Wear analysis of PVD-coated twist drills under MQL

Abstract

Purpose Deep drilling of hardened steels is a difficult machining operation because of the high wear level of tools. This paper aims to present the main wear mechanisms observed in physical vapor deposition (PVD)-coated twist drills during deep drilling of SAE4144M steel under minimum quantity lubrication, assessed in the production of injection holders. Design/methodology/approach Two PVD coatings were tested: TiAlN and AlCrN, industrially processed, the last one being a multilayer coating. The workpiece was heat treated for a hardness of 39 HRC to be applied in a diesel engine component. The tests were performed in an industrial environment for a fixed number of holes. Two levels of cutting speed and feed rate were selected for the experiments. In addition, minimum quantity of lubrication (MQL) was compared with conventional lubrication. Scanning electron microscope was used to reveal the wear mechanisms. Findings Spalling of PVD-coating was revealed for conventional lubrication, while adhesion was observed in MQL conditions. The use of multilayered AlCrN-based coating promoted a significant reduction of adhered material on the twist drill, which is the reason for this selection in industrial operation. Practical implications Results showed that the MQL regime can be applied for this industrial application. Originality/value A detailed description of wear mechanisms, which allows a suitable selection of coating and machining variables was found for a very difficult operation, using a more economic process in terms of lubrication.

Experimental and Simulation Study on Tool Life Models in Drilling of Forging Brass Using Uncoated-WC and AlCrN Coated-WC Tools

“…However, in this study, the cutting speed and feed rate, and their levels were selected from the tool manufacturer's recommendation and based on the real production process as well as some literature reviews. Some researchers studied the effects of different feed rates and cutting speeds on burr formation [16], drilled hole surface roughness [11,17], tool life [18,19], and tool wear [20,21] during drilling of various materials.…”

“…Polli and Cardoso [20] carried out the deep drilling experiments on the forged and heat-treated SAE 4144M steel using solid cemented carbide twist drills with cutting speeds of 50, 65 and 70 m/min and feed rates of 0.05, 0.12 and 0.15 mm/rev. Cardoso et al [21] selected two cutting speeds and two feed rates in drilling of SAE4144M steel with TiAlN and AlCrN coated drills. They stated that AlCrN coated drill had better performance than TiAlN coated drill based on a significant reduction of adhered material on the drill.…”

Effect of process parameters on the growth and wear resistance of CrAlN coating on silicon nitride surface

“…CrAlN coatings feature high hardness and wear resistance, making them widely used as wear-resistant coatings (Raja Abdullah et al , 2017). Preparing CrAlN solid lubricant coatings on the surface of Si 3 N 4 bearings can extend bearing service life (Cardoso et al , 2018; Prabakaran and Thambu, 2017). The wear resistance of the CrAlN coatings depends on the process parameters (Ling et al , 2022).…”