CAD‐CAM‐RTV – lost‐wax casting technology for medical implants

Abstract

PurposeThe purpose of this paper is to present the development of a technical procedure for the manufacturing of medical implant prototypes.Design/methodology/approachThe paper was performed on a new hip implant design and manufactured with different metallic alloys F75 (ASTM) commonly used in biomedical applications. Dimensional parameters between the computer‐aided design (CAD) geometry and the prototypes and surface roughness for different casting alloy were compared. A CAD model was used for machining of a prototype. Room temperature vulcanising (RTV) rubber moulds allowed the manufacturing of wax models of the femoral prosthesis. A specific lost‐wax casting (LWC) technology was used to manufacture prototypes for in vitro tests. The final geometry was dimensionally controlled using different type of parameters (performance, average, standard, maximum and minimum deviations), surface roughness (Ra, Rt and Rp) were measured for all prototypes.FindingsTo obtain a small number of implants, RTV rubber vacuum casting technique can be used to obtain lost wax models with good dimensional stability. No significant dimensional differences were observed relatively to the virtual model. However, the temperature of the wax and the rubber mould were important parameters to obtain good quality wax models. Surface roughness was different for different alloys.Practical implicationsThe design and development of a new hip femoral prosthesis prototype based on rapid tooling techniques to manufacture LWC prototypes is suitable for clinical trials.Originality/valueThis paper describes a biomanufacturing methodology to manufacture biomedical implant prototypes.