The Trend to Blend
The Construction Specialist April 1, 2005

A circular saw blade can actually cut steel as easily as a traditional blade can cut wood. What's the catch, you ask? There is no catch.

Premier manufacturers of saw blades have recently developed carbide-tipped circular saw blade programs that cut mild steel on portable circular saw machines as easily as they cut wood. Designs can cut stainless steel and non-ferrous metal, as well.

The magic of the blade's design is in the composition of the carbide and the geometry of the teeth. A blend of tungsten, titanium, and tantalum carbide enables the tooth tips to remain tough at very high local temperatures at the cutting edge. Conventional carbide tips typically break down and fracture if subjected to these higher impact loads at elevated temperatures.

When the steel is cut with the blade, the offal piece and the primary piece of steel are cool to the touch immediately after the cut. All heat is directed into the metal chips rather than being transferred into the piece being cut or the blade itself. No coolant is necessary. The result is a fast, dry, clean, and cool cut produced with limited sparking and no dust, which is common with abrasive blades.

Economic benefits are achieved because more material is cut per dollar than with other common solutions. For example, a 7 in. steel cutting blade with 36 teeth can cut through a 2 in. × 2 in. × 1/4 in. piece of angle iron in as little as six seconds. Similar speeds are achieved with the conventional 7 1/4 in. saw. Typical life for the 7 in. application is 400 cuts, ranging from six to nine seconds per cut over the life of the blade, compared to an abrasive blade at a typical life of 13 cuts ranging from 52 to 99 seconds per cut (see chart at right).

Cost per cut is two to three times improved with the carbide-tipped blade based only on blade cost. The cost advantage escalates from there when considering the cutting time difference over the life of the blade, the cost and inconvenience of blade changes, and the cost of downtime from waiting for a typically very hot piece, cut with other conventional technologies, to cool down.

Because of the broad range of blade diameters (5 3/8 in. to 14 in.) now available on the market, the potential applications for this dry cutting technology with contractors, fabricators, iron workers, and other tradesmen, are extensive. Blades can be used either on conventional portable circular saws (5 3/8 in., 7 1/4 in. and 8 1/4 in.) or on machines designed specifically for steel-cutting applications. These machines feature moderately lower RPM's, higher torque, and chip collection cavities to capture the waste from the cut.

Conventional 5 3/8 in. saws are making inroads with HVAC, electrical, plumbing, and other tradesmen when cutting pipe, tubing, conduit, structural steel, thin wall sheet, and other steel-cutting tasks. The conventional 7 1/4 in. provides value to the fabricator and contractor when occasionally cutting both the heavier-wall and thin-wall material. Newer hand-held machines (typical: 7 in. and 9 in.) and portable chop saws (typical: 12 in. and 14 in.) provide value over a wide range of mild steel cutting applications.

So how can you help your customer choose the right circular blade for dry cutting? Consider the following:
        What diameter of blade do they need?
        How many teeth is optimum?
        What tooth geometry is required?

In choosing a blade diameter, consider the conventional portable saw that is available and the application. Given the user's anticipated level of use, it may make sense to buy one of the new specially designed machines.

Each blade diameter and machine combination yields a maximum depth of cut. This is the first question: Will there be enough depth of cut to accomplish the steel-cutting task? For example, if you are cutting a 4-in. diameter piece of black iron pipe, a 14-in. diameter blade with a 14-in. portable chop saw designed for cutting steel would be required. If you are cutting a 1 in. × 1 in. ×¼ in. piece of angle iron or a ¼ in. × 12 in. piece of plate steel, many options are available ranging from a conventional 5 3/8 in. saw or 7¼ in. saw to one of the new machines typically ranging from 7 in. to 9 in.

Once the diameter and type of portable saw or machine are determined, the next decision is the number of teeth. As with all saw blades, the general rule is as the material gets thinner, the required number of teeth increases. Fortunately for the users, most manufacturers distinguish their blades by labeling them "steel" or "thin steel." The "thin steel" blades are designed for wall thickness or sheet thickness of 1/8 in. and thinner. The "steel blades" are for applications thicker than 1/8 in. The labeling also takes care of the tooth geometry decision. The optimum geometry for "steel," "thin steel," "stainless steel," and "aluminum" is taken care of by the manufacturers, making success in selecting the right blade even easier.

The new steel-cutting, carbide-tipped circular saws are intended to be disposable. The carbide experiences fatigue during cutting and develops small micro-cracks. For this reason, most manufacturers clearly identify that the blades should not be re-sharpened because the results are unpredictable after regrinding. When the blade wears out and does not cut acceptably for the application, buy a new blade. The value will be there.

When selecting a blade brand, choose a manufacturer that has significant experience designing and marketing all types of saw blades for cutting steel. Those who have experience with contractor steel-cutting blades such as reciprocating saws, hole saws, portable band saws and larger band saws have a solid understanding of the design and manufacturing attention to detail that is required to achieve reliable and repeatable results. These manufacturers understand the devil is in the details and that no contractor likes to experience nuisance failures from inferior tools when on the jobsite.

For more information , contact MK Morse Co. at (330) 453-8187 or visit them at www.mkmorse.com.

Copyright 2005, Reed Business Information, a division of Reed Elsevier Inc. All Rights Reserved.

For forty years M.K. Morse has been providing professional quality products and dependable service. Morse offers a wide range of hand tool and power tool accessories, including hole saws, reciprocating saw blades, jig saw blades, portable band saw blades and hack saw blades, as well as industrial quality band and circular saws. Morse also offers an extensive line of abrasives and mounted points. M.K. Morse products are readily available from contractor and industrial supply houses worldwide. For more information, contact The M.K. Morse Company, P.O. Box 8677, Canton, OH 44711, telephone (800) 733-3377 or visit their website at www.mkmorse.com.