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Surface treatment
 

Surface treatment

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    Surface treatment Surface treatment Presentation Transcript

    • Surface Treatment BY WAQAS AHMED
    • Surface Treatment Treatment of metals can be of essential importance in many industries. It is not a new process, but a process that dates back as early as mankind started using gold decoratively before 4000 BC. Today there can be several reasons why it is necessary to change the surface properties of metals. For example surface treatment of metals used for: • Decoration and/or reflectivity • Improved hardness (eg. for resistance to damage and wear) • Prevention of corrosion
    • Basic process is:The process of metal surface treatment involves more than a few steps. Firstly, the stamping compounds and mill oils are cleaned away from the surface leading to rinsing. This is followed by the application of an organicinorganic sealer. And finally, the surface is rinsed with water that’s free of contaminants e.g. water obtained through reverse osmosis or deionization.
    • Surface treatment has further processes mentioned below. • Case hardening • Hard Facing • Ion Implantation • Electroplating • Vapor Deposition
    • Case Hardening • Case hardening or surface hardening is the process of hardening the surface of a metal object while allowing the metal deeper underneath to remain soft, thus forming a thin layer of harder metal (called the "case") at the surface. • Case hardening is a manufacturing process involving changes in composition of metallic objects. • low carbon steel will be given added strength by applying material that makes for a stronger alloy. • Examples of this would include gun barrels and high pressure pipelines.
    • A replica Colt 1873 revolver, showing case hardening colors on the frame
    • Hard Facing • To harden the surface of (metal), as by chilling or casehard ening • In hard facing, a relatively thick layer, edge or point of wear resistant hard metal is deposited by any of the welding techniques. A number of layers are usually deposited (weld overlap). • Hard facing alloys are available as electrodes, rod, wire and powder. • Typical applications of hard facing are valve seats, oilwell drilling tools, and dies for hot metalworking, worn parts .
    • Ion Implantation • Ion implantation is a materials engineering process by which ions of a material are accelerated in an electrical field and impacted into a solid. This process is used to change the physical, chemical, or electrical properties of the solid. Ion implantation is used in semiconductor device fabrication and in metal finishing, as well as various applications in materials science research. • In ion implantation, ions (charged atoms) are introduced on the surface of work piece material. The ions are accelerated in a vacuum to such an extent that they penetrate the substance to few µm. • Effective for aluminum, stainless steels, titanium, tool and die steels, carbides and chromium coatings. • In semiconductors, this process is called doping where the base material is doped with alloying element e.g. n-type & p-type semiconductors.
    • Electroplating • In electroplating, the work piece material (cathode) is plated with a different metal (anode), while both are suspended in a bath containing a water-base electrolyte solution. In basic process, metal ions from the anode are discharged under the potential from the external source of electricity, combine with the ion in the solution, and are deposited on the cathode. • Common plating materials are chromium, nickel, copper, cadmium, zinc and tin. • Typical electroplating applications are copper plating aluminium wire and plastic boards for printed circuits, chrome plating hardware, tin plating copper electrical terminals for ease of soldering.
    • Vapor Deposition • Vapor deposition is a process in which the substrate (workpiece surface) is subjected to chemical reactions by gases that contains chemical compounds of the material to be deposited. • The deposited materials may be metals, alloys, carbides, nitrides, borides, ceramics or various oxides. • The substrate may be a plastic, paper, metal or glass. • Applications are coating cutting tools, drills, reamers, milling cutters, punches, dies and wear surfaces.
    • Joining Joining is a manufacturing process in which different materials are combined to one another and final composite has composition of both the materials.
    • Joining is further characterized into following types: • • • • Welding Brazing Soldering Riveting
    • Welding • Definition:Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. • Basic Process Firstly,melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, but sometimes pressure is used in conjunction with heat, or by itself, to produce the weld.
    • • Many different energy sources can be used for welding, including a gas flame, an electric arc, a laser, an electron beam, friction, and ultrasound. • Welding has • Safety regarding welding is very important as it is dangerous.
    • Types Welding has further types: • • • • • Electric arc welding Resistance seam welding Oxyfuel gas welding Laser-Beam welding Thermit welding
    • Brazing • Definition:Brazing is a joining process in which a filler metal is melted and drawn into a capillary formed by the assembly of two or more work pieces. • Basic process The filler metal reacts metallurgically with the workpiece(s) and solidifies in the capillary, forming a strong joint.
    • • Brazing is similar to soldering, but occurs at temperatures in excess of 450 °C (842 °F). • Brazing has the advantage of producing less thermal stresses than welding, and brazed assemblies tend to be more ductile than weldments because alloying elements can not segregate and precipitate.
    • Types • • • • • • • Dip brazing Cast iron welding Furnace brazing Torch brazing Silver brazing Braze welding Vacuum brazing
    • Soldering Definition:Soldering is a joining process that occurs at temperatures below 450 °C (842 °F). Basic process Filler is melted and drawn into a capillary to form a join, although at a lower temperature.
    • • Suitable for very low temperature metals. • Mostly electric components such as semiconductor chips, mother boards of computers, etc are soldered.
    • Riveting • Riveting is one of the most ancient metalwork joining processes. • A rivet is essentially a two-headed and unthreaded bolt which holds two other pieces of metal together. • When it is necessary to remove rivets, one of the rivet's heads is sheared off with a cold chisel. The rivet is then driven out with a hammer and punch.
    • Cutting • Cutting is a collection of processes where in material is brought to a specified geometry by removing excess material using various kinds of tooling to leave a finished part that meets specifications.
    • Modern technologies • Manual technologies: saw, chisel, shear or snips • Machine technologies: turning, milling, drilling, grinding, sawing • Welding/burning technologies: burning by laser, oxy-fuel burning, and plasma • Erosion technologies: by water jet, electric discharge, or abrasive flow machining.
    • Types Basically cutting is characterized as follows: • Milling • Turning • Threading • Grinding • Filing
    • Milling • Milling:• Milling is the complex shaping of metal or other materials by removing material to form the final shape. It is generally done on a milling machine, a power-driven machine that in its basic form consists of a milling cutter that rotates about the spindle axis (like a drill), and a worktable that can move in multiple directions (usually two dimensions [x and y axis] relative to the workpiece). The spindle usually moves in the
    • Turning • Turning is a metal cutting process for producing a cylindrical surface with a single point tool. The workpiece is rotated on a spindle and the cutting tool is fed into it radially, axially or both. Producing surfaces perpendicular to the workpiece axis is called facing. Producing surfaces using both radial and axial feeds is called profiling. • A lathe is a machine tool which spins a block or cylinder of material so that when abrasive, cutting, or deformation tools are applied to the workpiece, it can be shaped to produce an object which has rotational symmetry about an axis of rotation. Examples of objects that can be produced on a lathe include candlestick holders, table legs, bowls, baseball • bats, crankshafts, camshafts, and bearing mounts
    • Threading • Three types of tools which are used for threading • Bottoming type • Plug type • Tapper type
    • GRINDING • Grinding:• Grinding uses an abrasive process to remove material from the workpiece. A grinding machine is a machine tool used for producing very fine finishes, making very light cuts, or high precision forms using anabrasive wheel as the cutting device. This wheel can be made up of various sizes and types of stones,diamonds or inorganic materials.
    • Filing • Filing:• Filing is combination of grinding and saw tooth cutting using a file. Prior to the development of modern machining equipment it provided a relatively accurate means for the production of small parts, especially those with flat surfaces.
    • BROACHING • Broaching is a machining operation used to cut keyways into shafts. Electron beam machining (EBM) is a machining process where high-velocity electrons are directed toward a work piece, creating heat and vaporizing the material. Ultrasonic machining uses ultrasonic vibrations to machine very hard or brittle materials.