Take the old with the new - Selecting saw blades with new technologies in mind

Practical Welding Today May/June 2003
May 29, 2003
By: Dave Byrley

New methods for cutting tube and pipe have been introduced to welding shops in the last few years—methods designed not only to cut metal, but also to cut costs.

Over the last few years, carbide-tipped, metal-cutting circular saw blades have come onto the market. These blades mount on standard or special metal-cutting circular saws and cut through steel or pipe and tubing, leaving minor, if any, burr along the cut edge.

This type of hardened steel blade has titanium and tungsten carbide-tipped teeth that cut through steel and can minimize heat transfer from the blade to the material being cut, making it possible for a welder to be able to handle parts immediately after they're cut without waiting for them to cool. In addition, these blades generate little sparking and no dust.

Cutting Costs When Cutting Bundles

When it comes to cutting large quantities of tube and pipe in welding shops, an industrial band saw machine still is a good choice, and over the years a quiet revolution has taken place in the manufacture of blades for these machines.

Although bimetal band saw blades were introduced more than 20 years ago and immediately offered improvements in blade durability compared to older carbon steel blades, some new variations of bimetal blades have proven to be suitable for cutting bundles of structural shapes like pipe and tubing.

The latest bimetal blades feature high-speed-steel cutting edges. This steel is manufactured with more carbides and higher percentages of the carbide-forming alloys, such as chrome, molybdenum, tungsten, and vanadium. The result is harder, tougher, and more wear-resistant materials that help teeth retain their sharpness longer.

But no matter which band saw blade you purchase for cutting tube or pipe, two important factors to consider are how you plan to cut it and what tooth pitch, or the number of teeth per inch of blade, you need for the job.

Cutting round pipe and tubing presents different challenges than cutting square tubing.

The biggest challenge with round pipe is the possibility of movement in the bundle and spinners. Pipe sections that spin or move while being cut can destroy a blade.

To prevent any movement, make sure the bundle is packed tightly in a hexagonal shape. You can use angle vises to make sure the bundle is arranged properly and pressed tightly together. You also can tack-weld the ends to prevent movement.

Selecting the Right Blade. When cutting round or square tube and pipe, it's also important to choose the proper tooth pitch. This can be difficult because of the varying cross sections, or wall thicknesses, that the blade will encounter.

Some factors to consider when choosing tooth pitch are:

  • Material wall thickness
  • Part orientation relative to the blade
  • Whether you're cutting a single piece or a bundle

The best choice is a variable tooth pitch. Using a variable tooth pitch allows you to cut a broader range of pipe and square tubing wall thicknesses with only one blade.

However, if the wall thicknesses vary too much, more than one tooth pitch might be necessary. As a rule, a coarse tooth pitch can be used for thinner-walled material if the saw head's feed, or drop rate, is reduced and blade speed is increased slightly.

However, if you try to use a finer pitch to cut thicker-walled material, the result may be premature tooth wear or strippage.

As a rule, when bundle cutting, find the correct tooth pitch for cutting a single piece of the material bundled, then choose the next coarsest tooth pitch. This will allow for the varying wall thicknesses in the bundle.

Whether you need to cut bundles or individual pieces, new saw blades are available to help you do the job better, safer, and more cost-efficiently. Keeping on top of new technologies can help you improve efficiency and make cleaner cuts. It also can help you keep your costs in line.

Dave Byrley

Director of New Product Development & Quality
The M.K. Morse Co.
P.O. Box 8677
Canton, OH 44711
Phone: 330-453-8187

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Practical Welding Today

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Practical Welding Today was created to fill a void in the industry for hands-on information, real-world applications, and down-to-earth advice for welders. No other welding magazine fills the need for this kind of practical information.

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