Obrobitelnost pomocí mikro-frézování čistého molybdénu

Micro-milling machinability of pure molybdenum

journal article in Web of Science

en

As a result of the miniaturization of machined shapes, the conventional micro-milling technology has been widely used in many industrial areas. However, the machining of some types of materials proved to be very difficult. One of the hard-to-machine materials is also pure molybdenum, which, thanks to its high melting temperature, is used, besides others, in the energy industry and for physical applications. To ensure proper functionality of the manufactured parts, it is essential that they are machined without defects and with the required surface quality. The aim of this study was to find an optimal tool with a diameter of 0.8 mm and to set the machine parameters for machining of pure molybdenum with the highest quality of the surface layer possible without any defects. For this purpose, 26-round design of experiment (DoE) was carried out, in which the parameters, like cutting speed, feed and coating (yes/no) were systematically changed. The machined samples were evaluated for topography using a 3D profilometer, their morphology and burrs were studied using an electron microscope, and the microscopic implications on the microstructure of the subsurface layer were studied on the produced lamellae using transmission electron microscope (TEM). In addition, the tool wear curve was examined and evaluated. In this study, an optimal setup of machining parameters for pure molybdenum machining (cutting speed = 80 m/min, feed = 0.002 mm/tooth, non-coated tool) was found with which high-quality and defect-free surfaces can be machined.

V důsledku miniaturizace obráběných tvarů nalezla konvenční technologie mikrofrézování široké uplatnění v mnoha průmyslových oblastech. Obrábění některých druhů materiálů se však ukázalo být velmi obtížné. Jedním z těžkoobrobitelných materiálů je i čistý molybden, který je díky své vysoké teplotě tání používán mj. v energetickém průmyslu a pro fyzikální aplikace. Pro dodržení správné funkčnosti vyrobených součástí je nezbytné, aby byly obrobeny bez defektů a s požadovanou jakostí povrchu. Cílem této studie tedy bylo nalezení optimálního nástroje o průměru 0.8 mm a nastavení parametrů stroje pro obrábění čistého molybdénu s co možná nejvyšší jakostí povrchové vrstvy bez případných defektů. Za tím účelem byl proveden plánovaný experiment (DoE) obsahující 26 kol, při kterém byly systematicky měněny parametry: cutting speed, feed a povlak ano/ne. Obrobené vzorky byly posuzovány z hlediska topografie a to užitím 3D profilometru, jejich morfologie a otřepy byly studovány pomocí elektronové mikroskope a následky mikroobrábění na mikrostrukturu podpovrchové vrstvy byly studovány na vyrobené lamele v transmisním elektronovém mikroskopu (TEM). Dále byla zkoumána a posuzována křivka opotřebení nástroje. V této studii bylo nalezeno optimální nastavení parametrů stroje pro obrábění čistého molybdénu (cutting speed = 80 m/min, feed = 0.002 mm/rev, nepovlakovaný nástroj), s kterýmž lze obrábět povrchy s vysokou jakostí a bez defektů.

As a result of the miniaturization of machined shapes, the conventional micro-milling technology has been widely used in many industrial areas. However, the machining of some types of materials proved to be very difficult. One of the hard-to-machine materials is also pure molybdenum, which, thanks to its high melting temperature, is used, besides others, in the energy industry and for physical applications. To ensure proper functionality of the manufactured parts, it is essential that they are machined without defects and with the required surface quality. The aim of this study was to find an optimal tool with a diameter of 0.8 mm and to set the machine parameters for machining of pure molybdenum with the highest quality of the surface layer possible without any defects. For this purpose, 26-round design of experiment (DoE) was carried out, in which the parameters, like cutting speed, feed and coating (yes/no) were systematically changed. The machined samples were evaluated for topography using a 3D profilometer, their morphology and burrs were studied using an electron microscope, and the microscopic implications on the microstructure of the subsurface layer were studied on the produced lamellae using transmission electron microscope (TEM). In addition, the tool wear curve was examined and evaluated. In this study, an optimal setup of machining parameters for pure molybdenum machining (cutting speed = 80 m/min, feed = 0.002 mm/tooth, non-coated tool) was found with which high-quality and defect-free surfaces can be machined.

frézování, mikroobrábění, čistý molybdén, topografie, TEM lamela, plánovaný experiment

milling, micro machining, pure molybdenum, topography, TEM lamella, Design of experiment

02.02.2019

Springer

Spojené království Velké Británie a Severního Irska

1433-3015

102

9

4153–4165

13