Should I use high speed steel, coated or carbide knife steel?

Think about this for a second: when was the last time you took a step back and questioned the tooling in your operation? Have you been using the same knife steel for 2, 3 or even 5 years? Because ‘that’s what we’ve always done’. Innovation in knife steel has evolved over this period and with many of the country’s top timber manufacturers regularly trialling new steels with a different set of objectives…

The type of knife steel you use is determined by a variety of factors such as timber species, lineal metres produced, moisture content and condition of timber plus grinding equipment available. Once this is understood, from here you can then narrow your options based on your own objectives:

• Do you want to produce more?
• Are you looking for an improved finish?
• Do you want to get extra life?
• Will you be working with fire-affected or recycled timbers?
• Or perhaps you want to reduce the amount of time it takes to grind the steel again?

 
There are many different types of knife steels, but for our industry this falls under three specific categories:

• High speed steels are the entry point to knife steels which includes HSS, D2 (high carbon, high chrome) and T1 (sometimes referred to ‘18%’ due to its tungsten content).
• Coated steels are essentially high speed steels with a specific coating to provide extra life and hold its edge. The most common are WR, ER+ and ST1.
• Carbides are technically a ceramic and not a steel, and are used for large production runs, with the recommended knife highly dependent on whether you’re running abrasive timbers or knotty timbers. Carbides include tungsten-carbide tipped (TCT), solid carbide and double back. Carbides will require specific grinding equipment such as diamond wheels plus a rotative dresser to optimise the life of the grinding wheels.

Every knife steel whether it’s HSS or solid carbide, will eventually lose its ‘edge’ and require time in the grinding room for sharpening. However, by moving into coated and carbide steels you may be able to achieve more life out of your knife steel before sending it back to the grinding room.

 
Take three very different scenarios: 

• A processor working with pine might have been using HSS since their operation opened, however trialling T1 may achieve a better finish and get more life.
• A high-volume softwood framing operation will most likely be using D2 as a cost-effective steel solution. However, some may upgrade to WR to achieve even more knife life in their runs.
• If you’re cutting Cypress or have a hardwood with many knots, impurities or foreign objects, TCT is more suitable than solid carbide. For high volume production runs of hardwood timber with a superior finish and life that joints better, consider solid carbide.

 
Not sure which knife steel is right for you? We’ve developed a new recommendation table which can be used as a guide to understand if you’re using the most optimal knife steel. Have a chat to your technical representative to discuss your unique situation.