Tibial
Cutting Tools for Machining Tibial Trays in Cobalt- Chrome Alloys
In the realm of total knee arthroplasty, the tibial baseplate is a foundational element. Acting as the critical junction between the host bone and the polyethylene spacer, these components require unparalleled geometric accuracy and surface integrity. Fabricating these from Cobalt-Chromium (CoCr) alloys ensures life-long wear resistance, but it also presents a formidable challenge for standard machining processes.
Mikron Tool engineers specialized cutting geometries designed to face the high toughness, hardness and abrasiveness and low thermal conductivity of medical-grade alloys. We provide the stability required to transform tough raw materials into high-precision orthopaedic implants with repeatable success.
Navigating the Complexity of CoCr Implant Fabrication
The metallurgical properties of CoCr alloys, while beneficial for the patient, are notoriously aggressive toward cutting tools. Success in tibial baseplate machining requires a strategy that addresses the following production hurdles:
- Thermal Extremes: CoCr’s poor heat dissipation leads to localized thermal spikes. Without specialized strategies and tool coatings, this results in rapid edge degradation.
- Geometric Intricacy: Modern designs feature complex locking mechanism machining requirements and undercuts that demand high-rigidity micro-tools.
- Surface Friction: Achieving Ra values below 0.2 µm is essential to minimize contamination risks deriving from wear on the plastic insert, requiring tools that maintain a sharp, stable edge throughout the cycle.
- Structural Integrity: Maintaining thin wall stability while managing the high cutting forces necessary for material removal.
Machining Process for Tibial Components
Mikron Tool offers a comprehensive sequence of operations to streamline the production of knee components, from bulk material removal to the final finishing of a tibial tray undercut.
Specialized Dovetail Milling for Under-Cuts
Creating the recessed channels that hold the insert in place requires highly specific tool geometries. Our dovetail milling strategy utilizes custom-tapered end mills to reach difficult-to-access areas with high stability, ensuring the tibial tray undercut meets strict dimensional tolerances without tool deflection.
High-Efficiency Finishing Operations
To eliminate the need for manual polishing, our cylindrical wiper mills and conical finishers produce a mirror-like surface directly on the machine. This "one-shot" approach reduces cycle times and ensures every part is identical.
A smooth, optimized machining process
Here is an example of a typical machining process of a tibial tray in CoCr alloys for posterior stabilized knee implants (also called posterior cruciate substituting – PCL):
| Tool | Key Features | Application |
|---|---|---|
| 1 CrazyMill Cool Corner Radius | Z5, from Ø6 to Ø8 mm corner radius endmills | Pocket, upper plane roughing, finishing and end external side milling to remove oxides and melting residues (casting skin, casting gates), finishing with the same endmill |
| 6 CrazyMill Cool Corner Radius | Z5, from Ø6 to Ø8 mm corner radius endmills | Finishing, external contouring and internal wall finishing |
| 8 CrazyMill Wiper Dove Tail Mill | Z4, custom dove tail endmill | Side milling, undercut roughing to guarantee constant stock material for the following finishing tool |
| 9 CrazyMill Wiper Dove Tail Mill | Z4, custom dove tail endmill | Bottom finishing and internal radius finishing to guarantee the undercut shape and tolerance |
| 2 CrazyMill Front Chamfer | Z6 | Chamfering the upper, inner, and outer edges to remove burrs |
Another strategy for machining the same type of component is:
| Tool | Key Features | Application |
|---|---|---|
| 1 CrazyMill Cool Corner Radius | Z5, from Ø6 to Ø8 mm corner radius endmills | Pocket, upper plane roughing, finishing and end external side milling to remove oxides and melting residues (casting skin, casting gates), finishing with the same endmill |
| 6 CrazyMill Cool Corner Radius | Z5, from Ø6 to Ø8 mm corner radius endmills | Finishing, external contouring and internal wall finishing |
| 4 Cylindrical Wiper Mill | Z5, Ø8 mm - wiper, corner radius mill | Surface milling, finishing |
| 2 CrazyMill Front Chamfer | Z6 | Chamfering the upper, inner, and outer edges to remove burrs |
The following is an example of the typical machining process of tibial trays in CoCr alloys for mobile-bearing (MB) total knee replacement (TKR) implants:
| Tool | Key Features | Application |
|---|---|---|
| CrazyMill Cool Corner Radius | Z5, from Ø6 to Ø8 mm corner radius endmills | Pocket, upper plane roughing, finishing and end external side milling to remove oxides and melting residues (casting skin, casting gates), finishing with the same endmill |
| Cylindrical Wiper Mill | Z5, Ø8 mm - wiper, corner radius mill | Surface milling, finishing |
| Crazy Drill Cool SST-Inox | One-shot drilling | |
| CrazyMill Cool CF Corner Radius | Depending on customer’s drawing | Side milling, roughing to guarantee high MRR, reduce radial forces on workpiece and guarantee constant stock material |
| Conical mill | Depending on customer’s drawing | Side milling, finishing |
| CrazyMill Front Chamfer | Z6 | Chamfering the upper, inner, and outer edges to remove burrs |
All tools are available with advanced coatings designed for optimal heat resistance and surface protection, enabling high-speed cutting and long tool life in even the most challenging environments.
The Mikron Tool Competitive Edge in Orthopaedics
Partnering with Mikron Tool means more than just purchasing a cutter; it means adopting a validated machining strategy. Our medical industry focus ensures:
- Reduced Cycle Times: Optimized designs enable aggressive feed rates with CoCr.
- Extended Tool Life: State-of-the-art coatings prevent thermal stress and chipping.
- Process Stability: Consistent performance across cast, forged or billet materials.
- Swiss-Engineered Precision: Tools designed to maintain tight tolerances for the most sensitive locking mechanism machining tasks.
Elevate Your Implant Manufacturing Standards
Are you looking to reduce scrap rates or accelerate your production of knee components? Mikron Tool provides the expertise to optimize your most challenging orthopaedic applications.