Developments in investment casting process—A review

Investment casting has been used to manufacture weapons, jewellery and art castings during the ancient civilization. Today, its applications include jewellery/art castings, turbine blades and many more industrial/scientific components. The present paper reviews various investigations made by researchers in different stages of investment casting and highlights their importance. The paper initially highlights the investigations made on pattern wax properties, effects of blending, additives and fillers. Different ways through which pattern properties (like surface finish, dimensional accuracy, etc.) could be enhanced by properly controlling the injection processing parameters are thoroughly discussed. The paper also looks into the investigations made to enhance the strength, surface finish, etc. of ceramic shell for ferrous alloys/non-ferrous alloys as well as superalloys in investment casting. Investigations made on incorporation of nylon fibers and polymer additions confirm that a ceramic shell reinforced with nylon fibers attains additional permeability compared to the one with polymer additions.Different investigations carried out on autoclave dewaxing and microwave dewaxing conclude that the wax properties are less altered with microwave dewaxing when compared to an autoclave dewaxing. Some recent investigations carried out on pouring and post-treatment operations are also discussed in the paper. The advent and emergence of rapid prototyping in investment casting are broadly exposed in the subsequent sections of the paper. Various aspects of rapid prototyping like rapid investment casting, rapid freeze prototyping, etc., along with their advantages are projected. The emerging areas of applications of rapid prototyping like dentistry, etc., are duly discussed.