By: Willy Goellner, Chairman & Founder—Advanced Machine & Engineering/AMSAW

Circular metal saws, or cold saws, are sawing machines that cut materials with high speed steel (HSS) carbide or cermet-tipped, circular saw blades. Smaller diameter blades are known as one-way blades because they are scrapped once they become dull. Larger diameter blades can be re-sharpened and reused multiple times. 

The blades of cold saws cut material at higher rotational speeds to create a high chip load per tooth. Cold saws don’t require flood coolant because the heat generated by the cutting action is transferred to the chips. The chips are ejected by centrifugal forces of the rotating blade. This process allows both the blade and the cut material to remain cool, hence the name “cold saws”—but beware of the chips. Depending on the alloy, they can be red hot.

At an international machine tool show during some test cutting, a hot chip fell on my head. I did not feel it, but I smelled burnt hair. When it had burned through the hair, it was still hot enough to burn into my skin. OUCH! It was an experience I will never forget, and now I wear head protection during test cuts.

The use of Minimum Quantity Lubrication (MQL) on colds saws prevents heat build up through friction reduction. MQL keeps the tool cooler and reduces tool wear as chips expelle.

Cold Saws vs. Hot Saws

Hot saws are an alternative to cold saws. Friction saws and abrasive saws are considered hot saws due to their hot cutting actions.

Friction saws feature hardened, high carbon circular blades with a variety of sharpened teeth. The teeth cut material by creating friction from the rotating blade. This cutting action melts the material while oxidizing and burning it away.

Abrasive saws are very similar to friction saws except the material gets abraded in form of grinding dust. Abrasive cutting expands both the blade and the material being cut, producing more heat through friction, and increasing blade wear and energy consumption.

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