The most difficult-to-cut metals are nickel-base superalloys, according to Jay Gordon, North American sales manager for saws and hand tools at the saw division of The L.S. Starrett Co., Mount Airy, North Carolina. “People are running into them more often.”
The sawing parameters not only have to remain consistent but must be correct. “With a carbon steel product, you can get away with the feeds and speeds being somewhat out of whack,” Gordon said. “But when you get into these difficult alloys, they have to be correct if you want to get any blade life and production out of it.”
While the compositions of standard alloys, such as Inconel 718 or Hastelloy C-276, are known, part manufacturers also must saw proprietary metals, Gordon noted. “Of course, when it is proprietary, you don’t know what’s in it.”
To help, he recommended asking the material supplier what the proprietary metal cuts like. “It becomes a lot more dependent on the saw specialist to be able to read chips and determine what may be required.”
If the chips look black and blue because of excessive heat and are similar to chips produced on a turning machine, Gordon said something is wrong. Instead, chips should look like steel wool or the familiar curled shape, depending on the application.
“I would say there’s a lot of trial and error in some of these materials,” he said. “For proprietary materials, you just have to work your way through it and keep adjusting until you arrive at the best solution.”
Available from Starrett are the Advanz MC5 and MC7 carbide-tipped bandsaw blades, which utilize a multiple-chip grind with a high/low tooth sequence to distribute the load over five or seven teeth.
“It allows you to saw more aggressively because the load on each tooth is less than it would be without the progressive tooth grind,” Gordon said. “That will also increase your speed. In most cases, the smoothness of the cut increases as well.”
“It allows you to push a little harder because each tooth is taking as much load as possible to that chip,” Gordon said. “That will also increase your speed. In most cases, the smoothness of the cut increases as well.”
Gordon added that Advanz MC5 is more user-friendly whereas Advanz MC7 boosts production. “If an operation has 10 saws and all are heavy-duty machines with no vibration, has the right coolant, good operators and needs to go as hard and as fast as possible, we recommend the MC7,” Gordon said. “On the other hand, if a shop has a few saws that are older and operators that are not as well-trained, they would probably be better off with the MC5.”
Also, Starrett AMP technology is available on some Starrett bandsaw blades, including Advanz MC5 and MC7 ones, which increases cutting efficiency and blade life, according to the company. A custom back-edge enhancement on the blade generates a rocking motion while cutting, increasing tooth penetration without adding feed pressure. This cutting motion also serves to minimize the surface contact area, increasing blade life when sawing difficult-to-cut alloys.
Related Glossary Terms
Substances having metallic properties and being composed of two or more chemical elements of which at least one is a metal.
Machine that utilizes an endless band, normally with serrated teeth, for cutoff or contour sawing. See saw, sawing machine.
Fluid that reduces temperature buildup at the tool/workpiece interface during machining. Normally takes the form of a liquid such as soluble or chemical mixtures (semisynthetic, synthetic) but can be pressurized air or other gas. Because of water’s ability to absorb great quantities of heat, it is widely used as a coolant and vehicle for various cutting compounds, with the water-to-compound ratio varying with the machining task. See cutting fluid; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.
Rate of change of position of the tool as a whole, relative to the workpiece while cutting.
Machining operation in which a powered machine, usually equipped with a blade having milled or ground teeth, is used to part material (cutoff) or give it a new shape (contour bandsawing, band machining). Four basic types of sawing operations are: hacksawing (power or manual operation in which the blade moves back and forth through the work, cutting on one of the strokes); cold or circular sawing (a rotating, circular, toothed blade parts the material much as a workshop table saw or radial-arm saw cuts wood); bandsawing (a flexible, toothed blade rides on wheels under tension and is guided through the work); and abrasive sawing (abrasive points attached to a fiber or metal backing part stock, could be considered a grinding operation).
- sawing machine ( saw)
sawing machine ( saw)
Machine designed to use a serrated-tooth blade to cut metal or other material. Comes in a wide variety of styles but takes one of four basic forms: hacksaw (a simple, rugged machine that uses a reciprocating motion to part metal or other material); cold or circular saw (powers a circular blade that cuts structural materials); bandsaw (runs an endless band; the two basic types are cutoff and contour band machines, which cut intricate contours and shapes); and abrasive cutoff saw (similar in appearance to the cold saw, but uses an abrasive disc that rotates at high speeds rather than a blade with serrated teeth).
Tough, difficult-to-machine alloys; includes Hastelloy, Inconel and Monel. Many are nickel-base metals.
Workpiece is held in a chuck, mounted on a face plate or secured between centers and rotated while a cutting tool, normally a single-point tool, is fed into it along its periphery or across its end or face. Takes the form of straight turning (cutting along the periphery of the workpiece); taper turning (creating a taper); step turning (turning different-size diameters on the same work); chamfering (beveling an edge or shoulder); facing (cutting on an end); turning threads (usually external but can be internal); roughing (high-volume metal removal); and finishing (final light cuts). Performed on lathes, turning centers, chucking machines, automatic screw machines and similar machines.
- turning machine
Any machine that rotates a workpiece while feeding a cutting tool into it. See lathe.