Superfinishing with stone tools: process kinematics as the key to optimizing roundness

In many key applications, compliance with the tightest roundness and surface tolerances is crucial for functional reliability, service life and tribological performance – especially for high-precision mating surfaces. With superfinishing usingstone tools, Nagel Technologies GmbH offers a tried and tested solution that is both geometrically and economically convincing.

Finishing process with defined wrapping for maximum shape fidelity

The finishing process is based on an abrasive stone tool that is applied to the rotating workpiece with an adjustable specific contact pressure. The superimposed axial oscillation with an amplitude of up to 3 mm, as well as a defined wrap of e.g. 70 degrees depending on the task, ensure targeted material removal. The kinematics used remove geometric shape errors such as polygons and other roundness deviations in the area of macro and micro geometry, or reduce them to such an extent that they no longer have a disruptive effect.

“Especially with rotationally symmetrical components, we achieve significant improvements in roundness and surface waviness thanks to our finishing kinematics with defined wrap – this is directly noticeable in the component function,” explains Christian Feuchter, Technical Sales Superfinishing at Nagel.

Spectral analysis (according to Fourier) as a quality assurance tool

Spectral surface analysis is used to break down the profile (the temporal signals thereof) of the machined component into its harmonic frequency components. This enables a precise evaluation of recurring structural components such as periodic waves and their amplitudes – a valid indicator of possible effects on wear, noise emissions and tribological interactions.

The measurement is carried out using scanning form measurement technology with a ball probe (Ø 1 mm) with coordinated parameters for scanning force and measuring speed. The combination of the finishing process and frequency analysis allows reproducible fine machining at micrometer level.

Technological and economic benefits at a glance

• Significant reduction of polygonality, fine ripple and other roundness errors through targeted kinematics
• Reliable compliance with shape and position tolerances in the µm range
• Optimization of tribological properties through improved surface topography
• Extended service life and reduced noise during use

“Our customers benefit not only from compliance with even very tight workpiece tolerances, but also from measurable improvements in functionality when using the system – especially for dynamically stressed components,” emphasizes Feuchter.