SHEET METAL-FITTER ONLINE NOTE

SHEET METAL 

i)- Sheet metal is any metal such as iron,steel,aluminium,copper,brass,tin plates etc.

ii)- It can be easily rolled in to thin sheet.

iii)- A wire gauge is used to measure the thickness of sheet.

METALS USED IN SHEET METAL WORK

Black Iron:- 

i)- It is uncoated iron, which corrodes rapidly. 

ii)- It is used for making articles, 

iii)- These are painted and enameled such as tanks, pans, stoves, pipes etc.

Galvanized Iron:- 

i)- It is zinc coated and referred to as GI sheet. 

ii)- The zinc coating resists corrosion and improves appearance. 

iii)- It is used for articles like pans, buckets, furnaces, heating ducts, cabinets etc.

Stainless Sheet:- 

i)- It is an alloy of steel with chromium, nickel and other metals. 

ii)- It has good resistance to corrosion, but it is very costly. 

iii)- Stainless steel is used in dairies, food processing, chemical plants, kitchenware etc.

Copper Sheet:- 

i)- Copper sheets are available as cold-rolled or hot-rolled sheets. 

ii)- Gutters, expansion joints, roof flashings, hoods, utensils and boiler plates are some of the common examples where copper sheet is used.

Aluminium:- 

i)- Aluminium cannot be used in pure form.

ii)- It is mixed with a very small amount of copper, Silicon, manganese and iron.

iii)- It is widely used in the manufacture of articles as household appliances,lighting fixtures, and in many electrical and transport industries.

Tinned Plate:-

i)- It is sheet iron coated with tin.

ii)- It is used for marking containers, dairy equipment, furnace fittings, cans and pans etc.

Lead:-

i)- It is very soft and heavy.

ii)- Lead sheet are used for marking highly corrosive acid tanks.

Sheet metal tool and equipment:-

Snip:-

i)- A snip all so called hand shear.

ii)- It is used like a pair of scissors to cut thin soft sheet.

iii)- Snip are used to cut metal up to 1.2 mm thickness.

iv)- The hand shear snip are two types a)- straight snip, b)- bent snip.

v)- Straight snip are used for making straight cut and large external curves.

vi)- Bent snip are used curved blades for marking circular cut and also used for trimming cylindrical or conical work in sheet metal.

vii)- The snip are specified by the overall length and shape of blade.

MALLET

Mallets are soft hammers.

It is made of rawhide, hard rubber, copper, brass, lead or wood.

It is used to strike a soft and light blow on the metal.

Several types of mallets are used such as

a) Standard Wooden Mallet: It is used for geneneral purpose sheet metal work.

b)- Bossing Mallet: It is used for hollowing, panel beatings etc.

c)- End-faked Mallet: It is used for stretching, hammering etc.

HAMMER:-

Shaping of sheet metal by hand is done by hammering. The following hammers are generally usea

(a) Ball Pane Hammer :- 

It is used to spread metal in all directions.

(b) Cross Pane Hammer:- 

Itis used to spread metal in one direction in the line of striking.

(c) Straight Pane Hammer:- 

It is used to spread metal in one direction at right angle to the line striking.

BLOW LAMP: 

i)- It is used to heat the soldering iron to carry out the soldering on sheet metal job. 

ii)- It is also used to melt white metal, babitt metal etc.

STEEL SQUARE:-

i)- A steel square is a 'L' shaped piece of hardened steel.

ii)- With graduation marks on the edges for measuring and marking. 

iii)- Though L' square is normally 90°, squares.

iv)- It is also available in 60°, 45°, and 30° in different sizes.

TRAMMEL:-

i)- A large circle or an arc having a large radius may be made with a tool is called 'TRAMMEL'.

HAND GROOVER:-

i)- A groover is hand tool used for closing and locking of seams in sheet-metal work.

ii)- The hand groover is used to groove and flatten a seam.

iii)- Groove ends fast, then finish the rest of the seam.

iv)- Groovers are available in various sizes viz. 3 mm, 4 mm, 5 mm etc. 

v)- Generally a groover 1.5 mm wider than the width of the fold is used. 

vi)- For thicker materials, a groover 3 mm larger than the width of the fold is used.

STAKES:-

i)- Stake are the sheet metal worker's anvil.

ii)- It is bending,seaming,and forming types of used.

iii)- The better class stakes are made of forged steel or of cast steel. 

Types of stakes:-

Round bottom stake:-

i)- It has a round and a concave face head.  

ii)- It is used for hollowing the sheet. 

Hatchet stake:-

i)- The hatchet stake has a sharp, straight edge, beveled along one side.  

ii)- It is very useful for making sharp bends, folding the edges of sheet metal, forming boxes and pans by hand.

Half moon stake:- 

i)- This stake has a sharp head in the form of an arc of a circle, beveled along one side.  

ii)- It is used for turning up flanges on metal discs.

Funnel stake:- 

i)- This stake is used when shaping and seaming funnels and tapered articles.

Beak or Bick Iron stake:- 

i)- This stake has two horns, one of which is tapered the other is a rectangular shaped anvil.  

ii)- The thick tapered horn or beak is used when making spouts and sharp tapered articles.  

iii)- The anvil may be used for squaring corners, seaming and light riveting.

Creasing Iron:- 

i)- This stake has two rectangular shaped horns, one of which is plain.  

ii)- The other horn contains a series of grooving slots of various sizes.  

iii)- The grooves are used when ‘Sinking’ a bead on a straight edge of a flat sheet.  

iv)- This is also used when making small diameter tubes with thin gauge metal.

Pipe stake or Square edge stake:- 

i)- This stake has the horn and the shank.  

ii)- The horn is available in two types. one is with flat face and Other one is with curved face.

iii)- Flat face horn stake is used to fold the edges, and to turn up straight edges. 

iv)- The curved face horn stake is used to turn circular disc or curved edges and to make knocked up joints

Planishing Anvil:-

i)- It is used for planishing all types of flat shaped works.  

ii)- It is highly polished on its working surface.

Tinman’s Horse:-

i)- This stake has two arms at its both ends.

ii)- One of which is usually cranked downwards for clearance purpose. 

iii)- There is a square hole for the reception of a wide variety of heads.

What is Edge Stiffening ?

i)- The edge of light gauge sheet metal articles are very sharp and unsafe to handle.

ii)- Safe edge are provided to strengthen the sheet metal and enhance the appearance of the finished job. Is called Edge Stiffening.

What is a Hem ?

i)- A hem is an edge or border made by folding.

ii)- It stiffens the sheet of the metal and avoids sharp edges.

iii)- It also prevents damage and wear of the edge.

Types of Hem

Single Hem:-

i)- A single hem is made by folding the edge of the sheet metal with single folding.

ii)- It make the edge smooth and stiff and is done while making small articles.

Double Hem:-

i)- A double hem is made by folding the edge of the sheet metal with double folding.

ii)- It makes smooth and this is done normally to strengthen the edges of lengthy job.

Wired Edge Hem:-

i)- The wired edge is done for round and lengthy job to enhance the appearance and increase the strength.

ii)- The wired edge is smooth and is very strong.

What is a Seams ?

A seam is a joint made by the fastening of two edges of two pieces of metal together.

Types of Seams

a)- Lap seam, b)- Grooved Seam, c)- Single Seam, d)- Double Seam, e)- Double grooved Seam.

What is Notches ?

i)- Notches are the spaces provided for joining the edges when sheet metals are cut from the layout.

Purpose of Notches:-

i)- To allow the work to assemble better.

ii)- To allow the work to be formed to the required size and shape.

iii)- To prevent surplus material from overlapping and causing a bulge at the seam and edges.

Types of Notches:-

Straight notch or Slit:-

i)- Straight cuts made in the edge of the sheet where it is to be bent is known as a straight Notch.

Square Notch:-

i)- A square notch is used when forming a square or rectangular box.

Slant Notch:-

i)- This notch is cut at an angle of 45 degree to the corner of the sheet.

ii)- It is used when a single hem meets at right angle.

'V' Notch:-

i)- In this notch both the sides are cut at a 45 degree angle to the edge of the sheet.

ii)- The sides of the notch meet at 90 degree.

Wire Notch:-

The angle of the notch is usually 30 degree and the distance from which the notch is started is 3 times the diameter of the wire.