Design of
Progressive
Die
MODULE 2
MEDLO6021
PRESS TOOL DESIGN
PRESS TOOL DESIGN 1
Syllabus
• 2.1 Calculations for Economic Strip Layout, Calculations of Cutting force and
Stripping force, recommending minimum tonnage of a press, Methods of
reducing cutting loads on press tools
• 2.2 Design aspects of Press tool elements viz. Punches & methods of
mounting punches, types of Die block, Stripper, Pilot, stock guides, stock
stops, Selection and arrangement of Hardware used in Press tools. Selection
of steels and its hardness for different elements of Press tools.
• 2.3 Centre of pressure, Different types Die sets and its selection, shut height of
die, Problems based design of progressive die
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Types of Punches and Dies
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Punch and Die Assembly
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Design Aspects of Press Tool Elements
The design of the Punch and Die set involves following elements:
1. Die
2. Punch
3. Stripper
4. Pilots
5. Guides
6. Stock Stops
7. Hardware
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Design of Dies
• The design of the die block depends basically upon the workpiece size and thickness,
although the contours of the workpiece and type of die may be influential at times.
• Die blocks for small workpiece are usually constructed from a solid block of tool steel.
• Size of Die Block is generally based of past experience of die designer
Strip Thickness (mm) Die-Block thickness (mm)
Up to 1.6 19 – 25
1.6 – 3.2 25 – 29
4.8 - 6.4 35 – 41
Over 6.4 41 – 51
• The distance between the die opening and the outside edge of the die block should be 1.25
times the thickness of the die block for smaller dies and around 1.5 to 2 times the die
thickness for large dies.
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Design of Punches
• The design of punches largely depends upon the area to be pierced or blanked and the
pressure required to penetrate the workpiece material.
• The area to be pierced or blanked determines the method of mounting punches.
• Punches for larger workpieces may be bolted directly to the punch holder and small punches
may require punch plate (or block) for mounting.
• Small punches may require support to prevent breakage.
• Types of Punches:
• Plain Punch
• Pedestal Punch
• Perforator Punch
• Punches mounted in Punch Plates
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Plain Punches:
• The side walls of the plain punches are in a
straight line.
• There is no vertically step in side walls of plain
punches.
• The side walls of the plain punch are extended
in a straight line from the base surface (cutting
surface).
• These side walls follow the cutting contour of
the punch.
• Plain punches are economical.
• They are easy to manufacture.
• These punches are positioned and retained in
tool by means of screw and dowels
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Pedestal Punch
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Perforator Punches
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Design of Stripper
• The purpose of a stripper is to remove the stock from the punch after a blanking or piercing
operation.
• Fixed Strippers are generally solidly attached to the die block or die shoe, while spring-
operated strippers travel up and down on the shank of a punch.
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Polyurethane Stripper
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