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http://www.iaeme.com/IJMET/index.asp 889 [email protected]
International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 11, November 2017, pp. 889–898, Article ID: IJMET_08_11_090
Available online at http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=11
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication Scopus Indexed
DESIGN AND ANALYSIS OF INDEXING TYPE
DRILL JIG FOR A MISSSILE COMPONENT
S R V Narsaiah .S, L.Radhakrishna
Department of Mechanical Engineering, S R Engineering College, Warangal, India
Lakshmipathi Yerra
Department of Mechanical Engineering, MLR Institute of Technology, Hyderabad, India
Prasanna V
Department of Mechanical Engineering, Kakatiya Institute of Technology, Warangal, India
ABSTRACT
The main objective of this project is to design an “Indexing Type of Drill Jig for a
missile component” by understanding the design concept, modeling it and to perform
the analysis by which the design is validated. The component design was studied in
detail and then the drill jig was designed, and tested and was found to produce
components of acceptable quality. The design of each component of jig was carried
out and the designs of all components are included in this thesis.
The evaluation technique generally involves the implementation of CAD software
that helps for designing drafting, assembly and analysis which may be useful for
customized applications and manipulations.
Keywords: Aluminum alloy, Drill jig, indexing, Cylindrical Shells.
Cite this Article: S R V Narsaiah .S, Lakshmipathi Yerra, Prasanna V and
L.Radhakrishna, Design and Analysis of Indexing Type Drill Jig for a Misssile
Component, International Journal of Mechanical Engineering and Technology 8(11),
2017, pp. 889–898.
http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=11
1. INTRODUCTION
Mass production aims at high productivity to reduce unit cost and Interchangeability to
facilitate easy assembly. This necessitates production devices to increase the rate of
manufacture and inspection device to speed-up inspection procedure.
Jigs are special purpose tools which are used to facilitate production like machining,
assembling and inspection operations. The mass production of work-piece is base on the
concept of interchangeability according to which every part produced within an established
tolerance. Jigs provide a means of manufacturing interchangeable parts since they establish a
relation with predetermined tolerances, between the work and the cutting tool. Once the jig is
Design and Analysis of Indexing Type Drill Jig for a Misssile Component
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properly set up, any number of duplicate parts may be readily produced without additional set
up
To increase production in drilling and milling process for cylindrical part, it is a challenge
to hold with an angle. This chapter discussed about project background to design jigs for
holding cylindrical part and the important to use jig in production.
1.1 Problem Statement
Holding cylindrical parts to be drilled is one of major problems faced by the manufacturing
company, especially small medium company. Sometimes they need expensive equipment to
holds the parts to be drill. Today, customers request in industries is increasing. So, the
company must find new method to improve their productivity.
2. DESIGN OF DRILL JIG
2.1. Design Procedure Of Indexing Type Of Drill Jig:
In this design of indexing type of Drill Jig for a casted component can be explained in a
systematic procedure.
Initially the component was designed, modeled and edited to get the necessary details for
designer of the jig.
Secondly the individual parts such as Base plate, Locator, Clamping Devices, Bushes, Jig
plate and Indexing mechanism has been developed. All these parts have been Designed,
Modeled, Drafting has been done individually.
The whole Design procedure was completed with the help of CAD software(Pro-e) by
which the software helps for Designing, Drafting, Assembly, and Analysis done by ANSYS
software and manipulations.
2.2. Component Details
The component for which the Jig is designed is a casted component which is having angular
hole inclined at 25degrees equi-shaped.
The particulars of the component can be stated as follows
• Component: Casted component
• Material: Al Alloy (LM20)
• Operation performed:
1. Boring.
2. Facing.
3. Drilling.
APPLICATION: These types of components are used in missile applications where
propulsion of gases takes place and the gases are released through Four Holes.
The design done with the help of AUTO CAD where the component is studied, designed,
modeled and drafting is done.
S R V Narsaiah .S, Lakshmipathi Yerra, Prasanna V and L.Radhakrishna
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Figure 1 Component Aluminium Casting Alloy (AL - Si12Cu)
2.3. Designing of Drill Jig Components
2.3.1. Design of base plate
The base plate designed here is also a casted component in which some cavities are provided
to reduce the material cost.
According to the dimensions of the component the base plate is designed and modeled and
it satisfies all the parameters to support the other parts.
Figure 2 Base Model Figure 3 Locator Model
2.3.2. Design of locator
A large portion of the tool designer`s time spent in the solution of locating and clamping
problems.
The type of locator used in this design is locator for circular surfaces in which the inner
diameter is taken as the locating surface of the component. The surface clamping and other
mechanisms are developed.
2.3.3. Design of clamping device
While performing a manufacturing operation it is necessary to provide some kind of
CLAMPING mechanism to hold the work piece in the desired position and to resist the
effects of gravity and operational forces.
The function of any clamping devices is that of applying and maintaining sufficient
counteracting and holding forces to a work piece to withstand all tooling forces.
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Proper clamp design based up on simplicity utility. This affects the total tool cost and
product cost and permits optimum production, surface finish, and tool life. Clamp selection is
based up on the analysis of the work piece. Clamp design considerations should include its
location.
Figure 4 Strap Clamp Arrangement
2.3.4. Design of bushes
Bushings are used to guide drills, reamers, and other cutting tools into proper position on the
work piece.
These are made of tool steel and are hardened to RC60 to 64 to provide a wear resisting
surface.
The length of bushing is quite important and it is approximately equal to twice the
diameter of the bushing Hole.
2.5. Indexing Type Drill Jig Assembly
From this assembly clearly observed that the drill axis consider with the hole axis hence the
design is satisfied for hole positioning in which the hole are inclined at 25degrees with base.
In the design of drill jig the most vital part is locator pin, because it is very much
important that how the relationship is maintained hence for this a locator pin is used.
Hence the concept of fool proof design is also satisfied, it means that any unskilled
operator can easily operate the jig since the component is arrested in the desired position and
there is no other chance for any positional errors.
Figure 5 Drill Jig Assembly isometric View Figure 6 Assembly of Drill Jig Top View
S R V Narsaiah .S, Lakshmipathi Yerra, Prasanna V and L.Radhakrishna
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3. CLAMPING FORCE
3.1. Calculation of Drilling Forces
One of the primary objectives for the design of Indexing type of drill Jig is the calculation for
the drilling forces.
The various calculation involved in the design process are explained in the following
While drilling the drill is subjected to the action of the cutting forces, which can be
continently resolved in to three components a tangential component Fz, a radial component
Fy and an axial component Fx, which is commonly referred to as thrust force in drilling. The
extrusion torque at the chisel edge is negligible and the torque acting in the drill is mainly
constituted by the Tangential force Fz. The radial component Fy on both lips usually cancel
out and are taken care of by the rigidity of the work piece and the drill.
Various empirical formulae exist for the calculation of the axial force F, and the torque.
But because of the uncertain conditions of the chisel edge and other more suitable factors,
there is considerable variation in the computed values. The following equation by Shaw and
Oxford can be used for the computation of the Torque and Thrust.
Drilling Thrust
The axial thrust F (N) can be estimated with the following formula:
F �kxk�xfxd
2
kc: specific cutting force (N mm−2
), which depends primarily on the material being
machined.
f: feed per rotation (mm)
d: tool diameter (mm) and
k: The coefficient depends on the geometry of the tip of the tool we can consider an
average value of 0.5.
From The Standard Tables,
kc = 1050N/mm2
f = 0.4mm
d = 24mm
k = 0.5
F �0.5x1050x0.4x24
2
Thrust Force =2520N
Drilling Torque
Example: drilling with a monobloc carbide spiral drill
Drilling torque is expressed as:
M� �k�xfxd
�
8000
Design and Analysis of Indexing Type Drill Jig for a Misssile Component
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Mc : drilling torque in m N
kc : specific cutting force in N mm−2
f: feed per rotation in mm
d: tool diameter in mm
M� �������. 4x24�
2
Torque=30.24N-mm
Cutting Parameters
The cutting parameters, and therefore the operating parameters of a drill for drilling
operations are:
d:tool and hole diameter (mm)
vc: cutting speed (m min−1
) which gives the rotational speed of the tool (rev min−1
)
N �1000xv�
∏xd
f: feed per rotation in mm rev−1
N=Spindle Speed in RPM
1400 �1000v�
π. d
vc=105.5 rev min−1
The resulting performance parameter is:
*vf: feed rate in mm min−1
vf = f × N
=0.4x1440
vf =576 mm min−1
The feed rate is one of the main factors of productivity, as it conditions chip-to-chip
Time t = p / vf.
p: hole depth
Time=20/576
=0.03472min.
t =2.08sec.
Power of Cut
Drilling with a Monobloc carbide spiral drill
Cutting power is expressed as:
S R V Narsaiah .S, Lakshmipathi Yerra, Prasanna V and L.Radhakrishna
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P� �k�xfxv�
8000
Pc: cutting power in kW
kc: specific cutting force (N mm−2
)
f: feed per rotation (mm)
d: tool diameter (mm)
vc: cutting speed (m min−1
)
P� �1050x0.4x24x576
240000
Cutting Power=4.431KW
3.2. Strap Clamp Design
For our case we are selecting a bolt of M8 size
Width of clamp W=2.3 x d+1.5748
Where‘d’ is the diameter of the bolt selectors
W=2.3 x (8) +1.5748=19.17
W=20 mm
Thicknesses of clamp for bolt dia. ‘d’ is given as
T=√ [0.85dA (1-(A/B))]
Where‘d’ is the diameter of the bolt
‘A’ is the distance between pivot & bolt=40
‘B’ is the span, pivot to work piece =60
‘W’ is the width clamp
‘T’ is the thickness of clamp
T=0.85x8x40x (1-(40/60))
T= 9.60≈10mm
Width of the slot C = d+1.5748
C = 8+1.5748=9.57
C = 10mm
3.3. Clamping Forces
CLAMPING FORCE OF STANDARD CLAMP STRAPS
Stud size Recommended torque
N-M
Clamping force
KN
Tensile force in stud
KN
M6 5.42 2.24 4.44
M8 12.20 4.0 8.00
M10 27.11 6.67 13.34
M12 47.45 9.78 19.57
M16 113.88 17.79 35.58
M20 223.71 28.02 56.04
M24 383.69 40.03 80.06
Design and Analysis of Indexing Type Drill Jig for a Misssile Component
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Figure 7 Clamping Arrangement
The clamping force generated can be calculated from the following equation:
P �B
AxF
Where,
P = output force (clamping force acting on the part)
F = input force (applied force or effort)
B = input distance (from fulcrum to input force application location
A = output distance (from fulcrum to output force application location
1. For maximum use of leverage, the support or fulcrum should be placed as close as
possible to the work piece.
F � 4003.40 127
76.2
F = 6672.33N
2. The required torque to produce the needed input force is
T=0.2 x 24 x 6672.33
Torque=10.620 NM
This is in fact equal to T = k x d x F, where k is torque coefficient.
k is written in terms of coefficient of friction as k = 1.33μ, but sometimes it is considered
as:
k = 0.2 for unlubricated case
k = 0.15 for lubricated case (greased)
4. RESULTS AND DISCUSSION
• The Thrust force is 2520N
• The clamping force is 6672.33N
• The analysis i.e. Maximum equivalent stress obtained is 24.058 Mpa,
• Maximum deflection obtained is 0.048409 mm,
S R V Narsaiah .S, Lakshmipathi Yerra, Prasanna V and L.Radhakrishna
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4.1. Drill Jig Fixed Support and structural force Representation
4.2. Total Deformation Representation & Equivalent Stress Representation
5. CONCLUSIONS
• The design of Indexing type of drill jig for BDL involved about 308x312mm
dimensions.
• The clamping force is more than the drilling force (calculated)
• The analysis i.e. Maximum equivalent stress obtained is 24.058 Mpa, maximum
permissible limit is 450 Mpa, and the values are within the elastic limit, hence the
design is safe.
• Maximum deflection obtained is 0.048409 mm, so, it is within the elastic limit hence
it can be concluded that the structure designed is safe and it can withstand the
maximum Cutting forces developed during machining.
• The assembly of the Indexing type of Drill Jig is found satisfactory.
• The results obtained after drilling like bore, surface finish. etc. are found to be within
the limit as specified by the customer.
• The design of the Indexing type of Drill Jig was verified and approved by BDL
Hyderabad.
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