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Xu Wang, Xiaotong Sun, Huadong Yu, Jinkai Xu, Zhanjiang Yu,

Yiquan Li, Valentin L. Popov

Research on the micro-hole texture forming of

PCD tool surface

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X. Wang et al. (2021) Research on the micro-hole texture forming of PCD tool surface. 2021 IEEE

International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO),

2021, pp. 365–368, https://doi.org/10.1109/3M-NANO49087.2021.9599816.

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Research on the micro-hole texture

forming of PCD tool surface

Xu Wanga,b,c, Xiaotong Suna,c, Huadong Yua,c, Jinkai Xua,c, Zhanjiang Yu*a,c, Yiquan Lia,c, Valentin L.

Popov*b,

a. National and Local Joint Engineering Laboratory for Precision Manufacturing and Detection

Technology, Changchun University of Science and Technology, Changchun 130012, Jilin, PR China;

b. Technische Universität Berlin, 10623, Berlin, Germany,

c. National and Local Joint Engineering Laboratory for Precision Manufacturing and Detection

Technology

Changchun 130012, Jilin, PR China

Technische Universität Berlin, 10623, Berlin, Germany

v.popov@tu-berlin.de

13514310244@163.com

Abstract—Based on the research on the

forming mechanism of textured PCD tool surface,

the nanosecond laser is used to study the influence

of laser machining parameters on the size and

topography of PCD tool surface micro texture. The

micro-hole texture is prepared on the surface of

the PCD tool, and a single factor experiment is

designed to study the influence of laser power,

pulse frequency and defocusing amount on the

micro-hole texture. The results show that, the

micro-hole diameter increases gradually with the

laser power, but decreases with the pulse

frequency; the overall micro-hole diameter tends

to increase with the defocus. The pulse frequency

has the greatest impact on the micro-hole diameter,

followed by the defocus amount, and finally the

laser power. The influence of different parameters

on the surface recast layer is also completely

different. As a result, the surface and laser power

are the main factors that affect the surface recast

layer.

Keywords—PCD; Forming mechanism;

Micro-hole diameter.

Ⅰ INTRODUCTION

Polycrystalline diamond tools have the

characteristics of high cutting efficiency, low

friction coefficient, low thermal expansion

coefficient, good thermal conductivity, low

affinity with materials and high machining

accuracy, so it is widely used in automobiles,

aerospace and micro-components. People use

high-pressure synthesis technology to synthesize

polycrystalline diamond (PCD), which solves the

problem of scarcity and high price of natural

diamond [1]. Nevertheless, the use of PCD tools

to machine some super hard materials or metal

matrix composites will still have edge chipping,

and the machining of some metal materials with

higher plasticity will also cause sticking.

Micro-texture improves the friction behavior of

the surface by reducing the contact area, thereby

improving the wear resistance of the tool. At

present, there are few researches on the surface

texture of PCD tools, so it is very important to

study the preparation of PCD tools surface

texture to improve the cutting performance and

life of the tools. The preparation of hole arrays on

the tool surface is the most economical and

efficient way to solve this problem [2-5].

At present, the preparation of the surface

texture of PCD tools mainly includes laser

machining and electrical discharge machining

(EDM). EDM machining is pretty difficult for

preparation of smaller holes, and the machining

cycle is longer. Wang et al. [6] used EDM to

machine micro-holes in PCD materials. The

minimum size of the micro-holes is 130 μm and

the maximum is 200 μm. Su et al. [7] used a fiber

laser to prepare micro-grooves on the surface of

the PCD tool, and the average width of the

microgrooves was between 56-60 μm. And the

results show that PCD textured tool has improved

the cutting performance. Knowles [7] used three

high-intensity lasers (with magnitude of order

GW/cm2) to prepare textures for metals,

ceramics, and polymers. The smallest hole size

can reach 50 μm. Khan and Zheng et al. [8-9]

used nanosecond lasers to prepare textures of

nickel-coated tungsten carbide and cemented

carbide materials. The size of the hole texture was

about 50 μm, and the size of the groove-texture

was about 50-160 μm. They all reduced the wear

of the tool and the adhesion of the workpiece

surface, and improved the surface quality of the

workpiece. Uhlmann [10] studied the preparation

and cutting performance of CVD diamond texture

tools. The texture with a size of 60 μm was

prepared on the surface of CVD diamond tools.

The results show that the texture can effectively

reduce the cutting force. From the point of view

of both machining method and machining

efficiency, the better choice for micro-hole

machining on the surface of PCD tools is laser

machining.

There have been many researches on the

machining of texture on the surface of PCD tools

by laser, but quite few on the influence of laser

machine parameters on the microscopic

morphology and micro-hole diameter of the

surface hole array of PCD tools. In this work a

single-factor experiment is designed for study on

the preparation of PCD surface micro-holes. The

effects of laser power, pulse frequency and

defocusing amount on the surface

micro-morphology and micro-hole diameter will

be studied. A quantitative relationship will be

obtained to analyze the degree of the influence.

The micro-hole array textured PCD tool is

prepared by selecting appropriate machine

parameters, which provides a basis for the

selection of the machine parameters of the

micro-hole array textured PCD tool.

Ⅱ EXPERIMENTAL EQUIPMENT AND

METHODS

The PCD tool produced by Xiamen Golden

Egret Special Alloy Co., Ltd. was selected in the

experiment. Its material properties are shown in

Table I. The laser parameters for the single factor

experiment are chosen as shown in Table II. The

effects of 4 different laser powers, seven

defocusing amounts varying from -3 μm to 3 μm,

and 9 pulse frequencies ranging from 20 kHz to

100 kHz on the surface texture morphology and

hole diameter of PCD tools are respectively

investigated. The laser is a nanosecond laser with

a maximum power of 20W, and the incident angle

is 90°, as shown in Fig 1. Due to the high

hardness of PCD tools, the high power is selected

from 70% of the maximum power to the full

power. Three holes are prepared for each

combination of the three laser parameters, and the

value of hole diameter is averaged for analysis.

The observation and detection are carried out on a

scanning electron microscope (SEM).

TABLE I. PCD TOOL PHYSICAL PARAMETERS

Density (g/cm3)

3.47-4.12

Elastic Modulus (GPa)

820-1050

Hardness

HV8000-10000

Thermal Conductivity (W/(m

⋅

K))

500-2000

Thermal Expansion Coefficient

0.9-4.8

TABLE II. SINGLE FACTOR MACHINING

PARAMETER

Power

(W)

Defocus Amount

(μm)

Pulse Frequency

(kHz)

70% -3 20

80% -2 30

90% -1 40

100% 0 50

1 60

2 70

3 80

100

Fig. 1 Schematic diagram of nanosecond laser machining

system

The PCD tool is cleaned before and after

machining by ultrasonic cleaning machine. Fig. 2

(a) is a side cross-sectional view of the PCD tool

after machining. The laser enters into the PCD

tool through periodic pulses, and high-energy

makes the material melt and evaporate quickly,

finally produces micro-hole. As shown in the

schematic diagram of Fig.2(c), the PCD material

absorbs the energy in the laser irradiated area, and

the energy is converted into heat, which

accumulates in a very short time, so that the

material rapidly oxidizes, changes phase, and

begins to melt. As the temperature continues to

increase, the PCD material is evaporated and

sprayed to remove the material, and a recast layer

is possibly formed on the surface of the tool, as

shown in Fig. 2(b).

(c)

Fig. 2 SEM image and schematic diagram of laser machining

PCD tool (a) Side view of laser machining PCD tool, (b) Top

view of laser machining PCD tool. (c) Schematic diagram of

micro hole producing.

III EXPERIMENTAL RESULTS AND

ANALYSYS

As shown in Fig. 3, as the pulse frequency

increases from 20 kHz to 100 kHz, the micro-hole

diameter decreases from about 5 μm to about 2

μm. The main reason is that as the pulse

frequency increases, the working time between a

single pulse and the material decreases, so that

the energy density per unit area of the machined

material becomes lower, which leads to a

decreasing of micro-hole diameter.

As the laser power increases from 14 W to 20

W, the acting area of laser on the PCD tool

material becomes larger, then the diameter of the

micro-hole increases. Due to the Gaussian

distribution of laser energy density, the laser spot

diameter limits the diameter of the micro-hole, so

that the hole size increases as the power increases.

For a certain value of pulse frequency and

defocusing amount, the maximum difference of

hole diameter is about 0.962 μm, and the

minimum is about 0.464 μm. It can be seen that

the influence of the laser power in this range on

the hole size is not obvious than that of the pulse

frequency.

Considering the effect of the defocusing

amount, it is found that the hole’s diameter

fluctuates by 0.192~1.295 μm. For the power

70%, the largest diameter of the micro-hole is

found at the defocus -3. For the power 80% and

90%, the change of the hole diameter is not

obvious when the defocus amount increases. For

the power is 100%, the largest hole is found at the

defocus 3 and -3. As the amount of defocus

increases in both directions, the overall hole’s

diameter shows an increasing trend.

Fig. 3 The effect of pulse frequency and defocusing amount

on hole diameter under different laser powers. The

dependence of pulse frequencies on the hole diameter for

different values of defocus with (a) 70% power, (b) 80%

power, (c) 90% power and (d) 100% power.

Fig. 4 The micro-hole surface micro-morphology under

different machining parameters.

A few examples of the PCD surface

micromorphology of the machined hole are

shown in Fig 4. There are mainly three types: (1)

the surface is flat and there is almost no recast

layer; (2) the surface is bowl-shaped and there is

almost no the recast layer; (3) the surface is

bowl-shaped and recast layers exist. The holes

without bowl-like structure were prepared when

the focus was located on the surface or below the

surface of the workpiece (negative defocusing).

With a gradually increasing the laser energy, a

flat micro-hole structure on the tool surface is

produced. For the bowl-shaped structure, since

the laser focus is above the surface of the

workpiece, the energy decreases from the focus to

the surface of the workpiece, and then the

bowl-shaped structure is produced. The surface

recast layer is mainly determined by the laser

power. In the case of focusing or positive

defocusing, high power will cause the surface to

produce an excessively large recast layer area.

To predict the cutting performance, we

numerically simulated the cutting of this textured

tool with SiCp/Al composite. The cutting model

was established by ABAQUS software. The

maximum stress at the tool texture was compared

for different hole diameters and the holes with

and without rounded corners. The stress

distribution on the surface is shown in Fig. 5. It

can be seen that with an increasing hole diameter

(from left to right), the maximum stress of the

tool’s texture becomes gradually larger. And it is

smaller when the texture has rounded corners (in

the bottom row). Therefore, the texture with

rounded corners can reduce the maximum stress

at the tool’s texture during the machining,

thereby reducing tool wear.

Fig. 5 The maximum stress in the machining of textured

PCD tools on SiCp/Al composite. The texture of hole

diameter of (a) 2 μm, (b) 4 μm and (c) 6 μm without rounded

corners, and the same hole sizes (d)(e)(f) with rounded

corners.

IV CONCLUSIONS

The effects of laser power, pulse frequency

and defocusing amount on the micro-hole

diameter and micro morphology of the PCD tool

surface was studied, and the conclusions are as

follows:

(1) By changing the laser power, pulse

frequency and defocus amount, the size and

micro-morphology of the surface texture of the

PCD tool can be controlled;

(2) The diameter of the micro-holes on the

surface of the PCD tool decreases significantly

with the pulse frequency; shows a decreasing

With the increase of the laser power and the

defocusing amount, the hole diameter shows an

increasing trend. The order of the influence of

laser parameters on the diameter of the

micro-hole is: pulse frequency>defocus

amount>laser power.

(3) The micro-hole machined by laser on the

surface of PCD tools have mainly three forms:

relatively flat surface without recast layer in the

micro-hole; bowl-shaped surface without recast

layer; bowl-shaped surface with heavy cast layer.

The bowl-shaped structure is determined by the

defocus amount, and the recast layer is mainly

determined by the laser power.

(4) The texture with rounded corners can

reduce the stress concentration, extend the

effectiveness of the textured tool, and further

improve the tool life.

ACKNOWLEDGMENT

This work was supported by the National Key

Research and Development Plan Project

(No.2018YFB1107400), the National Key

Research and Development Plan Project

(No.2018YFB1107403), the “111” Project of

China (No.D17017), Jilin Province Scientific and

Technological Development Program

(No.20190101005JH, No.20180201057GX,

No.20190302076GX), and Science Fund for

Youth Scholar of Changchun University of

Science Technology (No.XQNJJ-2018-09).

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