Critical issues in near net shape forming via green machining of ceramics: A case study of alumina dental crown

Green machining of ceramics through Computer Numerical Control (CNC) is efficient for near net shape fabrication due to minimum consumption of energy, less tool wear, and high material removal rate. However, there are numerous critical issues need to be addressed while manufacturing customized components through green state machining including fabrication of machinable green ceramics, designing of suitable mold for slurry casting, manufacture of suitable sample holders for mounting the fragile green samples during machining, and designing of machining tools for good surface finishing. This article introspects these critical issues and its possible solutions for efficient fabrication of dental crowns as a case study via green state machining. Highly loaded (55 vol%) alumina slurry was prepared for the fabrication of machinable dense alumina compacts by Protein Coagulation Casting (PCC) technique. Cylindrical alumina compacts were fabricated by casting alumina slurry into the polyvinyl chloride (PVC) mold. Metallic cylindrical sample holder was fabricated for mounting the green alumina samples for CNC machining. Diamond impregnated tool (∼3 mm diameter) was used for near net shaping of dental crown by grinding/milling. Dental crown (incisor) was successfully fabricated by optimizing different machining parameters.