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The secondary wood industry traditionally uses tungsten carbide tooling (TCT). Perhaps the most significant improvement in tooling, TCT reduced tooling changes, increased tool life and improved quality. Most importantly, TCT reduced costs.
Almost 100 years old, tungsten carbide is a compound of sintered material or powder that is compressed and heated. The composition and percentage of powder will determine the toughness of the resultant compound. The TC compound is made from tungsten and carbon powders, cobalt (bonding agent) and titanium as a possible additive. Woodworking tooling saw the first use of TCT in the 1950s.
The process of producing TC tips requires a mixture of fine grains of tungsten and carbon, initially compressed into the general shape of a saw tip. The additives and bonding agents are used to keep the compressed shape and properties intact. After this compression the tips are heated to 700 to 800 degrees C, cooled and processed to a desired shape.
The saw tips are still not ready to cut or be applied to a saw body. Further heating which melts the cobalt bonding agent, called sintering (at 1, 400 to 1,600 degrees C) continue to change and combine the granular structure of the tips. Subsequent cooling produces the crystalline structure important for the sharp cutting edges of the TCT product. These tips are now able to be brazed onto the saw body and ground with the appropriate geometry for the customer.
Long-lasting
Over the years the granular powder manufacturing process has produced finer and finer materials. Essentially, the newest generation TCT saw will machine wood with similar quality to high-speed steel and last considerably longer. Another property of TCT products is their resistance to the abrasiveness of naturally occurring crystalline woods and composite materials such as MDF, plywood, etc.
A further enhancement to tooling was the introduction of diamond tooling, commonly called Polycrystalline Diamond or PCD. Layered onto a TCT with a sintering process and pressure, PCD tooling has higher abrasion resistance than TCT and considerably longer life.
The PCD payoff
PCD is more expensive and must be justified prior to purchase. For long runs or typical profiles, PCD tooling will pay for itself with reduced tooling changes and sharpening intervals. In many cases, multiple TCT tools will have to be purchased to expect the same life as one PCD tool. The quality of the PCD edge will cut deeper, faster and with better quality. The sharpening intervals for a PCD tool could be yearly vs. weekly with TCT. The savings are dramatic.
Still longer-lasting
If PCD is not hard or long-lasting enough for your application, Monocryrstalline Diamond or MCD will outlast PCD. Using a single diamond crystal vs. multiple crystals in a PCD, a single edge will be sharper than the multiple edges of a PCD. A MCD tip will have better abrasion resistance and longer life between regrinds. The text reports that 83 times more material was cut using MCD vs. PCD. The PCD tool needed to be reground 15 times in this example with considerable downtime.
Every tool has its unique properties, cost and life expectancy. Once, high-speed steel was the only product to cut wood. With the introduction of unique woods and composite products as well as the need to reduce costs, tooling edge technology changed rapidly. Each improvement increased the life expectancy of the tool hundreds of times over, reduced costs and improved quality and throughput. High-output CNC equipment would not be possible without carbide or diamond tooling.
The Final Word: Cutting wood requires attention to detail. Protect yourself and your employees by testing the air and insisting on the proper personal protective equipment. Safety glasses must be worn when there is a potential of flying particles in the air. In order to protect your face, a face shield will deflect large particles from cutting your face.
If you find technical information, please let the class know about them on Blackboards Discussion Board or e-mail them to me. Thank you to Northwest Research Institute, Inc. for the carbide saw manuals. Information such as this is hard to come by.
Text: Circular Saws, their manufacture, maintenance & application in the woodworking industries, by Eric Stephenson, 2002 ed., Stobart Davies
author: Steve Ehle