 Open Access
 Total Downloads : 1722
 Authors : Ankit B. Sidhpara, Vashim I. Kureshi, Prof. Pinank A. Patel
 Paper ID : IJERTV2IS50731
 Volume & Issue : Volume 02, Issue 05 (May 2013)
 Published (First Online): 23052013
 ISSN (Online) : 22780181
 Publisher Name : IJERT
 License: This work is licensed under a Creative Commons Attribution 4.0 International License
Comparision Of Manufacturing Methods And Analysis Of Connecting Rod For Reducing Cost
Ankit B. Sidhpara, Vashim I. Kureshi, Prof. Pinank A. Patel Department of Mechanical Engineering
Marwadi education foundations group of institutions, Rajkot, 360 003, Gujarat, India
Abstract
This Paper mainly focuses to reduce weight and manufacturing cost of the Air compressor connecting rod while maintaining or improving strength. The connecting rod is one important part of compressor. Existing steel material Connecting rod is manufactured by using Forging Process. Other S.G. iron material connecting rod is manufactured by sand casting Process. The objective of this project is to make 3d model of connecting rod using Pro Engineer software and apply static analysis, Buckling analysis and Fatigue analysis though Ansys 12.1 software. After perform analysis on steel material connecting rod and S.G. iron material connecting rod result of both connecting rod Analysis is compared. After that cost calculation is performed. That cost calculation shows that S.G. Iron material connecting rod has same strength as steel material connecting rod with reduction in unit cost of connecting rod.
Key words: Connecting Rod, S.G. iron ,Pro/E wildfire 4, Finite Element Analysis, Ansys 12.1, cost calculation.

Introduction
Connecting rod is an important component in an engine. Connecting rod used to connect between piston and crankshaft. In a reciprocating piston engine, the connecting rod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion.
Manufacturing costs and strength of a connecting rod depend on various service conditions, geometry, types of materials and manufacturing processes. Therefore, material and manufacturing processes are attempted in this study as key points.
To aid decisionmaking when a choice Is to be made among various alternatives for geometric, material or process parameters, an early cost estimation tool is useful and perhaps even essential on manufacturing cost. It can also be used during design iterations to verify if the targeted ost can be.

Manufacturing Methods
A connecting rod in a compressor is subjected to inertial forces. It should be able to withstand these forces for a fatigue strength. The connecting rod undergoes cyclic tension, compression stress. Furthermore the connecting rod is subjected to a large compressive load so that it is imperative that buckling does not occur. So for this purpose there are mainly three methods of manufacturing.

Sand csting process
Sand casting, also known as sand molded casting, is a metal casting process characterized by using sand as the mold material. The term "sand casting" can also refer to an object produced via the sand casting process. Sand castings are produced in specialized factories called foundries. Over 70% of all metal castings are produced via a sand casting process.

Forging
Forging is a manufacturing process involving the shaping of metal using localized compressive forces. Forging is often classified according to the temperature at which it is performed: "cold", "warm", or "hot" forging.

Powder Forging
Powder forging (P/F) is used to produce components essentially free of internal porosity. The associated properties are equivalent to those developed in conventional precision forged products made from billets. The P/F process is performed in three steps with the first two similar to normal Powder Metallurgy (PM) processing. A preform is pressed as a conventional PM compact.

Materials
A connecting rod is one of the most mechanically stressed components in air acompressor. The
objective of the activity is to select the appropriate material for a connecting rod where the constraints are to make the product as light and cheap as possible and yet strong enough to carry the peak load without failure in high cycle fatigue.

Mechanical Properties of C40 steel
Density = 7800 kg/m^3
Youngs Modulus = 210000 mpa
Possions Ratio = 0.3
5.1 Theoritical static analysis of steel material connecting rod
Available data : Power P = 1 hp RPM N = 750
Piston Dia. D = 65 mm
Conn. Rod length L = 182 mm Weight Of Piston assembly = 0.6 kg Weight Of Conn. Rod = 0.48313 kg Length of stroke l = 64 mm
Crank radius r = 50 mm
Tensile Ultimate strength = 680 mpa
Tensile Yield strength = 330 mpa
Angular velocity =
=
3.2 Mechanical Properties Of ENGJS600 3 OR ISO 1083 6003 OR IS 1865 SG 600/3 S.G. Iron material
=78.5 rad/sec Ratio n = L = 3.5
1
1
r
p
p
Now from the applied thermodynamics I = BP =
Density = 7100 kg/m^3
Youngs Modulus = 174000 mpa
Poissions Ratio = 0.275 Tensile Ultimate strength = 600 mpa
1×748 = 0.935 Kw
0.80
Where, indicated power, Ip = pm l A n
Tensile yield strength = 370 mpa
So, pm
= Ip = 0.35 N/mm2
l A n

Modeling of connecting rod
3D model of connecting rod is created using Pro Engineer 4 software. Different view are shown
A = Cross section area of piston = D2
4
= 652 = 3316 mm2
4
below.
Max explosion pressure, Pmax
= 9 * pm
= 3.17 N/mm2

Force on the piston due to gas pressure

FL= D2 P



max
Figure 1 3D model

Analysis of Connecting rod
The first step in order to start the analysis with the Ansys programs help is to choose the type of analysis. The type of analysis will decide which type of results will be obtained. For the case of the connecting rods analysis, a structural analysis will be performed. The model is made in Pro/E Wildfire

and saved within this program in *.STP format.
= 10518 N

Inertia force of Reciprocating Parts

r
r
FI = m 2 r cos + cos 2
n1
Where, the angular velocity of the crank is, =
2N
60
And the mass of reciprocating parts is given by,
mr = [mass of piston assembly + (1/3) mass of connecting rod] = 0.76 kg
The inertia force on the connecting rod will be maximum at the top dead centre position where ( = 0). So when = 0 then cos = 1 and cos 2 = 1 and substituting the above values and get;
r
r
FI = m 2 r 1 + 1
n1
FI = 301 N
FN ( net force ) = FL – FI = 10217 N
1 = = 42.92 N/mm2
3016 17

Theoritical static analysis of S.G. Iron material connecting rod
Power P = 1 hp RPM N = 750
Piston Dia. D = 65 mm
Conn. Rod length L = 182 mm Weight Of Piston = 0.6 kg
Weight Of Conn. Rod = 0.43977 kg Length of stroke l = 64 mm
Crank radius r = 50 mm
Angular velocity = 78.5 rad/sec Ratio n1 = 3.5
p
p
Now from the applied thermodynamics I = BP =
1×748 = 0.935 Kw
0.80

Buckling load of connecting rod ( steel )
The connecting rod is a slender engine component that has considerable length in proprtaion to its width and breadth. It is subjected to axial compressive force equal to maximum gas load on the piston. The compressive stress is of significant magnitude. Therefire the connecting rod is designed as a column or strut.
Figure 2 Cross section of connecting rod Moment of inretia about Xaxis Ixx = 3 11^3
12
= 10566 mm^4
Radious of gyration about Xaxis Kxx
So, pm
= Ip = 0.35 N/mm2
l A n
Kxx^2 =
A = Cross section area of piston = D2
4
= 652 = 3316 mm2
4
Max explosion pressure, Pmax = 9 * pm
Kxx = 8.07 mm
After deciding the proportions for Isection of the connecting rod, its dimensions are determined by considering the buckling of the rod about Xaxis (assuming both ends hinged) and applying the Rankins formula. We know that buckling load,
= 3.17 N/mm2

Force on the piston due to gas pressure
FL= D2 P
Pcr = c
L
L
1+a
K xx
a = 1/7500 for steel c = 300 N/mm^2
4 max
= 10518 N

Inertia force of Reciprocating Parts

r
r
FI = m 2 r cos + cos 2
n1
mr = [mass of piston assembly + (1/3) mass of connecting rod] = 0.74 kg
r
r
FI = m 2r 1 + 1
n1
Pcr = 45545 N

Buckling load of connecting rod ( s.g. iron material )
MoI about Xaxis Ixx = 3 11^3 = 10556 mm^4
12
Radious of gyration about Xaxis Kxx
FI = 295 N
FN ( net force ) = 10223 N
1 =
3016 17
= 42.95 N/mm2
Kxx = 8.07 mm
1 + a L
1 + a L
P c
cr =
Kxx
a = 1/1600 for s.g. iron c = 400 N/mm^2
Pcr =49300 N

FEA Static Analysis ( Steel )
Any continuous object has infinite degrees of freedom. Finite Element Method reduces this from infinite to finite by means of Meshing (i.e. creating nodes and elements). The goal of meshing in ANSYS Workbench is to provide robust, easy to use meshing tools that will simplify the mesh generation process. These tools have the benefit of being highly automated along with having a moderate to high degree of user control. Here Meshing element chooses is 10 nodes Tetrahedron named Solid187.
Figure 3 Apply meshing

Loading and Boundary Conditions

Figure 4 Force apply at piston end
Figure 5 Fixed at crank end
Figure 6 Max. Principal stress

FEA Static Analysis ( s.g. iron )

Loading and Boundary Conditions

Figure 7 Force apply at piston end
Figure 8 Fixed at crank end
Figure 9 Max. principal stress

FEA Static Analysis result

Steel connecting rod
Type
Applie d
Fixed at
Max. Principal
Max. Princip
OF
Net
Stress (
al
Loading
Force at
MPA )
Stress ( MPA )
Theoritiac al
FEA
compressi
Piston
Cranc
1 =
1
ve
end
k end
42.92
= 39.40

S.G. Iron Connecting rod
Type
Applie d
Fixed at
Max. Principal
Max. Princip
OF
Net
Stress (
al
Loading
Force at
MPA )
Stress ( MPA )
Theoritiac al
FEA
compressi
Piston
Cranc
1 =
1
ve
end
k end
42.95
= 39.92


Buckling analysis ( steel )
Figure 10 Buckling analysis
Figure 11 Equivalent stress

Buckling analysis ( s.g. iron )
Figure 12 Buckling analysis
Figure 13 Equivalent stress

Fatigue Analysis of steel Connecting Rod
Figure 14 Fatigue Life analysis of steel
Figure 15 Fatigue safety factor analysis of steel
5.6 Fatigue Analysis of s.g. iron Connecting Rod
Figure 16 Fatigue Life analysis of S.G. iron
Figure 17 Fatigue safety factor analysis of S.G. iron

Cost calculation
6.1 Casting Cost Calculation
Minimum order quantity is 1000 connecting rod.
ESTIMATION OF COST OF CASTINGS
The total cost of manufacturing a component consists of following elements :

Material cost.

Labour cost.

Direct other expenses.

Energy Cost.

Overhead expenses.

Material Cost
C material ( C mat )= C direct + C indirect C direct = C um * Wt * Fm* Fp * Ff
Cum ( unit material cost ) = 80 INR/ kg Wc ( casting weight ) = 0.43977 kg Fm ( melting loss factor ) = 1.02
Fp ( pouring loss factor ) = 1.01 Ff ( fettling loss factor ) = 1.05
Psc ( process scrap ) = 40 % of weight of part = 0.1759 kg
Wt = Wc +Psc = 0.6156 kg
C direct = 80 * 0.6156 * 1.02 * 1.01 * 1.05
= 53.27 INR
C indirect = C ms + C cs
Mould box size = 0.35 m * 0.20 m * 0.20 m Volume = 0.014 m^3
Density of Green sand = 800 kg/ m^3 Weight of Sand = density * volume of box
= 800 * 0.014 = 11.2 kg/m^3
Mould sand cost = 1.2 INR / kg
C ms = 1.2 * 11.2 = 13.44 INR
Core volume = 2.07*10^4 m^3 Weight of the core = Volume * Density
= 2.07*10^4 * 800 = 0.1656 kg
Cost of core sand = 3 INR / kg = 3 * 0.1656
C cs = 0.49 INR
C indirect = C ms + C cs
= 13.44 + .49
= 13.93 INR
C material = C direct + Cindirect
= 53.27 + 13.93
C mat = 67.2 INR

labour cost

Requires no. Of labour
Core making = 1 Mould preparation = 2
Handling and pouring = 2 Machining and cleaning = 1

Rate of Labour charge
Core making ( 1 ) = 14 INR /hr * 1 = 14 INR Mould preparation ( 2 ) = 15 INR /hr * 2 = 30 INR
Handling and pouring ( 3 ) = 12 INR /hr *2 = 24 INR Machining and cleaning ( 4 ) = 10 INR /hr * 1 = 10 INR
Average total time for making 1 conn. rod = 0.5 hr Total labour rate ( 1+2+3+4 ) = 78 INR
Total cost for labour charge = 0.5 * 78
Cl = 39 INR


Direct other expences
Pattern Cost = 10000 INR Pattern Life = 3500 pieces
Pattern cost for one connecting rod ( C p )
= 10000/3500 = 2.85 INR
Machining and cleaning cost ( C ma ) = 40 INR

Energy cost
C energy cost ( C e )= C melting + C other energy C melting = C ue * Fn * Wc * Fy * Fr * Fm * Fp * Ff
Cue = 6 INR/unit
Fn ( Furnace efficiency ) = 2 Wc = 0.49
Fy ( over all yield factor ) = 1.3
Fr ( casting rejection factor ) = 1.05 Fm = 1.05
Fp = 1.07
Ff = 1.07
C melting = 6 * 2 * 0.49 * 1.3 * 1.05 * 1.05 * 1.07 *
1.07 = 9.64 INR
C energy cost = C melting + C other energy
= 9.64 + 0 ( C e ) = 9.64 INR

Overhead expences
Salery and wages of the staff for this one connecting rod C o= 22.84 INR
Total cost of casting connecting rod
Total cost = C mat + Cl + C p + C ma + C e + C o
= 67.2 + 39 + 2.85 + 40 + 9.64 + 22.84
= 181.53 INR
6.2 Forging cost calculation
Minimum order quantity is 1000 connecting rod.
Estimation of Cost of Forgings
The cost of a forged component consists of following elements :

Cost of direct materials.

Cost of drect labour.

Direct expenses such as cost of dies and cost of press.

Overheads.

Cost of Direct Material
Net weight w = 0.48313
Shear ( Ls ) = 5 % of W = 0.0241563 kg
Tonghold loss ( Lt ) = 0.025 * 3.14/4 * 0.030^2 = 0.13776 kg

Scale loss ( Lsc ) = 6 % of W = 0.02898 kg
Flash loss ( Lf ) = 2.298 * 10^5 * 7800
= 0.1792 kg

Sprue loss ( Lsp ) = 7 % of W = 0.03381 kg
Total material loss = Ls + Lt + Lsc + Lf + lsp
= 0.0241565 + 0.13776 + 0.02898 + 0.1792
+ 0.03381 = 0.4039 kg
Gross weight = Net weight + Material loss
= 0.48313 + 0.4039
= 0.8870 kg
Ratio of gross weigth to net weigth ( C gr )
= 0.8870/0.4039 = 1.8359
C ut = Unit cost of material = 80 INR /kg C material ( C m ) = W * C ut * C gr
= 0.48313 * 80 * 1.8359
C m = 70.96 INR


Direct labour cost
Direct labour cost ( C ld ) = t Ã— l
Wh. t = time for forging per piece (in hours) = 0.5 hr l = labour rate per hour.
N = no. Labours requires = 5
Rate of 1 labour for Heating billet = 21 INR /hr Rate of 1 labour for Press operation = 32 INR /hr
Rate of 1 labour for Handling part = 16 INR /hr * 2 = 32 INR /hr
Rate of 1 labour for machining and cleaning = 26 INR /hr
Total labour rate = 21 + 32 + 32 + 26 = 111 INR /hr
C ld = t * l = 0.5 * 111= 55.5 INR

Direct expences
Let cost of Die = Rs. X = 30000
No. of components that can be produced using this die (i.e., die life) = Y components = 3000
Cost of die/component = Rs. X/Y = 30000/3000
= 10 INR
Let cost of press = Rs. A = 400,000 Life of press = n years 5
= n Ã— 12 Ã— 8 Ã— 6 Ã— 4 = 2304 n hours
(Assuming 8 hours of working per day, 6 days a week and 4 weeks a month in 12 months of year)
Hourly cost of press =
2304
No. of components produced per hour = N = 10
rod. Cost reduction in per unit is near about 15 % cost of steel material connecting rod.
8. references

Mechanical Properties of Spheroidal Graphite Cast Iron Made by Reduced Pressure Frozen Mold Casting,Process
Materials Transactions, Vol. 50, No. 5 (2009) pp.
1128 to 1134 #2009 The Japan Institute of Metals

Fatigue Numerical Analysis for Connecting Rod
International Journal of Engineering Research and Applications (IJERA) ISSN:22489622 www.ijera.com Vol. 2, Issue 6, November
December 2012, pp.628 632

Stress Analysis of Connecting Rod of Nissan Z24 Engine by the Finite Elements Method
Australian Journal of Basic and Applied Sciences, 5(12): 20842089, 2011 ISSN 19918178

Modeling and Analysis of Two Wheeler Connecting Rod
Cost of using press per component = Rs.
2304
International Journal of Modern Engineering


Overheads cost
( C de ) = 3.47 INR
Research (IJMER) Vol.2, Issue.5, SepOct. 2012 pp 33673371 ISSN: 22496645

Stress Analysis of I.C. Engine Connecting Rod by
The overheads are generally expressed as percentage of direct labour cost. Overhead cost ( Co ) = 150 % of labour cost = 83.25 INR
Total Cost of Forging connecting rod Total cost = C m + C ld + C de + C o
= 70.96 + 55.5 + 3.47 + 83.25
= 213.18 INR
7. Conclusion
The Air compressor connecting rod is generally made by steel material from forging process. This connecting rod can be replaced by S.G. iron material connecting rod which is made from sand casting process. Here in this research work, from various analysis i found that S.G. iron material connecting rod has same strength as steel material connecting rod. When no. of quantity require of connecting rod is less, then unit cost of connecting rod of S.G. iron material is less compare to steel material connecting
FEM
International Journal of Engineering and Innovative Technology (IJEIT) Volume 1, Issue 3, March 2012
ISSN: 22773754

A Comparison of Manufacturing Technologies in the Connecting Rod Industry
Danielle Visser Department of Metallurgical and Materials Engineering Colorado School of Mines Golden, CO 80401

DEVELOPMENT OF COST ESTIMATION OF EQUATIONS FOR FORGING
A thesis presented to the faculty of the Russ College of Engineering and Technology of Ohio University In partial fulfilment of the requirements for the degree Master of Science John C. Rankin November 2005.

A textbook of Machine Design by R.S. Khurmi and J.K. Gupta

PSG Design data book