Bandsawing a structural workpiece, such as a steel H-beam, is challenging for the bandsaw blade. This is because as the blade enters the cut, it starts sawing the beam’s flanges before contacting the crossbar, or web. On average, each flange measures only about ½ " wide while the web might be 20 " wide.
Courtesy of Peddinghaus
Smart Saw technology from Peddinghaus automatically adjusts a bandsaw’s feed rate as the workpiece cutting area changes, such as when transitioning into a structural H-beam’s web from its flanges.
When a bandsaw blade, typically made of HSS, cuts through significantly more material while processing one section of the workpiece than the rest of it, the feed rate must be decreased to extend blade life, according to Nick Hajewski, marketing manager for Peddinghaus Corp. The company supplies CNC bandsaw machines and other equipment for the structural steel industry. When the blade exits the area with more material, the feed rate should be increased for the remainder of the cut to enhance productivity.
To overcome this challenge, the company introduced Smart Saw bandsaw pressure-sensing technology to manipulate the feed rate without operator intervention. As the saw encounters a beam’s web, the technology almost instantaneously recognizes the increased stress the saw blade experiences. A proximity switch on the machine’s ballscrew feed system detects the increase or decrease in stress on the saw blade.
Hajewski explained that there’s a mechanical gap between the proximity switch and a pressure plate, and as pressure is applied to the plate—meaning more back pressure is exerted on the blade—the plate gets closer to the proximity switch. When the plate reaches a specific distance from the switch, the machine control receives a signal to reduce the feed. Then, when the distance increases while sawing through less material, the proximity switch is disengaged and the control restores the original feed rate.
In addition to reducing premature blade wear, Smart Saw technology minimizes blade breakage. It can take 10 to 20 minutes to change a broken blade, depending on its size, and around three or four cuts at a slow cutting speed to break-in the blade once changed, Hajewski noted. According to the company, the technology cuts blade failures in half.
Another benefit of the technology is higher cut quality. A blade that’s pushed too aggressively through a high-density section does not cut as straight and clean and the workpiece might require grinding to remove bow and burrs, Hajewski said. “Shop managers don’t want their people handling anything with jagged edges; they don’t want them cutting themselves on a section while moving it.”
For more information, contact Peddinghaus Corp., Bradley, Ill., at (815) 937-3800 or www.peddinghaus.com. CTE
Related Glossary Terms
- bandsaw
bandsaw
Machine that utilizes an endless band, normally with serrated teeth, for cutoff or contour sawing. See saw, sawing machine.
- bandsaw blade ( band)
bandsaw blade ( band)
Endless band, normally with serrated teeth, that serves as the cutting tool for cutoff or contour band machines.
- bandsawing
bandsawing
Long, endless band with many small teeth traveling over two or more wheels (one is a driven wheel, and the others are idlers) in one direction. The band, with only a portion exposed, produces a continuous and uniform cutting action with evenly distributed low, individual tooth loads. Often called band machining.
- computer numerical control ( CNC)
computer numerical control ( CNC)
Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.
- cutting speed
cutting speed
Tangential velocity on the surface of the tool or workpiece at the cutting interface. The formula for cutting speed (sfm) is tool diameter 5 0.26 5 spindle speed (rpm). The formula for feed per tooth (fpt) is table feed (ipm)/number of flutes/spindle speed (rpm). The formula for spindle speed (rpm) is cutting speed (sfm) 5 3.82/tool diameter. The formula for table feed (ipm) is feed per tooth (ftp) 5 number of tool flutes 5 spindle speed (rpm).
- feed
feed
Rate of change of position of the tool as a whole, relative to the workpiece while cutting.
- grinding
grinding
Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.
- high-speed steels ( HSS)
high-speed steels ( HSS)
Available in two major types: tungsten high-speed steels (designated by letter T having tungsten as the principal alloying element) and molybdenum high-speed steels (designated by letter M having molybdenum as the principal alloying element). The type T high-speed steels containing cobalt have higher wear resistance and greater red (hot) hardness, withstanding cutting temperature up to 1,100º F (590º C). The type T steels are used to fabricate metalcutting tools (milling cutters, drills, reamers and taps), woodworking tools, various types of punches and dies, ball and roller bearings. The type M steels are used for cutting tools and various types of dies.
- sawing
sawing
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).
- web
web
On a rotating tool, the portion of the tool body that joins the lands. Web is thicker at the shank end, relative to the point end, providing maximum torsional strength.
Author
Alan holds a bachelor’s degree in journalism from Southern Illinois University Carbondale. Including his 20 years at CTE, Alan has more than 30 years of trade journalism experience.
