Chip Formation and Shear Plane Angle Analysis on Carbon Steel

Drilling using Solid Carbide Tools

Rieza Zulrian Aldio

Department of Mechanical Engineering, Universitas Islam Riau, Pekanbaru, Indonesia

Keywords:

Carbide Drill Bit, Chip Formation, Drilling, Shear Plane Angle

Abstract:

The analysis of the chip formation and shear plane angle from the drilling process are conducted as a mean to

determine the best drill bit used. Both aspects that inﬂuenced by the drill bit will deﬁne the machinability and

quality of the machining process. The aim of this experiment is to determine which is the best drill bit to use.

There are nine types of drill bit used in this experiment. All of the drills used are made of the solid carbide.

The chips are obtained from the drilling conducted by HPMT Industries Sdn Bhd. There are several types of

chips from the experiment, such as continuous, discontinuous and segmented chip. It is found that the chip’s

thickness and the helix angle of the drill bit affect the value of the shear plane angle created. Since all drill

bits are made of the same material, the helix angle of the drill bit become the main factor of choosing the best

drill bit because of the relationship between it inﬂuenced the shear plane angle value.

1 INTRODUCTION

One of the workpiece that is frequently and generally

used in the machining process is steel. There are sev-

eral types of steel used in the machining process such

as stainless steel, carbon steel and others. Each type

of steel has a different nature. Stainless steel is the

most common type of steel used in the manufactur-

ing industry. For example, corrosion resistant prop-

erties of stainless steel is due to a chromium content

of 10-12 percent of the total weight of stainless steel

(Kalpakjian and Schmid, 2006). Then there is also

carbon steel which is also often used in industry be-

cause of its low cost and ease of manufacture (Smith

and Hashemi, 2006).

One of the type of machining process which is of-

ten used for steel is drilling process. Drilling pro-

cess is the process by which drill bit will result in a

hole in the workpiece through direct contact between

the tool and the workpiece surface. Drilling process

is one of the most important machining processes in

the automotive and aircraft industries. (El-Sonbaty

et al., 2004) states that the industries required more

than 100,000 holes for small aircraft engines, mostly

used as a fastener. There are several forms of chips

that could resulted from the drilling process (Shar-

man et al., 2008). For example, the long continuous

chips are bad shape because chips will stick to the

surface of the tool and affect the performance of the

tool while performing the drilling process (Feng et al.,

2005). Long chips also make the chip evacuation be-

come more difﬁcult and cause the drill to require more

power, which would increase the risk of broken drill

(Batzer et al., 1998). For this reason, the form and

evacuation process of the chips have important roles.

Chips will have direct contact with the ﬂutes on

the twist drill during the drilling process. The geome-

try of the tool used will have an impact on the process

of moving chips (Abrao et al., 2008). Because of that,

the shape that commonly found has curls form, which

is according to the ﬂute’s shape. (Bakkal et al., 2005)

in experiments on the chip’s morphology of drilling

metal glass found that there are six forms of chips

such as powder, short ribbon, long ribbon, long spi-

ral, long twisted ribbon and fan shape.

Movement of the chips on the ﬂutes will cause

bending moments which can lead to chip fracture.

(Sakaurai et al., 1998) states that the chip will be

broken when the friction torque between the hole

wall and chip’s surface is beyond the chip’s torque.

The size of the chip will have impact on the sur-

face roughness, which will produce rougher surface

(Batzer et al., 1998). The performance of a tool can

be determined by the shape of the resulting chips.

Therefore, apart from the chip removal process,

the shape and length of chips resulted from the

drilling process should be reviewed in order to accom-

plish better performance of the drilling process. In

Zulrian Aldio, R.

Chip Formation and Shear Plane Angle Analysis on Carbon Steel Drilling using Solid Carbide Tools.

DOI: 10.5220/0009406203370341

In Proceedings of the Second International Conference on Science, Engineering and Technology (ICoSET 2019), pages 337-341

ISBN: 978-989-758-463-3

337

addition to differences in material and machining pa-

rameters on the tool used, the difference in the shape

or geometry of the tool will affect the shape of the re-

sulted chips (Wan and Tang, 2011). Geometric dif-

ferences such as rake angle or helix angle and the

point angle will affect the shape, size and length of

the chips. Point angle, helix angle and size of ﬂutes

on the tool will affect the movement of chips (Feng

et al., 2005).

So in this experiment will be analyzed on the frag-

ments resulting from each type of device used. Each

tool has a different geometry and analysis on the re-

lationship between the different tool geometry and

shape of the pieces will also be done. Then the re-

lationship between the rake angle of the tool with the

resulting shear plane angle will also be reviewed.

Figure 1 shows the geometry of the typical drill

bit used in machining.

Figure 1: Drill Bit Geometry

2 EQUIPMENT

The workpiece used is carbon steel S45C. CNC ma-

chine is used for the drilling process. The diameter of

all cutting tool used is 8 mm. All of them are not us-

ing coolant. There 9 drill bits, each has different helix

angle value. Figure 2 shows the holes produced from

the drilling process. From the process, there are 600

holes produced by using each cutting tools. Then ﬁg-

ure 3 show the CNC Drilling Machine Makino S-33

that used in the drilling process.

3 METHODOLOGY

Every drill bit will drill 600 holes with same machin-

ing parameters, shown in table 1. Then the chips

are taken randomly between the drilling process.

the chip’s thickness measured using vernier calliper.

Thus, using the thickness ratio and helix angle value,

the shear plane angle value can be found. These

formulas are used for the calculation.

Figure 2: Carbon Steel S45C

Figure 3: Makino S-33 CNC Machine

Figure 4: Drill Bits Used In The Drilling Process

r =

(1)

tanΦ =

r cos α

1 − r sinα

(2)

ICoSET 2019 - The Second International Conference on Science, Engineering and Technology

338

Table 1: Machining Parameters Used

Cutting speed Feed rate Depth of cut

140 m/min 0.16 mm/rev 42 mm

4 RESULTS AND DISCUSSION

4.1 Chip Formation

From the chips sample, there are several forms of chip

resulted from each type of cutting tools. Long heli-

cal continuous chip is always resulted in the drilling

process. There are also discontinuous and segmented

chip resulted. But there are only two cutting tools re-

sulting segmented chips. Beside the shape, the length

and thickness of the chips are also measured. The

length of the chips are between 3 to 6 cm. Figure 5

below shows the sample of the chips.

Figure 5: Type of Chips Resulted From The Drilling Pro-

cess

There are several types shapes of the chips re-

sulted. With continuous being the dominant one,

while some discontinuous and segmented are also re-

covered. There are no real signiﬁcant difference in the

shape due to the similarity value of the rake angle.

For the thickness value however, the differences

between all the chips resulted from each cutting tools

are quite similar. This is due to the similarity of the

feed rate used in the drilling process. Table 2 show the

value from the maximum length and thickness mea-

surement of the resulted chips.

Chips from cutting tool C8 has the least maximum

length of all the chips. As for he longest is from

the cutting tool WT. Cutting tool ZC produce longest

chips at 4.5 mm, and this cutting tool is the cutting

tool that produce the most many long continuous he-

lical chips. Long continuous chips also resulted from

the use of all the cutting tools. But only ZC produce it

as the most dominant chip’s form. For the segmented

chips, there are two cutting tools produced it, they are

HT and MT. Using MT, there is also produced long

continous string chips. As for the cause of this oc-

curence, is likely due to the high cutting speed and

inﬂuenced by the wear condition of the cutting tools.

From table 2, it can also show the value of the chip

thickness. The small difference might happened due

to the similar use of machining parameter,, especially

feed rate that affect the chip thickness. There is no

change in the parameter, which is making unclear to

compare the chip thickness resulted from each cutting

tools. Thus, the similarities between the values are

obtained.

4.2 Surface Integrity of the Chip

Observation of the surface of the resulting chips were

also conducted. The both of the chip surface was ob-

served using an optical microscope. Of all the pieces,

it is found that many chips with good machined sur-

face (outside) or good quality. However, there is also

the outer surface of chips having a surface shape is

not good, as there is friction and cracked. The condi-

tion of the chip surface in contact with the workpiece

has a resemblance to each other. There are traces of

the strain acting on the surface of the chip, which oc-

curred during the drilling process. The traces are re-

sulted by the cutting tools.

From observation, it can be seen that the shape

of the surface of the chips of each tool has a shape

similar or even identical. Due to the dominant circu-

lar chip, it is difﬁcult to observe the inner part of the

chip. To do the observation of this part, the discontin-

uous chip type is observed so the inner surface can be

observed. From the ﬁgure below, it is shown that the

chips surface from HPMT DRNiTiCo has poor condi-

tion than the others. It can occured due to the cutting

tools became dull (due to the wear).

4.3 Shear Plane Angle Analysis

Feed rate is used as the replacement for the t

.There

is a relationship between shear plane angle and rake

angle. Because rake angle will deﬁne the sharpness

of the cutting tool. Rake angle will affect the shear

plane angle resulted. For drilling process, the rake

angle is replace by the helix angle. Because helix an-

gle (on ﬂute) is the part that directy cut or touch with

Chip Formation and Shear Plane Angle Analysis on Carbon Steel Drilling using Solid Carbide Tools

339

Table 2: Chip’s Length And Thickness Measurement

No Drill Bit Max Length (cm)

Thickness (mm)

1 2 3 Average

1 ZC 4.5 0.23 0.25 0.25 0.24

2 HT 4 0.29 0.24 0.23 0.25

3 SU 4.2 0.21 0.24 0.25 0.23

4 MT 4.4 0.26 0.2 0.21 0.22

5 WT 6 0.27 0.31 0.29 0.29

6 HPMT DR45 3.8 0.24 0.26 0.23 0.24

7 HPMT DRNiTiCo 3.5 0.31 0.29 0.25 0.28

8 C4 4.5 0.24 0.27 0.26 0.26

9 C8 3 0.21 0.22 0.25 0.23

Figure 6: Chips of Drill Bit C8

Figure 7: Chips of MT

the workpiece’s surface and resulting the chip. The

chip also ﬂow through this part. So in this case, helix

angle is related to the shear plane angle.Table 3 shows

the rake angle and shear plane value.

From the table 3, it is known that the least thick-

ness will cause the shear plane angle to increase. That

Figure 8: Chips of HPMT DRNiTiCo

shows the relationship between thickness and shear

plane angle. Beside that, rake angle also inﬂuence the

shear plane angle. It is seen that the smaller rake an-

gle tend to produce smaller shear plane angle, except

for C4 and C8. The value of the shear angle also will

decreased if the rake angle is too large, such as WT

show. This means that the rake angle value should be

optimized to get the optimum value of the shear plane

angle.

The chip thickness has more clear relationship

with the shear angle. The smaller thickness will re-

sulting the bigger shear plane angle. As ﬁgure 6,7 and

8 shows that the optimum value of the shear plane is

around rake angle with 30

◦

5 CONCLUSION

From the measurement and observation of the chip,

it is concluded that there are several type of chip

ICoSET 2019 - The Second International Conference on Science, Engineering and Technology

340

Table 3: Shear Plane Angle Value of Every Drill Bit

No Drill Type Chip Thickness (tc)(mm) Cutting Ratio Helix / Rake Angle Shear Plane Angle

1 ZCC 0.24 0.67 30.21 41.14

2 Hitachi (HT) 0.25 0.64 28.67 39.02

3 Sumitomo (SU) 0.23 0.7 30.16 43.03

4 Mitsubishi (MT) 0.22 0.73 30.69 45.02

5 Walter Titex (WT) 0.29 0.55 33.17 33.37

6 HPMT DR459670800 0.24 0.67 30.22 41.14

7 HPMT DRNiTiCoD08800 0.28 0.57 30.16 34.63

8 Coromant 460 (C4) 0.26 0.62 26.24 37.46

9 Coromant 860 (C8) 0.23 0.7 26.41 42.32

resulted such as continuous, discontinuous and seg-

mented chip. Continuous is the most dominant chip

of all, since it appeared on each tool. The segmented

only appeared on HT and MT, and could occured due

to the tool wear and randomness of the chip collected

from the drilling process.

Shear plane angle is calculated and shows that it

has strong and clear relationship with chip thickness

value. As for the rake angle, it shows that the opti-

mum value of rake angle must be speciﬁed if want

to increase the shear plane angle. Meaning also to

reduce the chip thickness to accomodate better chip

evacuation during drilling process.

ACKNOWLEDGEMENTS

The author would like to give an acknowledgment to

HPMT Industries Sdn. Bhd. members, especially

Research and Development Department for their co-

operation in data. The author also thanks Universiti

Kebangsaan Malaysia as the organisation that provide

their facilities for the research’s purpose.

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