DESIGN AND FABRICATION OF A BLANKING TOOL
A PROJECT REPORT
Submitted by GOPI KRISHNAN. C [30408114309]
VAIBHAV VASAN. M. S [30408114092]
in partial fulfillment for the award of the degree
of
BACHELOR OF ENGINEERING
IN
MECHANICAL ENGINNERING
EASWARI ENGINNEERING COLLEGE, CHENNAI – 600 089
ANNA UNIVERSITY : CHENNAI 600 025
APRIL - 2011
ANNA UNIVERSITY : CHENNAI 600 025
BONAFIDE CERTIFICATE
Certified that this design and fabrication project report
“DESIGN AND FABRICATION OF A BLANKING TOOL” is the bonafide
work of “ GOPI KRISHNAN. C and VAIBHAV VASAN. M. S ” who carried out
the project work under my supervision.
SIGNATURE SIGNATURE DR.V. ELANGO, ME, PhD MR. M. SENTHIL KUMAR, ME
PROFESSOR AND HEAD SUPERVISOR
Department of Mechanical Engineering Assistant Professor (Sl. Gr)
Easwari Engineering College Department of Mechanical Engineering
Ramapuram, Chennai – 89 Easwari Engineering college
Ramapuram, Chennai - 89
INTERNAL EXAMINER EXTERNAL EXAMINER
ACKNOWLEDGEMENT
We take the opportunity to acknowledge the assistance and contribution of the
people towards our successful project completion.
We would like to thank the Management of our college, the Director and our
beloved principal, Dr. K. ABDHUL GHANI, PhD, for all his support and words of
wisdom.
We sincerely thank Dr. V. ELANGO, PhD, Professor and Head, Department of
Mechanical Engineering for encouraging us during the course of this project.
We would like to thank and acknowledge our Project Guide, Coordinator and
Class counselor, Mr. M. SENTHIL KUMAR, ME, Assistant Professor (Sl. Gr) for
motivation and guiding throughout the project.
We also thank our Class coordinator, Mr. D. BALAJEE, ME, Assistant
Professor for helping us towards the project.
We express our gratitude to all the teaching and non-teaching staffs, members
of workshop, our class friends and our parents for their invaluable cooperation
towards the project.
iv
ABSTRACT
Press tools are tools, used to produce a particular component in large quantity,
out of sheet metals by using presses.
The different types of press tool operations are blanking, piercing, forming,
drawing, cutting off, parting off, embossing, coining, extrusion, perforating, trimming,
notching, shaving, lancing, dinking, broaching, curling, bulging, swaging, flaring, etc.
Blanking is a process of producing flat components. The entire periphery is cut.
The cut-out piece is called blank. This process is called blanking and tool used is
called as blanking tool.
For producing any sheet metal components, blanking operation is the primary
process to carry-out. In this project, a real time design of a blanking tool and
fabrication of a prototype working model is presented.
v
TABLE OF CONTENTS CHAPTER NO. TITLE PAGE NO.
ABSTRACT iv
LIST OF TABLE ix
LIST OF FIGURES x
LIST OF SYMBOLS xii
1 INTRODUCTION 01
2 LITERATURE REVIEW 02
2.1 INTRODUCTION 02
2.2 SHEET PROCESSING 02
2.3 SHEETMETAL PROCESSES 02
2.3.1 Shearing Process 03
2.3.2 Forming Process 03
2.4 SHEARING THEORY 03
2.4.1 Plastic Deformation 04
vi
2.4.2 Penetration 04
2.4.3 Fracture 05
2.5 PRESSES 05
2.5.1 Mechanical Press 05
2.5.2 Hydraulic Press 05
3 DESIGN CALCULATIONS 07
3.1 BLANKING FORCE CALCULATION 07
3.2 PRESS CAPACITY 07
3.3 DIE OPENING DIMENSIONS 08
3.4 PUNCH DIMENSIONS 08
4 DESIGN DRAWINGS 09
4.1 CHILD PARTS AND FUNCTION 09
4.1.1 Top Plate 09
4.1.2 Bottom Plate 09
4.1.3 Blanking Die Plate 09
4.1.4 Blanking Punch 09
vii
4.1.5 Stripper Plate 10
4.1.6 Thrust Plate 10
4.1.7 Punch Holder 10
4.1.8 Guide Bush and Pillar 10
4.1.9 Shank 10
5 FABRICATION AND ASSEMBLY 24
5.1 FABRICATION 24
5.1.1 General Process Flow 24
5.1.2 Top Plate 24
5.1.3 Bottom Plate 25
5.1.4 Blanking Die Plate 25
5.1.5 Blanking Punch 25
5.1.6 Stripper Plate 26
5.1.7 Thrust Plate 26
5.1.8 Punch Holder 27
5.1.9 Guide Bush 27
viii
5.1.10 Guide Pillar 27
5.2 ASSEMBLY 28
5.2.1 Top Assembly 28
5.2.2 Bottom Assembly 28
5.2.3 Final Assembly 29
6 RESULT AND DISCUSSION 30
6.1 MATERIAL 30
6.2 MACHINING 30
6.3 ALIGNMENT 30
7 CONCLUSION 31
REFERENCES 32
ix
LIST OF TABLES TABLE NO. DESCRIPTION PAGE NO.
4.1 BILL OF MATERIALS 23
x
LIST OF FIGURES FIGURE NO. DESCRIPTION PAGE NO.
2.1 PLASTIC DEFORMATION 04
2.2 PENETRATION 04
2.3 FRACTURE 05
2.4 MECHANICAL PRESS 06
2.5 HYDRAULIC PRESS 06
4.1 FINISHED BLANK COMPONENT 11
4.2 BLANKING TOOL PART: TOP PLATE 12
4.3 BLANKING TOOL PART: BOTTOM PLATE 13
4.4 BLANKING TOOL PART: BLANKING DIE PLATE 14
4.5 BLANKING TOOL PART: BLANKING PUNCH 15
4.6 BLANKING TOOL PART: STRIPPER PLATE 16
4.7 BLANKING TOOL PART: THRUST PLATE 17
4.8 BLANKING TOOL PART: PUNCH HOLDER 18
4.9 BLANKING TOOL PART: GUIDE BUSH 19
xi
4.10 BLANKING TOOL PART: GUIDE PILLAR 20
4.11 BLANKING TOOL CATIA 3D ASSEMBLY 21
4.12 BLANKING TOOL CATIA 2D ASSEMBLY 22
5.1 FABRICATED BLANKING TOOL ASSEMBLY 29
xii
LIST OF SYMBOLS
SYMBOLS DESCRIPTION
C - CONSTANT
CSK - COUNTER SUNK
EDM - ELECTRIC DISCHARGE MACHINING
F - BLANKING FORCE
Fus - ULTIMATE SHEAR STRENGTH OF MATERIAL
HCHCR - HIGH CARBON HIGH CHROMIUM STEEL
M - METRIC
MS - MILD STEEL
N - NEWTON (UNIT)
p - PERIMETER
R - RADIUS
t - THICKNESS OF SHEET
Ø - DIAMETER
1
CHAPTER 1
INTRODUCTION
The press is a metal forming machine tool, designed to shape or cut metal
by applying mechanical force or pressure with help of press tool. The metal is formed
to desired shape without removal of chips.
Press tools are exclusively intended for mass production work. Sheet metal
operation plays an important role in engineering works. Press tool are made to
produce a particular component in very large numbers, mainly out of sheet metal. The
principle press tool operations are cutting and forming operations of sheet metal.
Sheet metal components such as automobile parts, parts of house hold appliances and
electronic equipments are produced by press tools.
Nowadays lot of sheet metals parts are being utilised in lot of sectors irrespective of
particular fields like mechanical, electrical, electronics, computers.
Sheet metal components are mainly used for the followings,
Lesser in weight
Less Expensive
Replaceable and better aesthetics
2
CHAPTER 2
LITERATURE REVIEW
2.1 INTRODUCTION
Sheet metal is simply metal formed into thin and flat pieces. It is one of the
fundamental forms used in metalworking, and can be cut and bent into a variety of
different shapes. Countless everyday objects are constructed of the material.
Thicknesses can vary significantly, although extremely thin thicknesses are considered
foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate.
2.2 SHEET PROCESSING
The raw material for sheet metal manufacturing processes is the output of the
rolling process. Typically, sheets of metal are sold as flat, rectangular sheets of standard
size. If the sheets are thin and very long, they may be in the form of rolls. Therefore the
first step in any sheet metal process is to cut the correct shape and sized ‘blank’ from
larger sheet.
2.3 SHEET METAL PROCESSES
Sheet metal processes can be broken down into two major classifications and one
minor classification.
Shearing processes: Processes which apply shearing forces to cut, fracture, or separate the material.
Forming processes: Processes which cause the metal to undergo desired shape changes without failure, excessive thinning, or cracking. This includes bending and stretching.
Finishing processes: Processes which are used to improve the final surface characteristics.
3
2.3.1 Shearing Processes
1. Punching: Shearing process using a die and punch where the interior portion of
the sheared sheet is to be discarded.
2. Blanking: Shearing process using a die and punch where the exterior portion of
the shearing operation is to be discarded.
3. Perforating: Punching a number of holes in a sheet
4. Parting: Shearing the sheet into two or more pieces
5. Notching: Removing pieces from the edges
6. Lancing: Leaving a tab without removing any material
2.3.2 Forming Processes
1. Bending: Forming process causes the sheet metal to undergo the desired shape
change by bending without failure.
2. Stretching: Forming process causes the sheet metal to undergo the desired shape
change by stretching without failure.
3. Drawing: Forming process causes the sheet metal to undergo the desired shape
change by drawing without failure.
4. Roll forming: Roll forming is a process by which a metal strip is progressively
bent as it passes through a series of forming rolls.
2.4 STAGES OF SHEARING OR SHEARING THEORY
Shearing is a method of cutting sheets without forming chips. The force for
shearing is applied by the shearing blades.
4
2.4.1 Plastic Deformation
Figure 2.1 Plastic Deformation
The force applied by the punch on the stock material deforms it into the die
opening. When the plastic limit of the stock material is exceeded by further
application of force, the material is forced in to the die opening in the form of an
embossed pad. A corresponding depression is formed on the upper face. This stage
imparts a radius on the upper edge of the opening in the strip and on the lower edge of
the punched out material.
2.4.2 Penetration
Figure 2.2 Penetration
As the load is further increased, the punch will penetrate into the material to a
certain depth. An equally thick portion of the material is forced into the die. This
imparts a bright polished finish (cut band) on both the strip and the blank.
5
2.4.3 Fracture
Figure 2.3 Fracture
In this stage, fracture starts from both upper and lower cutting edges. As the
punch travels further, these fractures will extend towards each other and meet to cause
complete separation.
2.5 PRESSES
2.5.1 Mechanical Press
The ram is actuated using a flywheel. Stroke motion is not uniform.
1. High forces at bottom of stroke
2. Suited to blanking and punching
2.5.2 Hydraulic Press
Longer strokes than mechanical presses, and develop full force throughout the stroke.
Stroke motion is of uniform speed, especially adapted to deep drawing operations.
1. Longer ram stroke than mechanical types
2. Suited to deep drawing
3. Slower than mechanical drives
6
Figure 2.4 Mechanical Press
Figure 2.5 Hydraulic Press
7
CHAPTER 3
DESIGN CALCULATIONS
3.1 BLANKING FORCE CALCULATION
The blanking force or cutting force is the force required to punch a blank. This
determines the capacity of the press to be used for the tool.
F = p x t x fus
Where,
F – Blanking force (N)
p – Perimeter (mm)
t – Thickness of sheet (mm)
Fus – Ultimate shear strength of sheet (N/mm2)
F = 130 x 0.5 x 300
Blanking Force, F = 19500 N
3.2 PRESS CAPACITY
The rated capacity of press is the force which the slide or ram will exert near the
bottom of the stroke.
Capacity = 1.1 of Blanking force
(10% more than blanking force)
Where,
Blank force = 19500 N
Capacity = 1.1 x 19500 = 21500 N
Capacity = 21500 / (9.81 x 1000) = 2.2 ton
Press Capacity (Tonnage) = 2.2 Ton
8
3.3 DIE OPENING DIMENSIONS
Die is one of the cutting elements of a blanking tool. It admits the punch to enter in for
cutting action. For blanking process, die dimensions are same as the output
component.
Slot Length = 50 mm
Slot Width = 25 mm (Radius 12.5mm)
3.4 PUNCH DIMENSIONS
Punch is the other cutting element of a blanking tool. It exerts a force on the strip
material placed on the die to punch the desired contour.
Length = (Dimension – 2 x clearance)
Width = (Dimension – 2 x clearance)
Clearance = C x t x √ (Fus/10)
[C = constant 0.01, t = thick of sheet, fus = shear strength of sheet]
Length = (50 – 2 x 0.01 x 0.5 x √300/10) = 49.94 mm
Width = (25 – 2 x 0.01 x 0.5 x √300/10) = 24.94 mm
Punch Length = 49.94 mm
Punch Width = 24.94 mm
9
CHAPTER 4
DESIGN DRAWINGS
4.1 CHILD PARTS AND FUNCTION
The blanking tool consists of following major parts and their functions are
stated below.
4.1.1 Top Plate
The punch assembly consisting of punch, punch holder and thrust plate is
mounted on the top plate with screws and dowels. Shank also screwed to top plate.
4.1.2 Bottom Plate
Bottom plate is the base of the tool. The die and guide pillars are fitted to this
plate. It provides cushioning effect to the die. It employs an opening at bottom to
collect the output blanked part.
4.1.3 Blanking Die Plate
Die is one of important cutting tool in the blanking tool. The size or contour of
the die opening will be same as the dimension of the desired output component.
4.1.4 Blanking Punch
Punch is the other important cutting tool in the blanking tool. A force is exerted
on the punch by the press to punch the strip placed on the die. The size of the punch
will be smaller than the dimension of the desired component. It will penetrate into die
for minimum of 3 to 5mm.
10
4.1.5 Stripper Plate
After blanking operation when punch is withdrawn back, the blanked part
adhere (Stick on) to punch surface. To facilitate removal of part from punch, stripper
used. Also it used for guiding punch and to hold the strip flat during punching
operation.
4.1.6 Thrust Plate
While punching the strip, the punch exerts an upward thrust. To prevent that
thrust being transmitted to top plate, a thrust or back plate is provided behind the
punch. Otherwise it will damage the top plate.
4.1.7 Punch Holder
It is a plate used to hold the punch in position without any transition. Punch
holder provides a rigid support to the punch during punching.
4.1.8 Guide Bush and Pillar
Guide pillar and bushes are used to align the top and bottom plate. They keep
the complete alignment of tool during entire operation.
4.1.9 Shank
Shank is a connector between tool and the press ram. It is screwed to the top
plate firmly.
The individual part drawings with dimensions are followed.
All dimensions are in “mm”
Tolerances
Length: ± 0.1mm
Diameter: ± 0.05mm
11
Figure 4.1 Finished Blank Component
12
Figure 4.2 Blanking Tool Part: Top Plate
13
Figure 4.3 Blanking Tool Part: Bottom Plate
14
Figure 4.4 Blanking Tool Part: Blanking Die Plate
15
Figure 4.5 Blanking Tool Part: Blanking Punch
16
Figure 4.6 Blanking Tool Part: Stripper Plate
17
Figure 4.7 Blanking Tool Part: Thrust Plate
18
Figure 4.8 Blanking Tool Part: Punch Holder
19
Figure 4.9 Blanking Tool Part: Guide Bush
20
Figure 4.10 Blanking Tool Part: Guide Pillar
21
Figure 4.11 Blanking Tool CATIA 3D Assembly
22
Figure 4.12 Blanking Tool CATIA 2D Assembly
23
Table 4.1 Blanking Tool Assembly: Bill of Materials
PART NO. DESCRIPTION MATERIAL NO. OFF
1 BOTTOM PLATE MILD STEEL 1
2 BLANKING DIE PLATE HCHCR 1
3 STRIPPER PLATE MILD STEEL 1
4 BLANKING PUNCH HCHCR 1
5 PUNCH HOLDER MILD STEEL 1
6 THRUST PLATE MILD STEEL 1
7 TOP PLATE MILD STEEL 1
8 GUIDE PILLAR MILD STEEL 2
9 GUIDE BUSH MILD STEEL 2
10 SHANK MILD STEEL 1
11 SCREWS STD --
24
CHAPTER 5
FABRICATION AND ASSEMBLY 5.1 FABRICATION The fabrication of each part of the blanking tool was almost carried out in
conventional machines such as lathe, vertical milling machine, surface grinder, etc.
The process planning for individual parts have been discussed below.
5.1.1 General Process Flow
1. Choosing Raw material
2. Sizing the edges to desired dimension in surface grinder
3. Marking and punching the coordinates points
4. Drilling and Counter Drilling in vertical milling machine
5. Slot opening in EDM wire cut or vertical milling machine
6. Filing slot surface and edges
7. Tapping using tap wrench
8. Top and bottom surface grinding
9. Chamfering the edges
5.1.2 Top Plate The raw material dimension of (Mild Steel) plate 170 x 100 mm is taken
Edges were grinded in a surface grinder
Marking and punching done to get coordinates for hole centers as per the
drawing
Holes of Ø22x2 Nos., Ø19 and Ø6.6x6 Nos were drilled in vertical milling
machine
Counter boring done for Ø11x4 Nos
Top and bottom surfaces were grinded
Chamfering of 2x45° done at all corners
25
5.1.3 Bottom Plate The raw material dimension of (Mild Steel) plate 170 x 100 mm is taken
Edges were grinded in a surface grinder
Marking and punching done to get coordinates for hole centers as per the
drawing
Holes of Ø16x2 Nos and Ø6.6x6 Nos were drilled in vertical milling machine
Counter boring done for Ø11x4 Nos
Slot were cut in vertical milling machine
Filing done on the slot surfaces and edges
Top and bottom surfaces were grinded
Chamfering of 2x45° done at all corners
5.1.4 Blanking Die Plate The raw material dimension of (HCHCR) plate 100 x 100 mm is taken
Edges were grinded in a surface grinder
Marking and punching done to get coordinates for hole centers as per the
drawing
Holes of Ø6.6x4 Nos and Ø6x2 Nos were drilled in vertical milling machine
Slot were cut in EDM wire cut process
Top and bottom surfaces were grinded
Chamfering of 2x45° done at all corners 5.1.5 Blanking Punch The raw material dimension of (HCHCR) plate 75 x 75 x 30 mm is taken
Slot profile were cut in EDM wire cut process
Marking and punching done to get coordinates for hole centers as per the
drawing
26
Holes of Ø4.7x2 Nos were drilled in vertical milling machine
Tapping done for M5x2 Nos
Top and bottom surfaces were grinded 5.1.6 Stripper Plate The raw material dimension of (Mild Steel) plate 100 x 100 mm is taken
Edges were grinded in a surface grinder
Marking and punching done to get coordinates for hole centers as per the
drawing
Holes of Ø5.5x4 Nos and Ø6x2 Nos were drilled in vertical milling machine
Tapping done for M6x4 Nos
Slot were cut in vertical milling machine
Filing done on the slot surfaces and edges
Strip feed channel cut in vertical milling machine
Top and bottom surfaces were grinded
Chamfering of 2x45° done at all corners 5.1.7 Thrust Plate The raw material dimension of (Mild Steel) plate 100 x 100 mm is taken
Edges were grinded in a surface grinder
Marking and punching done to get coordinates for hole centers as per the
drawing
Holes of Ø6.6x6, Ø5.5x2 Nos were drilled in vertical milling machine
Counter sinking done for M5x2 Nos
Top and bottom surfaces were grinded
Chamfering of 1x45° done at all corners
27
5.1.8 Punch Holder The raw material dimension of (Mild Steel) plate 100 x 100 mm is taken
Edges were grinded in a surface grinder
Marking and punching done to get coordinates for hole centers as per the
drawing
Holes of Ø5.5x4 Nos and Ø6x2 Nos were drilled in vertical milling machine
Tapping done for M6x4 Nos
Slot were cut in vertical milling machine
Filing done on the slot surfaces and edges
Top and bottom surfaces were grinded
Chamfering of 2x45° done at all corners
5.1.9 Guide Bush The raw material dimension of (Mild Steel) bar Ø32 x 30 mm is taken
Facing and step turning done to reduce Ø16 x 10 mm and Ø22 x 14.5 mm
Drilling and boring done for Ø16
Chamfering of 1x45° done at both ends
5.1.10 Guide Pillar The raw material dimension of (Mild Steel) bar Ø24 x 125 mm is taken
Facing and turning done to reduce to Ø16 x 120 mm
Chamfering of 1x45° done at both ends
28
5.2 ASSEMBLY
Assembling the fabricated parts plays vital role in order to accomplish the
blanking tool. In Blanking tool we can split into sub-assembly. One is top assembly
and other is bottom assembly.
5.2.1 Top Assembly
Top assembly comprises of top plate, thrust plate, punch holder, punch, guide
bush and shank. Punch screwed to the punch holder, subsequently punch holder and
thrust plate screwed to top plate. Guide bush is inserted into top plate in tight fit.
5.2.2 Bottom Assembly
Bottom assembly comprises of bottom plate, die plate, stripper plate and guide
pillar. Die plate and stripper plate screwed to bottom plate, while guide pillar inserted
into bottom plate in tight fit.
29
5.2.3 Final Assembly
Finally, both top and bottom assemblies are aligned together to accomplish the
blanking tool assembly.
Figure 5.1 Fabricated Blanking Tool Assembly
30
CHAPTER 6
RESULT AND DISCUSSION
The machining and fabrication plays a critical role in the project, since all the
individual parts has employed machining. Those significant points are discussed
below.
6.1 MATERIAL
Mild steel have been used for majority of the parts, since it is ductile and can be
easily machined. Moreover it is economical. Exclusively for die and punch we have
employed HCHCR (High Carbon High Chromium) steel. It is done since the punch
and die are the cutting members in the tool, they have to withstand cutting force and
resist wear. Even the die and punch could be hardened and tempered for effective
purpose.
6.2 MACHINING
Majority of conventional machines has been used for machining. Especially for
obtaining excellent corners and radius in punch and die we has outsourced for EDM
WIRE-CUT process. The conventional machines like lathe, vertical milling machine,
vertical drilling machine, tapping have been used for machining the tool.
6.3 ALIGNMENT
Lot of care has been taken for the alignment of the tool. The punch and die
seems to be the heart of the tool, but the die set consisting of top plate, bottom plate,
guide pillar and bush stood more critical during machining and assembly. Since the
top plate has to travel longitudinally in the guide pillar placed in bottom plate. If these
is not achieved the entire process will be in vain. So lot of care has been taken for its
alignment.
31
CHAPTER 7
CONCLUSION
Thus a prototype blanking tool is fabricated and its functions have been
demonstrated and explained.
The tool could be utilised in mass production to produce identical parts with
good geometrical tolerances. By choosing appropriate tool steels for die, punch and
other parts, the tool life could increased for maximum range. It has the capacity to
blank the sheet up to the thickness of 0.5mm of mild steel, aluminium and zinc, etc.
Our tool could be used in presses for medium production quantity of 8,000 to 12,000
units. By using the high grade die sets quantity can be increased over 25,000 units.
32
REFERENCES
1. “Tool & Die Maker 2nd Year: Press Tools, Jigs & Fixtures” CIMI (Central
Instructional Media Institute), Guindy.
2. “Tool & Die Maker 3rd Year: Press Tools, Jigs & Fixtures” CIMI (Central
Instructional Media Institute), Guindy.
3. S.K. Hajra Choudhury, A.K. Hajra Choudhury and Nirjhar Roy, (2005)
“Elements of Workshop Technology” Machine Tools Vol.2, 11th Edition.