TPT November 2019

AR T I C L E

Advanced Machine & Engineering I AMSAW

How to cut cost using different types of carbide-tipped circular saw blades Carbide-tipped circular saw blades are offered in three versions with different cost structures By Willy Goellner, chairman and founder – Advanced Machine & Engineering/AMSAW

Saw blade types Regrind (re-sharpen) carbide-tipped saw blades The first carbide-tipped saw blades had carbide tips brazed to the circular blade body. The brazing compound was silver- based and bonded at high temperatures of about 1,380°F (750°C).

have replaced the regrind blades of smaller sizes. Another advantage is the reduced material waste. The saw blades can be thinner because the fatigue life of the blade body does not have to extend for more regrinds. Replaceable carbide tip circular saw blades The experience with replaceable tip slotting cutters for milling, and the advantage of using already hard-coated carbide tips, inspired manufacturers to use this technology on larger circular saw blades. Replacing the tips in your own shop eliminates exchanging the blades on your machine and saves the cost of transportation to the blade grinding shop.

This method is still used for regrind carbide-tipped circular saw blades, but has been improved over the last 50 years. Today, copper shims are used between the carbide tips and the body of the saw blade to dampen the impact when the carbide teeth engage the metal. The shims also take care of

different thermal expansion coefficients between the carbide tip and the steel body. The flux and silver brazing material that guarantee a solid connection has also been improved. One-way (throwaway) blades One-way blades are available up to 36" (914mm) diameter and are used for specific steel and general-purpose sawing.

However, not every saw machine is capable of using replaceable tip blades. The machine must have sufficient power to cut with wider teeth and of a rigid design to reduce vibrations, and must be equipped with sensors that can detect tooth breaks and wear and tear to shut off the saw before the blade gets damaged. Replaceable carbide tip blades are expensive because the blade body requires precision machining of the carbide tip seats. If the carbide seats are damaged, it may be hard to fix and the blade body may have to be discarded. Up to now, the market share of replaceable tip saw blades is small. Cost comparison of blade types An accurate comparison of cost depends on many factors: is cutting rate more important than tool life?; is transportation to and from blade repair shops an issue and so on? If the blades are professionally handled, regrind blades can be re-sharpened about eight times and re-tipped four times before the blade body gets fatigued or is worn beyond repair. That is eight times regrinding the new blade, plus 8x4 regrinds

Larger diameter blade bodies are too expensive to be thrown away after only one use. One-way blades are also hard coated in special chambers. The hard coating of the carbide tips increases the wear resistance of the cutting edges. They are also suitable for cutting stainless steel, because

their coating prevents the welding of the chips to the carbide tip. Presently, these blades cannot be cost-effectively re-sharpened because of the hard coating, and they are discarded after one use. Small diameter and thin blade bodies are cost effective because the blade body cost is absorbed by the higher tool life of the coated carbide tips. These one-way saw blades

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NOVEMBER 2019