What Is Spot Welding and How Does it Work?
A common method used to join sheet metal, spot welding works through a combination of low-voltage electrical currents and pressure.
Despite its popularity in the industry, spot welding presents several complications and limitations you should consider before choosing this as your sheet metal fastening method.
This article outlines the spot welding process, examining how it works and the common areas of application before evaluating the advantages and disadvantages of the spot welding method. We’ll then consider valid alternatives to spot welding, including self-clinching fasteners.
- What Is Spot Welding?
- How Does Spot Welding Work?
- What Is Spot Welding Used For?
- What Are the Advantages and Disadvantages of Spot Welding?
- What Are the Alternatives to Spot Welding?
- Self-Clinching Fasteners vs. Spot Welding: An Overview
- Learn More About Self-Clinching Fastener Technology
What Is Spot Welding?
Spot welding is a type of resistance welding used to join sheet metal by applying pressure and passing an electric current through the joined materials.
In the spot welding process, the heat required to join two or more pieces of metal together is generated due to the metal’s internal resistance to the electric current being applied.
How Does Spot Welding Work?
In spot welding, copper alloy electrodes are placed on either side of the joined metal pieces and an electric current is passed between them.
This subsequently creates heat and melts the metal at the point of contact while the pressure from the electrodes squeezes the molten metal to form a weld.
What Is Spot Welding Used For?
Spot welding is a common joining method used in the production and manufacture of automobiles and electric vehicles, with the body panels of one vehicle typically featuring over 1,000 spot welds.
Resistance spot welding is also common in aerospace, rail, manufacturing, electronics and construction industries, with most spot welding work carried out by robots in large industrial settings.
When completed manually, spot welding is favored by engineers as it can be used to create complex shapes with much less effort when compared with TIG or MIG welding methods.
What Are the Advantages and Disadvantages of Spot Welding?
Like any other joining method, spot welding has advantages and disadvantages.
Advantages of Using Spot Welding
- It’s fast and efficient
- It can be used on any conductive metal
- It produces strong, durable welds
- The process can be automated for use in mass production
- It’s relatively easy to do
- It’s a popular, time-tested method with lots of content available for learning how to perfect the process
Disadvantages of Using Spot Welding
- Both sides of the metal need to be accessible
- As the voltages used are so small (1-20V), any fluctuation can impact the weld's quality
- Spot welding can affect the chemical and physical properties of the metals being fused, meaning resistance to corrosion may be reduced in stainless steel, aluminum and other metals
- It isn't a suitable method for joining very thin or very thick pieces of metal
- It can’t be used to weld non-conductive materials
- Controlling the heat and pressure in the spot welding process can be difficult
- If not adequately maintained, the fumes that spot welding produces can be harmful to engineers
What Are the Alternatives to Spot Welding?
Some alternatives to spot welding include using adhesives or mechanical fasteners. As with spot welding, each method has its advantages and disadvantages, outlined below.
Read our article to learn more about the viable alternatives to welding.
Self Clinching Fasteners vs. Spot Welding: An Overview
Although spot welding is commonly used to join sheet metal, self clinching fasteners will be equally familiar to most.
Self clinching fastener technology affords design engineers several key benefits, including:
Self clinching fasteners have a single-step, in-die installation process which eliminates the need for secondary operations, increasing throughput and, ultimately, cutting costs.
Join Dissimilar Materials
One of the critical disadvantages of spot welding is that both metals being joined together need to be conductive.
Self clinching fasteners don’t present this problem — they can be fastened into common steel, HSS, hot-forming steels, aluminum and a host of other materials.
Produce Water-Tight Seals
While water-tight seals are difficult to achieve in spot welding, leading to water damage and/or corrosion, self clinching fasteners can create a reliable, leak-proof seal in aluminum and steel applications.
Create Stronger Joints
As spot welding produces a lot of heat to fuse the metal pieces, this thermal effect can produce weak points, leaving the parts vulnerable to thermal stress or annealing. Self clinching fasteners combat this challenge, as no heat is required for their installation.
Zero Impact on Coating of Components
The welding process can put components at risk of corrosion because pre-applied coatings are usually burned off during the welding process.
When using self-clinching fasteners, it’s possible to install a coated fastener into a panel without damaging the coating or KTL of either component.
Learn More About the Benefits of Self Clinching Fastener Technology
Strong and straightforward to install in various applications, self clinching fasteners offer a versatile and reliable alternative to conventional spot weld fasteners.
Learn more about this technology and the wide range of PEM® self clinching fasteners.