Preparation of Polycrystalline Diamond Micro End Mill and Experiment of Its Micro-milling Process for Sapphire

doi:10.12068/j.issn.1005-3026.2025.20249032

Abstract

Abstract:

The polycrystalline diamond single-edged helical micro end mill with a diameter of less than 1 mm was fabricated using electrical discharge turning technology featuring non-contact and independence from material strength and hardness limitations. The intrinsic relationship of the tool structure of the polycrystalline diamond spiral micro end mill by electrical discharge turning relative to the feed speed and rotational speed was established， as well as the morphological simulation model of the micro end mill， which successfully solved the difficulties in preparing a polycrystalline diamond helical micro end mill with the diameter of less than 1 mm in the actual machining. The prepared polycrystalline diamond micro end mill was used to carry out experimental research on the micro-milling process of sapphire， and the influence of micro-milling parameters on the three-dimensional surface roughness S_a， S_z， and the triaxial micro-milling force of sapphire was investigated. Moreover， the surface quality， micro-milling force， and tool wear were analyzed to evaluate the micro-milling performance of the polycrystalline diamond micro end mill prepared by electrical discharge turning. The results indicate that the surface roughness S_a of the sapphire processed by the polycrystalline diamond single-edged helical micro end mill can be stably controlled within the range of 0.76~1.00 μm， and the tool wear mode is primarily characterized by damage to the bottom surface of the micro end mill.

Key words: polycrystalline diamond micro end mill, electrical discharge turning, micro-milling, sapphire, micro-milling force

CLC Number:

TH 161

Si-qian GONG, Yao SUN, Si-hui LI. Preparation of Polycrystalline Diamond Micro End Mill and Experiment of Its Micro-milling Process for Sapphire[J]. Journal of Northeastern University(Natural Science), 2025, 46(12): 78-84.

Figures/Tables 12

Fig.1 Agiecharmilles CA20 low-speed wire electrical discharge machine(WEDM) tool

Fig.2 Simulation results of cutting head of single-edged helical micro end mill for electrical discharge turning

Fig.3 Independently developed micro-milling machine tool and laser confocal microscope

Table 1 Technical specifications of micro-milling machine tool

机床的技术参数	值
机床主体外形尺寸/mm	360×200×350
X,Y,Z工作台行程/mm	50
全闭环数控系统分辨率/μm	0.01
主轴最高转速/(r·min^-1)	60 000
各向工作台最大速度/(mm·s^-1)	30
各向工作台最大加速度/(mm·s^-2)	2
花岗石平台底座尺寸/mm	1 000×630×750

Table 2 Parameters of polycrystalline diamond single-edged helical micro end mill using electrical discharge turning

参数名称	符号	单位	数值
冲液压力	p	MPa	0.1
峰值电流	I	A	120
开路电压	U	V	100
脉冲宽度	t_on	μs	13
工件转速	v_n	r/min	2
走丝速度	v_w	mm/s	30
丝张力	F_w	N	15
电极丝进给速度	v_s	mm/min	2

Fig.4 Observation results of morphology and surface roughness of polycrystalline diamond single-edged helical micro end mill using electrical discharge turning

Fig.5 Effect of micro-milling depth on surface topography of sapphire

Fig.6 Effect of micro-milling feed speed on surface topography of sapphire

Fig.7 Effect of micro-milling feed speed on surface cross-sectional（Fig.6） profile of sapphire

Fig.8 Effects of micro-milling feed speed and depth on surface roughness Sa and Sz of sapphire（a）—进给速度；（b）—微铣削深度.

Fig.9 Effect of micro-milling feed speed and depth on micro-milling force

Fig.10 Observation results of wear surface morphology of polycrystalline diamond single-edged helical micro end mill after micro-milling

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