As a world leader in the mould-making industry and a manufacturer of precision components, GF Machining Solutions is creating surface property modulation in the high-precision cutting of materials for medical applications.
Current advances in conventional and unconventional cutting technologies are now able to solve the traditional problems that limit or make complex the manufacture of medical implants and devices - problems such as machining material range and geometry; accuracy; adapted surface and mechanical properties influencing lifetime and tissue compatibility; as well as intolerances related to corrosion and toxic element residues left by the machining process.
Present and future technologies allow the production of complex parts in shorter times, thanks to:
Various studies describe specific application test parts prepared with GF Machining Solutions' Mikron HSM400U ProdMed and Cut 200 wire electric discharge machining (EDM) devices, integrating JauchSchmider rotary axes. Surface analyses were made with LEO SEM and EDX devices and mechanical properties were probed with CSM nano-hardness and tribometer testers. The main materials tested were chromium-cobalt, titanium-aluminum-vanadium, magnesium alloys, 316L steels and zirconia-based ceramics. Specific test cuts were performed involving the adjustment of the main machining parameters for high-speed milling and EDM processing of such materials.
High-speed cutting processes facilitate outstanding processing of implants with accuracies within 2µm, leading to surfaces polished down to 0.12µm Ra and 0.4µm Rz on titanium alloys, thanks to adapted CAD-CAM strategies, the use of adapted tools, and new machining and tool control sensors. This will also allow the processing of new glass ceramics and the optimisation of the efficiency in terms of wasted base material for the series production of dental implants in chromium-cobalt alloys.
Unconventional EDM processing shows a leap in performances for the manufacturing of implants and medical devices through the implementation of supplementary rotary axes, on-machine vision systems and high-frequency generators (above 10MHz range pulses). These factors are able to modulate surface parameters independently, with dedicated strategies and the use of alternative electrode materials. This eliminates the undesired zinc and copper components present at the surface and partially transfers them to the part during the process.
Such elements can be replaced by refractory titanium or tungsten in order to produce surface modifications on the part that improves their resistance to corrosion and wear (the friction coefficient can be reduced by half with respect to standard processes). This provides a method to eliminate intolerance risks at low cost by suppressing the chemical post-processing phases needed with the traditional EDM.
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