Make your first cuts count

Before machine shops begin machining metal parts, the raw material to be used is normally cut down to size by a saw. Like machining, the sawing process goes much better when shops follow the recommendations of the firms that supply the cutting equipment — in this case, both blades and sawing machines. In recent years, manufacturers of these products have made significant upgrades to sawing technology so they can offer better performance and useful new features to customers.

When it comes to sawing raw material, shops typically have two options: doing it themselves or leaving it to a service center or processor that supplies pre-cut material, said Kent Hughes, vice president of sales and marketing at Cosen Saws International Inc. in Charlotte, North Carolina. He pointed out that some shops may feel it’s more efficient to buy pre-cut material than to purchase and store uncut material and then cut it themselves. On the other hand, he said, shops that want to be in control of the process will purchase a sawing machine so they can cut material whenever they need it. He added that an in-house sawing machine is also the less expensive option in the long run and should pay for itself in three to five years, according to most customers he’s spoken to.

Versatix MP bimetal bandsaw blades feature triple-tempered, high-speed M-42 cobalt steel teeth with an alloy steel backing strip. The patented tooth design reportedly dissipates stress during cutting to reduce tooth breakage and lengthen blade life. Image courtesy of L.S. Starrett

Although sawing is sometimes outsourced, an in-house sawing machine is pretty much standard equipment at shops.

“In 40 years, I cannot think of a machine shop that I’ve ever been in that didn’t have at least one saw,” said Jay Gordon, North American sales manager for saws and hand tools at The L.S. Starrett Co. in Athol, Massachusetts.

Bandsaw Basics

Saw types normally found at shops include bandsaws and circular saws. The popular bandsaw is a power saw featuring a blade consisting of a continuous band of toothed metal that runs over wheels. Hughes said circular saws offer tighter tolerances, better finishes and faster cut times than bandsaws, but these advantages come with a hefty price tag. A high-production circular saw usually costs from $125,000 to $150,000 compared with about $30,000 for an entry-level bandsaw machine for production cutting, he noted.

“A job of 10 or 20 pieces doesn’t justify” a circular saw, he said. “That’s going to be put under a bandsaw machine.”

Bandsaws can be used to cut a variety of metal shapes, including round solids, tubing and structural members, such as beams and angles. Materials commonly cut by the machine include aluminum, steels, alloys and some exotics.

The bandsaw “is a very versatile machine,” Gordon said. “It can cut just about anything.”

Best Practices

Users of bandsaws can benefit in many ways by following advice from the manufacturers of the machines and blades. For example, the diameter of solid, round stock should be no more than half the maximum capacity of a saw while tubing diameters and dimensions of structural members should be no more than 70% of a saw’s maximum capacity, said Ernie Torkilsen, vice president of sales and marketing at Palmgren, a maker of bandsaws in Naperville, Illinois.

“That doesn’t mean you couldn’t buy a 7″ (178 mm) saw and cut a 7″ solid diameter,” he said, “but it takes a long time and you’re not going to have the same accuracy as you would if you doubled up the size of the saw.”

For maximum saw performance and longer blade life, Torkilsen also recommends using a blade at least 25 mm (1″) wide.

Another key to successful sawing is providing the saw and blade manufacturer with specific information about the materials cut at the shop.

Bandsaws can be fully automatic like this 0.305 m × 0.305 m (1’×1′) dual-column machine. Image courtesy of Palmgren

“Many times, when you ask what they’re cutting, the response is, ‘We’re cutting steel,'” Gordon said. “Well, there’s a bunch of different kinds of steel, and some cut the same, and some don’t. So just the word ‘steel’ doesn’t tell you anything.” On the other hand, providing the manufacturer with the grade of the material being cut “will go a long way toward making things easier and getting better production and blade life.”

In addition to knowing the specific material being cut, shops should adjust saw speeds and feeds for different materials and use the right coolant for the process. In some cases, he said misting coolants are used instead of conventional liquid coolants when sawing tubing and structural materials.

“The big advantage of that is that there is no (coolant) going down the end of the tube and onto the floor, so it’s a lot less messy” than traditional liquid coolants, Gordon said. “But an argument could be made (that) it doesn’t work as well either, so it’s kind of a trade-off.”

For recommendations on the right speeds, feeds and coolants to use for particular sawing applications, shops should check the manuals provided by equipment manufacturers. In addition, he pointed out that some manufacturers put speed and feed charts right on the machines themselves.

“All blades are going to operate the best if all the settings are correct,” Gordon said.