A Guide to Different Methods of Welding Sheet Metal Fabricated Parts

Welding is the cornerstone of sheet metal production, beginning with flat sheets and bending them into complex, durable parts used in everything from automobiles to airplanes. Constructing enclosures, brackets, or other assemblies, having a few weld processes of sheet metal products is the difference between strength, appearance, and worth needed.

Following is a summary by the Sheet Metal Fabrication Company of the most common sheet metal welding methods, their advantages and disadvantages, and what to watch out for so that you can be a well-informed option for your project.

1. Introduction to Sheet Metal Welding Fundamentals

Sheet metal usually means flat metal material that is thin and between 0.5 mm and 6 mm in thickness. Welding sheet metal is in itself a fairly demanding task, its difficulty being how to keep heat input in balance so material will not warp, burn through, or become distorted. Material type (steel, stainless steel, aluminum), thickness, joint design, and end-use dictate what process to use.

2. General Welding Processes for Sheeting Fabrication

2.1 Gas Metal Arc Welding (GMAW/MIG)

Description:

Gas Metal Arc Welding, or MIG (Metal Inert Gas) welding as it is popularly called, involves the use of a continuously fed electrode wire and a shield gas (argon or argon-carbon dioxide mixture) to protect the weld pool from contamination.

Advantages:

• Continuous wire feeding and high production rate.

• Can be applied to most metals like mild steel, stainless steel, and aluminum.

• Reduced post-weld cleaning since it leaves less slag behind.

• Easier to mechanize and thus ideal for assembly lines.

Disadvantages:

• Not suitable to be done outdoors (wind would disrupt the shielding gas).

• Less control than TIG welding, especially on sheet.

Best Applications:

• Car body panels, air conditioning ducts, and medium-gauge sheet metal assemblies.

• 2.2 Gas Tungsten Arc Welding (GTAW/TIG)

Description

Gas Tungsten Arc Welding (TIG) employs a non-consumable filler and electrode rod of tungsten to produce a clean, accurate weld. Inert shielding gas (helium or argon) protects the weld area from oxidation.

Advantages:

• Better heat input and control of weld bead.

• Enhance appearance with less splatter.

• Free-form, thin light sheet metal, such as aluminum and stainless steel.

Disadvantages:

• More time-consuming than MIG, thus more labour expense.

• Very skilled operators must use it to be efficient.

• Less effective on heavy-duty or thick welds.

Best Applications:

• Welding of aerospace parts, stainless steel components, and artistic/architectural models.

2.3 Resistance Spot Welding

Description:

Spot welding holds the metal pieces together in an overlapping position and flows an electric current through the joint, generating high heat to heat up and melt the metal.

Advantages:

• Very fast and very repeatable, best suited for mass production.

• Lower distortion when using local heating.

• No filler metal required.

Disadvantages:

• Applied to lap joints (only overlapping sheets).

• Only thin sheets and basic shapes.

• Electrical equipment and electrodes should be maintained.

Best Applications:

• Automotive body panels, appliance casings, and battery boxes.

2.4 Laser Beam Welding (LBW)

Definition:

Laser welding refers to metal sheet joint joining and welding with a high-intensity laser beam and very little heat input and distortion. It is with or without filler.

Advantages:

• High speed and precision.

• Reduced heat-affected zone (HAZ), less distortion.

• Excellent for robot and automated welding.

Weak points:

• Much too expensive the initial equipment cost.

• Effective joint preparation and fixturing must be employed.

• Reflecting materials such as aluminium may require special handling.

• Optimum Applications:

• Luxury car body panels, electric enclosures, and high-accuracy aerospace parts.

2.5 Plasma Arc Welding (PAW)

Description:

Similar to TIG, plasma welding utilizes a pressurized arc that is blown downward through a thin-bore copper nozzle to generate a high-energy plasma jet with deep penetration and adequate control.

Advantages:

• Stable with high penetration.

• Able to weld from thin to heavy gauges with little distortion.

• Can be mechanized to execute precision work.

Disadvantages:

• More advanced equipment than TIG.

• Experienced people must be used to setting parameters and torch control.

Ideal Applications: High-accuracy aerospace components, stainless steel sheets, and titanium structures.

3. What to Consider in Selecting a Welding Process ?

3.1 Thickness and Type of Material

Aluminum, mild steel, and stainless steel respond differently when subjected to heat. Thin sheet (below 2 mm) needs low heat input techniques like TIG or laser welding so as not to warp or burn through. Lap joints, butt joints, or T-joints all require the best welding process. Spot welding is best in lap joints, for instance, while TIG is best in butt joints of thin stock.

3.2 Volume of Production

Mass production prefers such processes as MIG, resistance spot welding, or laser welding because they can be more easily automated and are quicker. On prototype or low-volume production, TIG may be more costly but slower.

3.3 Appearance

Surface welds on end products typically require smooth, clean surfaces that can be achieved by TIG or laser welding.

3.4 Equipment Cost and Accessibility

Don't just look at initial equipment cost but also operating costs like shielding gas, electrode consumption, and human capability.

Conclusion

Welding is a highly critical operation in shaping sheet metal into functional, durable products. Welding is extremely important to the quality, look, and cost of your product. Depending on how much speed, accuracy, or looks you need, there's a process of welding for you: MIG welding for general use and convenience. TIG welding for accuracy and looks. Spot welding for high-volume manufacturing. Laser welding of high-tech, precision assemblies. Plasma welding for superior, high-quality joints.

Not spending time to select the proper process to fit your material, joint configuration, production rate, and investment guarantees the best possible result for your sheet metal fabricated parts. Having trouble figuring out the proper welding process for your next sheet metal fabrication part? Allow a qualified fabricator to walk you through the advantages and disadvantages so you have the best match!

Also Read: What Determines The Cost of Custom Aluminum Parts?