Sawing tubes is not without its challenges. Unlike the contact a blade makes with solid stock, as a blade makes its way into the hollow portion of the tube, the transition from solid to hollow can have damaging effects on the blade’s teeth. Furthermore, blades can become pinched and damaged, and vibration can lead to inaccurate cuts on bundled material.
Probably one of the more critical aspects of cutting tube stock is in regard to the chips that settle in the tube as the blade makes its way through the material. When the teeth chomp into the nest of chips, the effects are often damaging, drastically reducing blade life. This equates to more downtime and more money spent on blades, not to mention damaged stock that becomes scrap.
Bringing in the Upcut
Kasto, a German-based metalcutting saw manufacturer, introduced its KastoWin line of bandsaws in 2014. With the latest addition, the KastoWin tube A 5.0, the company offers a saw designed for effectively cutting tubular material.
The A 5.0 cuts from the bottom up, which means there are considerably less chips gathering inside the tube compared to saws that cut from the top down. Designing the upcut saw was a challenge, especially in keeping the footprint of the machine relatively small and in configuring how the coolant would be applied to cool the blade. But, according to Sönke Krebber, manager of strategic advanced development at Kasto and a member of the owner family, it was definitely worth the effort.
“When sawing with a carbide-tipped blade, for instance, in the traditional way,” Krebber says, “and you come into this chip nest, the carbide tips will be ruined. With this new process, you begin with an empty tube, but chips don’t accumulate because you’re sawing from the bottom up. It increases blade life significantly.”
The amount of cuts a fabricator can get out of each blade depends on how it’s being used and what material it’s cutting, but it can range from twice as many to 10 times as many cuts per blade with the A 5.0.
Productivity improvement advantages include:
- A modular system design that offers a customized approach to specific applications
- Quick and easy programming through a color touchscreen interface
- Automated band guide arm adjustment
- Incremental feed for cutting batches of short pieces
- Fast motion via servodrive and ballscrew spindle for the material feed and the linear-guided saw frame
Extending Blade Life
The upcut saw is suitable for many applications, but Krebber says it’s of particular interest to customers in the oil and gas industry where fast cutting of difficult-to-cut materials is the norm. The cutting range is 10 mm (0.39 in.) to 520 mm (20 in.), which also falls in line with the tube diameters used by the oil and gas sector.
Kasto includes a frequency-controlled drive in the saw, which allows operators to cut a variety of materials without sacrificing blade life or the quality of cut. The cutting speed range is 12 m to 150 m per min.
“Different materials require different cutting speeds,” says Alexander Krapp, sales and engineering manager at Kasto. “With the KastoWin tube, we have a large range of infinite adjustable cutting speeds due to the powerful frequency-controlled sawing motor. Thus, stainless steel tubing at slow speeds and aluminum tubing at high speeds can be cut efficiently.”
Krapp says the A 5.0 was designed from the beginning to be able to use a carbide tipped blade with a result of maximum possible blade life.
“One of the most important features for this is the ‘both-side blade clearance’ after the cut,” he says, “which avoids scratching and damaging the sensitive carbide teeth when taking the blade back.”
There are also the intelligent control and software features that assist in making sure the blade life is extensive. SmartControl is the company’s control interface that uses symbols instead of text, which makes controlling the saw quite easy, even for the novice operator. This can reduce operator error that leads to miscuts and issues that compromise blade life.
The software behind it all is KastoRespond, which was developed specifically for the KastoWin series. It continuously records what happens while the saw is in operation, including the forces on the tool, without using any additional and often error-prone sensor systems.
“It intelligently converts information into the optimal digital feed rate,” Krapp says. “Thick-walled and thin-walled material, constantly changing contact lengths in round material as well as hard spots in the material are recognized in real time by the system, and the feed rate is smartly adapted, automatically and accordingly.”
When SmartControl and KastoRespond are paired with the accuracy of the KastoWin’s guiding and positioning system, the customer gets the “most accurate, fast and efficient bandsawing.” Krapp says that the operator can also use the interface to edit and lock in recurring sawing orders for quick access to frequent cuts.
When the application calls for a thin-walled material, such as square tubing, a large number of teeth are in contact with the material, which can result in the blade becoming overloaded as the spaces between the teeth become filled with material. In a situation like this, KastoRespond reacts within a fraction of a second, reducing the in-feed so the tool advances slowly with a more moderate feed rate. As the blade emerges from the surface and into the sides of the material, the system reduces cutting force while the controller increases the feed rate to the highest-performing value.
The zero-play linear guide and ballscrew spindle drive improve accuracy of the guiding and positioning system. This works in concert with KastoRespond, which the company says is nearly free of maintenance requirements and provides continuous accuracy for a long time.
Chip Removal and Accessories
Another important design element of the A 5.0 is the patented chip removal brush. It’s set up at an optimal angle to the blade and is self-adjusted.
“One of the biggest issues that destroys blades is taking the chips with the blade through the material again,” Krapp says. “Our chip brush is designed in a way that the blade is free of chips after coming out of the cutting gap.”
Workholding for round material can also be a challenge, but customers can employ a hydraulic clamping system that prevents material from slipping, providing durable and stable clamping during the cutting process.
The KastoWin tube A 5.0 comes standard with the software and control interface. The chip removal brush, hydraulic saw blade tension, horizontal vise, clamping system, material clearance stroke system and continuous machine roller conveyor are also standard.
Optional add-ons for the A 5.0 include automatic material moving, a sorting system, chip conveyors, cooling/heating packages and marking systems.
No matter which, if any, add-ons customers choose, there are wide-ranging features of the A 5.0 that benefit all customers. These include a machine base with heavy-duty, distortion-free welded construction; a machine enclosure that adheres to the latest CE criteria; linear guides, each one with two guide carriages on one guide rail; an extremely quiet running machine without vibration; and lateral guiding by hydraulically pretensioned carbide slideways.