Tungsten carbide roll rings run in the fastest, hardest-working passes of a rod mill. A ring that lasts its full life saves money; a ring that cracks early costs a ring and a stop. This guide covers how to choose the grade and how to look after it.
What a carbide ring is made of
Cemented carbide is made of very hard tungsten carbide grains held together by a metal binder. Two things set the properties: how much binder there is, and what the binder is.
- Less binder — harder, more wear-resistant, but more brittle. Suits the final finishing passes.
- More binder — tougher, better against shock and cracks. Suits pre-finishing, reducing and higher-load passes.
- Cobalt binder — the standard choice.
- Cobalt-nickel-chromium binder — better resistance to corrosion from cooling water, which helps against surface cracks in some mills.
Choosing the grade by position
Work from the end of the mill backwards. The last stands of the finishing block see the highest speed and lowest load, so they take the hardest grades. Earlier stands and reducing / sizing blocks take tougher grades. Pinch rolls before the laying head need wear resistance plus good toughness against impact.
Cooling water
Carbide rings need a lot of clean, well-aimed water. Scale and solids in the water wear the grooves; acidic or poorly treated water attacks the binder. Check flow, pressure, nozzle condition and water quality as part of every ring failure review.
Regrinding and handling
- Regrind enough to remove all fatigue cracks from the groove; small cracks left behind grow fast.
- Use the correct grinding wheels and coolant for carbide.
- Fit rings carefully — carbide does not tolerate impact or uneven clamping.
- Keep records of tons per groove per stand, so you can see which positions need a different grade.
What to send for a quote
Send the ring drawing (OD × ID × width), the block type and stand position, the current grade if known, groove drawings if you want pre-grooved rings, and yearly consumption.
See our tungsten carbide rolls page, or send your ring list for a quote.