Development of Research for Machining of Implants with Novel Materials for Bone Surgery
The paper is targeted to inform on the novel techniques and cutting machine for precision surfacing of hip joint heads of the new materials developed in Ukraine, like artificial sapphire, zirconium ceramics and the titanium alloy without vanadium and aluminum in its composition. These materials having favorable combination of their biocompatibility, toxicity, strength, wear resistance and life time in a living organism are used for a manufacture of femoral heads, acetabular cups in total hip-joint replacements.
Today next requirements to hip joint heads are considered as enough for successful functioning: sphericity less than 1.0 µm and roughness of the polished surface Ra 0.010...0.020 µm. However, for instance, anisotropy of properties of sapphire or low elastic properties of the titanic alloy essentially hampers machining of such products. Therefore, it was required to develop techniques and cutting machine for precision surfacing of hip joint heads of the new materials.
Suggested techniques includes preliminary shaping spherical surface of sapphire from cubic- or cylindrical-type blanks by circular diamond tool which has a feed under some angle to the axis of blank. Finish machining has several stages of fine grinding and lapping with diamond tools from micro- to nano powder. For this purpose special grinding and polishing machine was especially designed. Such approach provides making sapphire hip joint heads with a sphericity 0.4...1.0 µm and roughness of polished surface Ra 0.006...0.015 µm. Surface plastic deformation is provided preliminary and finish polishing finally for surfacing of hip joint heads of the new titanium alloy. Some aspects of developed techniques and cutting machine can be used for a manufacture of components of knee-joint prostheses from these materials.
KeywordsSapphire zirconium ceramics titanium alloy femoral heads for total hip joint replacements
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