MIG welding is a versatile and efficient process that can be used to weld a variety of metals, including thin materials. However, welding thin materials with MIG requires some special considerations and adjustments to avoid common problems such as burn-through, distortion, lack of penetration, and spatter. In this blog post, we will share some tips on how to set up your MIG welder for thin metal welding and achieve the best results.
I. What is considered thin material?
The American Welding Society (AWS) defines thin material as 3/16 inch or thinner in its AWS D1.3/D1.3M: 2018 Structural Welding Code – Sheet Steel. Thin materials, such as basic carbon steel, are often used in automotive frames and panels, consumer goods, light structural components, and ancillary connections. Read Welding Materials Unveiled: Understanding the Characteristics of Metals and Alloys.
II. Why is welding thin material challenging?
Welding thin material poses several challenges, mainly due to the high heat input that can cause damage to the metal. High heat input can be caused by excessive voltage or amperage settings, too slow a travel speed, or needlessly long welds. These factors can lead to:
Burnthrough: This occurs when the weld pool melts through the base metal, creating a hole or a weak spot in the joint.
Distortion: This occurs when the metal expands and contracts due to the heat and cooling cycles of welding, resulting in warping, twisting, or bending of the metal.
Lack of penetration: This occurs when the weld does not fuse sufficiently with the base metal, leaving gaps or voids in the joint.
Spatter: This occurs when molten metal droplets are ejected from the weld pool and stick to the surrounding metal, creating a rough and unsightly surface.
Read FAQs Address Welding of Thin Materials.
III. How to set up your MIG welder for thin material?
To avoid these problems and achieve a strong and clean weld on thin material, you need to adjust your MIG welder settings according to the type and thickness of the metal, the type of wire and shielding gas, and the position of the weld. Here are some general guidelines to follow:
1）Choose a smaller wire diameter:
A smaller wire diameter will reduce the heat input and the size of the weld pool, making it easier to control and prevent burn-through. The recommended wire diameters for thin material are 0.024 inch or 0.030 inch for solid wires, and 0.035 inch or 0.045 inch for flux-cored wires.
2） Choose a suitable shielding gas:
The shielding gas protects the weld pool from atmospheric contamination and influences the arc characteristics and weld quality. For thin material, a gas mixture of 75% argon and 25% carbon dioxide (C25) is commonly used for both solid and flux-cored wires, as it provides a stable arc, good penetration, and low spatter. Other gas mixtures, such as 100% argon, 90% argon, and 10% carbon dioxide, or 98% argon and 2% oxygen, can also be used depending on the application and the desired weld appearance.
3） Set the correct voltage and amperage:
The voltage and amperage settings determine the heat input and the shape of the weld bead. For thin materials, you need to use lower voltage and amperage settings to avoid overheating and burning through the metal. The optimal settings depend on the wire diameter, the metal thickness, and the joint design, but as a general rule, each 0.001 inch of material thickness requires 1 amp of output. For example, to weld 24-gauge material (0.024 inches thick), you can use a welding current of 30 to 50 amps and a voltage of 10 to 30 volts.
4） Adjust the wire feed speed:
The wire feed speed determines the amount of filler metal deposited and the travel speed of the welding gun. For thin material, you need to use a higher wire feed speed to match the lower voltage and amperage settings, and to avoid excessive dwell time and heat buildup. The wire feed speed should be adjusted according to the wire diameter and the welding current, but as a general rule, every 100 amps of output requires 100 inches per minute (ipm) of wire feed speed. For example, to weld 24-gauge material with a 0.024-inch wire and a welding current of 40 amps, you can use a wire feed speed of 40 ipm.
5） Use a short circuit transfer mode:
The transfer mode refers to the way the filler metal is transferred from the wire to the weld pool. For thin material, the short circuit transfer mode is preferred, as it produces a low heat input and a small weld pool, making it suitable for out-of-position welding and gap filling. In this mode, the wire touches the base metal and creates a short circuit, which causes the wire to melt and detach a droplet into the weld pool. This process repeats rapidly, creating a fast and smooth weld.
6） Use a push or drag technique:
The technique refers to the angle and direction of the welding gun in relation to the weld pool. For thin material, you can use either a push or a drag technique, depending on the type of wire and the desired weld appearance. In the push technique, the welding gun is tilted 10 to 15 degrees away from the direction of travel, creating a flatter and wider weld bead. In the drag technique, the welding gun is tilted 10 to 15 degrees toward the direction of travel, creating a deeper and narrower weld bead. The push technique is more suitable for solid wires, while the drag technique is more suitable for flux-cored wires.
7） Use a short and intermittent weld:
The length and duration of the weld affect the heat input and the distortion of the metal. For thin material, you need to use a short and intermittent weld, rather than a long and continuous weld, to minimize the heat input and the distortion. You can use a stitch or a spot welding technique, where you weld a small section at a time, and then move to another section, leaving a gap between the welds. This allows the metal to cool down and reduce the stress and warping. The size and spacing of the welds depend on the metal thickness and the joint design, but as a general rule, the weld length should be 1.5 times the metal thickness, and the gap between the welds should be 4 times the metal thickness.
IV. Conclusion
MIG welding thin material can be challenging, but with the right equipment and settings, you can achieve a strong and clean weld. By following these tips, you can optimize your MIG welder for thin metal welding and avoid common problems such as burn-through, distortion, lack of penetration, and spatter. Remember to always test your settings on a scrap piece of metal before welding your actual workpiece, and adjust them as needed to get the best results.
