Experimental optimization of annealing of cylindrical brass casings
2019
Gulbis, J., Riga Technical Univ. (Latvia) | Viba, J., Riga Technical Univ. (Latvia) | Irbe, M., Riga Technical Univ. (Latvia) | Spade, K., Riga Technical Univ. (Latvia)
Induction heat treatment is an important tool in metallurgy. Induction annealing is a complex yet efficient manufacturing process with great potential for quality control of produced parts. Induction annealing is rarely used, but has its place and the control methods are similar to induction hardening. It allows much greater control over convection type heat treatment and allows more easily treating only selected regions on the material. One of the obstacles with heat treatment of brass parts is that it is not possible to get a direct reading with the infrared temperature sensor off the surface, therefore making the induction method heat treatment more practical than convection, as it offers almost direct control of the amount of energy inserted into material. We used induction to stress relief and anneal a hollow brass material cylinder to the desired hardness gradient. Four types of variables were controlled until the desired result was found. They are in shape of solenoid, location of solenoid in relation to the part, maximum power used and total induction time. Hardness was measured both on the outer surface of the parts and on parts cut in half. Hardness was measured using appropriate scale measurement systems using the Vickers scale. It was found that hardness differs on the surface measurement from the measurement on the inside, yet there seems to be a certain correlation on the differing amount. Induction offers a very quality controllable process with little difference in hardness form part to part. Empirical optimization is very time consuming and investing time in creating a mathematical model to do the bulk of optimization could be worth it.
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