How to Weld Thin Metal

Working with thinner sheets of metal is tricky. If you use too much heat, you may end up with a burn through. Too little may result in not enough weld penetration and will produce brittle joints.

The welding process you choose plays a critical role in the success of the procedure. If you want to know how to weld thin metal, then keep on reading.

To ensure a successful joint when working with thin gauge material, you need to keep a few things in mind.

Minimizing Burn Through

A burn through occurs when the molten weld pool collapses, dismembering itself from the workpiece. The result is a large hole instead of a perfect joint. The defect arises due to high-temperature inputs and is impossible to workaround. The welder will then have to start again on a new workpiece.

Weld Bead Appearance

Because thin-gauge metals warrant the use of lower heat inputs, the weld bead appearance may produce a higher amount of spatter. Welders usually face this problem when working with stainless steel filler metals.

Torch Angle

The placement of the torch significantly impacts the amount of energy transfer. You need to take into account the properties of the metal and its melting point when deciding on the working angle and travel speed. All these factors impact the amount of energy the metal is exposed to at one time. It can either increase or reduce the risk of a burn-through.

Shield Gas

Your choice of gas significantly affects the productivity rate of the process. If it does not transfer energy as effectively as it should, it could produce weak quality joints. If it has incredibly high energy transfer rates, it will create a significant amount of spatter, and you also run the risk of blowing through the material.

You can use either the tungsten Inert Gas (TIG) or Metal Inert Gas (MIG) welding procedure for these types of joints.

Metal Inert Gas for Thin Sheets

Gas Metal Arc or Metal Inert Gas welding is the most commonly used welding procedure for metal sheets. Depending upon the weld type and the size of the sheet, you can use either the regular MIG welding technique or combine it with the pulsing method to avoid a blow through.

Pulsing

In this method, you heat a small segment of the plates that are to be joined and then allow the weld pool to cool completely. You should not attempt to fill in the join all at once as it can create a hole in the workpiece instead.

The process has high material penetration and metal deposition rates. The intense energy exposure in this technique warrants extra care when working with brittle material. To control the amount of risk, always use the shortest wire diameter in the process. It takes less energy to melt, which limits the amount of heat transfer to the base metal.

A significant reason why this method is so widely employed when working with sheet materials is the control it allows over the energy input. It also allows for better control over the weld bead appearance, which makes it easier to fix mistakes that may arise due to lower deposition rates.

Tips and Tricks:

  • Never use a filler wire with a diameter that’s more significant than the thickness of the base material
  • For mild steel, use an ER70S-6 cable as per the American Welders Association Classification. It has a broader wetting coverage and maximizes the contact area.
  • Use a shielding gas with a high argon percentage – it transfers less heat than pure carbon dioxide does.
  • Use a Direct Current Electrode Positive polarity. It releases more heat towards the metal wire and less toward the base metal.
  • Using a Direct Current Electrode Negative can be dangerous and counterproductive. It passes on less heat to the filler wire and more to the base material. You may end up overheating the workpiece and not have enough filler deposit to form the joint.

TIG for Thin Sheets

TIG provides additional control over energy input. You can regulate it through the size of the electrode you use as well as through the pulsing technique. It also allows you to focus the arc on a particular area better.

Tips and Tricks

  • Use an electrode smaller than 1/8 inches – they are easier to start and perform better at lower heat settings.
  • Use a wire thinner than the base material
  • Use an inverter-based power source for use on thinner aluminum sheets
  • Utilize a pointed electrode for more excellent arc stability as it minimizes distortion
  • TIG is usable on various materials and performs exceptionally well on almost all. Combine either of these with one of the following techniques as per the joint and its requirements

Skip Welding

You can minimize warping and irregular bead appearance by making smaller intermittent stitch-like joints. In this technique, you divide the joint into equal parts and only direct energy towards alternate sections. Through the skipping technique, you reduce the amount of energy each section is exposed to at one time, reducing the risk of a failed joint. The result is a neat looking joint, which is also durable.

Backing Bars

To diminish the risk of burning the sheet, you can attach the workpiece to cool bars. While you heat them from the front, the bars cool them from the back, which reduces the risk of ruining the weld joint, by regulating heat input.

Fit-Up and Joint Design

Joints in thinner sheets are tricky. You need to ensure they are tightly fit together as even the minutest of holes counts as a burn through and creates a weak joint. To avoid that, make sure both metals perfectly match each other before you start welding.

With thinner sheets, you do not have room for error, as there isn’t much material that you can redirect in place. The rule is measure twice and cut once. If you can manage that, you won’t run the risk of ruining the joint.

How to Join Thin Sheet to Thick Sheet

When joining a thicker sheet to, let’s say, a 22- gauge sheet, you won’t just use a weaving technique or skip welding technique. They will not prove useful as you won’t achieve high penetration levels with it.

Instead, what you should do is first place all the tacks and hold it in place. Then, you need to direct the energy towards the thicker sheet of metal. Make sure you work well towards the edge of the joint. Doing so ensures that the weld puddle reaches the thinner metal sheet, allowing for weld penetration.

For this to work, you will set your amperage and temperature levels as per the requirement of the heavier sheet, which means they will be relatively high. Keep the energy source well away from the thinner sheet, or you will burn a hole in it. It takes a little bit of practice, but once you get the hang of it, the process becomes relatively more straightforward.

With the right welding method, filler wire, and controlled energy input, you can create the perfect weld.

Related Questions

How thin can you weld with MIG welding?

If you can control the amount of heat, you can even weld on virtually any sheet below 0.8 mm using MIG. However, we suggest that you use MIG for metals thicker than 0.6 mm. Ideally, you should use TIG for sheets 0.6mm or thinner.

What is Better – MIG or TIG Welding?

TIG produces better, cleaner welds than MIG does. The resultant product is a lot more precise, durable, and neater than MIG or other arc welding procedures. However, different welds require different methods, and you need to know the requirements and metal properties before you decide on which technique or process to use. If you require high metal deposition rates and weld penetration to boost productivity levels, MIG might be the one for you.

What is the Best Way to Weld Thin Metal?

TIG and MIG are both ideal when it comes to welding thinner sheets of metal. Both work particularly well for almost all types of materials. However, for an extremely thin sheet of stainless steel and aluminum, we suggest that you use the TIG method as it allows for better control over heat input. You can even guarantee that you won’t end up penetrating through the material.

MIG is considerably more comfortable to use, and many people employ automated robots to perform the task. However, it is not suitable for use on fragile sheets. We suggest you use it for thicker materials like structural steel. With its high productivity and metal deposition rates, MIG gives better penetration and joint quality for slightly thicker sheets.

About Pierre Young

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Hey, I'm Pierre Young a qualified AWS Certified Welder. I got into welding in 2009 as a side hustle. Ever since then, I've been doing all kinds of welds - both for business and pleasure. While immersing myself in this wonderful hobby, I've learned from hands-on experience what welding gear works and what doesn't. Welding Headquarters is the site where I share everything I've learned.

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