This document discusses power presses. It provides classifications of presses based on their mechanism, function, structure, and controllability. The main types are mechanical, hydraulic, and pneumatic presses. It also describes the construction and working of gap frame presses, including their components like the flywheel, clutch, brakes, and ram. Cutting operations performed by presses include blanking, piercing, notching, and perforating. Forming operations change the contour through bending and drawing. Safety measures for presses include bi-manual controls and light sensors.

1. Power Presses
Group Members:
Syed Taha Ahmed (IM-096)
Syed Ziauddin (IM-103)
Muhammad Hassam (IM-114)
Faisal Siddique Awan (IM-118)

2. Introduction
Presses:
 The press represents a specific type of machine tool,
essential in the performance of industrial manufacturing
processes
 Press machines are also the primary machine tool used in
metal extrusion and sheet metal fabrication processes.
 Presses deliver energy through a force that acts over a
distance or stroke

3. Classifications:
Presses can be classified according to their
MECHANISM: Hydraulic, Mechanical, Pneumatic.
FUNCTION: Forging presses, Stamping presses, Press
brakes, Punch press.
STRUCTURE: Knuckle-joint press, Screw press.
CONTROLLABILITY: Conventional, Servo-presses.

4. Classification on the basis of Mechanism
 Manual Presses: Either hand or foot operated
through levers, screws or gears.
 Mechanical presses: These presses utilize
flywheel energy which is transferred to the work piece
by gears, cranks, eccentrics, or levers.

5.  Hydraulic Presses: These presses provide
working force through the application of fluid
pressure on a piston by means of pumps, valves,
intensifiers, and accumulators.
 Pneumatic Presses: These presses utilize
air cylinders to exert the required force.

6. Classification on the basis of Structure
 Gap Frame Presses: These presses have a
C-shaped frame. These are most versatile and
common in use.
 Straight Side Presses: These presses are
stronger since the heavy loads can be taken in a
vertical direction by the massive side frame and
there is little tendency for the punch and die
alignment to be affected by the strain

7.  Fly Wheel: The flywheel is mounted at the edge of the driving shaft and is
connected to it through a clutch.
 Clutch: The clutch is used for connecting and disconnecting the driving shaft with
the flywheel when it is necessary to start or stop the movement of the ram.
 Brakes: The brakes are used to stop the movement of the driving shaft
immediately after it is disconnected from the fly wheel
 Driving mechanism: The rotary movement of the motor is converted into the
reciprocating movement of the ram by crank and connecting rod, eccentric and
connecting rod in mechanical presses
 Ram: Ram reciprocates to and fro within its guide ways with prescribed stroke
length and power. Ram at its bottom end carries punch to process the work piece.
Pitman: It is the part which connects the ram and crankshaft or ram eccentric.
Construction of Gap Frame Press:

8. Construction of Gap Frame Press:
1. Fastest acting Hydraulic Overload Protection
(HOLP), adjustable from 60-100% of rated
press tonnage
2. Adjusting screw threads never exposed
3. Oil lube to pinion shaft and rear crank
bearings
4. AC variable frequency drive
5. Taper fit of main gear to crankshaft
6. AIDA wet clutch
7. Quill mounted flywheel
8. Hardened and ground pinion and ground
main gear
9. Electric brake on slide adjusting motor

9. Press working operations
Press working operations may be grouped into two categories:
 Cutting operations
 Forming operations

10. Cutting Operations:
In cutting operations the work piece is stressed by its ultimate strength. The stresses caused
in the metal the applied forces will be shear stresses. The cutting operations include:
1. Blanking:
Punching or blanking is a process in which the punch removes a portion of material from
the larger piece or a strip of sheet metal. The small removed piece is the useful part and
the rest is scrap, the operation is called blanking (as shown in fig a).
2. Piercing:
It is a process by which a hole is cut (or torn) in metal. It is different from blanking in a way that
small removed part is scrap and the rest is useful (as shown in fig b).

11. 3. Notching:
It is an operation in which a specified small amount
of metal is cut from a blank. The purpose of
notching is generally to release metal for fitting up.
4. Perforating:
Perforating is an operation is which a number of uniformly spaced
holes are punched in a sheet of metal. The holes may be of any
size or shape. They usually cover the entire sheet of metal.

12. 5. Lancing :
Creating a partial cut in the sheet, so that no material is
removed. The material is left attached to be bent and
form a shape, such as a tab, vent, or louver.
6. Slitting :
Cutting straight lines in the sheet. No scrap
material is produced.
7. Parting :
Separating a part from the remaining sheet, by
punching away the material between parts.

13. Forming operations:
In this operation , there is no cutting of the metal but only the contour of the work piece
is changed to get the desired product. The forming operations include:
1.Bending
Bending is a metal forming process in which a force is applied to
a piece of sheet metal, causing it to bend at an angle and form the
desired shape.
2. Drawing
Deep drawing is a manufacturing process that is
used extensively in the forming of sheet metal
into cup or box like structures

14. Safety:
Machine presses can be hazardous, so safety
measures must always be taken.
1. Bi-manual controls:
Controls the use of which requires both hands
to be on the buttons to operate are a very good way
to prevent accidents.
2. Light sensors:
That keep the machine from working if the
operator is in range of the die.