Arc or CD – Which Process Is Right For My Application?

Should I Use An Arc Or CD Stud?

Many customers who are not familiar with stud welding ask us whether their application is best accomplished by using the CD (Capacitor Discharge) process or the drawn arc process. Each has distinct advantages in certain applications. And in some cases, the characteristics and end result of both processes may be acceptable for different reasons

CD Process

The CD process involves loading a stud gun with specially designed weld studs made most commonly of low carbon steel, 300 series Stainless Steel or aluminum. The most often used CD process is the contact method. The loaded stud gun is set up to allow about 1/16” of “stick out” of the stud from the end of the gun. The gun is then pressed down against the base material. The stud will retract into the gun under spring pressure. When the trigger is pulled, high energy is released for about 7 milliseconds as the capacitors discharge. This energy, directed through the specially sized tip, will create a weld.

Arc Process

Like CD, the drawn arc stud welding process is also a form of single sided fastening. Generally, this process is used with a ceramic ferrule. The ferrule molds the fillet around the base of the stud when it is welded. With arc stud welding, the operator determines and manually sets the best electric current and time settings into the stud welder.

When the trigger of the gun is pulled, a solenoid in the gun lifts the stud off the metal substrate and an arc is drawn for a preset time between the stud and the base material. When the solenoid is de-energized, the stud plunges home into the molten pool of metal created by the arc. The ferrule is then broken-off, and the process is complete. Generally Arc stud Welding becomes an option when the base material is at least 1/8” thick and a stud is used that is 3/8” or less in diameter. There will be some backside marking, but if that is not a concern, arc generally offers a more reliable option.

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