Bandsawing Evolution

The bandsaw often gets short shrift in a shop filled with high-tech gadgets, such as multi-million-dollar laser cutting systems. Despite the “lowly” status of the saw, however, those initial cuts made with the bandsaw are often the first critical steps in the manufacturing process, and thus vastly important. The technology has been slow growing since Englishman William Newberry invented of the bandsaw in 1809. But in recent years, it’s quickly advanced.

In the early 1800s, no one had come up with a continuous metal saw blade that would work with any reliability. Therefore, Newberry’s idea couldn’t truly be capitalized on and it’s not known if he ever actually built a usable bandsaw.

That may explain why many people believe the bandsaw is a French invention. When Frenchwoman Anne Paulin Crepin adopted a welding technique for the blades some 40 years after Newberry received his patent, the bandsaw became useful. Crepin’s patent was for a brazen ends blade, which made it more flexible and less prone to breakage than her predecessors’ blades.

Over in the United States, Benjamin Barker, from Maine, was the first American to patent a bandsaw, which he referred to as an “elastic revolving belt saw” in 1836. According to data from the U.S. Patent and Trademark Office, the two wheels on Barker’s machine were 5 ft. in diameter, and the saw blade, according to the original patent document, was “about thirty-four feet long, nine inches wide and one twelfth (sic) of an inch thick.”

Two saw manufacturers of note that have been major players in the evolution of sawing technology include Kasto, which celebrates 175 years in business this year, and Behringer GmbH, which recently reached its centennial milestone. Kasto made a significant move in 1947 when it released its hacksaw machine, marking the company’s transition into modern machine tool manufacturing.

Behringer began bandsaw production in the 1970s, introducing a column-guided design for precise and efficient sawing. Today, both companies produce bandsaws that cover a wide range of applications.

Stepping Stones

Kasto and Behringer were both early adopters of hacksaw technology, which is the predecessor of the bandsaw. Michael Finklea, president at Finklea Mfg. Technology Inc., began his career decades ago with a company that also made its splash into the industry with a hacksaw. He worked for Peerless Saws, which was founded as Wisconsin Machine Co. in the early 1900s by brothers Charlie and Andy Rasmussen. The brothers had an idea for cutting metal in a more efficient manner, and this idea turned into the first power-driven, high-speed, wet-cutting hacksaw.

“There were still a lot of limits,” Finklea says. “The hacksaw was relatively slow. It was just an articulated arm going back and forth. The advantage was that the hacksaw took the labor out of the equation for the operator, who would have had to make the cuts manually. Plus, it gave operators a lot of capacity in a small footprint.”

The first bandsaws of the modern era, Finklea says, were still “somewhat manual,” in that operators had to advance the material forward by hand, measure, make the cut, move the material out and then repeat the whole process again and again.

By the mid-1900s, manufacturers saw a need for automated solutions to ease bottlenecks, which led to roller feed and shuttle-style bandsaws that used mechanical relays to advance material into the cutting area. Often, a switch stopped the material from advancing once it reached the desired length.

The technology for sawing remained somewhat stagnant for decades after, even when machine manufacturers in other industries began ditching mechanical relays for numerical control (NC) systems. Finally, in the early 1980s when programmable controllers (PCs) hit the market, the sawing industry took notice.

Initially, the problem with the first PCs was that they were expensive, and they were segmented into electronic boards, each programmed for a specific function, whether it was a timing or motion control or anything in between. If an electronic board failed and the manufacturer of that board went out of business, the saw owner was out of luck.

“That’s kind of when the PLCs (programmable logic controllers) started to really enter into the industry,” Finklea says. “Everything was built into one component. They were more ‘plug and play.’ Those have all developed now into single piece components that have all kinds of capabilities. As the controls have advanced, the technology in the machine has advanced on the mechanical side of things, as well.”

Catching Up

Unless it’s a steel service center, the bandsaw is not likely regarded as the “moneymaker” in any shop, which could be why the machine doesn’t receive the same level of focus on R&D that other types of equipment, such as laser cutters and welders, enjoy.

Because of the bandsaw’s lowly status in the shop, it could be argued that advancing the technology too fast would outmatch the skills of the bandsaw operator, who is often the least skilled person in the shop. There’s also the mentality, Finklea says, of “it’s working, why make a change to this if it’s not the primary function of our shop?”

Fortunately, saw manufacturers are stepping up, offering the same bells and whistles that can be found on other machines in the shop, including Industry 4.0 amenities that track productivity and send an alert when a blade needs to be changed and anything else that a sensor can detect.

Beyond the saw itself, the blade technology is improving.

“They’re making the blade material harder, but the blade keeps its flexibility, so it lasts longer,” Finklea says. “You’re getting multiple grinds now on carbide, so you can cut harder materials faster.”

Blade Matters

The bandsaw is the machine and the blade is the tool. You can’t talk about one without the other, something Jay Gordon, North American sales manager/saw and hand tools, The L.S. Starrett Co., puts a lot of thought into.

Gordon says in decades past, sawing operations in steel service centers were primarily cutting carbon steels. More recently, the introduction of exotic alloys made it necessary for bandsaw and blade manufacturers to produce solutions that would make the blade last longer, cut straighter and increase production.

“Saw operators then and now,” he says, “continually seek ways to eliminate processes to speed up production.”

Saw manufacturers answered the call by creating more rigid and accurate machines that could handle the challenges presented by cutting exotic materials. At the same time, blade manufacturers faced similar challenges.

“Bandsaw blades would not only have to cut much straighter and last significantly longer,” Gordon says, “ they also had to produce a considerably smoother cut in an effort to eliminate extra milling operations and reduce costly scrap.”

The considerations were manifold, but a winning approach included creating a bi-metal blade, which is widely used for cutting carbon steels, stainless and tool steels. But what about more exotic materials?

“Bi-metal blades cannot perform at the same level as carbide-tipped blades in exotic, aerospace and high-nickel alloy steels,” Gordon notes.

The solution came in the form of a technology that actually began in the 1950s, Gordon says. In the beginning, carbide blades included a triple-chip design, which is still in use today, but was not as effective when cutting exotic materials. Blade manufacturers looked to the blade backer, which Gordon refers to as the “foundation of any blade.”

“(The backer) needed to provide beam strength,” he says, “as well as the flexibility to twist through the guides while rotating around the band wheels hundreds or thousands of times without cracking.”

Creating a more durable carbide-tipped blade involved bringing chrome and nickel into the mix, which allows the blades the flexibility to withstand the higher feed force required for exotic materials, while resisting cracking, Gordon says.

Teeth Considerations

The backer is a huge component in the evolution of more effective saw blades, but so too is the approach to the blade teeth if providing longevity, speed and smooth finish is going to be achieved.

Gordon says experts invested in R&D industry-wide in an effort to determine the best options for carbide and backer materials.

“For example,” he says, “carbide-tipped blades for abrasive applications are completely different from carbide-tipped blades for nickel alloys. Cutting gates and risers is an abrasive operation where carbide shines, but typically, the material is soft and chip loads are light. On the other hand, cutting Inconel requires substantial feed pressure, resulting in higher chip loads. This demands different tooth grinds and even different grades of carbide to increase cutting efficiency.”

Over the past 10 years or so, the increase in the number of carbide grades alone has led to better options for cutting the exotics.

“Some carbide grades are very hard and prone to chipping when pushed hard in certain materials,” Gordon says.

“Others are somewhat softer and less prone to chipping in the same application. This variety of carbide grades has allowed manufacturers to produce blades for specific applications.

“And while the resulting blades may be capable of cutting most any material,” he continues, “the blades excel when used as designed. Optimizing cutting operations by using the blade for the material it was designed to cut enables increased feed rates and results in smoother cutting, while maintaining or increasing blade life.”

Gordon says that customers have increasingly demanded cutting solutions for more challenging materials, and saw blade manufacturers have responded.

“The latest carbide-tipped bandsaw blades produce multiple chips,” he says, “reducing the chip load while maintaining performance. Blade life is extended by reducing the rounding or chipping of each tooth as it wears. This allows for benchmark performance and life when cutting exotic type materials.”