Ceramic Ferrules

What are ceramic ferrules? Ceramic ferrules are the single use arc shields that make drawn arc stud welding work. Moulded from a technical ceramic, typically cordierite, they ring the base of the stud during welding to contain the molten pool, concentrate arc heat, exclude air from the weld zone, and vent process gases through moulded slots in the base. Ceramic is used because it withstands the thermal shock long enough to do its job and costs little enough to be consumed on every weld. AlbanyCountyFasteners.com stocks these in 3/8, 1/2, 5/8, 3/4, and 7/8 inch to match our weld stud sizes.

Ceramic

Diameter:

Ferrule Ceramic Cap

Why ceramic rather than a durable material

Because the ferrule is meant to break. Arc temperatures well above 1,300 degrees Celsius crack ceramic under thermal shock, and that is by design: after the weld cools, the operator knocks the ferrule off with a hammer to expose the fillet for inspection. A material tough enough to survive repeatedly would also be difficult to remove, and the cost per unit would no longer suit a part consumed on every weld. Ceramic also has the advantage of being cheap enough that its geometry can be optimised for one weld rather than compromised for durability, so vent sizing and fillet cavity dimensions are exactly what the process needs.

Why choose ceramic ferrules

Contains the molten pool so a sound weld fillet forms
Concentrates arc heat where the fusion needs to happen
Excludes air from the weld zone, preventing porosity
Moulded vents let weld gases escape rather than becoming trapped
Breaks away cleanly after the weld for fillet inspection
Economical enough to consume one per weld

Sizes stocked

3/8 inch, matching 3/8 inch headed concrete anchor studs
1/2 inch, matching 1/2 inch headed concrete anchor studs
5/8 inch, matching 5/8 inch headed concrete anchor studs
3/4 inch, matching 3/4 inch shear connector studs
7/8 inch, matching 7/8 inch shear connector studs
Match to stud diameter, and order extra for handling breakage

Common applications

Drawn arc welding of headed concrete anchor studs
Shear connector welding in composite construction
Bridge deck and structural steel fabrication
Precast and cast in place embed plate work
Any drawn arc stud welding on flat plate

Order these alongside your studs, whether headed concrete anchor studs or shear connector studs. Background on the drawn arc process is on our weld studs page.

Related Categories

Ceramic Ferrule FAQs

Are these reusable?

No. Standard ceramic ferrules crack under the thermal shock of the weld and are designed to be broken away afterwards. Plan on one per stud plus a margin for breakage in handling.

How do I remove one after welding?

Once the weld has cooled, a tap with a hammer or a chipping tool breaks it away, exposing the fillet around the stud base for inspection. They are designed to fracture cleanly.

What happens if the ferrule is off centre?

The molten pool is not contained evenly, so the fillet forms unevenly around the stud base. That is a visible defect on inspection and it means the weld is not what the design assumed. Check that the ferrule grip on the gun holds it concentric.

Can I weld without one?

Not with the drawn arc process. The molten pool spreads without containment, leaving insufficient metal at the joint and no fillet. There are specialist ferrule-free robotic systems, but conventional drawn arc welding requires the arc shield.

Why is one side vented differently on some ferrules?

Vent configuration is matched to weld orientation. Flat ferrules for horizontal work vent all round, while vertical wall applications use ferrules vented on one side only so molten steel does not run out the bottom under gravity.

How should I store them?

Dry and protected from impact. Ceramic is brittle and chips easily in a site environment, and a chipped ferrule will not contain the pool properly. Keep them in their packaging until use.