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Hard Cutting

May 2013

To cut tough exotic metals like Hastelloy, Inconel and others, it takes the correct saw, know how and the right blade.

Dale Petts, global product manager of metal products at Simonds International says, “You can cut through exotic alloys with varying degrees of success with a variety of tools. In the bandsaw world, there are two types of bandsaw blades that are generally used for these tougher materials.

“One is bi-metal which is a combination of a spring-steel backer with a high-speed-steel tooth tip that has been milled or ground to form. Another is a carbide tipped blade. There are a number of carbide grades on the market that are capable of cutting tough materials, and there are a variety of geometries associated with each of these carbide grades. Most of the market has migrated toward carbide tipped bandsaw blades. This is not necessarily because of the cost of the blade, but more due to the higher number of cuts achieved, as well as the reduction in cut times.”

“Depending on the size of the material, DoAll has a few blades that we offer for cutting exotic materials,” says Pat Schmidt, northeastern regional sales manager for DoAll. Powdered bi-metal blades are a less expensive option to cut these types of materials. It’s a blade with a powdered metal tooth tip on it, and it’s much more abrasion resistant to these types of materials. Another blade would be our carbide-tipped ones. The standard bi-metal blades will cut exotic materials, but they won’t last very long.”

Asked if a bandsaw blade has to be specific to the exotic material being cut, Petts remarks, “A lot of it depends on the machinability of the metal (how easy is it to cut).”

Chris Davis, product development manager of DoAll adds in, “To cut a particular material, you need to be about 20 points harder on the Rockwell C scale. That’s why we tend to use carbide tipped blades to cut these exotic materials. A 90/10 carbide tipped bandsaw blade works well for these materials. You can also use it for abrasive materials like high-silicon aluminum.”

Schmidt mentions, “The whole key to sawing is having a good steady sawing action along with a well-maintained machine, and you need to use coolant or lubrication correctly. These exotic materials are all work hardening, and if the blade sits or dwells during the cut, the material will end up harder than the tooth tips, and they will no longer cut properly. The blade always has to pull a chip.

“In fact, a saw with a heavier head weight will cut these materials a lot better than a lighter one. A bandsaw with a 2-in. bandsaw blade will cut a 3-in. thick piece of material a lot better than a saw with a 1 in. blade, because of the difference in beam strength of the band. This coupled with the weight difference between a 1 in. and 2 in. machine will allow us to pull a chip.”

Petts says the grade of carbide that Simonds uses for its blades offers a combination of abrasion and shock resistance. But Simonds also has a unique blade that Petts says offers exceptional capabilities.

“Today company owners understand their cost of doing business, which we refer to as the shop rate or burden rate, and blade changes are idle non-productive time,” he remarks. “The longer a blade is on the machine the better. This, in combination with how quickly it cuts, is beginning to gain more focus.

“During the great recession of 2008, the surviving companies paid very particular attention to how efficient and effective every one of their machining operations were, including bandsawing. We were well-positioned to help these companies become more efficient and productive. Not only did we have a very strong line of carbide tipped bandsaw blades, but we were also the original inventors and patent holders of a technology that uses tapered geometries on the back of the blade. We call it SineWave.”

Simonds SineWave technology

This is how Simonds SineWave technology works.

Petts says this technology has been around for probably 30 to 35 years, but about 10 or 15 years ago, Simonds began to really look at not only the teeth and material, but also the blade’s back edge.

“We developed an entirely new technology designed for tough cutting applications to make the saw work in a unique manner,” notes Petts.

This technology incorporates a series of ramps on the back edge of the bandsaw blade (similar to a wave on the blade’s back edge), which allows bandsaw machines to exert more force into a cut without increasing machine pressure notes the company’s website. The SineWave blade introduces a rocking motion that enables fewer teeth to contact the workpiece, increasing penetration for faster cutting, while offering a much more aggressive cutting action across a wider section of the cut.

By changing the blade’s back-edge geometry, it can cut tough materials up to 40 percent faster and the blades can last up to twice as long, says Petts.

The blade’s ramp depth and length can be engineered to a customer’s specific cutting applications, operating parameters and production requirements to optimize material cutting performance.

Supplied in welded-to-length bands, the technology is ideal for blades cutting high chrome, tool, die, stainless, titanium, exotic materials and nickel-based steels, mentions Simonds. It can be used on almost all bandsaw machines.

“We generally find that the more difficult the material is to cut, the greater the advantage the SineWave technology offers,” remarks Petts.

Saw dynamics

Along with the blade, how the saw is set up is very important to efficiently cut exotic materials. Davis mentions that to properly cut these materials the saw’s feed force should be dramatically increased and using the saw’s fall rate to control the cut time.

“Once the material is entered, you don’t want the blade to get jammed up. If the cut gets stalled, you could break a tooth, which means a very hard piece of material is now embedded in the cut, which will most likely break other teeth when they hit it destroying the blade and stopping the cut. You really don’t want carbide teeth stuck in the cut, because nothing will cut them.”

When cutting exotic materials lubrication is very important noted all the people interviewed. Schmidt says, “Personally I like a soluble oil as a coolant for cutting. But these also have a tendency to be hard for the user to get rid of later because of disposal costs. Whereas the synthetics and semi-synthetics are easier to dispose of.

Davis adds, “Coolant is tricky, but I would say to use lubrication misting over flood coolant. I feel that it’s better because carbide is heat shock sensitive, it doesn’t do well with a lot of heat. Coolant can crack carbide if introduced when the carbide is extremely hot. If coolant is used, we recommend heavily flooding the cut to prevent heat buildup. Otherwise, it’s best just to use a lubricant.”

Tackling these hard-to-cut alloys can be done successfully as mentioned here. All it takes is using the proper cutting blade, a heavy-duty saw that’s in good condition along with the right coolant or lubrication.

DoAll
Simonds