Michael Lahres

Applicability of different hard coatings in dry milling aluminium alloys

Abstract Today, a high proportion of machining processes is conducted with coolants. In this way, the workpiece, tool and machine tool are cooled, friction processes are reduced and the manufactured chips are removed from the cutting area. Unfortunately, coolants are dangerous for the environment and human health. Moreover, the disposal costs for used coolants are going to explode. Therefore, the movement towards green manufacturing cutting operations will be one of the most important challenges in the near future. Decreasing the costs of the cutting process and the associated reduction of environmental pollution by dry machining is the main key to remain competitive and profitable. In this contribution, results are presented for the dry milling of an aluminium malleable alloy for aircraft parts (AlZnMgCu1.5) and an aluminium casting alloy for automotive parts (AlSi10Mg). Different commercial coatings were investigated for their suitability in dry milling operations. It is shown that specific coating systems (e.g., partially crystalline hard coatings with “softer” morphological parts, or superhard diamond coatings) exhibit a great potential for such operations. However, it should be added that only an iterative development of the whole system (coatings, tool geometry optimization, chip transportation, machine tool adaption, etc.) will deliver a successful implementation of dry processes into production in the near future.

‘In-situ’ temperature measurement to determine the machining potential of different tool coatings

Abstract Measuring techniques for various machining operations were developed by DaimlerChrysler. These measuring techniques are based on the projection of the infrared radiation from the tool chip interface onto the scanner of a high resolution thermographic camera. In that way, it is possible to determine the absolute temperature and its distribution in the contact zone between the tool and the chip flow ‘in-situ’, whilst avoiding real time mechanical contact.

Applicability of different hard coatings in dry machining an austenitic steel

Abstract Today, a high proportion of machining processes are conducted with coolants. In this way, the workpiece, tool and machine tool are cooled, friction processes are reduced, and the manufactured chips are removed from the cutting area. Unfortunately, coolants are dangerous to the environment and human health. Moreover, the disposal costs for used coolants are set to soar. Therefore, the movement towards green manufacturing cutting operations will be one of the most important challenges in the near future. Decreasing the costs of the cutting process and the associated reduction of environmental pollution by dry machining is the main key to remain competitive and profitable. In this contribution, results are presented to introduce dry machining of synchronizing cones for automotive applications. Different CVD/PVD commercial coatings were investigated in preliminary investigations for their suitability in dry-machining the specific austenitic steel. It will be shown that coating systems (like hard/soft double layers) exhibit a great potential for such operations, even under a minimal lubricant system. Furthermore, several parameter studies were carried out towards accuracy to size, workpiece morphology and process stability. In a last step, field tests were done performed on this results.

Suitability of mechanical characterization methods for diamond-coated cemented carbide tools with regard to tooling applications

Abstract In the last few years the world-wide development of diamond coatings for cutting tools has led to a quality level of commercialization, with customers increasingly tending to replace conventional cutting tools with diamond-coated cemented carbide tools. Unfortunately, different tooling applications require specific properties of the substrate/coating system with different loading characteristics. As there was no well-understood and reliable laboratory test method available up to now, cutting tests were the usual techniques used to classify the adhesion of diamond coatings. In this paper the results obtained by an investigation of the cutting performance and the coating adhesion of diamond-coated cemented carbide inserts with modified properties are presented and the possibility of a correlation is verified. Concerning the cutting performance, turning, milling and drilling operations of an AlSi10Mg alloy were carried out. Furthermore, the Rockwell test was investigated for evaluating the adhesion of diamond coatings.

Deposition of CVD diamond onto ion beam modified ASP 23 cutting tools

Abstract The effect of ion implantation in high speed steel ASP 23 on chemical vapour deposition (CVD) diamond nucleation has been studied. N, C and Si have been implanted at 100–150 keV and fluences in the range from 5×10 17 to 2×10 18 ions cm −2 . Tribological measurements and dry turning tests were carried out to investigate the influence of the ion implantation on the steel. The results are compared with those of untreated high speed steel substrates. The diamond deposition onto the ion beam modified steel substrates was carried out in a microwave plasma CVD apparatus. The substrate temperature was kept below 520 °C, because of the fusing temperature of the steel. By means of scanning electron microscopy, Raman spectroscopy, Auger electron spectroscopy and Rockwell indentation tests, the deposition parameters for the CVD process were optimized. It was found, that the Si implantation was advantageous for the consecutive diamond deposition.

Hochleistungszerspanung für Werkstoffe der Luft- und Raumfahrt

Mit der Hochleistungszerspanung kann der Zeitaufwand fur die Bearbeitung von Werkstoffen der Luft- und Raumfahrt reduziert werden. Die Zielsetzung, diese Prozesse zugig in der Serienproduktion einzusetzen, erforderte eine Untersuchung der bei der Zerspanung auftretenden thermischen Einflusse auf das Bauteil und deren Vermeidung. Der Ansatz zur Verminderung dieser Einflusse fuhrte zur Optimierung der eingesetzten Werkzeuge.