Coating Gets Most Out of Precision Tools
Higher chip removal rates, shorter cycle times — and this includes carbide machining: Precision tools are in high demand. Tool coatings make a significant contribution to meeting these user requirements.
Sandvik has launched two new developments for this purpose: Inveio and Zertivo. The first coating is applied by chemical vapor deposition (CVD), the second by physical vapor deposition (PVD). "In conventional CVD alumina coatings, the growth direction of the crystals is arbitrary. During the development of Inveio, our experts found a way to control growth in this coating layer," explains Dr. Ina Terwey, Product Manager Milling and Drilling/Boring in the Product and Industry Segment Management of Sandvik's Sales Area Central Europe. Thus, all crystals are arranged in the same direction, with the strongest part facing towards the surface.
Unidirectionally Arranged Crystals in the CVD Coating
The crystals create a barrier in the direction of the cutting zone and the chip, "This improves the both scour and flank wear resistance. A further effect is the fast heat dissipation, with the cutting edge offering high process reliability even during prolonged procedures," says Terwey.
For the Zertivo coating, Sandvik has greatly improved process control, she says. Process conditions have a direct impact on the performance of a tool. "Each grade is therefore manufactured with the exact requirements for its area of application in mind. This results in improved coating adhesion and optimized cutting-edge integrity," says Terwey.
CVD and PVD are also used in the production of Ceratizit. "The latter are applied by means of the arc evaporation process, sputtering process and in HIPIMS/S3P. CVD diamond coatings are also used for drilling applications in the aerospace industry," explains Dr. Christoph Czettl, Head of Carbide and Coating Development.
Continuously Optimized PVD Coatings
According to Sankvik, the company has developed, refined and improved the details of a large number of coatings over the past few years. "The chemical composition and material properties of PVD coatings are constantly being improved to meet the requirements of the machining process. For instance, in the CTPM245 grade, a new alloy concept adding tantalum to titanium aluminum nitride has been introduced," says Czettl. The aluminum oxide coatings produced by CVD are also being continuously further developed.
"Recently, there has been an increase in the number of applications that require filigree cutting edges," says Bastian Gaedike of Paul Horn’s coating development. "This results in the requirement to deposit high-performance coatings even on extremely sharp geometries". For this purpose, the tool manufacturer has developed the new grade ES1, which remains stable even on sharp cutting edges thanks to a special pretreatment process. "In addition, the service life can be increased by up to three times compared to the previous coating. Due to the high stability of the cutting edge, fluctuations in tool life could also be reduced to a minimum," says Gaedike. The Tübingen-based company focuses on Hipims when it comes to coating processes. "With this magnetron sputtering process, we were able to outperform the tool life of already existing arc and sputter coatings by a factor of 2 to 5," explains the developer.
Three New Hipims Coatings
Cemecon has developed three new Hipims coating materials, reports Manfred Weigand, Product Management Round Tools. The first is Ferrocon for applications in unalloyed, alloyed and high-speed steels. Inoxacon coated tools are suitable for machining very hard materials such as stainless, high-alloy steels and titanium. Thanks to its low affinity to aluminum and other non-ferrous metals, Alucon based on TiB2 is particularly suitable for machining aluminum, copper, lead-free copper, titanium and their alloys. Previously, Hipims coatings were usually deposited using a hybrid technique consisting of DC and Hipims technology. "The new CC800-Hipims coating system, on the other hand, produces pure Hipims coating materials in an economical way for the first time," explains Weigand. Compared to conventional PVD coatings, their properties ensure longer tool life, better workpiece surfaces and higher cutting data.
Cemecon is breaking new ground with the combination of Hipims and diamond to create the coating material CC-Dia Hi-Speed. Among other things, Hipims guarantees the thermal insulation properties of the coating material. The energy is transferred into the chip, thus reducing scour wear. Diamond as heat conductor supports and distributes the residual heat evenly in the substrate and protects the carbide from overheating. This results in particularly heat-resistant coatings. The softer surface of the new coating materials compared to pure diamond coatings improves the run-in behavior of the tools into the material.
This article was first published by MM MaschinenMarkt
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