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Unit 9 Metals
By Usman - Coggle Diagram
Unit 9 Metals
By Usman
Finishes - Cellulose or acrylic - Provides both colour and protection against corrosion. Car bodies are often finished with cellulose paint. The paint is used on low cost metals, requires a primer and undercoat.
Finishes - Acrylic paint - Water based, durable, and hard wearing. used in bicycles, DIY, projects and can be applied with a brush
Finishes - Electroplating - Involves using a metal to coat a base metal, to provide a protective layer and to give a greater aesthetic appeal as well as a barrier to corrosion from contained liquids. The negative electrode is the object to be plated, and the positive electrode is the coating metal.
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Finishes - Sealants - Blocks the passage of air or fluids through metal joints. Prevents decay, weathering, and corrosion.
Finishes - Preservatives - Provide temporary or long term protection for metal surfaces. Often used in moulds and dies to prevent atmospheric corrosion or condensation build up.
Finishes - Anodising - Used on aluminium to provide a hard wearing corrosion resistant surface. 1) Oxygen ions released from the electrolyte combine with aluminium atoms on the surface increasing the aluminium oxide layer thickening and protecting the surface.
Dip Coating - Polymer dip coating - Provides thick wear and air tight finish. 1) The metal product is heated. The product is then dipped into a tank of polymer powder which has air blowing through it. The retained heat from the product allows the polymer powder to melt over the product which is then simply air cooled to allow the coating to set evenly. Used in wire coats, hangers, coat hooks.
Dip coating - Cathodic protection - Makes the metal to be protected the cathode of an electrochemical cell. Applications include fuel, pipelines, boat hulls and oil rigs
Dip Coating - Powder coating - Provides an even coating more hardwearing than paint. statically charged and powdered paint is sprayed on through an air gun. The charge creates a stronger attraction between powder and the work piece, used in dishwashers, fridges etc
Milling - Work is clamped onto the table of the machine. The table can run in the direction X, Y and Z, therefore can be machined in a range of directions. Can be used to cut, slots, shape the edge of the surface
Turning - Carried out on a center lathe. Can be done manually or using computer numerically controlled lathes. The material by cutting tools held in a tool post which can be moved in and out and along the bar.
Flame cutting - Uses oxyacetylene gas and a special flame cutting torch to deliver a very intense and focused flame above 3.5k degrees. It's very accurate.
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Laser cutting - Used to cut sheet metals. Laser is a wasting process that uses CAD to direct a laser to cut materials. Accurate, fast, and produce a higher quality finish than plasma or flame. They cannot cut a metal plate as thick as flame or plasma.
Punching & Stamping - Cuts out slots, holes. Following a CNC program it moves the table of the machine in an X and Y direction. The punch pushes through the sheet material.
MIG welding - Used to weld thin metal usually aluminium or medium carbon steel. MIG welding is suitable for thin gouge metals because the heat is generated by the electric arc. Used mainly for one off production, and used for bikes.
TIG welding - Process used to weld metals such as stainless steel and non ferrous metals. It is an electric arc welding process that is similar to MIG welding, expect that the electrode made from tungsten does not melt in the process.
Spot welding - Spot welding welds sheet metal together without a filer material. Heat and pressure applied to the area to be welded. It's quick and easy and doesn't require highly skilled staff.
oxy-Acetylene welding - used to weld tubes or plate. Useful in remote locations where is no electric power supply. Uses a mixture of oxygen and acetylene to form an intense flame that can burn at temperatures of around 3,500
Soft soldering - Used for lightweight applications thinner than gauge metals. Commonly used for joining precious metals such as gold and silver. Soldering requires the metal to be clean and its important their are no gaps. 2) The joint area is clamped up 3) The metal is heated up to the melting point of the solder. 4) The solder is added to the metal. 5) The metal is cleaned to remove any flux residue.
Brazing - Known as hard soldering and can be carried out using either oxy-acetylene or a gas. Uses a lower temperature than welding so is suitable for joining thinner gauge metals.
Riveting - A permanent joining method used to join sheet metal or plate. Rivets are metal fasteners that have a head at one end, and a shaft, or tail at the other end.
Pop riveting - Pop rivets are quicker and easier to use but not as strong. They require the use of a pop rivet gun. Used in aircrafts. It is ideal where the underside of the joint is inaccessible.