UTILIZATION OF EXTRUSION AS AN ADVANCED MANUFACTURING TECHNIQUE IN THE MANUFACTURE OF ELECTRIC CONTACTS Copyright IJAET

International Journal of Advances in Engineering & Technology, Jan 2012.

©IJAET ISSN: 2231-1963

Utilization of Extrusion as an Advanced
Manufacturing Technique in the Manufacture of

Electric Contacts

Virajit A. Gundale ,Vidyadhar M. Dandge
'Prof. & Academic-Incharge, Sharad Institute of Technology, College of Engineering,

Yadrav, Kolhapur India.
2 Asstt. Prof., Dr. J. J. Magdum College of Engineering Jaysingpur, Kolhapur, India

Abstract

It is common that each engineering assembly product has A,B and C class components which together
comprises assembly. A class component has high contribution in product function, cost and profitability of the
engineering enterprise. A special technical research is must for this class of components. Product assembly is
another crucial function where all failures are coming on the surface. Where all components are to be available
simultaneously to complete assembly. This is important stage because if component supply is interrupted
assembly function stops. Many times the components cannot be supplied due to selection and use of traditional
manufacturing techniques used at the time of sample lot submission. These short cuts taken during development
phase are becoming hurdles at the time of commercial or bulk production of assembly. Selection of most
suitable and advance techniques for manufacturing of all components gives quality and quantity of all
components and streamlines assembly functions. Keen approach towards manufacturing techniques eliminates
quality and productivity problems which occur at the supply stage of the product. This also derives long term
benefits such as customer satisfaction gain, product life cycle growth.

KEYWORDS: Manufacturing techniques, productivity, product life cycle

I. Introduction

This paper presents and discuses the results of the research work of application of advance
manufacturing techniques used for long term elimination of quality and productivity problems of
electrical contacts required for electro-mechanical power entry products. Due to highly competitive
global market the time available for design, development and sample submission of product assembly
is very short. Every manufacturing industry has to take each customer enquiry as an opportunity for
business growth. After submission and approval of sample lot of new developing products the next
immediate demand of the customer is bulk supplies of products. At this juncture the problem faced by
manufacturing organization and they are unable to expedite the supplies as per customers schedules.
This problem was taken for investigation after performing why-why analysis with related design and
development team for this problem. We understood that the root cause for occurrence of this critical
situation lies in the fact that is supplier has used traditional manufacturing techniques for
supplying sample lots of brass electrical contacts. This product is socket assembly. The assembly
has three varieties of components viz-Two types of plastic covers, three Brass contact of same
specifications, and pair of mild steel fasteners. The BOM of the product indicates that Brass contact
is a A class component and the supplies of these components are not made from Jamnagar based
vendor is unable to supply contacts in time results in continuous stoppage of assembly results in
business loss. This product is socket assembly of export market and brass electrical contact play key

501 Vol. 2, Issue 1, pp. 501-507

International Journal of Advances in Engineering & Technology, Jan 2012.

©IJAET ISSN: 2231-1963

role in the product assembly function. The samples are approved and at latter stage customer demands
commercial supplies of the product but the product supplies cannot be rushed with required rates e
due to low productivity and quality of contacts at vendor end. Frequent occurrence of this situation
ultimately resulted in the loss of customer satisfaction. This subject is very sensitive for the
organization starving for business growth. This is so alarming that this product has further no future
if this situation continues to remain the same. This has become major obstacle in export business
growth of the organization. Plastic covers and fastener pair have no problems for quality and
productivity. Hence to overcome this tricky business situation we focused on brass electrical contact
manufacturing technology used by vendor and used hot extrusion technique followed drawing as
advance metal forming techniques to give near and neat shape to T section of contact.

II. Contact Specifications

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Figure. 1 Contact
This figure above shows sectional, front & isometric view of said contact. The basic material is 70-30
Brass.

2.1 Research Methodology The three phase research methodology is used to achieve desired results.

Phases are as below.

Phase 1-Analyze existing Brass contact manufacturing technique and to find causes for low

productivity and high rejections at various stages.

Phase 2 -To evaluate and compare probable alternative manufacturing technologies and select the

most suitable one.

Phase 3-To select and establish most suitable advance manufacturing technique to come out with

productivity and quality solutions for bottleneck contacts due to which the assembly work of the

product is badly affected. This should solve organizational problem and rewarded new life to the

product.

Existing technique is manufacturing raw casted contacts using green sand molding technology and

machining all over. Technical evaluation of existing manufacturing technology this is done in two

steps.

Step 1 -Evaluation of green sand molding and casting technology. Step2-Evaluation machining

processes of the contacts to the finish dimensions.

The critical points observed as apart of casting process limitations are a) We must provide machining

allowance of 2.50 mm all over the contact surfaces since we cannot get finish contacts by casting

technique. Due to low sectional thickness (refer drawing) faster cooling of castings takes place

results in hard scale formation b) For lower cross sections streamlining metal flow a big question

mark. As a combined effect of these two heavy casting rejection occurs. This is as tabulated in table

No 1

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Vol. 2, Issue 1, pp. 501-507

International Journal of Advances in Engineering & Technology, Jan 2012.

©IJAET ISSN: 2231-1963

Table 1. Type of defect and rejection percentage

No

Type of defect

%

1

Pin holes and unfilled

12

2

Chilled surfaces

13

3

Scaling and blow holes

22

The total rejection is 47%. Existing sequence of operations of manufacturing of raw casted contacts is
in total 14 operations required to get finish contact.

Table 2 indicates process and estimation of the cost incurred.

No

Operation

Time

Estimate Base.

Per contact. (INR)

1

Melting

On Wt. basis

Rs 30 /Kg. contact Wt.
lOgm.

[NR 0.30

2

Material cost.

Wt. basis

RateINR315/Kg

INR 3.15 (Raw Contact Wt.
10 gm.)

3

Design ,Dev. of pattern.

72Hrs @250

!NR/Hr=Rs

18000

One time cost.

INR 0.18 (Pattern life 100000
castings)

4

Mounting.

24 Hrs @INR
250.

6000 One time.

To amortize on 1000 molds
ie25000castings =INR 0.24

5

Mold ing

100 /shift

1NR 500/Shift

25 castings per mold.
1NR.0.13.

6

Pouring.

10 Min.

2 persons INR 500/shift

2=00 Divide by 25 No of
patterns works INR 0.10

7

Knock out..

2Min.

1 person

1=00/25 works to INR 0.04

8

Fettling and cleaning

On Kg basis

1=50 works to INR 0.15

9

Hardness testing.

On per piece basis

0=20 works to INR 0.02

10

Facing.

0.5 Min

INR 80/Hr.

INR 0.66

11

Straddle milling.

0.25 Min

INR 80/Hr

[NR 0.33

12

Slot milling.

0.5 Min

1NR80/Hr

[NR 0.66

13

Drilling.

0.2Min

1NR25/Hr

[NR0.10

14

Tapping.

0.30Min

INR 25/Hr

[NR 0.15

The production cost per piece of the contact is Rs.6.07.Add hidden cost5% & the net cost

=Rs.6.37/Pc.

It is well understood that the process is non productive and gives poor quality. Cannot be used further

to satisfy customer's higher quantity demands. Hence search of better manufacturing technique is

must.

Research content Phase -2: This mainly covered study of probable alternative techniques through

industrial surveys and literature review this is as per Table 3.

Table 3 Industrial Survey findings

No

Name

Advantages

Limitations

1

Die forge.

Better Material Utilization

Further finishing by machining
required.

2

Powder Metallurgy

Finish parts. No machining

Higher set up and tool cost.

3

Press Tool .

Productive for low thickness
parts.

Poor tool life. Higher tool maintenance
cost.

4

Extrusion

Higher productivity. More
Yield..

Higher set up cost. Usable only for
long sections.

The above table concludes that for the said contacts it is preferable to select forward hot extrusion as
metal forming technique to extrude T-sectional long strips with additional allowance of 0.25 mm per

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Vol. 2, Issue 1, pp. 501-507

International Journal of Advances in Engineering & Technology, Jan 2012.

©IJAET ISSN: 2231-1963

face and further to use drawing technique to remove this allowance to get finish section dimensions.

Drawing being cold working operation gives better surface finish and closer tolerances as per drawing

in figure 1 .

Research content Phase3: Practical implication of Hydraulic forward extrusion and drawing

operations. These are very high productive techniques hence decided not to make any investment in

these set ups but to outsource from reliable sources with available spare capacity. The principle of

outsourcing is no investment needed in set up. We buy only technology and overhead cost saved.

2.2 Extrusion Die Development

One important step of extrusion die design & development activity is explained in following Bill of

Material Table 4.

Table 4 Extrusion die design & development activity

No

Part

R/M

Heat treatment done if any

1

Sub bolster

H13

Std part of press

2

Bolster

Hll

Std part.

3

Backer

Hll

Not required.

4

Die

H13

Quench and temper.

5

Die ring.

Hll

Not required.

6

Die slide

Hll

Not required.

7

Dummy block

Hll

Not required.

The manufacturing of various die components is done by using Machines such as ram turret milling,
spark erosion and wire cutting ,as per need lapping is also done manually. The half sectional view of
two cavity Extrusion die is as shown in the Figure 2.

DteRIng

"v Briryston

Belsstiw

. Sectional, view of two cavity extrusion Die

Figure 2 Sectional view of two cavity extrusion Die
2.3 Extrusion Press Capacity estimation

Other key area is finding extrusion press capacity. This works out to 250 MT from standard practice
based on brass max shear stress and extrusion Ration. This is cross verified by comparing capacity
required for extrusion of similar section components. For initial production runs single cavity die
design is used so that further two cavity die can be used after freezing die dimensions. The shrinkage
allowance provided is 2% on all linear cross sectional dimensions for brass. The weight of input and
output of brass remains constant in the process. Input weight = Output weight .On these basis output
extrusion sectional length is calculated. Extrusion ram speed is output speed of the cross section
extruded. This is 1200 mm / Min. & slitting saw width is decided 1 mm. By slitting we cut extruded
sections to suitable lengths. In this case this is 1000 mm. After extrusion these long sections are
further drawn so as to get cross sectional finish dimensions. After slitting we have to do three
machining operations viz.l Side slot milling by using SPM & HSS side and face cutter as cutting
tool.2 Drilling by using SPM .3Tapping by tapping machine. For design and development of These

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Vol. 2, Issue 1, pp. 501-507

International Journal of Advances in Engineering & Technology, Jan 2012.

©IJAET ISSN: 2231-1963

SPMS we have made a two engineers team dedicated to work with SPM developing vendor. The
prime objective of developing special purpose machines is to reduce manual handling of work piece
to reduce labor fatigue and fool proofing of machining operations. The production sequence and cost
estimation by using this technique as shown in the table Table 5.

Table 5 Production sequence and cost estimation

No

Name of the operation

Machine or set up used

Estimate Base .

Per contact Cost.

1

Raw material cost

Market Rate

INR315/Kg

INR.3.15

2

Billet casting
Pouring.

Melting +Pouring into
molds

INR 20/kg

12 Kg Billet wt=INR
240/Billet =INR 0.25

3

Heating of the billet

Oil/gas fired furnace

INR 10/kg

INR 120/billet= INR 0.12

4

Die Design,
development

Tool room machines

48 Tool room Hrs.
INR 250/Hr

INR 12,000/- is effective
of INR 0.12

5

Loading the die on
extrusion press

Manual( 30 Two
persons)

INR. 31.25 /Loading
INR=0.05

6

Extrusion and
drawing

Hydraulic extrusion
press.

INR/Hr

280

Ram Speed 1200 mm.
/Min=INR 0.05

7

Slitting the extrusion
to suitable length

Slitting saw

INR 8/Hr
Time 0.5 min

INR 0=06

8

Inspection

Manual

INR 30/Hr

INR0.02/Pc

9

Milling

SPM

INR80/Hr

INR0.22/Pc

10

Drilling

SPM

INR12/Hr.

INR0.05/Pc

11

Tapping

SPM

INR12/Hr

INR0.04/Pc

; tota

number of operatior

is is 11 Nos.

2.4. Commercial impact of the Research Cost per piece of the contacts as per advance
manufacturing technology is INR 4.13 /Pc add 5% in this for hidden cost.=INR 4.33 /Pc. Cost saved
per contact INR 2.04.Cost saved /Month=INR 612000 Qty. Basis 300000 is average
Annual savings= INR 6120000 assuming ten month assuming ten months business per year.

7

dating

5 -

Extrusion

AC

2
1

Figure 3 Cost per contact comparison
2.5 Quality improvement

Initial cumulative rejection stages =47%. Rejection after using advance manufacturing technique
average -7 %. Refer graph plotted from for three months field rejection data for both casting and
extrusion process .Figure 4 as below^ The Graph shows reduction in percentage rejection from 47 to
average 7 percentage for 3 months.
Figure 4 indicates process rejection.

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Vol. 2, Issue 1, pp. 501-507

International Journal of Advances in Engineering & Technology, Jan 2012.

©IJAET ISSN: 2231-1963

extrusion
process

Castingand

Machining
process

Figure 4 Reduction in percentage rejection
2.6 Lead Time Reduction

Lead time reduced from 15 days to 7 days a batch of 100 000 Nos.

20
15
10

5

Lead Time in days

Casting Process Extrusion Process

Figure 5 Lead Time Reduction
Figure 5 clearly indicates reduction in lead time.

2.7 Overall advantages

The overall advantages are lead time reduction and productivity and quality enhancement. Assembly
function runs in time .Customer expectations satisfied in time.

2.8 Results and Discussions

The estimated cost as per casting and machining process used initially was INR 6.21 per piece of
electrical contact and after implementation of extrusion technique, the cost reduced to INR 4.10 i.e.
there is net cost reduction of INR 2.11 per piece or say around 33%. Any saving done due to use of
advanced manufacturing technique directly contributes to the net profit of the product. Due to high
cost competition in the market, this cost reduction benefit is passed on to the customer to make
product more competent in the global market. If we look at cycle time required for completing a batch
of contacts we see that previously lead time required was 15 days. This is now reduced to 7 days. In
the long run manufacturer can think of reducing wip inventory. This is again long term benefit to the
organization. This research has extended product life cycle of the said product which was landed into
trouble at mass production stage itself.

III. Conclusions

Engineering manufacturing houses engaged in the design and development of products and selling
their products in high competitive market must go for study and practicing use of advance

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Vol. 2, Issue 1, pp. 501-507

International Journal of Advances in Engineering & Technology, Jan 2012.

©IJAET ISSN: 2231-1963

manufacturing techniques suitable to all class of components with priority for A class components
not at latter stage but at the design, development and prototyping stage of the components. This
derives long term benefits to the organization which mainly includes higher productivity, consistent
quality and more competitive prices for sales of the product. By this organization is in position to sell
the product at lower prices and capture more and more market at global levels. The cost reduction is
also achieved because of material waste reduction due to utilization of advanced manufacturing
techniques. Due to higher productivity the return on investment also starts at initial phase of mass
production. This is long term economic advantage to manufacturing organizations and they should
consistently starve for establishing a system of appropriate manufacturing technique selection through
team working with special focus on continuous assessment and updated knowledge of advanced
manufacturing techniques.

Acknowledgements

We are heartily thankful to Vikrant Industries, Jamnagar, Gujarat, INDIA for allowing us to do field
work for solving their bottle neck in Electric Contact manufacturing and providing necessary
resources and setup for performing necessary research and trials.

References

[1] Rao V. Dukkipatty, Pradip K. Ray. Process design for economy and reliability Publication. Publication -

New Age International -First Edition I.S.B.N.-978-81-224-2661.
[2] ASM Handbook Volume- 14,Forming and forging ASM International -The materials information society-

ISBN-87170-007-7(Vl) SAN-204-7586 Page. No-255- 259
[3] Richard W. Heine, Carl Loper, Philip C. Rosenthol Principles Of Metal Casting , Publication— Tata Mc.

GrawhillJSBN- 1 3,978-0-07-099348-.
[4] Philiphs Ostwald, Jairo Munz, Manufacturing Processes and Systems by Pub. - Wiley, India Pvt. Ltd.

ISBN-978-81-265-1894-
[5]Fundamentals of Tool Design - American Society of Tool and Manufacturing Engineers, A Publication of

ASTME Manufacturing Engineering Series, Pub. Prentice Hall Inc. New lersy.)
[6] Process and design for manufacturing Sheriff Dlwakil, Narinder Kumar Lijhara for overseas press India (P)

Ltd.ISBN 81-88689-70
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8 l-224-3089-9.Pg no 274-303.

Authors

Virajit A. Gundale is presently working as the Professor & Academic In-charge at Sharad
Institute of Technology College of Engineering, Yadrav Dist. Kolhapur, India. He obtained
his B.E. in Mechanical Engineering from Shivaji University and M.S. in Manufacturing
Management from BITS, Pilani. He obtained his Ph.D. in Manufacturing Technology from
UNEM, Costa Rica in 2010. His total experience including Teaching and Industry spans more
than 11 years. He is also a fellow of the International Institute of Mechanical Engineers, South
Africa.

Vidyadhar M. Dandge is presently working as the Assistant Professor at Dr.IJ.Magdum
College Of Engineering laysingpur, Dist-Kolhapur, India. He obtained his B.E. in Mechanical
Engineering from Karnataka University and M.E (Production) from Shivaji University. His
total experience including Teaching and Industry spans more than 25 years.

t

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