Bandsaws definitely pull a lot of weight in metal fabrication. But when it comes to sheer speed and the ability to hit high-production demands, circular saws are getting a lot of attention.
“Circular saws are becoming more popular than ever due to increases in production,” says Tim Piehel, regional sales manager at DoAll Sawing Products. Piehel has more than 35 years of experience in the metal saw market and is a co-founder of DoAll University, a program created to train operators on the fundamentals of cutting.
One of the biggest advantages to using a circular saw, according to Piehel, is cutting materials at a rapid pace, even unbundled. When using a bandsaw, material is bundled to reduce the time spent handling individual pieces. But with a circular saw, there’s no need to bundle material thanks to the fast rate at which the blade makes its cuts.
The operator loads the table and “it’s lights out! There’s no need to sit there and bundle the material or worry about stripping out the teeth on the blade,” Piehel says. “You can put a whole day’s worth of material on the table, stack up your pile of bars and run lights out – even overnight.”
Circular saw blades run at an extremely high RPM compared to bandsaw blades, which is what gives them the power to rip through metal much faster. And while this makes circular saws a prime candidate for high-production cutting, they are a poor candidate for super alloys, such as Inconel, Hastelloy, etc., which require much slower cutting speeds.
Given the popularity of bandsaws, it is understandable that DoAll would have 50-plus different models available to manufacturers. But, when a cut list calls for small diameters, short lengths and thousands of parts, DoAll offers three circular saws that can be fully automated. The SC-75A is for materials up to 3 in. in diameter, the SC-100A is for materials up to 4 in. in diameter and the SC-150A is for materials up to 6 in. in diameter.
Most users of circular saws cut steel, including carbon, stainless, bearing and tool steels, and other alloys. Manufacturers choose circular saws based on the size of material being cut. For example, if the largest materials are 3 in. in diameter, a shop would most likely choose a saw with a 285-mm blade capacity and 15-hp motor that can hit blade speeds of 30 to 150 rpm. For larger materials, such as those maxing out at 6-in. in diameter, a saw with a 460-mm blade capacity and 20-hp motor handles the extra girth quite handily.
“Circulars are replacing two to three bandsaws,” Piehel says of shops that implement circular saws to realize the higher production capabilities.
Rather than use hydraulics to move materials, which have their own maintenance difficulties and consumable costs to factor in, DoAll’s circular saws rely on servo-motors and
ballscrews to move the saw’s indexer. The saws also include high-pressure chip blowers, which are a big hit with customers cutting tubes because they need a more reliable method of clearing the chips. Adjustable power-drive blade cleaning brushes and a hydraulic sorting discharge chute are featured.
Another automated feature is a shutoff device related to the increased number of amps that a worn-out blade requires to continue making cuts. In sawing, whether it’s bandsaws or circular saws, blades are among the biggest consumables. Worn blades produce undesirable results and must be changed often.
“If a blade wears down, it’s going to pull more amperage right away,” Piehel says. “We can set the amps, so if it exceeds 17.5 amps for example, the machine shuts down.”
The right blade
Just as in bandsawing, choosing the correct blade is incredibly important in circular sawing. Piehel says when choosing a saw blade, it has to fit the size of material being cut, have the correct number of teeth per inch (TPI) and match up with the circular saw’s specifications, such as the diameter of the blade, bore hole size (the hole in the middle of the blade where the saw’s mechanism attaches to the blade), pinhole size and specification (smaller holes surrounding the bore hole), and kerf preferences.
When a circular saw, or a bandsaw, is equipped with a blade that has the wrong tooth count, several things can go wrong, from cut quality and the speed of the cut to the life of the blade. Getting the TPI right involves factoring in the diameter of the blade and the type of material being cut.
For example, an operator behind the SC-75A, which has a maximum blade diameter of 285 mm, should choose a 60-TPI blade, which is the ideal tooth count for cutting solid material 1.5 in. to 2 in. in diameter. Cutting the same size material with a blade that has a larger diameter, such as the 360-mm blade used in the SC-100A, requires a blade with 100 TPI.
“The diameter of the blade plays a very important part in the thickness of the material we’re cutting,” Piehel says.
Matters of material
For shops cutting an abundance of low carbon materials, using a blade made with cermet is ideal. Cermet is a composite material consisting of ceramic and metal materials. It’s often used in electronic components that are subjected to high temperatures, which is also why it is used in sawing – it can stand up to the heat caused by the friction of the blade moving over metal at high speeds.
DoAll produces cermet blades, which are built to take the punishment that’s doled out when cutting low-carbon metal, but also does a great job on higher carbon metals. The company also makes a blade branded as P Grade, which is heat resistant and has properties that makes it more durable against impact than cermet blades. The P Grade blades are a great choice on steel and some stainless cutting. Finally, DoAll offers the K Grade blade, which is a preferred blade for non-ferrous and stainless steels.