Senior Sales Application Engineer
- FMA
- The Fabricator
- FABTECH
- Canadian Metalworking
Categories
- Additive Manufacturing
- Aluminum Welding
- Arc Welding
- Assembly and Joining
- Automation and Robotics
- Bending and Forming
- Consumables
- Cutting and Weld Prep
- Electric Vehicles
- En Español
- Finishing
- Hydroforming
- Laser Cutting
- Laser Welding
- Machining
- Manufacturing Software
- Materials Handling
- Metals/Materials
- Oxyfuel Cutting
- Plasma Cutting
- Power Tools
- Punching and Other Holemaking
- Roll Forming
- Safety
- Sawing
- Shearing
- Shop Management
- Testing and Measuring
- Tube and Pipe Fabrication
- Tube and Pipe Production
- Waterjet Cutting
Industry Directory
Webcasts
Podcasts
FAB 40
Advertise
Subscribe
Account Login
Search
Choose wisely when welding thin sheet metal
How the equipment and techniques you use affect welding results
- By Jerry Mathison
- Updated August 10, 2023
- August 1, 2013
- Article
- Arc Welding
Gas metal arc welding (GMAW) is an effective method for joining light-gauge metals such as carbon steel and austenitic stainless steel. Thin-gauge materials—24-ga. to 0.1875-in. carbon steel and 18-ga. to 0.1875-in. stainless steel—are used in applications such as HVAC, automotive, mobile machinery guards and cabs, and small parts, as well as stainless steel food service and processing equipment, sanitation applications, and corrosive environments.
Thin Sheet Metal Weld Mode
Minimizing burn-through and distortion is essential to obtaining a good weld in thin-gauge materials. For this reason, the short-circuit transfer (SCT) mode, with its low heat input, often is used. The pulse mode of transfer also is used when the travel speed can be increased enough to prevent burn-through and the heat input [(Amps x Volts) x 60/Travel Speed = Joules per Inch] is comparable to SCT.
Newer machines can be programmed to pulse-on-pulse or pulse-on-short-circuit, so that two different weld conditions can be programmed for a preset time, and the power supply alternates between the two sets of weld parameters. However, if the heat input isn’t comparable to the SCT heat input, distortion can occur.
Welding in a sequence that limits the amount of heat can help minimize distortion in thin material. For instance, when producing a 3-ft. weld in the vertical-down position, weld 6 in. and then stop to allow the weld to cool down before restarting again. On larger thin-gauge material, spread out several smaller welds over the joint.
Slope and Inductance
The use of a power supply with slope or inductance control can offer improved weld bead appearance, especially when welding with stainless steel filler metals. Because of their lower thermal conductivity, stainless steel filler metals do not transfer heat as well as carbon steel, so the weld bead could have a higher amount of spatter, and the bead itself may not be as flat as a carbon steel weld made with an ER 70S-6 electrode using the same settings (see Figure 1).
Slope limits the short-circuit current, while inductance slows down the response time of the power supply, resulting in a slower, more controlled wire burnoff during the short circuit. Depending on the power supply and the welding amperage in the short-circuit transfer, you may have from 20 to more than 200 short circuits per second. The number increases with the wire feed speed.
Some newer equipment provides feedback from the arc to the power supply and automatically adjusts the voltage to deliver what is considered the optimum for the feedback received. These machines are suitable for less experienced welders and also maintain the flexibility to allow for adjustments, if necessary.
Shielding Gas for Welding Thin Sheet Metal
The shielding gas also can affect the current level, spatter, and bead appearance. The most common gases used for SCT are 75 percent argon/25 percent CO2 for carbon steel and 90 percent helium/7.5 percent argon/2.5 percent CO2 for stainless steel. The parameters listed in Table 1 were developed for these gas mixtures.
When using other gases, joint types, or configurations for SCT, you will need to make minor adjustments.
Torch Angle
Torch angle also is a critical variable when welding thin-gauge materials. Typically, a pushing torch angle is employed when welding in the flat, horizontal, and overhead positions, as this generally helps prevent burning through the material. When welding vertically on thinner materials in the SCT mode, your progression most often is from the top to the bottom of the joint.
When welding in the SCT mode, it is important to use a relatively short contact-tip-to-work distance, generally 0.25 to 0.5 in. maximum. Excessive contact-tip-to-work distance results in an unstable arc because of the greater resistance between the workpiece and the contact tip.
Welding Thin Sheet Metal Wire Diameter
Typical wire diameters for short-circuit welding of carbon steel include 0.023, 0.030, 0.035, and 0.045 in. While the stainless steel wire diameters used for SCT are predominantly 0.030, 0.035, and 0.045 in., you can use a smaller diameter when welding thin materials. However, you will need a higher wire feed speed to match the current level of the larger wire.
About the Author
Jerry Mathison
411 S. Ebenezer Road
Florence, SC 29501
843-669-4411
Related Companies
subscribe now
The Fabricator is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The Fabricator has served the industry since 1970.
start your free subscription- Stay connected from anywhere
Easily access valuable industry resources now with full access to the digital edition of The Fabricator.
Easily access valuable industry resources now with full access to the digital edition of The Welder.
Easily access valuable industry resources now with full access to the digital edition of The Tube and Pipe Journal.
Easily access valuable industry resources now with full access to the digital edition of The Fabricator en Español.
- Podcasting
- Podcast:
- The Fabricator Podcast
- Published:
- 04/16/2024
- Running Time:
- 63:29
In this episode of The Fabricator Podcast, Caleb Chamberlain, co-founder and CEO of OSH Cut, discusses his company’s...
- Trending Articles
Capturing, recording equipment inspection data for FMEA
Tips for creating sheet metal tubes with perforations
Are two heads better than one in fiber laser cutting?
Supporting the metal fabricating industry through FMA
Omco Solar opens second Alabama manufacturing facility
- Industry Events
16th Annual Safety Conference
- April 30 - May 1, 2024
- Elgin,
Pipe and Tube Conference
- May 21 - 22, 2024
- Omaha, NE
World-Class Roll Forming Workshop
- June 5 - 6, 2024
- Louisville, KY
Advanced Laser Application Workshop
- June 25 - 27, 2024
- Novi, MI