Feed-through loops

In throughfeed grinding - also known as centerless external cylindrical grinding - the workpiece is not clamped, but guided freely between the grinding wheel, control wheel and support ruler.

The grinding wheel removes the material, while the regulating wheel determines the feed rate with its defined angle and speed. The workpiece rotates around its own axis and is continuously transported axially through the grinding gap.

This kinematic arrangement enables permanent material removal with constant workpiece rotation - ideal for long, cylindrical parts. Precisely set grinding and regulating wheel angles allow surface roughness in the range of Ra 0.1-0.3 µm to be achieved.

The process is particularly suitable for rotationally symmetrical components with a constant outer diameter where there are no shoulders, shoulders or recesses.

Typical examples are shafts, bolts, bushes, axles, piston rods or round profiles. For components with variable diameters or complex transitions, plunge grinding (plunge grinding) is used, in which the workpiece is not moved axially during the grinding process, but is machined at a defined position.

The throughfeed grinding is therefore predestined for high quantities, constant cross-sections and uniform length geometries.

With modern CNC centerless grinding machines, we achieve dimensional tolerances of up to ± 0.005 mm and surface roughness of up to Ra 0.3 µm.

The stability of these values is ensured by in-process measuring systems, closed-loop control and temperature-compensated machine frames.
In addition, adaptive feed control and sensor-based process monitoring enable automatic compensation of tool wear and thermal expansion, which is particularly important for large series.

The result is reproducible grinding results at µ-precise level - documented in accordance with ISO 9001 and IATF 16949.

The material properties have a significant influence on the grinding strategy.

For tough or poorly thermally conductive materials such as stainless steels (1.4301, 1.4404) or titanium alloys, an adapted grinding wheel bond and increased cooling lubrication are used to prevent thermal cracking.

Harder materials such as 42CrMo4 or hardened bearing steels require the use of CBN or corundum grinding wheels with optimized cutting pressure.
For aluminium or copper alloys, the focus is on uniform chip removal and reduced adhesion, which is why fine-grained abrasives and special cooling emulsions are used.

By specifically adjusting the feed rate, infeed, grinding wheel hardness and cutting speed, machining is optimized individually for each material.

Centreless throughfeed grinding is characterized by high process speed, form accuracy and reproducibility.

As the workpiece is not clamped, there is no need for clamping deformations and time-consuming set-up processes. The continuous workpiece flow enables cycle times of just a few seconds per part, which makes the process particularly attractive for series production.

Another advantage is the even heat distribution, as there are no clamping points that could heat or deform the component locally.
In combination with automated feed systems, sensor-based process control and digital parameter control, throughfeed grinding enables extremely
stable, economical and precise machining.b>stable, economical and precise production that meets even the highest requirements in automotive, mechanical engineering or hydraulic applications.