Centerless loops

In centerless grinding (centerless external cylindrical grinding), the workpiece is not clamped, but guided on a support ruler between two rotating wheels - the grinding wheel and the control wheel.

The grinding wheel performs the actual material removal, while the regulating wheel rotates the workpiece at a defined peripheral speed and guides it axially. The contact angle and the relative speed of the two wheels determine feed, removal rate and surface quality.

This design eliminates the influence of clamping errors and enables stable machining of rotationally symmetrical parts with maximum repeat accuracy.

There are basically two main processes:

• Through-feed grinding : The workpiece is continuously fed through between the grinding wheel and regulating wheel. This process is ideal for long, cylindrical parts such as shafts, bolts, sleeves or pins and is used in series production.
  
• Plunge-cut grinding (in-feed grinding): The workpiece remains stationary during machining; the grinding wheel plunges radially. This process is used for shoulders, shoulders or complex geometries.
  

Both processes can be combined with automatic workpiece feed, in-process measuring technology and CNC-controlled feeds to ensure constant dimensional accuracy.

Modern centerless grinding systems enable extremely tight manufacturing and shape tolerances.
Depending on the material, geometry and grinding parameters, the following values apply:

Dimensional tolerance: up to ±0.002 mm
Roundness: Cylindricity: Surface roughness: up to Ra 0.1 µm (for fine grinding or superfinishing)

Thanks to closed-loop process control, adaptive infeed control and temperature-compensated machine frames, dimensional accuracy is kept constant even during long-term production.

The process can be used universally for almost all rotationally symmetrical materials.
Typical material groups:

• Steels and stainless steels (e.g. 42CrMo4, 1.4301, 1.4542)
  
• NE metals such as aluminum, brass, copper
  
• Hard metals and sintered materials
  
• Technical plastics (e.g. POM, PEEK) e.g. POM, PEEK, PTFE)
  

For each material group, grinding grain size, bond, infeed, feed and cooling strategy are individually optimized. This minimizes heat-affected zones and produces homogeneous surfaces without grinding burn.

Centerless grinding offers decisive advantages:

No clamping fixtures required → no deformation due to clamping forces
High process speed → ideal for large series
Continuous material flow → Short cycle times
Excellent repeat accuracy due to elimination of clamping errors
Uniform roundness and surface quality over the entire length

In combination with automated feed systems, CNC regulating wheel controland inline measuring systems, centerless grinding achieves maximum process reliability and cost-effectiveness - ideal for automotive, drive, hydraulic and medical technology components.

Our production works with in-process measurement technology and digital process monitoring. The workpiece diameter, roundness and surface roughness are continuously recorded during processing.

All grinding parameters are automatically adjusted via closed-loop control.
Downstream optical and tactile inspection stations and SPC (Statistical Process Control) evaluations document the quality in accordance with ISO 9001 / IATF 16949. The result: proven stable series processes with fully documented dimensional accuracy.