Grades of High-speed Steel for Manufacturing Molding Knives

Mirror Reflections manufactures all our high-speed steel and carbide profile knives on a Weinig Rondamat 960 profile grinder, it is our opinion that this model machine is superior to all other manual profile grinders available in the industry today. This time-tested profile grinder has superior accuracy and is a favorite among some of the most prestigious milling shops around the world. There are several custom options on our R960 knife grinder that allows us to manufacturer cutters with superior results, these options along with our disciplined approach, make’s our machine the “Technician's Choice” amongst professionals. Our most widely used high-speed knife steel is sixty-degree corrugated, with one-sixteenth- inch between each corrugation and a five-sixteenths thickness dimension. Our two-piece, three eighths thickness European style carbide has a one-quarter-inch thickness backer plate and a one-eighth-inch thick solid carbide piece that interlocks with one another using micro corrugations. Our V2+rw Williams and Hussey or Shop Fox high-speed steel retains a one quarter-inch thickness measurement, it is non-corrugated steel with one inch on center holes for securing the knives to the cutter head on the machinery.

Which quality of knife steel should you use?

Mirror Reflections uses some of the highest quality high-speed knife steels and carbide available in the industry. We offer three different grades of steel to choose from, V2+RW, Black Nitride, Endurance and a European style carbide for profile knives with some inlay carbide for straight planer knives. The choice of options and grades are summarized below.

• V2+RW Rockwell Hardness is about 58-62 beneath the coating, this is a good quality product that was designed for short runs roughly between one and one thousand lineal feet of high-quality millwork. This steel is flash coated with a special hard chrome coating (.002") thick to help provide very long wear on the cutting edge. It will outlast any standard uncoated M-2 steel, it is relatively straightforward to grind with a rough vitrified and a borazon finish grinding wheel, it is also easy to joint the knives on high-speed molder machinery.
• Black Nitride - Our premium quality steel offers longer run times than standard M2 or M3 high-speed steel, one thru two-thousand lineal feet between sharpening. Adding pure carbon to the surface of the knife steel hardens the cutting edge to about .010" deep to obtain about a seventy-two Rockwell on the surface. Our steel has a black oxide coating to reduce pitch build up and rust, it also gives the steel uniform color due to case hardening color differences, this steel is a bit more brittle than other non-case-hardened steels. Excellent for stubborn hardwoods and softwoods, but not recommended for woods like knotty Alder, the abrasive planing techniques of rough lumber mills on this species of wood leave abrasive particles in the face of the lumber and chips the cutting edge of the steel while milling, if you have profile jointers on your molder this steel will work perfectly for your application.
• Endurance - This is our superior quality grade of high-speed steel for making molding cutters. Starting with Vanadium base steel, we then apply Physical Vapor Deposits (PVD) coating in an Ion sputtering magnetron chamber. These deposits consist of a five-layer film of Aluminum, Chromium, Molybdenum, Nitride, and Titanium. This forms an extremely hard and heat resistant cutting edge twice as hard as C2 grade carbide. Because the coating is so thin (.002”), normal vitrified rough grinding wheels and cubic boron nitride (CBN) finish wheels can be used on this product. Special care must be taken not to hone the face of the knife with anything but a block of wood. Tool life is increased up to 600 percent (subject to one’s opinion) over normal high-speed steel. Small amounts of medium density fiberboard (MDF), five hundred lineal feet or less can be milled with this grade of steel.
• Tungsten Carbide - Expensive in cost (see pricelist), this application requires diamond grinding wheels to sharpen the knives. Excellent milling life from one thousand to twenty thousand lineal feet between sharpening. Used on products such as medium density fiberboard (MDF) and plastic composites, exotic wood species such as Anigre, Teak, Ironwood and Monkey Pod to name a few. We offer this in precut lengths of European style backer plate & solid carbide for profile knives, and inlay carbide for straight planer blades.

Every woodworking company has their own quality standards for the lumber they process; some shops will mill a wider range of lineal footage than others in the estimates given above. Many factors come into play when trying to determine the amount of actual footage of lumber you can mill between sharpening of the knives. Things such as design of the knives, quality of wood, whether the lumber was pre-surfaced or rough sawn before the milling process, whether the wood was abrasive planed rather than surface planed. If you hit a staple in the ends of the boards it will chip the steel or carbide regardless of the grade. As a woodworker we hope you realize the scenario and the points we are addressing, if we can be of any further assistance please feel free to contact us, we would be happy to help you.