Milling tools with SLX3 coating

Process reliability in titanium machining increases

Parts milled from titanium play important roles in dental technology and as a basic component of implants. DIN EN ISO 22674 specifies what to work with, and dental laboratories have to see how they efficiently process such demanding materials as titanium grade 4 and titanium grade 5. Reliable processes have top priority. New tools from Hufschmied Zerspanungssystems promise significant improvements.

In dental technology, demanding materials are processed - similar to the aerospace industry. But while entire teams of CAD/CAM and machining experts in the industry have specialized in optimizing processes and reducing machining times, for example, by coordinating machine tools, milling strategies and tools, dental laboratories have to rely on being supplied with an optimized complete solution. The machine market here is characterized by system providers. The goal: Processing at the push of a button with as little effort as possible through settings and maintenance. System providers usually also supply the tools for this. For easier handling, these are often versatile universal tools. However, just because it is not common does not mean that machining processes cannot also be optimized in the dental industry. In 2020, the Faculty of Mechanical and Process Engineering at the Augsburg University of Applied Sciences carried out a comparative scientific test of dental technology tools for zirconium dioxide processing. The result: The selection of the milling tools has a clear effect on the quality of the results and the efficiency of the processing. The winner of the benchmark was a tool from Hufschmied Zerspaninstrumente GmbH that was optimized for this material – today known as Zirkonator® as a patented tool for all common machine systems on the market.

Reduce tool wear

With its tool for zirconium dioxide, the toolmaker was able to increase the service life by up to 30 percent while maintaining the same quality. Hufschmied has specialized in material and process-specific tools and is known in various industries for the enormous optimization potential that can be leveraged with special tools, for example in the area of composite materials, hard metal, graphite or PMMA. Now the company has also been able to achieve significant improvements in titanium machining.

The main challenges in titanium processing: There is cold welding and adhesion, i.e. the adhesion of chips. The heating of the tool during machining is a problem - a solid carbide milling cutter without a coating is damaged from around 500 degrees Celsius. In wet machining, there are also chemical reactions between the additional elements in the titanium alloy and the hard metal of the tool. For these reasons, the tool needs to be coated. The previous state of the art was PVD coatings (physical vapor deposition). When developing new titanium processing tools, Hufschmied first dealt with the geometry of the cutting edges. The number of cutting edges - four or five - also has different effects and needs to be considered. The second question: is there a coating technique that makes the tool even hotter and smoother? Here Hufschmied trod a whole new path and tested the HiPIMS, the high-performance impulse magnetron sputtering. The SLX3 coating made of titanium aluminum silicon nitride applied with this process is extremely dense and hard. Its heat resistance and the protection it offers for the solid carbide body of the tool are impressive: temperatures in excess of 1000 degrees Celsius are no longer a problem.

In Hufschmied's technology center, extensive benchmarks were carried out with titanium grade 5 to develop the new tool. Since in dental technology it is not so much about large chip volume and speed, but about long-term process reliability, special attention was paid to the service life. It is important that the results in terms of accuracy and surface quality are consistent over the entire service life of the tool - even with fluctuations in the material quality of blanks. The result of the tests was promising. The SLX3-coated tools have a 30 to 35 percent longer tool life compared to previous high-end titanium machining tools.

Suitable for the machining centers

Hufschmied is proceeding with the development of the product portfolio of SLX3-coated tools based on the proven model and currently offers the tools to match the milling systems from AMANN GIRRBACH, DENTAL CONCEPT SYSTEMS, imes-icore CORiTEC, Roland, VHF, WIELAND DENTAL, YENA DENTAL and ZFX. Other manufacturers or their customers are advised on the ideal tools for them.