Preparing a rectangular tray from a metallic sheet

  • Objectives:
  1. To acquaint us with the procedure of sheet metal work.
  2. To know the working procedure of surface development.
  3. To develop the confidence in tin smithy operation.
  • Theory:-

Working of thin metallic sheets with the help of hand tools and some simple machines is known as sheet metal work. It is very important to know that for efficiency working in sheet metal one should have knowledge about constructional features and working principle of hand tools and machines. Also it is necessary to have the knowledge of development of surfaces, properties of metal sheets etc. The specification of metal sheet is given in terms of gauge number, length and width. The gauge number corresponds to definite thickness of the sheets. This number is also known as “standard wire gauge” (SWG). Higher the SWG smaller the thickness.

  • Types of sheet metal:-
  •  Diagram:
  • List of equipments used:
  1.  Anvil
  • List of tools used:

Marking and measuring tools:

  1. Steel rule
  2. Scriber
  3. Dot punch
  4. Try square

Cutting tool

  1. Snip

Striking tool

  1. Mallet

Snip:

Snip is cutting tool used in tin smithy shop. For cutting along straight line, straight snip is used whose blades are straight. For bent snip, blades are curved back from the cutting edge which allows the metal to slide over top blades. Snip is used to cut 22 S.W.G. or lighter sheet. To cut sheet of greater thickness lever shearing machine is used

fig:snip

. 

Mallet:

Mallet is basically a striking tool used in carpentry shop. It is used to strike the tools/materials which are soft like tin, wooden handle of chisel. It is made up of a hard wood and round or rectangular in shape. 

fig: Mallet

Raw material used: Galvanized Iron(GI) Sheet (26 SWG)
It is a soft iron sheet having Zinc coated on its surface. The Zinc coating makes the surface rust resistant, good look and enables easy soldering. 

  • Working Procedure:
  • Preparatory
  1. Collect and check the raw material for shape and dimensions.
  2. Collect tools required for the job.
  3. Acquaint with the working knowledge of the sheet metal working process.
  4. Acquaint with the knowledge of safety precaution about the process.
  • Operation:
  1. Flatten the metal sheet by mallet.
  2. Marking should be done on the sheet as per given dimension with the help of steel rule, scriber, dot punch.
  3. Cut the sheet as per the lay out with the help of snip.
  4.  Fold and bend different portion as per requirement using mallet by placing the job on the anvil. 
  • Observation Table:
Required Job Dimension Measured Dimension Variation Remarks
Length = L =   

Breadth = B =

Height = H =    

L =   

B =

H =    

L =   

B =

H =    

 
  • Discussion: 
  • Safety Precautions:
  1. Careful about the sharp edge of the sheet at the time of handling the sheet metal.
  2. snip should be carefully used at the time of sheet metal cutting. Don’t put hand under the sheet at the time of cutting.
  3. Tools should be kept in proper place.

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