Available from Absolute Machine Tools, the Precihole SBN300/1-600 skiving and roller burnishing machine is well-suited for ID finishing operations for hydraulic tubes ranging from 1.37" to 16" ID and as long as 40 ft. The skiving process rapidly removes a layer of material from the internal surface of a tube, preparing it for the burnishing process. The machine is equipped with a modified floating reamer with carbide inserts for cutting. The roller burnishing-finishing process cold works the surface by pressing multiple rollers against the surface to flatten the peaks and valleys creating by skiving, resulting in a mirror-like surface finish such as that required by off-road equipment, mining equipment, and material handling machine manufacturers, among others.
The company says that by combining skiving and roller burnishing into a single operation using a combination tool, the manufacturing process for plain carbon steel, ST-52, ST-55 or aluminum tubes is typically 40 to 50 times faster than honing. It also results in a tube ID that is not only more work-hardened than the parent material, but also features a higher-quality surface finish. Feed rates as fast as 100 ipm are possible as are bore tolerances of IT7-IT8 and a surface finish as of 4 to 6 Ra micro-inches, the company says.
The skiving and roller burnishing system uses a tool that is rotated and fed with a high-capacity AC spindle motor mounted on a rack and pinion arrangement for tubes longer than 6 ft., while a ballscrew and nut mechanism is used for shorter tubes. Self-centering vices feature programmable dual-pressure hydraulic clamping settings, helping to deliver uninterrupted smooth finish and uniform size control throughout the tube. Multiple self-centering vices are provided for support for longer tube applications. Dampers help support the tube and eliminate vibrations during operation. The system uses a recirculating high-pressure coolant system and a chip shredder to cut long chips prior to transport. A CNC and tool monitoring system are also standard.