How to choose the right knife steel for your application
By Leon Botes, Sales Manager
Your finished timber products can only be as good as the machinery and tooling that process them. By investing in the right knife steel for your particular applications, you benefit from higher productivity and profitability, greater customer satisfaction/repeat purchases, and less downtime.Choosing the right knife steel depends on a number of factors:
- Type of timber species
- Length of run
- Quality of surface finish required
- Your moulder’s RPM
- Degree of hook angle cutterhead
Knife steel types
Available in high carbon and high chrome, D2 is good for high-speed softwood planers and moulders. It offers the best value for many moulding producers and planer mills. It’s easy to grind and great for shorter hardwood runs, and also knotty softwoods because it resists nicks. D2 also resists chemical erosion when cutting wet cedar or redwood.
Specifically used for softwood material, HSS produces excellent finished results. It grinds very cool and can be used on a variety of different timber species.
These knives are HSS, with 18% tungsten, and represent the traditional system in knife and cutting performance. They’re good for both long and short runs on softwoods and hardwoods and offer better resistance to abrasive glue lines.
HSS-coated, WR knives are the new generation of cutting knives. They are the entry to Coated Steels - a new revolution in performance. They combine all the best features of HSS, including impact absorption and a supreme cutting edge, with the protection and durability the thin coating brings.
Compared to regular HSS knives, ST1 has a special coating that gives it an impressive edge life performance. This translates into increased machine run time and reduced grinding costs. ST1 is world-renowned for its cutting results with specific timber species like Western Red Cedar, American Oak and European Oak.
The last step before carbide, ER+ knives are an excellent choice for super long production runs and for cutting problem hardwoods. This material is not only coated but the core product is also through hardened to give that density and strength to the problematic running of Hardwoods.
Hard and robust, TCT knives are the obvious choice for hardwood; particularly on breakdown cutterheads. This design of carbide welded to a HSS backing plate achieves a strong execution when machining robust, dense and cranky timber. When used in combination with solid carbide on the finishing spindles, it will be the ultimate long-life tool and represent great value.
The hardwood machining holy grail - long run performance and perfect surface quality - it was considered a myth before the invention of solid carbide. Using the ‘pure’ carbide on finishing spindles has made it possible to deliver this ideal combination. The purity of this carbide now allows for the selection of the precise grade and grain of carbide to ideally match the application either in medium density or higher density hardwoods, as well as MDF.
Your tooling choices are critical
Who would have thought the old Castrol advertisement “Oils ain’t oils” would perfectly encapsulate the evolution of knife steel in 2021? Developments in knife steel have now achieved the ability to deliver a perfect fit to complement all timber species and moulding machines. Like fitting a square peg in a round hole, using the wrong knife steel can be a frustrating and lengthy process that will most likely not achieve the result you’re looking for.
Understanding that “Knife steels ain’t knife steels” will absolutely be a game changer for your
operation, your production and definitely your surface quality.