Machinability Study: Low Variation and High Repetitive Case

Abdul Haris Nasution, Muksin Rasyid Harahap, Suhardi Napid, Muhammad Rafiq Yanhar

Mechanichal Engineering, Faculty of Engineering, UISU, Medan

Keywords: Machinability, Mass Product, small and medium enterprise.

Abstract: Machining proses or metal cutting process is a main activity practised by small and medium metal

enterprise by using conventional machines. This machining process is directed to produce the mass products

(low variation and high repetition), such as components of machine or another equipments, but often also

the macining process is made inappropriately, or even in total false methode, such as false selection of tool,

thus the worn-out fastly, over cutting speed, thus surface is rougher, and etc. In this paper, the machinability

on cast iron cutting is assessed (the material usually worked in small and medium metal industries), i.e., by

making some experiment to obtain the most optimal cutting condition (v, f ,and a) to have the short cutting

time, big cutting volume, lower surface roghness and longer tool life .

1 INTRODUCTION

1.1 Background

Information on the mechinability of a product is

needed to find out the quality and quantity of the

product to be produced as well as the tool wear

information (Cerce and Pusavec, 2016). This

information is very important to know the level of

productivity that will be achieved in the

implementation of a production. Based on this

information, it can be determined the type of tool

and the right cutting conditions so that productivity

is better which affects the increase of the income of

small and medium industries (Nayyar et al., 2012).

Usually, small and medium industries carry out

the production process based on technology that is

usually carried out from generation to generation,

this results in difficult production quality to compete

in the local market and export markets.

To solve these problems, the machinability study

is very important to be done so that productivity

from the aspect of quality and quantity can be

increased.(Nasution et al., 2005)

1.2 Formulation of Problem

Problems commonly found in small and medium

me-tal industries in cast iron machining are as

follows:

Inconsistent cutting condition include the depth

of cut, tool geometry, cutting speed and feeding,

contributes to inconsistency of product geometry

produced, or in other word accuracy and precision of

product produced is poor. The cutting condition also

contributes to surface roughness, that feed is very

influential factor on surface roughness.

1.3 Purpose of Research

The purpose of this research are:

a. To investigate machinability of pulley from

cast iron materials.

b. To give input and suggestions to Small and

Medium Metal Enterprise to increase

productivity through study of machinability

factor.

2 MATERIAL, EQUIPMENTS

AND METHODOLOGY

2.1 Material

The material of pulley is cast iron with chemical

composition C = 3.04 %, S = 0.11 % Cr = 0.07 %,

Mn = 0.42 %, Cu = 0.05 %, Mo = 0.05 %, Ni =

0.02 %, P = 0.068 %, Si = 2.58 %, and mechanical

properties : Brinnel Hardness = 1500 HB, Tensile

Nasution, A., Harahap, M., Napid, S. and Yanhar, M.

Machinability Study: Low Variation and High Repetitive Case.

DOI: 10.5220/0008881500050010

In Proceedings of the 7th International Conference on Multidisciplinary Research (ICMR 2018) - , pages 5-10

ISBN: 978-989-758-437-4

Strength = Min 365 Mpa, Elongation Break = 10 %,

Modulus elasticity=300 GPa

2.2 Equipments

CNC Emcoturn 242 was used on cutting condition

research, uncoated carbide insert tools with complex

chipbreaker (CNMG 120412 EN – TM) was used on

cutting condition research. Insert tool chemical

properties: Co= 6,0 %, composite carbides = 0,6 %,

WC rest and mechanical properties: HV=1550

(Tiziloque, CERATIZIT cutting tool catalogues,

2003). Tool holder PCLN/R 2525 M12-T with Kr =

2.3 Methodology

The method of data collection was by Collecting the

data in cutting process of 15 samples, i.e.: cutting

time, product dimension, surface roughness (Kir et

al., 2016). The data collected was then analyzed to

see the performance of Small and Medium Metall

Enterprise from quality and quantity side by using

conventional machine, and then a testing was made

against several variation of cutting condition to

obtain the data as follows: machining time (t), tool

wear (VB), length of machining (L), material

removal rate (MRR), surface roughness (Ra) of

machining workpiece (Lin et al., 2016)

3 RESULT AND DISCUSSION

3.1 Cutting Condition in Small and

Medium Enterprise

The cutting process toward 15 samples obtained data

that average cutting time per product = 6.78 minute s

with lower control limit LCL = 6.32 minute dan

upper control limit UCL = 7.25 minute and deviation

standard = 0.16. Based in figure 1, shown with

clearly the significant variation cutting time found in

conventional machining process, and even there is

some data staying out of control limit. This

indicated inconsistency of machining time to

complete a product because the machining process is

largely effected by performance of machine operator

(Steel, Potong and Hss, no date).

Figure 1: Machining time of 15 product with

conventional lathe.

From the result of measurement of surface

roughness by using Surface Roughnes Profillometer

in figure 2. it was informed that the value of surface

roughness in conventional machine is also very

variuos with a verage = 4.00 and deviation

standard = 1.55. The reason of the coarse surface

finish is possible by:

1. Cutting tool factor ( geometry and material)

2. Feeding (f)

3. Cutting speed (V)

This case also indicates the inconsistency of

surface roghness that obtained of conventional

machining (Teknik et al., no date).

Figure 2: Product surface measured.

5.00

5.50

6.00

6.50

7.00

7.50

8.00

8.50

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Product (Σ)

Time (min)

produk UCL LCL

ICMR 2018 - International Conference on Multidisciplinary Research

Figure 3: Surface Roughness by Conventional Machining.

The measuring data result of product dimension

in table 1. shown inconsistency dimension that

obtained by conventional machining.

Figure 4: Product Dimension Expected.

Figure 5. Product Dimension.

3.2 Cutting Condition used Uncoated

Carbide Insert

Below is the new Cutting Condition test toward 9

(nine) variation of cutting condition variation, i.e :

CC1: v = 50 m/min ; f =0.04 mm/rev ; a =0.5 mm;

CC2: v = 50 m/min ; f = 0.1 mm/rev ; a = 0.5 mm;

CC3: v = 100 m/min ; f = 0.1 mm/rev ; a = 0.5 m;

CC4: v = 250 m/min ; f = 0.1 mm/rev ; a = 0.5 mm;

CC5: v = 300 m/min ; f = 0.1 mm/rev ; a = 0.5 mm;

CC6: v = 400 m/min ; f = 0.1 mm/rev ; a = 0.5 mm[

CC7: v = 500 m/min ; f = 0.1 mm/rev; a = 0.5 mm;

CC8: v = 300 m/min ; f = 0.2 mm/rev ; a = 0.5 mm;

CC9: v = 400 m/min ; f = 0.2 mm/rev ; a = 0.5 mm

3.2.1 Tool Wear

Figure 6 shows that each cutting process is done

about five minutes, and the faster worn-out occur on

the tool with cutting condition of CC5, CC6 and

CC7, but the resulting worn-out is still under 0.3

mm, it means it is still in allowable condition.

Figure 6: Machining Time and Tool Wear.

From figure 7, it shows that length of machining

done on Small and Medium Enterprise , CC1, is very

short, it means the productivity is very low

compared to CC2,CC3,CC4, CC5, CC6, CC8 and

CC9.

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

Measurement (Σ)

Ra (μm)

UCL

LCL

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

VB (um)

t (menit)

CC1 CC2 CC3

CC4 CC5 CC6

Machinability Study: Low Variation and High Repetitive Case

Figure 7: Length of Machining VS Tool Wear.

3.2.2 Surface Roughness

The expected limit of Surface Roughness is 2.4 µm,

from graph of Surface Roughness in figure 8, that

all of cutting conditions obtained athe suitable

surface roughness as expected, except cutting

condition of CC2.

Figure 8: Tool Wear VS Surface Roughness.

3.2.3 The Removal Material

From figure 9. it can be seen that the most

machining volume is in CC9, with v = 400 m /

min, f= 0.2 mm/ rad ; a = 0.5 mm, however the

lower machining volume on CC1, CC2, CC3 and

CC4.

Figure 9: Relationship Between Cutting Time VS

Machining Volume.

In perspective of tool wear, it can be seen clearly

in figure 10 that the cutting volume obtained of

CC1, CC2, CC3, CC4, CC5, CC6 and CC7 are

lower than CC8 and CC9. However, tool wear on

CC8 and CC9 is still permitted because it is below

0.3 mm

Figure 10: Cutting Volume VS Tool Wear.

Figure 11 Shows that Material Removal Rate

(MRR) on Small and Medium Enterprise (CC1) is

very low, about 1 cm

/menit, and then the significant

MRR increase from CC4 to CC9. This means that

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0 1 2 3

VB (mm)

Lt (km)

CC1 CC2 CC3

0.00

0.50

1.00

1.50

2.00

2.50

3.00

0 0.1 0.2

Ra (µm)

VB (mm)

CC1

CC2

CC3

CC4

CC5

CC6

CC7

CC8

CC9

50000

100000

150000

200000

250000

0 2 4 6 8

Volume(mm

)

t (menit)

CC1 CC2 CC3

CC4 CC5 CC6

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0 200,000 400,000

VB (mm)

Cutting Volume (mm

)

ICMR 2018 - International Conference on Multidisciplinary Research

the best productivity in terms of quantity is the CC9

cutting condition.

Figure 11: MRR VS Cutting Condition.

4 CONCLUSIONS

4.1 Product Quality Produced by Using

Earlier Technology

1. The conventional lathe and the old

machining process technology obtained the

machining time in wide because of

machining process with conventional

machining process depends on operator and

lowest cutting velocity.

2. Surface roughness is not as expected

(average 4,00 μm).

3. Product dimensions are not consistent.

4. Material Removal Rate (MRR) is lowest

i.e: 1 cm

/menit, thus machining time is

slower than new cuting conditon.

4.2 Expected Product Quality by New

Technology and New Cutting

Condition

New cutting conditions is obtained from the result of

analysis on machining process of cast iron by using

carbida insert tool. Those cutting conditions

produced the far higher productivity and better

machining quality, i.e. cutting condition of CC7,

CC8, CC9.

In relation to presentation above, the cutting

conditon recomended from the result of data analysis

above will be:

V= (300 - 500) m/min ; f = (0.1 – 0.2) mm/rad ; a =

0.5 mm

Thus, Quantity and quality of products expected

have been achieved, including as follows:

1. The shorter machining time.

This is seen clearly from figure 11, in which

material removal rate (MRR) in CC9 is 40

times as speed as of CC1, it is relevant to

cutting volume produced by CC9 more than

another cutting conditions.

2. In perspective of tool wear shown that the wear

occurs on CC7, CC8 dan CC9 still in allowable

limit.

3. The average surface roughness is under 2.5

µm.

4. Together with to increase in quality and

quantity of machining process by new

technology, it will be increase the profit of

enterprise.

ACKNOWLEDGEMENTS

The authors wish to acknowledge the Lembaga

Penelitian Universitas Islam Sumatera Utara.

REFERENCES

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machinability of grey cast iron using cubic boron

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pp. 65–78.

Kir, D. et al. (2016) ‘Determination of the cutting-tool

performance of high-alloyed white cast iron (Ni-Hard

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10.17222/mit.2014.270.

Lin, Y. et al. (2016) ‘Optimal Machining Parameters of

EDM in Gas Based on Response Surface

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10.11648/j.ijmsa.20160506.12.

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Kondisi Pemotongan

MRR (cm

/menit)

CC1 CC2 CC3 CC4 CC5

CC6 CC7 CC8 CC9

Machinability Study: Low Variation and High Repetitive Case

Steel, H. S., Potong, K. and Hss, P. (no date) ‘Ruslan

Dalimunthe: Pengaruh Kecepaatan Potong Terhadap

Umur Pahat HSS Pada Proses Pembubutan AISI 4340

139’, pp. 139–145.

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pembubutan’, pp. 26–34.

ICMR 2018 - International Conference on Multidisciplinary Research