Workshop Practice Manual-7

Department of Mechanical EngineeringGalgotias UniversityGreater Noida, UP

Contents

• Sheet metal shop

• Safety precautions in sheet metal shop

• Types of sheet metal

• Tools and equipments

Sheet metal shop• The sheet metal shop is very important for every engineering concern.

• It deals with the working of metal sheets.

• It requires a through knowledge of projective geometry particularly the development of surface, because the laying out of pattern and cutting of metal sheets to correct size and shape entirely depend upon the knowledge of workman.

• The various operations performed in a sheet metal shop are cutting, shearing, bending etc.

Safety precautions in sheet metal shop• Be very careful and attentive while working in sheet metal shop as one is

involved in sharp tools.

• Avoid putting or filling the cut portion by hand while cutting with snip.

• Use hand leather gloves while handling heavy sheets.

• Do not use tools with blunt cutting edge.

• Do not cut metal heavier than capacity of snip.

• The safest and most efficient method of testing a soldering to the solder being to flow the correct temperature has been achieved.

• Keep work area free from obstruction.

Types of sheet metal• Mild Steel sheets: It is known as black iron sheet susceptible to rust and

corrosion due to uncoating protected by painting and is mostly used for water tank, fabrication work, and agricultural implements.

• Stainless Steel sheets: It has silver-crome appearance. It is an alloy of high grade steel with chromium, nickel and traces of manganese, phosphorous, etc. It can be easily welded. It is used in canneries, dairies, food processing plants. It is very costly as compare to GI sheets.

• Galvanized Iron sheets: It is soft steel sheet coated with zinc. Sheets have corrosion resistance due to zinc coating. Welding is not easy. These are used for making AC duct, roof flashing, boxes buckets, cooler etc.

• Tin plate: Steel or iron coated with tin is called tin sheets. It is used for making food container, dairy equipment, and furnace fittings. These are now replaced by stainless steel, aluminum and other materials.

Tools and equipments• Bench Vice: It is a suitable tool for gripping different tools such as a straight

edge anvil, etc. It consists of a cast iron steel body; carrying a fixed jaw, a moveable jaw and threaded screw which is made to pass through the moveable jaw at outer end. It runs through the fixed nut longitudinally under the moveable jaw. The work is held between jaws and kept tightened.

Tools and equipmentsMeasuring and marking Tools• Steel rule: Overall dimensions, length and breadth of required piece of steel

are marked with the help of a steel rule. The rule is calibrated.

• Scriber: It is used for marking sheet pieces dimensions. It is steel wire of 200 mm length with one end sharp and hardened to make or draw lines on metal sheet.

Tools and equipments• Pliers: It is used for holding small articles which are difficult to be held by

hand.

• Steel square: It is a L-shaped piece of hardened steel. It is used to make square corners. It is also used for checking and marking right angles

Tools and equipments• Divider: It is used to scribe arcs and circles on metallic sheets and to divide

lines, arcs or circle into equal parts.

Punches: The following punches of tool steel are used in sheet metal shop– Prick punch: Used for marking indentation marks for locating the center position

or dividers, having included angle of 300

– Centre punch: Used for marking the location of the point and the centre of holes to be drilled. It tapered point is grounded to 900 included angle.

Tools and equipmentsCutting Tools• Straight Snip: For cutting along straight lines, straight snip is used whose

blades are straight. It is used to cut 22 SWG or lighter. To cut sheets of greater thicker lever shearing machine is used.

• Bent snip: Blades are curved back from the cutting edge which allows the metal to slide over top blades.

• Hollow punch: When circular holes are to be cut in the sheet then the hollow punch is used for thin sheets. The sheet should be placed over the wood of thick block of lead to avoid chipping of edges of the punch.

• Chisel: These are generally used in sheet metal shop for cutting sheets, rivet and bolts.

Tools and equipmentsStriking Tools• Hammer: The hammers are used for striking work, bending of sheets,

smoothing of sheets, locking of joints, etc. For these operations the following hammer are generally used.– Ball peen hammer: Has a round, a slightly curved face and a round head.– Setting hammer: Has a square, flat face and a tapered peen with beveled end.– Raising hammer: Has a oblong flat face with corners slightly rounded off.– Riveting hammer: Has a square, slightly curved face with beveled edges to prevent the head

of the hammer to marking the metal.

• Mallet: Mallet is made good gravity wood or plastic is used whenever light force is required. Mainly used for smoothing of sheets.

Tools and equipmentsSupporting Tools• Stakes: Stakes are used to support sheets in bending, seaming, forming,

riveting, punching etc. Some commonly used stakes are– Hand stake: It is handy stake with a flat face, two straight edges one concave edge and

other convex edge and is used for pressing the inner sides of straight joint.– Half round stake: It is used for pressing round seam joint on inner side.– Taper stake: It is used for rounding of tapering jobs such as conical jobs.– Grooving stake: It is made up of forged steel and is used to make grooves of different sizes.

Grooves are made to impart strength.

• Anvil: It is made of cast steel mounted on CI stand or provided with a handle. The top working or cutting face is made of tough steel. Square and round holes are provided for bending operation.

Thank You