Investigation of surface roughness of aluminium solid mould investment castings

Solid investment moulds are used for precious or non-precious metals and alloys castings, the most common application areas are dental prosthesis and jewellery fabrications. Investment casting is known for high dimensional accuracy and smooth surface finish. Casting of ultra-thin sections and small complex parts require vacuum assisted or centrifugal filling. In this study, solid investment casting of aluminium has been tried and surface quality of the castings was investigated. Specially designed steppedwedge surface roughness specimens were produced with A413 aluminium alloy casting into gypsum bonded solid moulds. Casting operations were carried out in two ways; the first only with gravitational force and the second with vacuum assistance. Surface roughness of as cast specimens were measured, effects of section thickness, vacuum assistance and location of the pattern on the wax tree were determined.