Drawn Arc Stud Welding

Drawn Arc Stud Welding is generally used to weld large diameter fasteners to rougher and thicker base metals. Arc studs may be almost any shape and there are literally hundreds. However, they must have one end of the fastener designed for arc welding. Mild steel, stainless steel, and aluminum are applicable materials for arc stud welding.

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1. The weld gun is positioned over the base material and the main gun spring is partially compressed.
2. The trigger is pressed and the stud lifts off the base, drawing an arc. The arc melts the end of the weld stud and the base material below. The arc shield (ferrule) concentrates the heat below the weld stud and contains the molten metal within the weld zone.
3. The main spring plunges the weld stud down into the molten pool of metal in the base material. The cycle is completed in less than a second and the resulting weld bond develops the full strength of the fastener in the weld zone.
4. The weld gun is withdrawn from the weld stud leaving and the ferrule. The ferrule is broken away and discarded.

Capacitor Discharge Stud Welding

Capacitor Discharge (CD) stud welding is generally used to weld smaller diameter fasteners to thin base metals. Since the entire weld cycle is completed in milliseconds, welds can be made without pronounced distortion, burn-through or reverse side discoloration. As long as one end of the fastener is designed for CD welding, CD studs can be manufactured in almost any shape.

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1. The weld gun and stud is positioned against the work plate. No ferrule is needed.
2. Stored energy discharged through special weld “timing” tip and the stud starts downward.
3. The stud is forced downward into the pool of molten metal.
4. Metal solidifies and weld is completed in a split second.

Stud Welding Guidelines

• Set appropriate time for the weld base diameter.
• Set appropriate amperage for the weld base diameter.
• Ensure that the negative polarity is to the stud gun.
• Align accessories so they are centered and adjust legs so that 3/16″ to 1/4″ of the stud protrudes beyond the ferrule.
• Ensure a good, clean ground connection.
• Keep work surface relatively clean so that impurities don not affect weld.
• Keep studs and ferrules clean and dry.
• Test welds at the beginning of each shift or change in stud (AWS Bend Test).
• Check burn off (1/8″ to 3/16″ depending on stud diameter).
• Check weld fillet (360 degrees).
• Visually inspect all welds.

Difference Between ARC and Capacitor Discharge Style Studs

Instantaneous energy is discharged from banks of low voltage DC electrostatic capacitors, electronically controlled and triggered on demand by the operator.

The trigger button initiates the cycle which energizes the gun solenoid, lifting the stud from the metal surface and creating an arc which melts a flux-loaded end of the fastener and its immediate area.

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Actuating the triggering circuit releases the stored energy from the capacitors through the stud, vaporizing the high resistance tip and creating an ionization path for peak current flow and arcing across the areas to be joined.

A ceramic ferrule shields the arc, concentrates the heat and contains the molten metal in the weld zone. Simultaneously, the gun solenoid becomes de-energized and the spring tension forces the fastener into the molten pool, integrating it with the parent metal.

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Spring or air pressure of the gun upon the partially melted stud fuses it to the parent metal surface, completing the weld in four to six milliseconds and creating a bond stronger than the fastener itself.

The cycle is completed in less than a second and the resulting weld bond develops the full strength of the fastener in the weld zone. The expendable ferrule is broken away to expose a smooth and complete fillet at the stud base.

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Length Information

Capacitor Discharge
Capacitor Weld Pins are available in 12-GA and 14-GA up to lengths of 6-inches as standard. Special lengths are available upon request.Capacitor Weld Studs are manufactured in minimum lengths of 1/4-inch up to 2-inch as standard. Other lengths are available upon request.Capacitor Weld Studs and Pins do not undergo any loss of length after welding.

Arc
Arc Studs are available from minimum lengths After Weld (AW) shown on individual specification sheets up to any length in increments of 1/8-inch. Please call one of our service representatives for specification sheets.All Arc Studs and Pins are reduced approximately 1/8-inch in length after welding for diameters up to 1/2-inch weld base diameter and approximately 3/16-inch for 5/8-inch weld base or larger.

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What Process Should You Use?

Capacitor Discharge
Capacitor Discharge stud welding is a semi-automatic arc welding process. However, with CD welding, you have the ability to weld small diameter studs to very thin material. Since the entire weld cycle is completed in several milliseconds, welds can be made to thin sheets of metal without pronounced distortion, burn through or discoloration. The CD process allows stud welding of dissimilar metals.The CD process is commonly used in most sheet metal shops.

Arc
Arc stud welding allows almost any size or type of weld stud to be welded. Studs must be manufactured from weldable material and designed with a special arc stud tip. With the Arc process, you obtain a full fusion weld that becomes stronger than the stud itself. Arc stud welding is applicable to mild steel, stainless steel and aluminum.The Arc process is commonly used in most fabricating/structural steel shops.