14 kW. The inlet water temperature and cut off water outlet temperature and pressure were set to 15–17°C and 5 bar respectively. The process parameters such as frequency, time for melting, power, inlet and outlet water temperatures were identified as crucial. Calibration of working of the induction furnace was done. Al 6061 was chosen for the calibration process. Al 6061 is a popular nonferrous and widely used alloy in aerospace and automobile industries, also its properties such as mechanical and thermo-physical are well documented and thus making it easy for comparison. Time required for melting different quantities (1–4 kg) of Al 6061 for different power ratings was tabulated. Also, the power versus frequency for different quantities of Al 6061 was determined. After tabulation and plotting of the graphs, the optimum or best power range for melting of 1–4 kg Al 6061 was found to be in the range of 6–12 kW. For this range, time required to melting different quantities (1–4 kg) of Al 6061 was in the range of 11–44 min. 1 kg of Al 6061 for 14 kW took only 11 min to melt, whereas 4 kg of Al 6061 took 44 min to melt. The variation of time required to melt 1 kg for 6–14 kW was found to be linear. Similar results were also obtained for 2, 3 and 4 kg. Time taken for melting of the Al 6061 drastically increased as the power supplied to the induction furnace was 4 kW. Partial melting of 4 kg Al 6061 for 4 kW of power was noticed in spite of heating for 131 min (About 2 h). Hence, melting of Al6061 for 4 kW is not recommended as the time taken is too long. Similar experiments are planned for different alloys in copper, mild steel, and cast iron family. Design of the heating coil for surface heat treatment of the steel rod will be taken up in the future.