04-01: The Review Questions for Basics of Sheet Metalworking
Q: 01
The main manufacturing requirement for most sheet metal applications is good formability. This is the
sheet metal ability to deform into intricate shapes without defects in the finished parts. In all sheet
metal forming operations one more type of deformation is involved including:
− Bending
− stretching and
− drawing
Part shape largely determine the relative severity of the sheet metal formability especially where
drawing and stretching occur. But other factors also influence ability those include: Metal ductility, Die
design, stamping press, press speed, lubrication, sheet metal feeding mechanisms and monitoring
\control systems, which safe and guard and synchronize the operation because of these various factors
formability differs from one part operations to the next. Basic die operations include:
− Cutting
− Bending
− Forming
− Drawing
− Squeezing
The two most common type of dies however are cutting dies and forming dies
Cutting which includes shearing, blanking, hole punching and trimming are the most common press
working operations using dies
Shearing is the process by which large sheet of material is cut into smaller sections, these pieces are
generally used in later operations
Blanking is a form of shearing that cut sheet metal stock around the complete perimeter of a shape to
form a workpiece blank. Reference to a bank in stamping usually implies the need to perform
subsequent operations to the workpiece.
Punching is the cutting of a slag from the sheet metal stock to produce a hole. Hole punching as well as
other form of die cutting requires specific clearance between the punch and the die.
Q: 02
DIFFERENCE BULK DEFORMATION SHEET METAL FORMING
DEFINITION Bulk deformation is the metal forming Sheet metal forming is a metal
operation where a significant change in forming operation in which the
shape occurs via plastic deformation in geometry of a piece of sheet
metallic parts undergoes modification upon the
addition of a force
WORKPIECE The area to volume ratio of workpiece is The area to volume ratio of
high workpiece is low
INITIAL SHAPE Can be billet, rod, slab etc. Only sheet
AREA TO VOLUME RATIO Increases considerably No significant increase
SHAPE AND CROSS Appreciable change in shape and cross Changes the shape significantly but
SECTION section no change in cross section
ELASTIC DEFORMATION Permanent Plastic deformation is higher Permanent Plastic deformation and
than elastic deformation elastic deformation is comparable
Similarities:
In both types of processes, the surfaces of the deforming metal and the tools are in contact, and friction
between them may have a major influence on material flow.
(Madhu, 2019)
Q: 03
Sheet Metal Working:
Serial Part Name Part Picture Part Usage
No
1 Barrels For storage and
transfer of Diesels and
fuel.
2 Cabinets For Storage use.
3 Nuts Use with bolt to for the
purpose of fastening.
4 Vending Machine For automatic retrieval
and storage of drinks.
5 Weighted Metal It comes in different
Plate weight sizes and use to
determine weight of
different products.
6 Metal Plate Use in 2 Wheels Electric
Hoverboard Scooter for Self-
Balancing.
7 iPhone Cases Most of the mobile
phones have metallic
body which is made of
metal sheets.
8 Yoke Plate It is used for strain
equalizing of insulator
string as well as spacing
of sub-conductor, Up to
220KV single conductor
system for important
locations like Highway
crossing.
9 Name/Number For Product or Car
Plates marking and tracking.
10 Perforated Steel Holes in the pate of
Plate on steam iron allow steam to
iron pass through.
Q: 04
Sheet Metalworking (Stamping) Operations:
The three major categories of sheet-metal processes are cutting, bending, and drawing.
Cutting:
Cutting operations involve the separation of the metal of the sheet in certain areas by shearing
mechanism i.e. shearing, blanking, and punching.
− Shearing is a sheet metal cutting operation along a straight line between two cut-ting edges by
means of a power shear.
− Blanking and punching are similar sheet metals cutting operations that involve cutting the sheet
metal along a closed outline.
Bending:
Bending in sheet-metalwork is defined as the straining of the metal around a straight axis. Bending
operations are performed using punch and die tooling.
The two common bending methods and associated
tooling are V-bending, performed with a V-die; and
edge bending, performed with a wiping die.
Drawing:
Drawing is a sheet-metal-forming operation used to make cup-shaped, box-shaped, or other complex-
curved and concave parts. It is performed by placing a piece of sheet metal over a die cavity and then
pushing the metal into the opening with a punch.
Common parts made by drawing include beverage
cans, ammunition shells, sinks, cooking pots, and
automobile body panels.
(Lecture 5, 2016)
Q: 05
Different Ways of Classifying Stamping Presses:
1- According to the source of power (Manual Driven, Mechanical or hydraulic or pneumatic).
2- According to number of Rams and Slides (Single, Double or Triple Action Type).
3- According to mechanism of power press (Method of transmitting power for Actuation of ram).
4- According to position of Ram (vertical, horizontal or inclined type).
5- According to its use (punching, blanking, drawing, forming, coining, embossing).
6- According to design of Frame (Straight side, Arch type, Gap type).
7- According to capacity (Tonnage).
(Classification of Presses | Machine Tools | Industrial Engineering, n.d.)
Q: 06
Mechanical Press Working:
Mechanical Press consists of motor, pinion, gear, flywheel, crank shaft and ram. It converts the circular
motion into a linear motion, and the main motor outputs the force to drive the flywheel. The clutch
drives the gear and the crankshaft to achieve the linear motion of the slider. And Flywheel resist
changes in rotational speed by its moment of inertia.
(Classification of Presses | Machine Tools | Industrial Engineering, n.d.)
Q: 07
C-frame press:
Bed:
The bed is the lower part of the press frame that serves as a table to which a Bolster plate is mounted.
Bolster plate:
This is a thick plate secured to the press bed, which is
used for locating and supporting the die assembly. It is
usually 5 to 12.5 cm thick.
Punch:
This is male component of a die assembly, which is
directly or indirectly moved by and fastened to the
press ram or slide.
Ram:
The ram, a solid piece of metal that is clamped to the
top portion of a stamping die, provides the stroke. This
action causes the die to produce parts from the metal
being fed through it.
Flywheel:
As material is pressed by the punch, it needs a strong and constant force, which is provided by the
rotation of the flywheel. Motor keeps the flywheel rotating, which is a simple way to keep it always
rotating with enough energy to drive the punch.
(Press-terminology, 2017)
Q: 08
Single-Action Double-Action Triple-Action
1 Ram 2 Rams 3 Rams
Both Rams move in the Third Ram moves
same direction upward
Use of Double and Triple-Action Presses:
− Double-Action for Deep drawing with combination dies.
− Triple-Action for combination embossing, blanking and drawing where the lower ram actuates
the embossing dies.
(Classification of Presses | Machine Tools | Industrial Engineering, n.d.)
Q: 09
A Press Brake:
A press brake is a machine pressing tool for bending sheet and plate
material, most commonly sheet metal. It forms predetermined bends by
clamping the workpiece between a matching punch and die.
(Wikipedia)
Q: 10
Die Set usage:
This is a tooling that is removed and replaced in a punch press during a changeover. A die set consists of
a set of male punches and female dies which, when pressed together either creates a hole in the work
piece or forms the work piece of different features.
Main Parts of Two post die set:
(M, n.d.)
Q: 11
A
Q: 12
Tonnage of a Press:
The force that the press is designed to exert against the work piece in the die. Higher tonnage allows for
bending thicker and harder metals, and lower tonnage is most appropriate for thinner metals.
Mechanical press tonnage Formula:
Punching Force = Perimeter (mm) * Pate Thickness (mm) * Shear Strength (psi).
Hydraulic press tonnage Formula:
F = D x π x L x I x P/2
Where:
F = force required in tons
D = diameter of the part to be pressed in inches
L = length of part to be pressed in inches (Note: the length of the interference fit only.)
I = interference in inches (usually .002" to .006")
P = pressure factor
(hydraulic-press-productivity-guide, n.d.)
Q: 13
STROKE SHUT HEIGHT
The reciprocating motion of a press slide, usually The shut height of a press is the distance from
specified as the number of inches between the the top of the bed (or to the top of the bolster
terminal points of the motion. plate) to the bottom of the slide indicating the
maximum die height that can be accommodated
Stroke length relates to speed ranges, the longer The shut height must always be defined either
the stroke the slower the from the top of the bed or from the top of the
press speed range. bolster.
(Press-terminology, 2017)
Q: 14
Shut Height of a die set:
Total opening between ram and base when ram is at its
extreme down position. This is the minimum height of
the processed workpiece.
(tt/en/press, 2012)
