Effective Recycling of Cast Aluminium Alloys for Small Foundries

Abstract

A method of effective recycling of aluminium castings suitable for small foundries was investigated. Automotive cast aluminium scrap obtained from various scrap vendors was sorted into groups of similar components, namely; pistons, cylinder heads and housings (gearbox and rear-axle housings). This sorting method was adopted with the hypothesis that the resulting alloys could be closely equivalent to the commercial alloys that were originally used to make the components. The remainder of the scrap was grouped as miscellaneous scrap and contained various parts such as alternator covers, exhaust manifolds, oil sumps and other assorted scrap. As hypothesised, the chemistry of the resulting alloys were found to be consistently equivalent to the commercial alloys commonly used to cast the various components that were melted. For example, the alloy chemistry of secondary alloys from piston scrap was consistently equivalent to commercial piston alloys such as AC8B and LM26. Furthermore, alloys from cylinder head scrap were equivalent to commercial alloys such as 319, LM27 and AC2B. On the other hand, the alloy chemistry from unsorted scrap was not found to be consistent nor equivalent to a specific group of commercial alloys except for the 319 and 380.0 workhorse alloys. These results are discussed against the possibility of reusing the alloys in casting components similar to those that they were recycled from, in addition to other possible applications.