Skiving and roller burnishing is one of the most surprisingly productive ways to achieve high-quality bore finishing in OEM production. Even experienced machinists are impressed when they see raw tubing converted into a mirror-like finish in a single pass at extremely high feed rates. This is achieved by combining two operations into a single tool & having the right machine for the job.
The process works by using a set of floating knives on the front of the tool, followed by rollers. The diameter and finish are adjustable on the head to ‘dial’ in the exact sizes, and the finish can be tuned by adjusting the roller pressure relative to the cutting diameter. Cutting fluid floods the tool to clear chips, and hydraulic actuation protects the finished surface as the tool retracts. The process delivers outstanding accuracy, surface durability, and repeatability across a wide range of bore sizes and production environments.
Achievable results
The result is a highly efficient method that routinely achieves:
- Cutting speeds up to 300m/min (1,000 SFM)
- Feed per revolution 3mm/rev (0.118 IPR)
- Feed rates over 4,000mm/min (157 IPM)
- Surface roughness Ra in the 0.2-micro-metre (8-micro-inch) range
- Circular form as close as 0.01mm (.0004 inch)
- Diameter tolerance IT8 to IT9
These capabilities significantly enhance surface durability, a crucial factor in hydraulic cylinder manufacturing and other critical applications.
Application and production flexibility
The process applies across a wide range of bore sizes and depths, from 30 to 500mm (1.18 to 20 inches) and beyond 6 metres (20 feet). UNISIG has applied this method to depths over 13 metres (43 feet) in demanding oil and gas environments.
Most applications remove a small amount of material efficiently, typically around 1.5mm (0.06 inches). When rough tubes require more cutting, a combined counterbore-skive-burnish tool may be used. Shorter parts can be processed vertically with separate skiving and burnishing tools, which simplifies setup and increases automation opportunities.
UNISIG machines built for the process
Skiving and roller burnishing places significant demands on the machine platform, often requiring more than 100kW (134hp) at the tool. UNISIG machines are engineered to meet these requirements with power, rigidity, and long-term reliability.
- S-Series machines are purpose-built for tube production, designed specifically around the skiving and roller burnishing process. Robot-ready configurations are available as a standard option.
- B-Series BTA deep hole drilling machines support both the creation of the starting bore and the final high-quality finish, offering manufacturers a single platform for multiple operations.
Although skiving and roller burnishing is not as common as conventional drilling, milling, or turning, it is a proven method to drastically increase productivity and quality. These machine platforms allow manufacturers to fully leverage the productivity and quality advantages in high-volume production environments.