Group members• M.Salahudin bsme 0111149• M. Aurangzeb bsme 01113122
SHEET METALCHARACERSITICS• Sheet metal is generally less than 6 mm thick and produced by reducing the thickness of the raw material by compressive forces applied through a set of rolls. The process of rolling began around 1500. Common sheet metals include aluminum alloys, copper, stainless steel, brass, steel, titanium, zinc alloys.
FORMABILITY OF SHEETMETAL• Sheet metal fabrication processes can mostly be placed into two categories - forming and cutting. Forming processes are those in which the applied force causes the material to plastically deform, but not to fail. Such processes are able to bend or stretch the sheet into the desired shape
Formability of Sheet Metal • Many types of metals are suitable for sheet metal working depending on their formability: • Aluminum, copper and their alloys - generally excellent • Mild steel and stainless steel generally - generally fair to excellent • Nickel and magnesium - generally fair to good
BENDING OF SHEET METAL ANDPLATE• One of the most common metalworking operation is bending
COMMON BENDING OPERATION• Press break forming• Sheet metal can bent with simple fixture called press.this machine use long dies in a mechanical and it is suitable for small production .the tooling is simple and adoptable to wide variety of shapes and the process can be easily automated die material for most application are carbon steel or grey iron
BEADING• The edge of the sheet is bent into cavity of a die .beading also improve the appearance of the part and eliminate sharp edge which may be safty hazard
FLANGING• Bending the edge of sheet metal typically to 90.in shrink flanging the flnge periphery is subjected to compressive stress if excessive cause to wrinkle.in streach flanging the flange is subjected to tensile stress if excessive cause to cracking and tearing at the adge
HEAMMING• In hemming process the edge of the sheet is folded itself heeming increase the stiffness of the part improve its appeance and eliminate its sharp edges
ROLL FORMING• This process is used for bending continues length sheet metal and for large production run salso called cold roll forming the metal strip bent in this operation is passed through the series of rolls typical product are frames panels .
BLANKING• Blanking is a cutting process in which a piece of sheet metal is removed from a larger piece of stock by applying a great enough shearing force. In this process, the piece removed, called the blank
Laser cuttingproduces part shapes by cutting sheet material using an intense laser beam. In CNC laser cutting a beam of high-density light energy is focused through a tiny hole in a nozzle. When this beam strikes the surface of the work piece, the material of the work piece is vaporized
CNC plasma cutting• is a process of cutting 2D shapes from sheet metal using a high temperature, high velocity stream of ionized gas
CNC waterjet cutting• is a process that produces shapes by cutting sheet material using a high pressure stream of water containing abrasive(finishing) particles
Photo chemical milling• is a process that produces 2D part shapes by creating a chemical resist mask on the surface of sheet metal and chemically dissolving material from unmasked areas
Band sawing• creates rough cuts by applying a continuous-loop saw blade to the material being cut. Band sawing is often a first step to other machining processes
Shearing ,• on a conventional straight shears, makes straight cuts in material of limited thickness using a scissors-like action
CNC turret punching• creates shapes in sheet material by successively punching a series of basic shapes such as circles and rectangles. The basic shapes are selected from a rotating turret under CNC control
Wire EDM cutting ,• also known as electrical discharge machining , is a process that uses an electrically energized thin wire to slice through metal. Wire EDM cutting uses rapid, controlled, repetitive spark discharges from the wire to the workpiece, thereby eroding the metal away. The workpiece must be electrically conductive.
• CNC milling is a cutting process in which material is removed from a block by a rotating tool.
Countersinking• creates a V shaped recess near the surface of a hole.• Countersinking is often used to recess a flat head screw or to chamfer hole edges. The process of countersinking is usually applied to round holes. Countersink tool
Roll formingThe process is performed on a roll forming line in which the sheet metal stock is fed through a series of roll stations. Each station has a roller, referred to as a roller die, positioned on both sides of the sheet. The shape and size of the roller die may be unique to that station, or several identical roller dies may be used in different positions. The roller dies may be above and below the sheet, along the sides, at an angle,
Fine blanking• IT is a shearing process that produces parts with a higher quality edge than conventional blanking. In fine blanking pressure is applied to both sides of the part during the shearing action. The image shows a part made by conventional blanking (top) and fine blanking (bottom)
SPINNING• Spinning, sometimes called spin forming, is a metal forming process used to form cylindrical parts by rotating a piece of sheet metal while forces are applied to one side. A sheet metal disc is rotated at high speeds while rollers press the sheet against a tool, called a mandrel, to form the shape of the desired part. Spun metal parts have a rotationally symmetric, hollow shape, such as a cylinder, cone, or hemisphere. Examples include cookware, hubcaps, satellite dishes, rocket nose cones, and musical instruments• ,good surface finish low tooling cost but labour unless automated.
Blanking• The blanking process requires a blanking press, sheet metal stock, blanking punch, and blanking die. The sheet metal stock is placed over the die in the blanking press. The hydraulic press drives the punch downward at high speed into the sheet. When the punch impacts the sheet, the metal in this clearance quickly bends and then fractures. The blank which has been sheared from the stock now falls freely into the gap in the die.
DEEP DRAWING• Deep drawing is a metal forming process in which sheet metal is stretched into the desired part shape. A tool pushes downward on the sheet metal, forcing it into a die cavity in the shape of the desired part. The tensile forces applied to the sheet cause it to plastically deform into a cup-shaped part. Deep drawing is most effective with ductile metals, such as aluminum, brass, copper, and mild steel. Examples of parts formed with deep drawing include automotive bodies and fuel tanks, cans, cups, kitchen sinks, and pots and pans.
Deep drawing• The deep drawing process requires a blank, blank holder, punch, and die. The blank is a piece of sheet metal, typically a disc or rectangle, which is pre-cut from stock material and will be formed into the part. The blank is clamped down by the blank holder over the die, which has a cavity in the external shape of the part. A tool called a punch moves downward into the blank and draws, or stretches, the material into the die cavity. The movement of the punch is usually hydraulically powered to apply enough force to the blank. Both the die and punch experience wear from the forces applied to the sheet metal and are therefore made from tool steel or carbon steel.
Can making Blanking• Deep drawing• Re drawing• Ironing• Dooming• Necking• sceaming
Strech FORMING• Stretch forming is a metal forming process in which a piece of sheet metal is stretched and bent simultaneously over a die in order to form large contoured parts. Stretch forming is performed on a stretch press, in which a piece of sheet metal is securely gripped along its edges by gripping jaws. The gripping jaws are each attached to a carriage that is pulled by pneumatic or hydraulic force to stretch the sheet
Stretch forming• Stretch formed parts are typically large and possess large radius bends. The shapes that can be produced vary from a simple curved surface to complex non-uniform cross sections. Stretch forming is capable of shaping parts with very high accuracy and smooth surfaces. Ductile materials are preferable, the most commonly used being aluminum, steel, and titanium
SHEARING• The shearing process is performed on a shear machine, often called a squaring shear or power shear, that can be operated manually (by hand or foot) or by hydraulic, pneumatic, or electric power. A typical shear machine includes a table with support arms to hold the sheet, stops or guides to secure the sheet, upper and lower straight-edge blades, and a gauging device to precisely position the sheet. The sheet is placed between the upper and lower blade, which are then forced together against the sheet, cutting the material.
PUNCHING• Punching is a cutting process in which material is removed from a piece of sheet metal by applying a great enough shearing force. Punching is very similar to blanking except that the removed material, called the slug, Punching can be used to produce holes and cutouts of various shapes and sizes .
Tube Bending• Bending and forming tubes and holllow sections. They require special tooling to avoid buckling and folding.
Sheet Metal Applications• Sheet metal is widely used for numerous industrial and non-industrial applications including:• Aircraft: Fuselages, wings, body panels, trim parts, etc.• Automotive : body panels, bumpers, doors, chassis, trim parts, brackets etc.• Construction: roofing, home building and structural applications.• Other applications: appliances, food and beverage containers, boilers, kitchen equipment, office equipment etc.