Boring System Contains Anti-Chatter Mechanism
Kennametal’s plug-and-play boring system contains an anti-chatter mechanism. The bars range from 1" to 4" (25 to 100 mm) in diameter. The bar contains a mass filled with damping fluid and supported by a pair of elastic supports. The mass vibrates at a predetermined frequency during machining, attenuating the natural frequency of the bar around it to suppress vibration. The system is said to offer performance in boring applications up to 10×D.
Features of the boring system include a serrated, bolt-on connection at the end of the bar that clamps a variety of styles and sizes of short, lightweight indexable heads. A reference flat on the top of the head is said to accommodate a visual angle finder, allowing the user to rotate the bar until the indicator reads zero, and then to clamp it into place. Machine-specific turret adapters along with a special split sleeve bushing provide maximum rigidity.
A variety of interchangeable heads includes screw-on and lever-style clamping mechanisms in positive and negative rake configurations. The heads are coolant-fed, providing a stream of high-pressure coolant to the cutting zone. The heads are said to be replaceable in the event of a crash, avoiding damage to the bar itself.
With macros and canned cycles resident in the CNC on most contemporary turning centers, single point turning of OD threads can seem like almost a default process decision. However, for numerous applications, OD thread rolling has inherent advantages as an alternative to cutting threads.
One of the most common methods of tapping in use today on CNC machines is 'rigid tapping' or 'synchronous feed tapping.' A rigid tapping cycle synchronizes the machine spindle rotation and feed to match a specific thread pitch. Since the feed into the hole is synchronized, in theory a solid holder without any tension-compression can be used.
Running rotary milling cutters at the proper speeds and feeds is critical to obtaining long tool life and superior results, and a good place to start is with the manufacturer's recommendations. These formulas and tips provide useful guidelines.