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
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.
Stick 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.
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
Vertical Welding Mig Tips
- position material so where you are welding can be seen the entire time you are welding, putting the piece a bit lower can help
- Keep the MIG gun close enough to the weld
- Keep the MIG gun angle correct since the tendency will be to have gravity and and your desire to see the weld puddle to pull the gun angle down
- Always Inspect Welding Equipment Before Use to ensure it is in proper working order and all safety devices and materials are in place and not damaged.
- Always wear safety glasses in addition to a face shield when grinding, one or the other is not enough, use both. Small bits of metal can bounce off you then your face shield and then your eye.
- Avoid touching random pieces of metal and assume that everything is extremely hot and sharp
- Clean metal before welding to make better welds and to remove harmful contaminates that might vaporize and be inhaled
- Wear a minimum of a P95 respirator at all times to reduce fume inhalation
- Have adequate venting of the work area and keep your head out of plumes of smoke
- Watch for trip hazards caused by the numerous cords and hoses required for metal work
- Pause to clean up and organize loose cords, hoses, tools and materials as soon as a task is finished to minimize tripping hazards and dangerous environmental hazards
- Always completely cover all skin when welding to prevent arc burns and skin cancer
- Always wear gloves when welding
- Never wear gloves when using rotating power tools or other rotating equipment, glove will get caught and pull your hands into the mechanism
- Always be aware of your surroundings, especially when working in a shared environment
- Never wear synthetic materials such as nylon or polyester since these fabrics will melt with enough heat and then stick to your skin causing severe burns
- Never wear synthetic shoes or open toe shoes, leather shoes with high tops offer the best foot protection, from spatter and molten slag droppings
- Wear long pants
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.