Direct machining of micro patterns on nickel alloy and mold steel by vibration assisted cutting

Abstract

NOMENCLATURE CCM: Conventional cutting method EVC: Elliptical vibration cutting V x (t),V x (t): Voltages applied to the horizontal (PZT x ) and vertical (PZT y ) piezoelectric actuators φ: Phase difference between two PZTs u(t),v(t): Displacements generated by PZT x (u(t)) and PZT y (v(t)) in the cutting(x) and thrust(y) direction v f : Feed speed [mm/s] d: Depth of cut [µm] f: Excitation frequency of elliptical vibration of cutting tool [kHz] A c (A t ): Amplitude of elliptical locus of cutting tool in the cutting (thrust) direction [µm] S v : Spacing between adjacent grooves [µm]Feasibility of direct machining of micro patterns for micro molds by 2-dimensional vibration assisted cutting or elliptical vibration cutting was investigated and its machinability was compared with the conventional cutting method. Micro patterns of successive V-grooves and micro pyramids were machined on workpieces of a pure nickel, nickel alloy and mold steels with single crystal diamond, cubic boron nitride and poly crystal diamond tools which move along a circular path with a diameter less than 2 µm at an excitation frequency of 18 kHz. It was observed that the utility of EVC, that is a decrease of cutting resistance and an improved machining quality, was retained regardless of materials of workpieces and tools, and the improvement compared to CCM was far clearer when machined with a worn cutting tool. The risk of catastrophic or fatigue failure of tool was, however, increased by the impulsive forces resulting from periodic contact making and breaking between the tool and workpiece of high strength and hardness.

Innovations in Micro/Nano Patterning Using Tool-Based Methods

“…Researchers have used vibration-assisted machining for patenting in both conventional and nonconventional machining processes. In a conventional vibration-assisted process, reduction in average chippings and better groove shape are reported [30][31][32]. Figure 20 shows an example of the improvement of surface pattern with the aid of elliptical vibration-assisted cutting.…”

“…Comparisons of pyramid patterns machined by conventional cutting (left) and elliptical-vibration cutting (right) (work piece material: Inconel 600)[30].…”

Hybrid micro-machining processes: A review

“…Nickel alloy [27], Mold steels [27], Al6061 [27], Copper [29][30] Better micro-groove shape [25,27] Reduction in average size of chippings [32] Vibration-assisted engraving Aluminium alloy [32], Piezoceramic material [32], Stainless steel [32] 60% reduction in cutting force [32] Vibration-assisted grinding Ultra-fine grain cemented carbide [24] 10-20 % smaller diameter and 50 % higher aspect ratio when fabricating of micro-tools [24] Vibration-assisted drilling Single crystalline silicon [23], Glass [53], AA2017 [54], SUS304 [54], Al6061-T6 [50], SS41 [50] 60-70% reduction in cutting force [53] Vibration-assisted polishing Binderless tungsten carbide [36][37][38] Achieved surface roughnesses are 7 nm…”

“…Ultrasonic vibration-assisted micro-milling, grinding, drilling and grooving are found to have the ability to produce better geometrical shape, surface quality, lower tool wear and chipping [22][23][24][25]. Ultrasonic vibration-assisted micro-machining can be performed by elliptical vibrations [26][27][28][29][30]. A two-dimensional elliptical cutting path can be created at the cutting tool with out-ofphase synchronous excitations of the cutting tool in the cutting and thrust directions.…”

Determination of the machining parameters of nickel-based alloys by High-Power diode laser

“…This is due to their high corrosion resistance and high temperature strength. 1,2 However, these are difficultto-machine materials due to their hardness and brittleness. Inconel 718 is a nickel-based superalloy, which is also well known as being among the most difficult-to-machine materials.…”