Sandvik Coromant’s cooling system for high-pressure coolant applications solves chip removal and swarf control problems, supports higher speed cutting data, and increases productivity.
According to Graham Smith, Midlands, U.K., Area Sales Engineer for Sandvik Coromant, there is growing use of heat-resistant super alloys (HRSAs) such as titanium and nickel-based materials by manufacturers of aerospace engines and landing gear, among other components. These materials, he said, have advantages in stability at high temperatures, resistance to corrosion, and weight-to-strength ratio. Made from forgings, the final components are usually only 50 to 80% of the original workpiece size after extensive cutting. Some HRSAs being particularly difficult to machine, “extreme” demands are often made of the cutting machines and cutting tools.
“Traditional machines and methods are no longer productive enough,” he said.
Many manufacturers are installing advanced machine tools that incorporate coolants at high pressure (70 bar and above) instead of normal pressure, according to Smith. Tool holders designed to optimize high-pressure coolant delivery are important, and Sandvik Coromant believes its CoroTurn HP tooling system fits the bill. It is designed specifically for use on machines delivering coolant at 70-80 bar. The tool holder guides the coolant through the Coromant Capto coupling and via the CoroTurn HP nozzles to a precise point on the insert. The result is improved chip control and extended tool life, according to Smith.
In the specific application (an aerospace engine maker) for which the tool holder system first demonstrated its value, the shaft component materials are CMV and Super CMV, which are machined on multi-task CNC lathes equipped for 70-bar coolant delivery. The system improved productivity, with a 25% increase in feed rate and 50% faster cutting speed, Smith said.
The engine maker had tried another solution that produced similar productivity in feed and cutting rates. But that system produced swarf (strands or fragments of metal waste) in such a way that it came up over the workpiece, constituting a threat of damage to the tool holder. And the swarf had to be removed frequently, exposing machine operators to greater potential for injury.
In addition to better managing swarf, the Sandvik system proved ergonomically better, needing only one Allen key to index inserts instead of three with the other system, said Smith.
CoroTurn HP construction incorporates small nozzles, delivering a high-pressure coolant jet that penetrates into the heat-affected zone, cooling the insert more effectively and faster and thereby optimizing chip control. The jet creates a hydraulic wedge between the top surface of the insert and the underside of the chip being removed from the component or material. This has two benefits, according to Smith: it helps reduce insert wear and breaks the chips into smaller pieces for quicker evacuation from the cutting edge. The nozzles, mounted close to the insert cutting edge, also help increase the velocity of the coolant jet at lower pressures while keeping the insert freely accessible for easy, unobstructed indexing.
CoroTurn HP can work with any machine that is equipped with high-pressure coolant and Coromant Capto couplings, including multitasking machines, vertical lathes, and turning centers.