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01.02 Welding

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Welding is the process of fusing metal together at high temperatures so that individual pieces of metal become a simgle piece of metal. Thermoplastics that can also be fused together with welding processes.

Types of Welding

Gas Welding

Oxyacetylene welding uses acetylene gas and oxygen that combine together in a torch to create a very hot and concentrated flame. This flame is hot enough to melt steel and provides some protection from atmospheric impurities. An oxyacetylene torch is also commonly used for Brazing and the cutting of thick pieces of metal.

Electric Welding

  • Mig Welding
  • TIG-Welding uses a hand held electric torch with Tungsten electrode to heat and melt the metal. A filler rod is used to complete the weld.
  • Arc Welding
  • Plastic Welding

Welding Safety

Always follow Welding Safety guidelines to prevent injury to yourself and others.

Cleaning Metal for Welding

If metal to be welded is not clean then the weld will not be sting and may need to be redone or the entire fabricated part might need to be discarded in mission critical situations such as aviation or nuclear power plants. In other less technical welding applications it is still necessary to properly prep and clean surfaces before welding. This will ensure proper penetration of the weld and fusing of the base metals.

Metal can have paint, oil, mill scale, rust, contaminates, weld spatter and many other imperfections that will prohibit a proper weld.

Cleaning mild steel with acetone can remove many contaminates. Metal should be cleaned of contaminates before sanding so the contamination is not ground deeper into the material. Aluminum requires special precautions to avoid weld contamination including keeping a set of prepping tools only used on aluminum and not other metals.

Removing rust and paint can be done with sandpaper, sandblasting, a wire wheel, or an angle grinder. Only use a grit that is just course enough to remove unwanted material without making deep grooves. Finer grits should be used to make the surface smooth since scratches and grinding groves can trap contaminates that will ruin a weld.

When TIG welding it is also important to wipe down and clean the filler rod before welding.

Weld Mistakes to Avoid

  • Cold Lapped Welds
  • Undercutting of Base Metal
  • Incomplete or Too Deep Weld Penetration
  • Incorrect Weld Bead Width
  • Cracks in the Weld
  • Contaminate Inclusions in Weld
  • Incorrect Filler Rod
  • Incorrect Gun Angle
  • Too much stick out or distance from the material to the mig gun

Welding Symbols

Welding symbols are used to communicate the desired weld process, location, and technique for a particular design. They allow an engineer or designer to accurately communicate to the welder what needs to be done.