Positive fit turning with InoGrip®.

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Positive fit turning with InoGrip®

The force-fit turning you have known up to now …

Konventionell Spannen
Conventional clamping with polygon formation

Processing round workpieces in conventional force-fit procedures needs high clamping forces to achieve acceptable machining results. Expensive collet chucks have to be used to achieve these high clamping forces. In addition, up to now materials were clamped with a material allowance of up to 25 mm. This often resulted in an unwanted deformation that then had to be corrected or eliminated in an elaborate procedure.

In addition, higher material allowances result in higher unit costs and in some cases make processing irrational. The high clamping forces expose the gripper jaws in particular to high wear.

Positive fit turning with InoGrip® by HWR …

Spannen mit InoGrip
Clamping with InoGrip®
for minimum deformation

InoGrip® uses the physical principle of the positive fit. Defined stamping produced by a holding and a stopper tooth makes the clamping jaw and the workpiece into one unit. The stopper tooth also provides an absolutely precise reference point.

Stamping is carried out separately in a stamping station with special stamping jaws and takes approx. 3-4 seconds. Work can continue on the lathe during the stamping process.

Application examples

Spannkraft Anwendungsbeispiel

Application example Clamping force

clamped with 30 N clamping force

Wiederholungsgenauigkeit Anwendungsbeispiel

Application example Repetition accuracy

Repetition accuracy of up to +/- 0.005 mm

Einspanntiefe Anwendungsbeispiel

Application example Clamping depth

Clamping depth only 5 mm

Your advantages

Far higher power transmission with low clamping pressures

The advantages are quite apparent: the positive fit makes power transmission far more effective. As a result, the workpiece is held with clearly reduced clamping force with far less deformation. Expensive clamping solutions such as special clamping jaws or pendulum jaws are no longer needed.

Costs are cut in many areas

Material wastage is minimised and unit costs are reduced to a minimum by optimising subsequent machining.

Thanks to the positive fit, it is now possible to remove the part while machining is in progress and then reposition it again precisely after measuring or heat treatment, for example. It is thus now also possible to change from the lathe to the milling machine without any problems.

Thanks to InoGrip® ...

  • workpiece deformation is reduced
  • higher true running precision is achieved
  • subsequent steps can be omitted
  • operation of the overall system is more stable
  • vibrations in the part are reduced
  • higher cutting speeds are achieved
  • only one set of clamping jaws is needed for scrubbing and finishing


Part roundness depends on the clamping system being used

Studies at IWT Bremen

In autumn 2003, studies on clamping thin-walled roller bearing rings were carried out in the Manufacturing Technology Department at the Foundation Institute of Materials Science (IWT) which belongs to Bremen University. Various different clamping systems were used and compared in the studies.
The results of the studies confirm that use of the InoGrip® clamping system guarantees secure workpiece clamping with only 10% of the clamping force that is otherwise required. This brings considerable advantages in clamping deformation-sensitive parts, as it minimises deformation and thus facilitates economical process control.

In many cases, the use of an InoGrip® clamping system makes it possible to dispense with expensive, type-specific special clamping equipment.


Do I need a stamping station?
Yes, to stamp a defined holding contour in the workpiece in just a few seconds and to transfer the high stamping forces.

What pressure is needed for stamping?
This depends on the material. You will quickly get the hang of this after just a few tests.

How can I see whether the stamping is deep enough?
Below the actual stamping tooth there is a stopper tooth. As a rule, this stopper tooth leaves a slight imprint below the stamping tooth. If this slight imprint is present, then stamping is deep enough.

Which materials can be stamped?
Unalloyed steel, case-hardened steel, tempering steel, cast iron, aluminium and plastics, high-alloy materials with special stamping jaws, but no rubber or chalky materials.

Does stamping deform the part?
The workpieces are only slightly deformed as the stamping pressure is adapted to the material.

Will I find the stamping when I insert my workpieces?
Every machine operator will be able to position the workpieces absolutely safely after only a few minutes.

Is scrubbing possible with the InoGrip® jaws?
Certainly! Stamping creates a positive fit with far higher clamping forces than conventional gripper jaws.

In short

How InoGrip® works


is a completely new clamping jaw that fixes the workpiece in the collet chuck with a holding tooth.

To this end, a defined stamping is applied to the workpiece, resulting in a positive fit between workpiece and clamping jaw with an extremely small clamping depth. This positive fit now makes it possible to clamp the piece with a fraction of the previously necessary clamping force. The workpiece goes through only minimum deformation, resulting in the highest levels of true running accuracy.

In addition, a guide tooth provides an absolutely precise reference point so that the workpiece can be inserted time and again with repetition accuracy of up to 0.005 mm.
Stamping can be carried out directly in the collect chuck or in a separate stamping station. Stamping is possible in all materials with strength values of up to 1,400 N/mm2.

The InoGrip® clamping system


is an extremely flexible, universal clamping system for machining round turned parts. The main element is the inogrip® clamping jaw. The clamping system consists of clamping cylinders, a manual collet chuck and a compact stamping station.

InoGrip® can be used for machining practically every workpiece in the first clamping phase, including thick-walled, solid and thin-walled deformation-sensitive parts for both scrubbing and finishing.

Possible uses

The existing system can be used with the InoGrip® clamping jaw for all deformation-sensitive turned parts.
If the clamping pressure cannot be reduced far enough, a manual collet chuck can be placed in the existing power chuck for quick and effective machining of deformation sensitive parts.

In view of the fact that InoGrip® manages with far less and more advantages clamping pressures than conventional clamping solutions, conventional cylinders with InoGrip® are not always necessary. They can be replaced by smaller cylinders. The compact stamping station is the ideal addition to every configuration.