Arc Welding vs. Gas Welding: Understanding the Differences
Arc and gas welding are methods that use intense heat to join metal materials together by melting them and fusing them together upon cooling. The main difference between the two is the way the heat is generated. Arc welding uses electricity to generate a much higher temperature. Gas welding creates a slightly lower temperature by burning gases (most commonly acetylene) with oxygen to generate a flame that melts the metal to be welded. This article will further compare arc welding vs. gas welding.
Arc welding is a process that uses the heat of an arc to join metal materials together. The arc—generated by electricity—melts the metal at the joint under the intense heat of around 6,500 °F. The molten metals then fuse together upon cooling.
A suitable filler metal is continuously supplied to assist in the joining of the metal workpieces. This filler, which becomes molten at the site of the weld pool, solidifies along with the workpiece metal upon cooling, creating a metallurgical bond. For more information, see our guide on Arc Welding.
Arc welding works by creating an electric arc to generate heat. This is achieved by attaching a grounding wire to a metal structure and placing the other end of the grounding electrode lead on the material to be welded. Once the electrode lead touches the material to be welded, an electric arc is created that produces a bright white light and sparks, as shown in Figure 1 above.
The resistance to the flow of electrons across the air gap is what produces the intense heat that melts the metal material and filler material (sometimes referred to as the welding rod). The resultant pool of metal then solidifies and fuses the edges of the original material to join the metal together. Metal can chemically react to oxygen and nitrogen when under extreme heat from the arc, this can affect the strength of the weld. To mitigate this, a protective shielding gas can be used to protect the molten metal from the air.
The purpose of arc welding is to join two pieces of metal together using electricity. This is done by creating an electric arc that melts the metal at the joint and then fuses both pieces of metal together. Upon cooling, the two metals are joined. By fusing the materials together in this way, arc welding ensures the bond between the metals is incredibly strong and sustainable.
Arc welding is used to join different materials together in a range of industries. One example is in the construction industry, in which arc welding is used to guarantee robust, durable, and secure connections between metals that support infrastructure such as buildings, bridges, and other forms of construction. Another example in which arc welding is used is in the aerospace industry to repair and manufacture parts for aircraft as well as join sheeting. Another example is heavy equipment repair and pipeline welding in the construction industry. Other examples include the: automotive, shipbuilding, oil, gas, and power industries.
In normal arc welding, there are no lasers used. Instead, an arc is produced using an electrode that locally melts the metal of the two workpiece sections. This is achieved by a grounding wire that attaches to a metal surface, and an electrode lead placed on the material to be welded. Once the electrode touches the material to be welded, an electric arc is created that generates heat to create a weld. For more information, see our guide on Types of Lasers.
Listed below are the advantages of arc welding:
- Low Equipment Cost: Less equipment is needed as the process uses electricity, rather than gas, to generate heat. AC or DC electric current can be used to produce this heat. The equipment that is necessary to carry out this form of welding is well-priced and affordable and can be maintained at a relatively low cost.
- Portable: Less equipment needed means it is easily transportable.
- Results in Smooth Appearance: Arc welding can be used on dirty metals and produces very little distortion. The final product has a smooth appearance.
- Strong Bond: Arc welding produces strong bonds between the two materials that have been welded together.
Listed below are the disadvantages of arc welding:
- Low Efficiency: This results in excess waste being produced.
- High Level of Skill Needed: The level of skill required by operators to guide the arc is extremely high. A lot of training is needed for professionals to be able to carry out this process, which can be costly.
- Limited Material: Arc welding cannot be used for reactive metals such as aluminum or titanium. Additionally, not all thin metals can be welded by arc welding.
Gas welding is one of the oldest forms of heat-based welding. Similar to arc welding, gas welding joins metals together by heating the metal which then fuses together upon cooling. However, the heat necessary for gas welding is produced by burning a combination of different gases rather than by an electric arc.
Gas welding works by using the heat generated from burning gases to then cut and/or fuse metals together. Fuel gas (stored in a fuel cylinder) such as acetylene is mixed with oxygen (from a separate oxygen cylinder) and burnt to produce a concentrated flame that can reach temperatures of around 5,700 °F. Both gases have individual control valves to regulate the oxygen ratio within a mixer chamber. The equipment from which the flame ultimately emerges is the welding torch. The flame is then used to locally melt the surface of the metals, which then combine with the metal from an appropriate filler rod.
The purpose of gas welding is to fuse materials together under a flame that is produced by burning gases such as acetylene. By fusing materials together in this way, there is no requirement for the use of electricity. Gas welding can be used to fuse together non-ferrous and ferrous materials.
Gas welding is used in a range of scenarios but is very suitable for welding pipes and tubes. One use of gas welding is in the construction and repair of heating, ventilation, and air conditioning systems. Another example is in the welding of gas bottles, hot water pipes, boilers, and nuclear heat exchangers.
Lasers are not used in traditional gas welding. Instead, the heat is generated by burning gases to produce a flame which is then concentrated on the metals which are to be fused together.
Listed below are the advantages of gas welding:
- Ease of Use: Compared to other forms of welding, such as arc welding, gas welding is relatively easy and does not necessarily require highly trained expert operators.
- Portability: Gas welding does not require any electricity, unlike arc welding, so can therefore be used in places that do not have an electricity source. The equipment itself is a lot cheaper and extremely portable for different jobs.
The disadvantages of gas welding are listed below:
- Lower Temperature: Gas welding has a lower temperature of 5,700 °F compared to arc welding which can reach 6,500 °F. Therefore it is not suitable for thick sections of metal, or high-strength steel.
- Requires Post-Welding Finish: Gas welding doesn’t provide a high surface finish. To make this aesthetically pleasing, a post-welding finish would be required.
The choice between arc welding and gas welding depends on the application and the part output requirement. For example, when welding together thick materials, arc welding is a much better option. As electricity can generate a much higher temperature, arc welding can cut through and join thicker metals, whereas gas welding cannot. However, gas welding is much more appropriate for thin metals, such as thin plates and sheet metals, whereas arc welding cannot fuse thinner materials together. When choosing between arc welding and gas welding, if cost is the driving factor, then it would be better to choose gas welding over arc welding as it is much cheaper and does not rely on a source of electricity.
Arc welding is much faster than gas welding. There is a much higher temperature in arc welding vs. gas welding. The extreme heat generated by the electric arc means the process is more efficient at melting metal and provides quicker heating times. This also means there is less distortion in the metals themselves.
The heat source in arc welding is produced by electricity which generates enough heat to melt metals and fuse them together. In gas welding, the heat is produced by burning a gas such as acetylene mixed with oxygen to generate a flame which then melts the metal. The difference between these two heat sources means that the resultant heat generated is slightly different. Arc welding can reach much higher temperatures than gas welding. Additionally, arc welders do not require preheating, whereas gas welding requires the metals to be preheated in order to achieve a more uniform weld.
Both arc welding and gas welding can be used to weld steel and iron. However, gas welding can weld much thinner sheet metal when compared to arc welding. Arc welding is much more efficient and economical over an extended period of time, and it can also create stronger welds.
Gas welding is slightly better suited for portability, despite arc welding also being well suited for portability. Gas welding only requires the gas cylinder containing whichever gas will be used and an oxygen cylinder to combine with the gas to be burnt to create the flame which melts the metal. However, with the arc welding procedure, an electricity source is required to generate the heat.
Both arc welding and gas welding are inherently dangerous activities. Arc welding has the potential to burn your skin, electrocute you, burn your retinas, damage hearing, and create carcinogenic fumes. The gas used for gas welding is flammable/explosive when mixed with oxygen or air in certain ratios, so leaks are extremely dangerous. Gas welding can also burn your skin, burn your retinas, create carcinogenic fumes and is at more risk of explosion than arc welding. Both forms of welding are inherently dangerous however risk is mitigated to appropriate levels with proper training and the use of personal protective equipment.
No, arc welding produces much stronger and more durable welds than gas welding on a consistent basis. The quality of the weld can be dependent on the welder’s skill and the temperature generated. As arc welding produces a much higher temperature to create the welds, there is deeper penetration which creates better fusing of metals and subsequently less distortion of the materials overall.
Yes, gas welding has a relatively cheap initial capital outlay. There are higher upfront costs with arc welding for the equipment needed, and, of course, electricity is required. However, in the long run, the difference between arc welding and gas welding is that arc welding is much more efficient and can weld materials far quicker. The consistency and precision of arc welding cut down on cost by preventing the need to grind out and re-weld. Additionally, the cost of purchasing welding gases combined with the maintenance of the gas welding bottles and torches doesn’t necessarily make it the cheaper option.
Yes, arc welding can be used for joining lighter metals, however, it can be much more difficult. Steel is the most common metal used in arc welding, and in comparison, aluminum is much harder. As aluminum is an active metal, it is much more challenging to create a binding filler to weld aluminum with. Additionally, aluminum has a high heat conductivity and a low melting point which makes it hard not to melt the pieces involved. However, arc welding can be used to join aluminum alloy series types such as: 1xxx, 3xxx, 5xxx, and 6xxx.
This article presented arc welding vs. gas welding, explained each of them, and discussed their differences. To learn more about both arc welding and laser welding, contact a Xometry representative.
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