Effect of Mill Type on Morphology of AA6013 Aluminium Powder

ABSTRACTIn conventional recycling method, metal chips are cast after pressing and melting in electric arc furnace. Material loss occurs during the recycling from liquid metal due to the several reasons. Direct recycling method which produces the aluminium powder from aluminium chips using mechanical mill can be an alternative to conventional recycling method. Thus material and energy losses, and labour cost will be reduced by direct recycling method without melting.In this study, the particle morphology of powder direct recycled from AA6013 aluminium alloy chips with cryogenic, disc and ball type grinders is investigated. Mechanical milling resulted flaky and irregular shaped AA6013 particles. It was ascertained that the chips did not break sufficiently in despite of the long duration milling mechanisms by ball mill. Cryogenic mill provides the energy required for milling mechanisms to act. Disc mill has the highest impact energy was determined. Consequently, efficiency of ball mill is lower than the efficiency of cryogenic and disc type mills. Shape factors of powders produced with ball and cryogenic mills were found greater than that of the powder produced by disc mill. Disc mill has the most efficient and effective impact energy which produces the smaller particles per minute, was determined.Keywords: Direct recycling method, powder production, scrap chips, aluminium alloy.

A flexible job shop cell scheduling with sequence-dependent family setup times and intercellular transportation times using conic scalarization method

In this paper, we propose novel mathematical models involving both single- and biobjective functions that deal with a flexible job shop scheduling problem in cellular manufacturing environment by taking into consideration exceptional parts, intercellular moves, intercellular transportation times, sequence-dependent family setup times, and recirculation. The problem has been known as NP-hard. The proposed models have been tested and solved using Lingo 11.0 with minimization of makespan for the problems involving about 4 cells, 4 part families, 15 parts, and 12 machines. The most suitable model among the proposed single-objective models is determined using the test results. Then, another objective function as total tardiness is added to this model. The obtained biobjective model is solved using the scalarization methods, the weighted sum method, e-constraint method, and conic scalarization method (CSM), in order to convert the mathematical model's objectives into a single-objective function. By utilizing these scalarization methods, the Pareto effective solutions are generated for a specific test problem. The advantages of the CSM are demonstrated by considering the Pareto effective solutions