Arc Welding Basics: Arc welding is a unique category under MIG welding which involves the use of an electric arc to melt and join two pieces of metals. A good power supply is used to create this arc between the consumable/ non-consumable electrode and the base material. It can be created using both ‘alternating current’ (AC) as well as ‘direct current’ (DC).
The electric arc creates a huge amount of heat of around 6500°F from the AC or DC power used that melts the joints between the two metal pieces. Using the arc to move it along the joint is possible by doing it both manually and mechanically where the electrode carries the current and also melts to supply some filler metal to the weld pool. Shielding gas is provided to the base metal as a protective layer to prevent the metal from reacting with nitrogen and oxygen when it is exposed to these high temperatures.
Arc welding differs somewhat from a normal soldering process as here the metals to be joined together are first melted and then joined together. Nearly every welder out there can get easy access to the arc welding machine and quickly learn to weld using this methodology. Also known as ‘Stick Welding, this is technically called ‘manual metal-arc welding’ (MMAW).
It is used in all fields of metalworking and engineering and the manufacture of large appliances and machinery. Mild steel thicknesses from 1/16thinches to around 2 inches be it stainless-steel or cast iron. The arc generates enough heat intensity to melt at any point and region as it is required to.
Choosing the right arc welder
Using a welding machine with either AC/DC output is recommended for any general-purpose welding. DC output method produces less sticking of the weld puddle with the electrode giving us a better overall experience. We also obtain better vertical and overhead welding with restricted amounts of spatter production and distortion.
Higher the power you can afford to supply, the better results you can get in your weld. Most arc welding applications need a maximum of 225 Amps in general. A welding machine with lower amperage supplied can be used to weld thinner metals of around 1 inch of thickness also by using several passes to perfect the required bead size.
Day by day due to the myth belief that welding is a tedious process, the number of professional welders has been at a declining rate. But it must be understood and remembered that welding isn’t, after all, a difficult task, and one can master it with a few years of practice by working on projects as much as possible.
It has been analyzed and reported that the average age of people joining companies as a professional welder is at 54 years which is very close to being retired soon. Moreover, many people consider arc welding a very dangerous occupation as it involves exposure to high voltage and current. This isn’t very true in today’s world with the safety measures taken and the advancement in welding machinery and equipment used. Arc welding is not as dangerous as doing some sort of occupational plumbing or carpentry. This can be a great career to start ahead with!
Consumable Electrode Methods
People who are whole-heartedly indulged in this profession of welding will be aware of the fact the most commonly referred to and used welding processes is shielded metal arc welding (SMAW) also known as ‘manual metal arc welding’ (MMAW).
Electric current is passed between the base metal and the consumable electric rod which produces an arc. Generally, the electric rod is made up of a material that is similar to that of the constituents of the base metal, and the flux that covers it acts as the shielding gas giving off vapors protecting the weld from harsh atmospheric conditions. The electrode core itself supplies the filler metal required reducing costs.
Weld is slower compared to other processes due to the inexpensive and simple equipment available and the welder requires minimal training to proceed.
Gas Electrode Metal Arc Welding (GMAW) is another process commonly referred to as MIG welding and is done either automatically or semi-automatically using a consumable wire that is continuously fed providing the functions of an electrode as well as the filler metal. A constant voltage is required for this welding and it can be provided with either DC or AC power supplies. When compared to the SMAW process, this process uses more complicated and less-versatile equipment making it a tedious process. GMAW can be used to weld thin aluminum sheets, steel, and non-ferrous metals too.
Flux-cored arc welding (FCAW) is a modified version of the GMAW technique. FCAW wire is actually a fine metal tube that is filled with powdered flux materials. The welding speed and portability enable it to be used in construction quite often.
Submerged Arc Welding (SAW) is a high-productivity welding process where a layer of granular flux is used as a protective layer to be on the arc that is stuck beneath it. The flux blocks any external contaminants that increase the arc quality and overall weld performance. Continuous wire feed provides higher weld deposition rates and here no smoke is produced whatsoever. This welding is used for large product manufacture in industries.
Without taking proper precautions, using welding equipment is a waste of time and resources and moreover a hazard to one’s life. Using the latest technological advancement in the equipment used along with proper measures before welding can be a great way to protect ourselves from any hazards.
Heat, fire, and explosion hazard
The risk of burns or skin rashes could be due to the exposure to heat and sparks for a large amount of time welding. Wearing protective welding clothing including heavy leather work shoes, protective full-sleeve jackets can be some of the best ways to avoid any sort of exposure to these flames, sparks, and fire. Moreover, we use a lot of shielding gas and compressed gases which themselves have high risks of fire and explosion.
Welding for long hours causes the welder to be exposed to bright sparks and light causing a condition in the eye known as ‘arc eye’. The ‘ultra-violet’ (UV) light coming out of it causes inflammation and sometimes can burn the retina of the eye directly. Wearing welding goggles and darkening welding helmets provide the best solution to protect your eyes from such hazards caused. Using curtains having polyvinyl chloride plastic film protecting any welder around that region from exposure to UV radiation.
Welders get generally exposed to a lot of toxic gases and contaminating particulate matter around the welding equipment while welding and these smokes produced are generally oxides. Adequate ventilation and good aeration around the workplace are essential for proper airflow.
When you are learning SMAW, keep in mind that the results are controlled by the management of five variables, regardless of the type of electrode or energy source:
Welding and Cancer
Welding in general produces a large number of hazardous contaminants via the welding fumes and ultraviolet(UV) radiation produced. These toxic substances come under Group 1 carcinogens which cause cancer in human cells.
|Beryllium||Hardening agent that is found in copper, magnesium, aluminum alloys|
|Cadmium Oxides||Stainless steel containing cadmium or plated materials, zinc alloy|
|Chromium||Most stainless-steel also includes high-alloy materials, welding rods. Also used as a plating material|
|Nickel||Stainless steel, nickel-chromium, nickel-copper, and welding rods, and plated steel.|
|Surface preparation||Remove any paint or coatings from surfaces before welding. It is advised not to use chlorinated solvents for cleaning.|
|Welding process and consumables||Where possible, choose a welding process and consumables that produce less fume and/or UV radiation. Change power settings to reduce fumes.|
|Welding fume and gases||A combination of local exhaust and forced dilution ventilation is best practice. Natural ventilation should not be used as a control measure.|
|PPE||Wear either air supplied or air-purifying respiratory protection that filters particulates and ozone. They should be fitted for each worker individually. Wear long trousers and long-sleeved shirts without cuffs in non-flammable material, covering all exposed skin; welding leathers are recommended. Wear insulated, flame-resistant welding gloves, and steel-toe leather boots.|
|Isolation||Separate welding activities from other work jobs. Many workers welding in one space can increase welding fume. Use welding screens to protect other workers from the welding arcs. Where possible, automate welding activities.|
|Share activities||Rotate job tasks between workers. This will help to reduce the duration of exposure to fumes, gases, and UV radiation.|
Sean Coby is a welder par excellence and well respected among the welding community in Woodbridge, VA. He prides himself to be the fabricator and mechanic in the automotive/ diesel industry for the past more than eight years now. As the chief editor of his https://weldinginfocenter.com, he shares his experience to be safe during welding and to take proactive steps for becoming a successful welder like him.