Investigation of injection molding process of titanium based screw bone implants

In this study, screw bone implant which is consist of Ti-6Al-4V producted by the method of Powder Injection Molding. The rheology process was experimental completed by using capillary reometer for four different feedstocks. Feedstocks which contains PW/PE/SA and PEG8000/PP/SA displayed ideal features, also bone implant screws were simulated by Moldflow Analysis Programme. PEG8000/PP/SA showed high quality features (viscosity: 72:1001 Pa·s, melt flow index: 261-1888g/10min, maximum powder volume 60%). Mold production were obtained via machining and heat treatment. Having been practiced various injection pressures (800-1500bar), pack and hold pressures (0-1000 bar), flow rate (10-25 cm3/sec), and temperatures (150-215 C), optimum injection criteria were found out. Solvent debinding temperatures(60-63 C) and thermal debinding speed (1 C/min) were determinated for moulded samples though TGA/DSC/DTA heat analysis. All sample was debinding by solvent (24hour) and thermal (25hour) debinding methods. Firstly, sintering was applied under vacuum and argon atmospheric for 2 hour to 1250 C by covered-uncovered conditions. Also this samples were cooled to room temperature, by argon and vacuum cooling. The best result was found for sintering at 1250 C for 2 hours as a covered conditions and argon cooling.