3 Expert Weldment Techniques for Sheet Metal Fabrication (Updated for 2024)

Last updated on February 16th, 2024 at 09:16 am

Welding is one of the oldest fabrication methods in the history of humankind. As far back as the Bronze Age, humans have been assembling smaller parts and fusing them together to create larger pieces. Even blacksmithing was an early form of welding.  

Today, welding is a common manufacturing process that produces parts for cars, aircraft, houses, buildings, engines, high-pressure vessels, and more. The old spark-to-metal application may seem archaic to some folks, but as the popular saying goes, “A good welder can weld anything from the crack of dawn to a broken heart.”

At Approved Sheet Metal, we specialize in various weldment techniques and leverage best practices to meet the specifications of every project we take on.

3 Expert Weldment Techniques at Approved Sheet Metal

Simply defined, a weldment is a larger unit formed by welding an assembly of custom sheet metal pieces together. 

When you’re dealing with larger parts, basic MIG or TIG welding techniques aren’t always the most efficient or cost-effective solutions. Our team uses different welding methods to streamline the process of creating quickturn assembled parts

Spot welding.

Spot welding consists of firing an electrical current through two pins pinching two or more layers of sheet metal together. As the wire heats up, the material melts into a coin at the point of contact, fusing the materials. 

The simple, automated process requires minimal setup, making spot welding the most efficient and cost-effective welding option for high-volume production. Common applications for spot welding include electronics, solar panels, and automobile parts.

Seam welding.

When layering two workpieces together to form a longer piece, the surface becomes irregular at the seams. Seam welding uses electrical resistance to create a smooth, continuous joint between the metal sheets. 

Resistance seam welding can produce airtight welds and watertight seals. It’s ideal for marine applications, tanks, shipping containers, pressure vessels, and nuclear components. 

Seam welding is faster than spot welding and doesn’t require filler material, however material thickness is limited to no more than 3 mm per sheet.

Plug welding.

Also known as rosette welding, plug welding is the method of choice for the automotive industry. 

Similar to spot welding, plug welding fuses material together by making coin-like deposits on overlapping sheet metal. But instead of using two pins to cinch the sheets, the welder cuts holes into one sheet and layers it over the other. Once heat is applied, the metal melts, fills the hole, and fuses the two parts together. 

If you’re manufacturing hot rods or doing auto repairs, plug welding is the most versatile and durable option.

Weldment Best Practices at Approved Sheet Metal

Led by our in-house master welder, Gerald Fanning, Approved Sheet Metal’s welding team is trained to the highest standards. Our best practices include:

• Using only low heat to avoid metal distortion. When too much heat is applied to a part during welding, it can curve, oil-can, or warp. Only an experienced team like ours has the know-how to dial in the welder’s temperature correctly to achieve optimal strength without heat distortion.
• Cleco holes for precision alignment. Using CAD software, we add alignment holes into your design. Alignment or “cleco” holes ensure precision placement for all the parts in the assembly.
• Custom fixtures. Parts tend to move when heat is applied, so we design and create custom fixtures to hold everything in place.

Although we’re experts at welding, we also specialize in welding alternatives like rivets and mechanical fasteners. In fact, the strongest and most sophisticated designs we see often don’t require welding at all. 

If you need weldments for your next project, you can rely on us to produce the best welds without worrying about uneven seams, heat distortion, or misalignment. Request a quote today!

Sheet Metal Part Design for Manufacturing Tip

CORNERS AND WELDING

Proper technique on corners that need to be welded is necessary to reduce cost and increase the overall strength of the corners. Approved Sheet Metal will always reprogram corners that need to be welded to ensure customers receive the best possible welds.

Get more DFM Tips

Sheet Metal Weldment Techniques FAQ

What is welding, and how does it relate to historical fabrication methods?

Welding is a fabrication method where smaller parts are fused together to create larger pieces. It has a long history, dating back to the Bronze Age and even blacksmithing. Today, it’s used in various industries to produce parts for cars, aircraft, buildings, and more.

What are some expert weldment techniques used at Approved Sheet Metal?

Approved Sheet Metal employs three key weldment techniques: spot welding, seam welding, and plug welding. These methods are tailored to specific applications and help streamline the creation of assembled parts.

What is spot welding, and where is it commonly used?

Spot welding involves using electrical current to fuse layers of sheet metal together. It’s highly efficient and cost-effective, making it a popular choice for high-volume production. Common applications include electronics, solar panels, and automobile parts.

When is seam welding preferred, and what are its advantages?

Seam welding is ideal for creating smooth, continuous joints between metal sheets. It’s commonly used in applications requiring airtight or watertight seals, such as marine components, tanks, and pressure vessels. Seam welding is faster than spot welding and doesn’t require filler material.

What is plug welding, and why is it popular in the automotive industry?

Plug welding, also known as rosette welding, is a versatile method used in the automotive industry. It involves creating coin-like deposits on overlapping sheet metal by cutting holes into one sheet and layering it over the other. This technique is highly durable and suitable for manufacturing hot rods and auto repairs.