Recipe for Lower Cost per Cut

Add a higher priced blade to carve out more profits

ARMOR® CT BLACK

ARMOR® CT BLACK is a band saw blade that has an AlTiN coating, allowing for low thermal conductivity and forcing heat into the chips rather than the blade or workpiece. Photo courtesy of LENOX.

What if adding one more ingredient to your circular or band saw mix could double the cut speed? And what if that same ingredient could also significantly extend the life of your blades? Interested?

That extra ingredient would be a coating. According to blade manufacturers, enhancing the surface of the teeth with a coating can extend blade life by 100 percent or more and slice cutting time in half—with the potential for even more time savings depending on the blade material, coating, and the material being cut.

A coating directs the heat generated on the tooth face away from the cutting tool and into the chip. As the chip pulls away from the workpiece, it draws the heat away from the material being cut and the blade itself. Less heat in the blade equals longer blade life and fewer stops for blade changes.

Speed It Up

“A coating will reduce friction,” said Richard Otter, vice president of sales at Tru-Cut Saw Inc., Brunswick, Ohio, which offers a full line of circular saw blades. “Reduced friction lets you saw through the material faster so you can cut more parts per hour. If you are cutting blocks of steel with an uncoated, 40-inch-diameter blade, it could need changing every couple hours. A coated blade could run the same job for 12 hours without stopping. That’s a big savings in machine downtime.” And tooling cost.

Coated blades for circular saws have been more prevalent than those for band saws. Unlike the round tools, the lengths of band saws have made them difficult to fit in a physical vapor deposition (PVD) chamber for the coating process. But the ability to offer the productivity increases gained by coatings to band saw blades made the awkward process worth pursuing.

“Band saw coatings are catching up,” said Daniel Fernandes, brand manager for band saw blades, LENOX® Industrial Products & Services, Newell Rubbermaid, East Longmeadow, Mass. “Adding a coating shields the tooth tips from heat, an enemy of band saw blades, and that allows the teeth to stay sharp and not wear as quickly.

“Bimetal and carbide blades can use similar coatings,” Fernandes said. “But as a general rule, you can run uncoated carbide blades faster than uncoated bimetal, so the combination of a carbide blade and a coating gives you real cutting speed. When a coating prevents heat buildup in the blade, you can push it much, much harder.”

Choose the Right Coating

The PVD coating process creates a chemical bond that doesn’t scrape off easily. A blade can spend up to 12 hours in the deposition chamber to complete a coating cycle.

The chemical composition of the coating and number of layers are based on the application. According to Fernandes, several chemicals are commonly used in coatings, such as aluminum, titanium, nitride, carbon, silicon, and chromium. “For example, you can add an element like chromium to the coating recipe to improve corrosion resistance.”

Ttitanium nitride (TiN) is a general, low-cost coating that helps keep the edge on the blade for ferrous and some nonferrous applications such as cutting aluminum. Otter said that a TiN-coated blade typically lasts 50 percent longer than an uncoated blade used in the same application, “but if you jump to an AlTiN [aluminum titanium nitride] coating, you could see between 100 and 200 percent better blade life.”

 AlTiN-coated carbide blade

LENOX reported that cutting time for a 6 ½-in. round of hardened stainless steel dropped from 25 minutes using an uncoated bimetal blade to 47 seconds using an AlTiN-coated carbide blade. Photo courtesy of LENOX.

Otter continued, “Special coatings like AlTiN are created by combining multiple layers of titanium and aluminum. There could be 14 to 22 layers. Then there is TiAl- SiN [titanium aluminum silicon nitride], which is one of the special coatings designed for cutting hardened materials.”

A blade with an exceptionally hard coating like titanium carbo-nitride (TiCN) will cut gummier materials.

Regrind, Recoat Option

Circular saws can be reground and recoated. “On carbide the regrind and recoat works great. With high-speed steel you have to strip the blade every few regrinds www.cimindustry.com CIM® May 2015 35 because the coating starts to build up and can flake off,” Otter said. “You do have to remember that each grind reduces the tooth size.”

Not so for the band saws. “We’re different than the circular saws,” said Fernandes. “In the band saw world, a fabricator typically runs a blade to its end of life when the teeth wear down or tooth tips are lost—so the blade is no longer functional. Resharpening or recoating services aren’t real options.”

Fernandes offered a tip to ensure that a coated band saw blade’s end of life is as distant as possible. “Build in a break-in period where you cut dry. This will get the blade hot enough to activate the coating so you get its full benefit. As a rule of thumb, let the blade fully submerge into the workpiece, especially if it is a hard-to-cut material, before you turn on the coolant.”

Justify the Investment

Coatings add a premium of 30 to 50 percent to the cost of a blade depending on the complexity of the recipe and the process time involved. So there has to be a need before a fabricator considers the investment.

“You need a reason like a challenging material, a need for extra performance, or a machine that is creating a bottleneck and needs to produce more parts. Upgrade to a coated blade and you can pump more jobs through the same equipment. You’ll get more out of your overhead costs and your labor,” said Fernandes.

A company running semiautomatic or fully automatic equipment will get the most benefit. With a manual machine, Otter said, coatings don’t help as much because the saw operation itself can vary depending on the operator, and the runs are usually small.

“Each coating has its place,” said Otter. “A lot of it comes down to how much a fabricator wants to spend. Those who understand that with a coating they can put a saw blade on and really run it believe in the benefits and see the extra cost as an investment in productivity.”

www.lenoxtools.com

50-in.-diameter saw blade

A technician inspects a nearly 50-in.-diameter saw blade after it is loaded into the PVD chamber for coating. Photo courtesy of Tru-Cut Saw.

www.trucutsaw.com