Arc Welding and CD Welding: What’s the Difference?

If you’ve read our previous blog, you know that stud welding comes in handy for a variety of situations. Whether you plan to build a boat, an apartment complex, or a bridge, stud welding strengthens your application.

But did you know that you can use multiple techniques to weld studs?

The two most common methods are arc stud welding and capacitor discharge (CD) stud welding. Though both methods involve fastening studs to base metals, they each offer their own benefits for different projects.

What Is Arc Welding?

Arc welding relies on either an AC or DC electrical current to create an arc. The current melts the metals at the welding point, and then the gun pushes the metals together. When the metals have cooled, they form a solid seam.

Arc welding breaks down into three different techniques:

  • Drawn arc stud welding. In this technique, you load the stud into your welding gun and place a ferrule (disposable ceramic shield) at the end. From there, you set the gun against the base metal and press the trigger. The electrical current energizes the gun’s lift mechanism and creates a
    pilot arc. The pilot arc paves the way for the welding current, which then heats the metal. When the lifting mechanism discharges, the stud plunges into the melted metal and solidifies. You can then discard the ferrule.
  • Gas arc stud welding. With gas arc welding, you use an inert shielding gas rather than placing a ferrule at the end of the welding gun. You load the stun into the gun and position the gun for welding. When you pull the trigger, shielding gas pours into the welding area. As the stud lifts, an electrical current creates the arc, which heats the stud and base metal. The gun then pushes the stud into the melted metal, and more gas blows onto the welding area to quickly cool the metals.
  • Short arc stud welding. Short arc welding is similar to drawn arc welding, but it doesn’t require a ferrule. It has a higher current and shorter weld time than drawn arc, though it also produces a more porous weld.

Though timing varies between techniques, all three arc welding methods offer similar benefits.

What Benefits Does Arc Welding Offer?

Arc stud welding methods allow you to quickly fasten almost any shape or size of metal. It offers maximum penetration and reliability, making it especially useful for thicker, rougher base metals. You can create a strong, one-sided weld in less than 0.06 seconds.

In general, arc stud welding enables you to create a bond stronger than either the stud or the surrounding base metal. The bond resists vibrations and breaking, so you don’t have to worry about your project loosening or weakening.

What Applications Work Best?

Some of the most common arc welding applications include:

  • Automotive (power steering, dashboards, insulation, and exhaust systems)
  • Farm equipment (cabs, spreaders, thresher teeth, and wiring)
  • Shipbuilding (insulation, hatch covers, and wire management)
  • Construction (piping, bridges, and buildings)

However, arc studs work well with most aluminum, stainless steel, and mild steel projects.

What Is CD Welding?

Capacitor discharge welding involves principles similar to arc welding. But rather than an AC or DC power supply, CD welding uses a capacitor storage system to create its electrical discharge. The discharge heats and melts the metals, and the gun then pushes the two pieces together. When the metal cools, you have a highintegrity weld.

As with arc welding, CD welding breaks down into multiple techniques:

  • Contact welding. With this technique, you load the stud with a specialized ignition tip into the gun and position the gun against the base metal. As energy discharges from the capacitors, the ignition tip vaporizes and creates a gap. The current then flows through the gap, melting the stud and the base metal. The gun forces the pieces together until they cool and harden.
  • Gap welding. Like contact welding, you load a stud with an ignition tip into the gun. But rather than placing the stud against the base metal or workpiece, you hold the gun above it. The stud accelerates toward the metal at the same time as an open-circuit shoots through the gap. The ignition tip vaporizes, the two pieces melt, and the weld forms as the metals cool.

Both techniques offer similar benefits, depending on the project you have in mind.

What Benefits Does CD Welding Offer?

CD stud welding allows you to join small studs to thinner, lightweight base metals, including materials as thin as 0.02 inches. You can typically complete a weld cycle in 0.01 seconds with minimal discoloration or distortion.

Furthermore, the process creates a one-sided weld, so the reverse side won’t show any dimples or rivets.
You can paint the reverse side before welding without worrying about damage to the finish.

What Applications Work Best?

If you have a project where cosmetic appearance is a top priority, choose CD welding over arc welding. Some popular applications include:

  • Jewelry (earrings, pins, and pendants)
  • Cookware (pots, pans, and utensils)
  • Electronics (motors, terminals, and pumps)
  • Doors (escutcheon plates, insulation, and commercial doors)

In general, CD studs work well with thin sheet metals as well as with projects where you weld two dissimilar metals.

Still Confused?

This simple guide will help you decide which welding technique will work best for your project. But, of course, the listed ideas are far from comprehensive. If you need additional help deciding whether to use arc studs or CD studs, meet with a professional welder to discuss your ideas.