shet mtl-.ppt
- 1. Internal Sheet metal is available in flat pieces or as a coiled strip. The coils are formed by running a continuous sheet of metal through a roll slitter. The thickness of the sheet metal is called its gauge. The gauge of sheet metal ranges from 30 gauge to about 8 gauge. Different metals that can be made into sheet metal, such as aluminum, brass, copper, steel, tin, nickel and titani um.
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- 3. Internal SHEET METAL WORKING In this simply metal formed into thin and flat pieces. It is one of the fundamental forms used in metalworking, and can be cut and bent into a variety of different shapes. Countless everyday objects are constructed of the material Low cost parts with very high rates at faster rates. Thicknesses can vary significantly, although extremely thin thicknesses are considered foil or leaf, and pieces thicker than 5 mm (0.25 in) are considered.
- 4. Internal For decorative uses, important sheet metals include silver, gold, and platinum Sheet metal has applications in car bodies, airplane wings, medical tables, roofs for buildings and many other things.
- 5. Internal SHEARING It is a cutting operation used to remove a blank of required dimensions from a large sheet. To understand the shearing mechanism, consider a metal being sheared between a punch and a die, Fig.
- 6. Internal Sheet Metal Forming processes Shearing processes -- processes which apply shearing forces to cut, fracture, or separate the material. Forming processes -- processes which cause the metal to undergo desired shape changes without failure, excessive thinning, or cracking. This includes bending and stretching. Finishing processes -- processes which are used to improve the final surface characteristics.
- 7. Internal Major processing parameters in shearing are shape and materials for punch and die, speed of punching, lubrication, clearance between punch and die . The clearance between the punch and the die plays an important role in the determination of the shape and quality of the sheared edge. There is an optimum range for the clearance, which is 2 to 10% of the sheet thickness, for the best results.
- 8. Internal SHEET METAL OPERATIONS It is the cheapest & fastest way of the complete manufacture of a component. sheet metal is considered to be a plate with thickness less than about 5mm. Classification of press tool operations: Stresses induced Operations 1.Shearing Blanking, shearing, Piercing, Trimming, Shaving, Notching ,Nibbling etc., 2. Tension Stretch forming 3. Compression Coining, sizing, ironing, hobbing 4. Tension & Compression Drawing, Spinning, bending, forming, embossing
- 9. Internal Shearing starts as the punch presses against the sheet metal. At first, cracks form in the sheet on both the top and bottom edges (marked T and T', in the figure). As the punch descends further, these cracks grow and eventually meet each other and the slug separates from the sheet. A close look at the fractured surfaces will reveal that these are quite rough and shiny.
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- 11. Internal PUNCHING & BLANKING It is a process in which the punch removes a portion of material from the larger piece or a strip of sheet metal. If the small removed piece is discarded, the operation is called punching(or Piercing), whereas if the small removed piece is the useful part and the rest is scrap, the operation is called blanking.
- 12. Internal Metal around the part is removed. Metal inside the part is removed
- 13. Internal CUTTING (SHEARING) OPERATIONS In this operation, the work piece is stressed beyond its ultimate strength. The stresses caused in the metal by the applied forces will be shearing stresses. The cutting operations include: Punching (Piercing) Blanking Notching Perforating Parting Lancing Slitting Shaving Trimming Fine blanking
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- 15. Internal NOTCHING: This is cutting operation by which metal pieces are cut from the edge of a sheet, strip or blank. PERFORATING: This is a process by which multiple holes which are very small and close together are cut in flat work material. PARTING: Parting involves cutting a sheet metal strip by a punch with two cutting edges that match the opposite sides of the blank. or shearing sheet in to 2/ more pieces.
- 16. Internal SHAPING OPERATIONS IN SHAPING OPERATIONS THE METAL IS DEFORMED INTO REQUIRED SHAPES BY PUNCH & DIE. IN FORMING, THE METAL IS DEFORMED OR BENT ALONG A CURVED AXIS. VARIOUS FORMING OPERATIONS ARE: 1. EMBOSSING 2. COINING 3. SPINNING 4. SWAGING 1. EMBOSSING: IT IS A SHALLOW FORMING OPERATION WHICH USES A MATCHED PUNCH & DIE. THE THICKNESS OF WORK PIECE IS UNIFORM, AND IS INTENDED FOR DUPLICATING OF THE PATTERN ON EITHER SIDES OF THE SHEET METAL. IT IS USED FOR DECORATIVE SHEET WORK AND TO OBTAIN THE IMPRESSIONS OF DESIRED FORM.
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- 18. Internal 2. COINING: COINING IS SQUEEZING OPERATION IN WHICH THE METAL FLOWS INTO THE CAVITY BETWEEN THE PUNCH & DIE. IT IS EMPLOYED FOR MAKING COINS, MEDALS AND SIMILAR ARTICLES.