SSRG International Journal of Mechanical Engineering (SSRG-IJME) – volume1 issue 5 September2014

ISSN: 2348 – 8360 www.internationaljournalssrg.org Page 14

Analytical Report Based on the Design and Simulation of a Weld Fixture 1M. Vishala, M.Tech, 2P. Sampath Rao, M.Tech; [P Hd]

Mechanical Dept., VREC, Nizamabad- 503003

Abstract: — A fixture is a work-holding or support

device used in the manufacturing industry Fixtures are

used to securely locate (position in a specific location

or orientation) and support the work, ensuring that all

parts produced using the fixture will maintain

conformity and interchange ability Locating and

supporting areas must usually be large and very sturdy

in order to accommodate welding operations; strong

clamps are also a requirement. For high-volume

automated processes, milling fixtures usually involve

hydraulic or pneumatic clamps. In this project, we have

modeled a weld fixture by using PRO-E software which

is one of the software used for modeling components in

most of the design based industries.

While the modeling of the components the

material selection is carried out simultaneously based

on the design considerations related to loads, etc. Later

the stress and strain concentration, deformation on the

blade of the weld fixture have been found by applying

certain load on the blade, using the Finite Element

Analysis (FEA) by using ANSYS software that

provides best output within few seconds. Finally the

stress and strain concentration, deformation results are

presented in the report section of this document.

I. INTRODUCTION

A fixture is a work-holding or support device

used in the manufacturing industry. Fixtures are used to

securely locate (position in a specific location or

orientation) and support the work, ensuring that all

parts produced using the fixture will maintain

conformity and interchange ability. Using a fixture

improves the economy of production by allowing

smooth operation and quick transition from part to part,

reducing the requirement for skilled labor by simplifying

how work pieces are mounted, and increasing conformity

across a production run. A fixture differs from a jig in that

when a fixture is used, the tool must move relative to the

work-piece; a jig moves the piece while the tool remains

stationary.

Purpose of using these fixtures: A fixture's

primary purpose is to create a secure mounting point for a

work-piece, allowing for support during operation and

increased accuracy, precision, reliability, and interchange

ability in the finished parts. It also serves to reduce

working time by allowing quick set-up, and by smoothing

the transition from part to part. It frequently reduces the

complexity of a process, allowing for unskilled workers to

perform it and effectively transferring the skill of the tool

maker to the unskilled worker. Fixtures also allow for a

higher degree of operator safety by reducing the

concentration and effort required to hold a piece steady.

Economically speaking the most valuable function of a

fixture is to reduce labour costs. Without a fixture,

operating a machine or process may require two or more

operators; using a fixture can eliminate one of the

operators by securing the work-piece.

Location of fixtures: Locating the components

ensures the geometrical stability of the work piece. They

make sure that the work piece rests in the correct position

and orientation for the operation by addressing and

impeding all the degrees of freedom the work piece

possesses.

For locating work pieces, fixtures employ pins

(or buttons), clamps, and surfaces. These components

ensure that the work piece is positioned correctly, and

remains in the same position throughout the operation.

Surfaces provide support for the piece, pins allow for

SSRG International Journal of Mechanical Engineering (SSRG-IJME) – volume1 issue 5 September2014

ISSN: 2348 – 8360 www.internationaljournalssrg.org Page 15

precise location at low surface area expense, and

clamps allow for the work piece to be removed or its

position adjusted. Locating pieces tend to be designed

and built to very tight specifications.

Support: In designing the locating parts of a

fixture, only the direction of forces applied by the

operation are considered, and not their magnitude.

Locating parts technically support the work piece, but

do not take into account the strength of forces applied

by the process and so are usually inadequate to actually

secure the work piece during operation. For this

purpose, support components are used.

To secure work pieces and prevent motion

during operation, support components primarily use

two techniques: positive stops and friction. A positive

stop is any immovable component (such as a solid

surface or pin) that, by its placement, physically

impedes the motion of the work piece. Support

components are more likely to be adjustable than

locating components, and normally do not press tightly

on the work piece or provide absolute location. Support

components usually bear the brunt of the forces

delivered during the operation. To reduce the chances

of failure, support components are usually not also

designed as clamps

II. TYPES OF FIXTURES

Fixtures are designed specifically for an

operation and so these are named on the base of the

operation to be carried out with their help. Fixtures are

used to hold the work piece properly to carry out the

operations. Different types of fixtures are listed below.

a) Turning fixtures

b) Milling fixtures

c) Fixture for grinding

d) Fixture for broaching

e) Fixture for boring/drilling

f) Tapping fixture

g) Fixture for welding

h) Assembling fixture

III. VARIOUS MATERIALS USED FOR THE

MANUFACTURING OF A WELD FIXTURE

Steel specified by SAE (Society of Automobile

Engineers) and AISI (American Iron and Steel Institute)

classification and standards.eg. SAE 1020 first two digit

indicate the class to which the steel belongs, the last two

digit indicate carbon contain.

CLASS TYPES OF STEEL

1) 10XX Plain carbon steel

2) 11XX Free cutting (carbon )steel

3) 13XX Manganese steels

4) 2XXX Nickel steels

5) 3XXX Nickel –chromium steels

6) 4XXX Molybdenum steels

7) 5XXX Chromium steels

8) 6XXX Chromium vanadium steels

9) 7XXX Tungsten steels

10) 8XXX Nickel chromium molybdenum steels

11) 9XXX Silicon manganese steels

SAE 1015 and below are highly ductile and are used for

press work but not for fixture.

Development of fixture assembly for machining

The steps involved for development of fixture for

machining of keyways on eccentric shaft are as follows:

• Analytical design for fixture.

• 3 - D Modeling in SOLIDWORKS Wildfire 5.0

• Fixture assembly

• Analysis by using ANSYS.

Analytical design for fixture:

It is included that design of base plate, base v-

block, threaded block, supporting v-block, clamp,

hexagonal bolt with washer, supporting pin.

3D Modeling in PRO – ENGINEER Wildfire 5.0:

It is included that generating of 3D model of all

details part of fixture like base plate, blade, shim, spacer,

bolts, riser, etc.

Fixture assembly:-

SSRG International Journal of Mechanical Engineering (SSRG-IJME) – volume1 issue 5 September2014

ISSN: 2348 – 8360 www.internationaljournalssrg.org Page 16

It is included that assemble of all the details

part of fixture step by step is carried out.

Analysis by using ANSYS:

It is included that static analysis is carried out,

deflection and von misses stresses find by the use of

software.

Approach to fixture design:

• Analysis of the work piece drawing.

• Identification of candidate elements (machined

surfaces for locating, possible clamps positions,

important regions of work piece, tool path, possible tool

interference points, etc.).

• Support, location, clamping, base, guiding, fasteners

taken in consideration.

• Methodology (modular, vice, v-block, point surface,

angular structure, multi work piece clamping, 3-2-1

principle etc.).

• Identification of solutions (successful sequence of

local solutions and creation of a consistent solution,

selection of a pattern for modular fixtures (positioning

of 2 or more work pieces)

• Fixture design

• Building of assembly.

IV. REPORTS

Properties and study results while using Material-1

Name: Malleable Cast Iron

Model type: Linear Elastic Isotropic

Default failure Max von Mises Stress

criterion:

Yield strength: 2.75742e+008 N/m^2

Tensile strength: 4.13613e+008 N/m^2

Elastic modulus: 1.9e+011 N/m^2

Poisson's ratio: 0.27

Mass density: 7300 kg/m^3

Shear modulus: 8.6e+010 N/m^2

Thermal expansion

coefficient:

1.2e-005 /Kelvin

Reaction Forces

Selection set Entire Model

Units N

Sum X -3.4232

Sum Y 194.814

Sum Z -1.77892e-005

Resultan 194.844

MIN STRESS: 46.3515 N/m^2

MAX STRESS: 1.63153e+006 N/m^2

MIN DISPLACEMENT: 0mm

MAX DISPLACEMENT: 0.0167773 mm

SSRG International Journal of Mechanical Engineering (SSRG-IJME) – volume1 issue 5 September2014

ISSN: 2348 – 8360 www.internationaljournalssrg.org Page 17

MIN STRAIN: 1.57838e-010

MAX STRAIN: 5.94414e-006

Properties and study results while using Material-2

Name: AISI 1045 Steel, cold

drawn

Model type: Linear Elastic Isotropic

Default failure

criterion:

Max von Mises Stress

Yield strength: 5.3e+008 N/m^2

Tensile strength: 6.25e+008 N/m^2

Elastic modulus: 2.05e+011 N/m^2

Poisson's ratio: 0.29

Mass density: 7850 kg/m^3

Shear modulus: 8e+010 N/m^2

Thermal expansion

coefficient:

1.15e-005 /Kelvin

Reaction Forces

Selection set Entire Model

Units N

Sum X -3.42204

Sum Y 208.787

Sum Z -0.000247106

Resultan 208.815

MIN STRESS: 50.6343 N/m^2

MAX STRESS: 1.74812e+006 N/m^2

SSRG International Journal of Mechanical Engineering (SSRG-IJME) – volume1 issue 5 September2014

ISSN: 2348 – 8360 www.internationaljournalssrg.org Page 18

MIN DISPLACEMENT: 0mm

MAX DISPLACEMENT: 0.016426 mm

MIN STRAIN: 1.60404e-010

MAX STRAIN: 6.00121e-006

V. CONCLUSION

The main purpose, objective and also the

necessity of a fixture have been clearly presented in the

introduction of this project. A series or bunch or

numerous weld fixtures together work in an automated

industry in providing the better gripping as well as the

location of the part that are being manufactured.

In this project, we have modeled a weld fixture

by using PRO-E software which is one of the software

used for modeling components in most of the design

based industries. While the modeling of the components

the material selection is carried out simultaneously based

on the design considerations related to loads, etc.

Later the stress and strain concentration,

deformation on the blade of the weld fixture have been

found by applying certain load on the blade, using the

Finite Element Analysis (FEA) by using ANSYS software

that provides best output, i.e.,

Allowable deflection:

Malleable Cast Iron - 0.0167773 mm

Alloy steel - 0.016426 mm

Von misses stress in :

Malleable Cast Iron - 1.63153e+006 N/m^2

Alloy steel - 1.74812e+006 N/m^2

So it can be said that design is safe less than 10 KN

(scaled load) within few seconds. Finally the stress and

strain concentration, deformation results are presented in

the report section of this document.

REFERENCES

1. Colvin, Fred H.; Haas, Lucian L. (1938). Jigs

and Fixtures: A Reference Book. New York and London:

McGraw-Hill Book Company.

2. Henriksen, Erik K. (1973). Jig and Fixture

Design Manual. New York, N.Y.: Industrial Press Inc.

3. Jig and Fixture Design Manual by Erik Karl

Henriksen.

4. MECHANICAL ENGINEERING DESIGN [IN

SI UNITS] By: JosephShigley, CharlesMischke, Richard

Budynas, Keith Nisbett Edition: 8 Pub Date: 12-FEB-08.

5. Design data hand book by k.Mahadevan,k

Balaveera reddy,ISBN:81-239-0162-3

6. Design data book by B. D. Shivalkar, Design

Data Book, Central Techno. Publication, Nagpur.

SSRG International Journal of Mechanical Engineering (SSRG-IJME) – volume1 issue 5 September2014

ISSN: 2348 – 8360 www.internationaljournalssrg.org Page 19

AUTHOR DETAILS:

First Author: Manda Vishala received B.Tech Degree in Mechanical Engineering

from Vijay Rural Engineering College in the year 2012.

She is currently M.Tech student in Mechanical

Engineering Department, Machine Design Stream from

Vijay Rural Engineering College. And her research

interested areas in the field of Design and Construction.

Second Author: Polusani

Sampathrao working as Professor and Head in Vijay

Rural Engineering College. He has completed his

M.Tech in Mechanical Engineering and he has 24 years

of teaching experience. His research interested areas are

Design and Construction, Machine Design.