Electric Resistance Welding- Ceramic Weld Rolls

International Syalons produces a variety of sialon advanced ceramic welding rolls for use in the electric resistance welding (ERW). ERW can create a forged weld that can be further used to fabricate steel pipes and tubes, for instance.

The welding rolls are also called “squeeze rolls” and are used in the ERW process to apply pressure to the tube while the metal is being heated. The metal heating is usually done with high-frequency induction heating. The combination provides a forged weld.  

The process is demanding on the welding roll material, requiring it to have high strength, thermal shock resistance, also resistance to wear and high electricity. Moreover, the pipe temperature can approach the melting point of the metal, and therefore, high temperature stability is required.

Material pick-up problems typically occur in high frequency welded tubes, but Syalon ceramics can eliminate those. This is evident with non-ferrous materials where surface condition is critical. Stainless steel, brass and aluminium tube manufacturers can now offer significant advancement on surface finishes, lacking the risks of rolling weld spatter or particles into the tube surface. Many tube manufacturers have changed to ceramic rolls through the complete forming section of the mill.

Sialons are silicon nitride-based advanced ceramics which offer excellent mechanical properties, as well as chemical and thermal stability, making them ideal for this application.

Syalon 101 meets all the above-mentioned requirements as a result from a number of key advantages over conventional metal weld rolls that it has, such as improved pipe quality, reduced roll maintenance, reduced welding failures and reduced cooling requirement. Those are achieved due to the sialon rolls’ ability to operate at high temperatures and speeds. Syalon 101 weld rolls usually achieve up to 12 times more life than tool steel rolls.

Practical tests have shown that ceramic weld rolls can reduce HF weld power by as much as 30 %. In reality, this also reduces unwanted “field” heating of local components, such as shafts, stands, lubrication points etc. Ceramic rolls also provide huge benefits for small diameter tubing manufacturers where upgrading to ceramic weld rolls can reduce weld vee length. Thus, more efficient positioning of the induction coil and impeder is ensured, which can reduce the H.A.Z. (heat affected zone) and produce a more aesthetically pleasing product.

International Syalons has been developing solutions for the industry in terms of high-quality engineering and process solutions for almost 40 years now. They currently provide a range of options for the tube industry, including weld and forming rolls, seam guides, tube expanders and drawing dies.

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