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Difference Between SMAW & GMAW Welding

Shielded metal arc welding and gas metal arc welding (SMAW and GMAW for short) are two of the most commonly used welding techniques. However, those outside the industry don’t always understand the difference between SMAW and GMAW, making it difficult for them to select the right process for their metalworking project. In this blog, we explain how each option works, the differences between them, and when you might want to choose one over the other.

What is SMAW Welding?

Shielded metal arc welding (SMAW) uses stick electrodes with a flux coating on their surfaces. The process is used to weld ferrous metals like alloy steel, carbon steel, stainless steel, and cast iron. SMAW is typically used in fabrication work, although it can be applied in tasks like maintenance and repair.

After an electrode is placed in the holder, the electric supply is activated. Immediately after tapping the electrode on the metal workpiece, it is immediately withdrawn. The result is an electric arc with a high temperature that melts both the electrode and the workpiece. 

During welding, the electrode transfers metal beads onto the workpiece, forming a weld pool. As flux melts, a shielding gas is released, covering the weld pool and preventing contamination. It is necessary to stop the process periodically to replace the electrode. The slag layer is chipped off after the weld pool solidifies.

What is GMAW Welding?

During gas metal arc welding (GMAW), a wire electrode is used, and no flux is added. GMAW welding, which can be used for alloys and metals like aluminum and stainless steel, is usually applied in metal fabrication and automotive processes. It’s also frequently seen in tasks involving brazing work and pipework.

The GMAW welding process is relatively straightforward. Once the shielding gas pressure and wire feed rate are selected, the DC supply is turned on and the electric arc is set up by tapping the electrode wire and withdrawing it. During the transfer of metal from the electrode to the weld pool, the shielding gas (usually argon, carbon dioxide, or helium) is ejected on the metal by the welding gun. Shielding gases are chemically inert, meaning that they do not interact with the weld pool. For this reason, GMAW is also known as metal inert gas welding, or MIG welding.

There are four types of GMAW welding:

• Short Circuit: An arc occurs between the consumable electrode wire and the base material, resulting in a short.
• Globular Transfer: The Globular method generates a large volume of weld metal that drips into the joint, as the wire is heated longer.
• Spray Arc: Weld joints are sprayed with small droplets of molten metal from the consumable electrode.
• Pulsed MIG: Pulse MIG welding produces one droplet of molten metal at the end of the consumable wire and the current, which pushes it across the arc and into the weld puddle.

What is the Difference Between SMAW and GMAW?

There are several important differences between the two processes.

• With GMAW welding, electrode changes are unnecessary because a wire feeder keeps supplying the gun with the electrode wire. This difference makes it more efficient than SMAW.
• An SMAW electrode has an external flux covering (one reason why it is known as stick welding), whereas a GMAW electrode has an external shielding gas.
• Due to its ability to lay down cleaner welds, GMAW promotes better efficiency. SMAW can leave slag deposits on the weld surface due to the vapourizing flux. The slag must be painstakingly removed once the weld has hardened, increasing the overall project duration. With GMAW, welds require less secondary cleaning.

VeriForm Inc.: Steel Fabricators You Can Trust

When you work with the steel fabrication team at VeriForm, you can be confident that whatever process is used (SMAW or GMAW), the welds will hold up to their intended applications. To ensure all specifications are met, we employ only CWB CSA W47.1 and W59 certified welders and retain a qualified CWB certified welding engineer. CWB-certified welding supervisors will also oversee your project from start to finish. To learn more, please visit our website, call 519-653-6000 or contact us online. 

What is The Best Gas for MIG Welding?

MIG welding is an arc welding process that uses consumable electrode wire along with gas that comes out of a nozzle that is connected to gas cylinders that contain different types of gases based on which metal is welded from here we take a deep dive into the types of gases used.

Types Of Gases that Could be Used in MIG Welding 

There are two types of gases that are used for MIG welding. These are Inert gases (Argon & Helium) and reactive gases (Carbon Dioxide & Oxygen). Inert gases are used for their stability as they have a very low chemical reactivity with their surroundings. This allows them to work as a shield to protect the welding process. On the other side, reactive gases are highly active and chemically react with the weld pool which can cause a change in the properties of the metal in the welding process. 

This also leads us to an important question of why gas is used in the welding process. The answer to this question is in the following points:

• Shielding
• Purging
• Blanketing
• Heating

Using Inert Gases Only for MIG Welding

As mentioned earlier, Argon has very low chemical reactivity. Using it alone for the welding process has its pros & cons.

Advantages of Using Argon in MIG Welding

• Handles long arcs at low voltages.
• Great results with non-ferrous metals like aluminum, copper, titanium, etc…

Disadvantages of Using Argon in MIG Welding

• The filler remains on top causing a tall bead.
• The outer edges of the arc remain cold, reducing penetration. 

Moreover, helium is not often used alone but rather mixed with argon to benefit from both gas properties. For example, helium burns hotter allowing the penetration of the welding to become deeper welds.

Using Reactive Gases Only for MIG Welding

In MIG welding Carbon Dioxide (CO2) is the most commonly used reactive gas. It is the only reactive gas that can be used alone without mixing it with any inert gas. 

Advantages of using only CO2 in MIG welding

• It’s the cheapest option out of the shielding gases. This makes it an attractive choice when low material costs are your main priority. 
• Using only CO2 results in very deep weld penetration, which is useful for welding thick material. 

Disadvantages of using only CO2 in MIG welding

• It has a less stable arc and more spatter is produced than when it is mixed with other gases. 
• The short circuit process is the only welding option if your using CO2 gas.

Oxygen Is another reactive gas that is mixed with either inert gas like argon or with reactive gas like CO2 but adding a very small proportion of oxygen to any of these gases can change the result of welding dramatically.

Mixing Inert & Reactive Gases for MIG Welding

When welding, it is important that the welder uses proper mixing techniques for the inert and reactive gases. Two different types of gases are used in MIG welding which needs a design process for creating the optimal MIG welding mixture. To do so it is important to consider the cost, availability, and source of each gas. For example, if high-purity helium is not available, lower-purity gases can be used with minimal negative effects on weld quality and fusibility. 

In addition to chemical properties, physical characteristics such as temperature, pressure, and composition must also be considered when planning a MIG Welding mix formula. the below table shows some of the mixing techniques used.

Metal	Thickness of Material	Shielding Gas
Carbon Steel	5/16 in. (8 mm) – 3/8 in. (10 mm) 3/32 in. (3 mm) – 5/8 in. (15 mm) 3/32 in. (3 mm) – 5/8 in. (15 mm) Above 3/8 in. (10 mm)	95% Ar + 5% CO2 92% Ar + 8% CO2 90% Ar + 10% CO2 80% Ar + 20% CO2 / 75% Ar + 25 % CO2
Aluminum	Up to 3/8 in. (10 mm) OIver 3/8 in. (10 mm)	100% Ar Ar +25%, 50%, or 75% He (Based on temperature)
Stainless Steel	1/25 in. (1 mm) – 1/4 in. (6 mm) 1/16 in. (2 mm) – 1/4 in. (6 mm) 1/16 in. (2 mm) – 1/4 in. (6 mm)	Ar + <35% He + <3% Co2 98% Ar +2% O2 10% Ar + 85%-90% He + 2-5% CO2

Best Practices for Choosing the Right Gas for your Welding Project

It’s important to pick a gas or gas mixture that matches the material being welded since some materials need certain types of gasses to properly weld. However, it also depends on cost and availability. For example, the most common gas used for MIG welding is argon because it has less carbon than other gases & doesn’t produce harmful gases to the environment. On the other hand, argon is much more expensive or penetrating compared to CO2.

For the best results consider the following:

• The penetration of the gas used.
• Arc Stability.
• Precautions for every gas & suitability for your welding environment.
• The availability of the gases used. For example, helium gas is not always available everywhere so replacing it with other gases might be the better option for a given situation. 
• Cost of the gases. Argon & helium are not cheap while CO2 is very cheap compared to the other two inert gases.

Lastly setting the quality of the weld you want will make the decision much easier & precise in choosing the right gas or gas mixture.

Water Jet Cutting vs Laser Cutting: Comparison of Advantages & Costs

What Are The Applications, Advantages & Disadvantages Of Waterjet Cutting?

Water jet cutting is a process that uses high-pressure water to cut materials. Waterjet cutting can be used to cut various materials, including metal, stone, glass, and plastics. Waterjets are popular in marble & stone factories as it makes it easier for them to cut and shape these types of materials.

 Advantages of Waterjet Cutting

• Can cut all types of materials, including high reflective materials or unequal material thickness. 
• The cutting process doesn’t result in overheating of the materials. 
• Waterjets don’t produce any hazardous fumes or smoke while cutting any materials.

Disadvantages of Waterjet Cutting

• High noise output compared to other cutting machines that are available commercially. 
• Precision can be an issue when cutting thick material. 
• The high-Pressure force used by the cutting process can cause the deformation of small-sized parts.

What Are The Applications, Advantages & Disadvantages Of Laser Cutting?

Laser cutting is a technology that uses a laser with special optics & computer numerical control to focus the laser beams on the material to start the cutting process. It has a range of applications, from using CO2 lasers to cut plastics & plywood to industrial applications such as using fibre lasers to cut metals & strong materials. Lately, YAG/YVO lasers have been used for rust removal & even human hair removal with high-quality results.

Advantages of Laser Cutting

• Laser cutting can achieve a very high accuracy reaching a quarter of the width of human hair. 
• Very low noise compared to all commercially available cutting machines. 
• As laser cutting is very common in production lines nowadays, some machines can achieve cutting speeds that exceed 100m/min.

Disadvantages of Laser Cutting

• Burn marks on the material – Overheating caused by cutting can leave burn marks on the cutting material. 
• Ineffective at cutting reflective material – The working principle of laser technology is based on reflected optics, making it inapplicable as a cutting method for any type of highly reflective material. 
• Higher safety & health regulations – High heat is generated, resulting in producing hazards & toxic smoke from some materials.

What Are The Cutting Costs?

Regarding cost, laser cutting is cheaper than waterjet in several aspects.

• If we look at the same machine specs for both technologies, a laser machine can cost around $10,000, while a waterjet can cost up to $30,000.
• Laser machines are also much faster it can cut more meters/min than the waterjet machines making them consume less time.
• The operation cost of laser machines per hour is lower than waterjets, making it more applicable for production lines.

Conclusion: Who Wins?

If you are keen on cutting all kinds of materials without producing any hazardous or toxic gas, waterjet is your choice. On the other hand, if you are looking for speed & lower cost, then laser cutting is your winner.

LASER CUTTING SERVICES AT VERIFORM

If you’re looking for premium laser-cutting services, look no further than Veriform. Our experts have over 20 years of experience using CNC laser cutting technology. We have provided high-accuracy cuts on some of the largest pieces of metal for clients across North America.

Our laser cutting offers up to 3/4 inches x 80 inches x 160 inches with an accuracy of +/- 0.005 inches. Besides laser cutting, VeriForm also offers numerous metal fabrication services and capabilities, including bending, rolling, welding and more. Contact VeriForm to get an estimate for your cut today!

What is Steel Fabrication?

Steel is an alloy of iron and other metals that is used for structural and fabrication purposes. Steel fabrication specifically is the process of transforming raw steel into a tool, part, or other asset used in assembly or construction.

This is a simple and straightforward definition, but steel fabrication today is an advanced and even sophisticated process. In this blog, we provide a brief overview of the fabrication process and discuss the key methods, many of which are in use at VeriForm.

Which Steel is Used for Fabrication?

Carbon steel is one of the most commonly-used materials due to its versatility, strength, and sturdiness. It is available in a variety of thicknesses and stock sizes and can withstand harsh conditions in industrial environments.

Steel fabricators commonly use stainless steel because it is relatively easy to work with. Due to its ability to bend readily, this material is ideal for welding. Applications requiring corrosion-resistant properties typically require stainless steel.

Aluminum is popular as a metal fabrication material because it’s lightweight, which is ideal for industries that need metal but can’t handle the weight. The automobile and aerospace industries are among those that often use this lightweight material.

What is the Fabrication Process?

Steel fabrication can be performed in a variety of ways. Some of the methods employed by steel fabricators like VeriForm are highlighted below.

Bending

Bending involves applying a massive force to a steel piece, usually using hammering or press machines, in order to change the shape. During the bending process, the steel piece is bent using press brakes or tube benders. 

Rolling

Rolling is a metal fabrication process where metal stock is passed through one or more pairs of rolls in order to reduce the thickness, to make the thickness uniform, or to deliver a mechanical property.

Welding

In welding, pieces of steel or other materials are welded together or bent using the fusion process, which involves heating steel parts to a high temperature, joining or bending them while they’re pliable, and letting them cool. VeriForm uses advanced welding methods such as:

• Pulsed gas metal arc welding
• Shielded metal arc welding
• Gas metal arc welding
• Gas tungsten arc welding

Machining

This method uses tools such as drills, lathes, mills, and others to shave away metal to form a specific shape. Veriform uses the following machining methods to fabricate steel components:

• CNC Countersinking: By countersinking, you create a conical hole in your part that matches the angle and head size of a screw.
• CNC Drilling: Using a rotating cutting tool, CNC drilling produces round holes in stationary workpieces
• CNC Laser Cutting: A CNC laser cutter uses a laser beam to vaporize, melt, or otherwise gradually remove materials. We offer laser cutting services up to 3/4” x 80” x 160” with an accuracy of +/- 0.005”.
• CNC Tapping: With tapping, a thread is cut inside a hole, which must be drilled with tap drills and chamfered at the end.

What Industries Require Steel Fabrication Services?

Steel fabrication services are needed across a wide range of industries, illustrating how versatile and reliable steel has become. These industries include commercial and residential construction, aerospace, the military, mining, automotive, and shipbuilding. 

VeriForm Inc.: Steel Fabricators You Can Trust

As experienced steel fabricators, VeriForm offers a wide range of steel fabrication services that can be customized according to client requirements. We maintain strict quality control throughout the whole fabrication process to meet and even exceed customer expectations, which is why so many of them have been trusting us with their steel fabrication needs for over 20 years.  To learn more, please visit our website, call 519-653-6000 or contact us online.