The influence of cutting parameters and tool wear on the quality of holes in package sheets used in heat exchangers

The presented research aimed to obtain information on the effect of cutting parameters and tool wear on the quality of shaped holes in stainless steel package sheets. The testing was planned to allow evaluation of the impact of drilling technology. For this reason, verification tests were performed on a monolithic sheet of the same material grade and thickness equal to the package of four base sheets. It was noted that the double-insert drill is not qualified for use in this process, as it does not provide adequate hole quality (even 0.7 mm deviation in measured diameter from nominal value) and does not provide the expected tool life. Significantly better results were obtained for the monolithic and indexable head drills (IT8). In addition, it was observed that the burr formed when the drill exits the hole, in the case of the indexable double-insert drill, is also significantly larger (~1mm) than for the other tools (less than 0.1 mm). Preliminary tests carried out in this way made it possible to select the tool with the best cutting capability and quality of the generated holes. It was decided to use a drill with an interchangeable head. Tests have shown that it is possible to produce up to 1,000 holes with a diameter of 18.5 mm in a sheet package of 316Ti material with a thickness of 40 mm while maintaining the assumed effective speed of the process (n=1200 rpm, fn=0.18 mm/rev). In experimental testing, a significant effect of cutting speed on tool wear was noted. A correlation between coolant concentration and tool life was also identified - raising the concentration from 8% to 12% increased tool life by virtually 100%. Testing of hole roughness over a full tool life cycle showed that a drill bit with a completed break-in phase provides better hole roughness than a new drill bit. Measuring equipment and software were used for the research and processing of the results – Wenzel XO55, Hommel Etamic LV 17, WM Quartis R2021-1, Grapher 18.3.400, Autodsk Inventor Professional 2023.

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Opracowanie rekordu ze środków MNiSW, umowa nr POPUL/SP/0154/2024/02 w ramach programu "Społeczna odpowiedzialność nauki II" - moduł: Popularyzacja nauki (2025).