Hip

Hip r

eplacement surgery or total hip arthroplasty, involves removing a diseased

hip joint and replacing it with an artificial joint, called a prosthesis /
hip implant.

Hip implants consist of:

• a socket (acetabular cup/shell), which has an insert or liner made of plastic, ceramic or metal
• a ball component (femoral head), made of metal or ceramic
• a metal stem (femoral stem) are made of titanium- or cobalt/chromium-based alloys (In some designs, the stem and ball are one piece; other designs are modular, allowing for additional customization)

Hip implants are usually made of cobalt chrome (e.g. ASTM F1537), titanium (e.g. Ti6Al4V ELI) or medical Grade Stainless Steel (316LVM).

Properties:

• Fixturing is a challenge
• Small batch production
• Some forged and cast blanks for the stem
• Bar work for the Femoral Head and Cup

The machines that are typically used for the component include Multi Axis Machines, 3 axis lathes, 5 axis VMC and Multi Task machines (e.g. Mazak Intergrex E410e).

Circular ramping machining of the internal sphere is a highly effective and secure process with the benefits of longer tool life, less tool breakage and short cycle time resulting in a high quality surfaces. Preferably use positive round inserts.

Benefits when machining the external sphere include increased tool life and a secure process.

External head machining gives high quality surfaces and increased tool life in a secure process. Preferably use positive round inserts.

Head taper hole machining is an effective process for flat bottom.

Selected component features

• Acetabular cup
• Femoral head