What is Arc Welding? – Basics, Definition, Process & Safety Measures

Description

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).

Basics Of ARC Welding

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).

Basics Of ARC Welding

It is used in all fields of metalworking and engineering and 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 believed 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!

Procedure

Step 1:
Starting Up:
The process begins simultaneously for properly fitting and welding the workpieces or metal. For thicker pieces, you may want to grind a bevel so that subsequent beads are placed in the grooves to fill them completely with a solid weld. Here are the basic steps to complete a simple weld.

It is the process of creating an electric arc between the electrode and the workpiece. If the electrode simply allows the current to pass directly into the grounded workpiece, enough heat will not be generated to melt the metal simultaneously.

Step 2:
Move the arc to make a bead. The bead is the metal from the melting electrode, combined with the molten metal from the base metal, to fill the space between the pieces joining the weld.

Weld Bead Shape: This is done by weaving in either zig-zag or figure 8 motions on the weld path back and forth of the arch so that the metal expands to the width that you want your finished weld to bead.

Weld brush between chip and pass: Every time you complete a pass or travel from one end of your weld to the other, you need to remove slag or molten electrode flux material from the surface of the weld bead, so only clean molten metal Will fill the weld. Later on.

Step 3:
Assemble the equipment and materials you will need to start welding. This means welding machines, electrodes, cables and clamps, and metal to be welded should be properly arranged in your workplace.

Step 4:
Establish a safe working area: Preferably with a table constructed from steel or other non-flammable materials. For practice, a few pieces of mild steel, at least 3 inches – 16 inches of thickness will work.

Step 5:
Prepare metal to be welded: If the metal has two pieces that are meant to be included in the welding process, you may need to prep or weld them, grinding a bezel edge on the joining sides. This allows for sufficient penetration of the welding arc to melt both sides into the molten state so that the filler metal bonds through the sectional thickness of the metal. At a minimum, you should remove any paint, grease, rust, or other contaminants so that you are working with a clean pool of molten metal.

Step 6:
Attach clamps to hold your metal pieces together if needed. For special projects, you may find that you have to secure the workpieces to adopt different techniques until they are joined.

Step 7:
Attach the ground clamp to the larger piece of stock that is being welded. Ensure that there is a clean space so that the electrical circuit can be completed at ground level with minimum resistance. Again, rust or paint will interfere with the grounding of your workpiece, making it difficult to create an arc when starting welding.

Step 8:
Select the correct rod and amperage range for the task you are trying for. Place the electrode in the electrode holder making sure that the conductive material of the stinger clamp is on the clean metal at the end of the electrode.

Step 9:
Turn on your welding machine: You should hear a lukewarm sound from the transformer. The sound of the cooling fan running may or may not be heard. Some welding machine fans only work when the machine needs cooling. If you do not, you may need to check the circuit that is supplying your power, and the breaker in the panel box.

Step 10:
Hold the stinger in your dominant hand by the insulated handle, with the rod in one position so that you grab its tip against the plate with which you are welding. Use a movement that can be as natural as possible. Just raise your welding shield high enough such that you can see the electrode move in just a few steps.

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 enables 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.

Safety Measures

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.

Eye Damage

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 the exposure to UV radiation.

Inhaling Contaminants

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 is essential for proper airflow.

Operating principles

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:

Current: It is set under power source control.

Travel angle: When welding in flat and horizontal positions, pull the electrode at a 5 to a 10-degree angle. When welding the vertical-up or overhead, push the electrode at a 5 to a 10-degree angle.

Arc Length: Generally, it is not more than the diameter of the electrode and is often 1/16 to 3/32 inches long. Remember that the voltage is proportional to the distance. Push the electrode closer to cool the puddle and hold the long arc to increase the heat.

Travel speed: Adjust the travel to control the width of the puddle. It should not exceed 1.5 times 2 times the diameter of the electrode.

Manipulation: Ask 10 operators about their manipulation technique and you will get 10 different answers. Furthermore, the methods vary depending on the type of electrode; amperage;

Position: Joint configuration; And whether weld root, fil, or cap pass. Start by learning to use the Straight Drag technique on a flat plate or by adding tight circular motion.

Unique Facts

  1. Arc welding was first invented in the 1800s when the Russian scientist Vasily Petrov manufactured an electric arc. Russian inventor, Nikolai Benardos is the one who demonstrated and proved that this electric arc can be used to weld two metals together.
  2. Electric arcs used for welding make it such an effective process because at the steaming hot temperatures that it functions at. The electric arc is used roughly at a temperature of around 10,000 degrees Fahrenheit.
  3. Arc welding played a key role in World War 1 as it helped in the manufacture of battleships. The Royal Navy used this arc welding process to build their battleships efficiently.
  4. There are around half-dozens of arc welding types. They use different approaches and welding equipment. Gas arc welding uses helium arc gas and plasma arc welding uses plasma for the arc.
  5. When you compare to other welding processes, arc welding is inexpensive due to the simple equipment used and its versatility. Arc welding machines are available for less than $200.

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.

Cancer could be caused based on:

  • Type of welding process
  • Material of the weld
  • Contaminants present in the air around you
  • Consumables and shielding gas used
  • Power parameters
  • Welding time
  • Location of your workplace
FUME TYPESOURCE
BerylliumHardening agent that is found in copper, magnesium, aluminum alloys
Cadmium OxidesStainless steel containing cadmium or plated materials, zinc alloy
ChromiumMost stainless-steel which also includes high-alloy materials, welding rods. Also used as a plating material
NickelStainless steel, nickel-chromium, nickel-copper, and welding rods and plated steel.

 

Control Measures

ACTIVITYCONTROL
Surface preparationRemove any paint or coatings from surfaces before welding. It is advised not to use chlorinated solvents for cleaning.
Welding process and consumablesWhere possible, choose a welding process and consumables that produce less fume and/or UV radiation. Change power settings to reduce fumes.
Welding fume and gasesA combination of local exhaust and forced dilution ventilation is best practice. Natural ventilation should not be used as a control measure.
PPEWear 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.
IsolationSeparate 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 activitiesRotate job tasks between workers. This will help to reduce the duration of exposure to fumes, gases, and UV radiation.