3. The sheet metal shop is very important for every
engineering concern. It deals with the working of metal
sheets. It requires through knowledge of projective
geometry, the development of surfaces because the
laying of the pattern and cutting of metal sheets
according to size and shapes initially depends upon the
knowledge of the workman. The various operations
performed in a sheet metal shop are marking cutting,
shearing, bending & joining etc.
4. TOOLS AND EQUIPMENTS USED IN SHEET METAL
SHOP
The various sheet metal tools inside a workshop lab can be
classified in to three categories:
A) Hand Tools
B) Bench Tools
C) Machine Tools
5. HAND TOOLS
They are basic working tools which are easily handled by the
common worker and without much effort give the desired output. On
broad classification the hand tools are described below:
a) Measuring and checking tools.
b) Marking tools
c) Cutting tools
d) Striking tools
e) General tools
6. STEEL RULE or SCALE
Steel rule is a flat, rectangular graduated tenthly stainless steel instrument,
used for measuring a dimension of various object for marking and drawing
purposes on the gap.
The straightness provides the accurate distance between two points. It has been
divided according to unit and sizes.
According to Unit:- Millimetre, Centimetre, Meter , Metric Steel Tape, Inch.
According to size :-15 Cm, 30 Cm, 100 Cm
Size in inch
i) 6 inch
ii) 12 inch
iii) 24 inch
7. L – SQUARE
Its one side is 24 inch or 60 cm, another is 12 inch or 30 cm. where its both
sides meet they make 900 angle. It is used to check the correctness of right
angle. It is made up of hard steel.
TRY SQUARE
It is checking tool. It has two parts.
a) Blade
b) Stock
8. BLADE:- It has graduation in inches and cm. It is used to check the
dimension and right of any work piece. It is also used to check the
flatness of any surface.
STOCK:- Usually it is made of steel or wood which is used to hold the
instrument.
WIRE GAUGE
The wire gauge is used to check the diameter of wires or thickness of sheet
metal. The commonly used wire gauge is Imperia1 Standard Wire Gauge
(known as SWG ). It has slots to indicate different width sizes. The most
common wire gauge used in sheet metal has 21 slots with gauges varying from
4 to 24.
9. CALIPERS
They are mostly used for measuring and marking purposes. They are of many
type:
Outside caliper:- It is used to take the outer measurement.
Inside caliper:- It is used to take inner measurement.
Jenny caliper:- It is also know as odd leg or hermaphrodite. It is used to draw
parallel line on rectangular or square work piece. It is also used to locate the
center of any round work piece.
Outside caliper Inside caliper Jenny caliper
10. MARKING TOOLS
SCRIBER
It is a piece of hardened steel wire about 150 to 200 mm long, 3 to 5 mm
diameter with pointed one or both ends like to needle. It is held like a pencil
to scratch or strive straight line on metal.
DIVIDER
It has two pointed vertical legs adjusted with spring points at top. It is used
to draw an arc circle on the metal sheet.
11. TRAMMEL
It is used alternative of divider, particularly in large work. Essentially it
consist of two adjustable vertical legs of trammel points mounted on a
common rod called beam, which can be brought closer or opened out as
desired. It is used beyond the limit of divider to draw a big arc or circle. It is
also called a beam compass.
PUNCH
It is used for marking out work, locating centre and punching work. They are
made up of steel.
12. TYPES OF PUNCH
Centre Punch
Pin Punch
Prick Punch Dot Punch
Hollow Punch
13. CUTING TOOLS
SNIPS:- It is also known as hand shear. It has pair of cutting blades like
scissors. It is used to cut a thing and soft sheet. They are two types.
i) Straight snips
ii) Bent or curved snips
STRAIGHT SNIPS:- They have straight cutting blades for straight line
cutting.
BENT or CURVED SNIPS:- They have curved cutting blades to make a
circular cuts.
14. CHISEL
It is cutting tool made of hexagon or octagon cast steel bar or high carbon steel bar.
TYPE OF CHISEL
Flat chisel Cross cut chisel Diamond point chisel
Round nose chisel Side cut chisel Cow mouth chisel
15. STRIKING TOOLS
HAMMERS:-
The hammer is a striking tool. It has a handle and a head.
Ball peen hammer Cross peen hammer Square hammer
Round Mallet hammer Rectangular Mallet hammer
17. SHEARING MACHINE
The simple shearing machine is used to shear the sheet metal using a compound lever.
The shearing machine has fixed bottom blade and a top shearing blade which is operated
by a lever. It is used to shear metal plates which can’t be cut or trim by snip.
18. FLY PRESS MACHINE
A Fly Press is a machine tool used to shape sheet metal by deforming it or cutting
it with punches and dies. If used for piercing holes in sheet metal work, the fly
press tool itself consists of a punch and clearance die, into which it just fits.
19. BENCH & SUPPORTING TOOLS
The tools which are first fitted on bench and then are used bench tools.
STRAIGHT EDGE
It is also known as bending bar it has barrel edge. It is used to bend the sheet. A
longitudinal groove is provided with it on back side for making channels. It is made up
of cast steel.
SUPPORTING TOOLS
They are following type:
Rail line piece.
Piece of mild steel round bar
Piece of mild steel square bar
Piece of mild steel plate.
20. Rail line piece. Piece of mild steel round bar.
Piece of mild steel square bar Piece of mild steel plate.
21. TYPE OF BENCH STAKE
FUNNEL STAKE HALF MOON STAKE BICK IRON STAKE
HATCHET STAKE PIPE STAKE
GROOVING STAKE
ANVIL STAKE
22. SHEET
Sheet are made by pressing the hot section in sheet rolling machine. The rolled
sheet become too hard hardness in removed by annealing.
METAL USED IN SHEET METAL
A fairly large variety of metals are used in the forms of sheet and plates.
23. GAUGE NUMBER
Corresponds to the definite thickness of sheet these number can be know by
using thickness gauge or thickness wire gauge. The thickness of sheet varies
inversely with higher gauge number, smaller thickness and vice versa upto 10
gauge number the object is known as sheet. Less than 10 gauge number it is
known as bar.
TYPE OF SHEET
1. Black iron sheet
2. Galvanized iron sheet
3. Copper sheet
4. Aluminum sheet
5. Stainless sheet
6. Tin coated sheet
7. Brass sheet
24. SHEET METAL OPERATIONS
MARKING
Development drawing or marking is done over the sheet before proceeding to
another operation. This gives it true shapes and reduce wastage of sheet.
LAYING OUT
It means the operation of the developments of the surface of the components on
the sheet together with added allowances for operating, overlapping , bending
& joining etc. which when cut of blank and folded and joint will give the
required component. Such a layout when made from the sheet is called pattern
and processed as pattern layout.
25. CUTTING AND SHEARING
The word cutting is normally used when the sheet metal is cut by means of
chisel and hammer mainly.
The term shearing stands for cutting of the sheet metal by two parallel
cutting edge moving in opposite direction. This can either be done mainly by
using hand shear or snips or by means of a machine called shearing
machines. The operation is then called machine or machines.
NOTCHING
When the pattern is drawn the necessary allowance are given on the sheet
and corners are cut to avoid cracks while bending is known as notching.
26. EDGE FORMING
The edge of the metal products are formed and folded to ensure safety of hands
while handing these products and to provide safeness to the product in order to
retain their shapes while handling.
HEMMING
There are two types of hemming:-
Single hemming : Folding of edges or ends of the sheet four to ten times of the
thickness of the sheet if the dimensions are not given.
Double hemming : The fold is given doubled to strengthened the edges of the
model.
28. WIRING OR WIRED EDGE
When very strong edges are needed they are reinforced by inserting a metal
wore or rod and then forming edges by curling the edges of sheet metal around
it. This is not only increases the strengthens of the edges but also to improve its
appearance. There are two types of wiring.
i. True wiring
ii. False wiring
SWAGING
Making a groove in sheet metal in round job by swaging machine is called
swaging.
BENDING
It is same as swaging but done away from the edge, it is done by bending
machine giving concave shape on the sheet.
29. HALLOWING
Giving concave shape or hallowing in sheet as in mud guard.
RASING
It is a process to give concavc shape over the body as halmet.
NIBBLING
It is a process of continuous cutting along a contour which may be straight or
irregular profile. Machines use in this operation are called nibblers.
HAND FORMING
It means shaping or bending of sheet in their dimensions in order to give it a
desired shape or sizes of final product.
SOLDERING
It is method of joining two metals without causing it to melt and destroy the
metal sheet. It is method of joining two metals by a third metal of soft metal by
solder in molten state.
30. SHEET METAL JOINTS
There are three type of joints:
1. Mechanical joints
2. Metallic joints
3. Riveted joints
31. MECHANICAL JOINTS
They are also known as folded joints or seam joints or without medium. They
are classified into –
a. Lap joints b. Locked grooved joints c. Panned down joints
d. Knocked up joints f. Corner joints
g. Cap joints
32. METALLIC JOINTS
This includes welding brazing hard and soft soldering.
SOFT SOLDERING
Soft soldering includes in following materials:
BIT
It is mainly of copper or iron.
SOFT SOLDER
It is a non ferrous alloy of tin and lead in some instances small percentage of
antimony are included. Bismuth is included sometimes for lowering the
melting point.
33. SOLDERING FLUX: There ate two type of fluxes:
Corrosive flux: which are alcohol salt or acid bases.
Non-corrosive flux: which are non acid bases eg: borax, rosin, fat.
RIVETED JOINTS
It is permanent fastening method. It is largely used in the manufacturing of
boilers, pressure vessel, coach ,furnace bodies, steel bridges and different type
of steel structures.
34. RIVET
It is a parallel shank metallic pin with head at one of its end. It has two pared. They are
shank and head.
35. TYPE OF RIVET
Shank is common part of rivet. So rivet are classified according to shape of its
head.
1. Flat head rivet
2. Round or cap head rivet
3. Conical head rivet
4. Half conical head rivet
5. Counter sunk head rivet
6. Half counter sunk head rivet
7. Pan head rivet
8. Split rivet.
36. PRECAUTIONS :-
1. Marking should be done correctly.
2. Cutting should be done efficiently to avoid flow in
measurement.
3. While soldering saddening bit should not over heated.
4. The flux should be spread efficiently.
37. Job No. 1
Object :- To make and development of Tray as per as given drawing.
Material Required:- G.I. Sheet 30 gauge [ size :- 180 x 145 mm]
Tools Required :-
1. Steel Rule
2. L- Square
3. Try Square
4. Wire Gauge
5. Scriber
6. Snip
7. Square Hammer
8. Mallet Hammer
9. Plier
10. File
11. Straight Edge
38. 12. Stakes
13. Soldering Iron
Theory :- What is sheet metal shop and its uses.
Procedure :- Write Point Wise
