Our products are top range grinding machines and centres "Made in Germany“. We have been one of the leading manufacturers worldwide – for more than 80 years.
Progress is a tradition at KEHREN.
Thanks to decades of experience in grinding machine manufacturing, KEHREN possesses extensive technical knowhow in machine design and application engineering.
The machines are designed, manufactured and assembled in house.
The motivation and the skills of our teams as well as the high precision design guarantee the outstanding quality of KEHREN grinding centres.
Over the past years, grinding operations have become more and more complex, a tendency which will further develop in the future. Here, the driving factor is the complete machining of workpieces in one set-up, resulting in highest precision possible and bringing the wanted rationalization effect.
Since 1950, KEHREN GmbH in Hennef/Sieg has built grinding machines. During this time, products have continuously developed to the high-tech machines of today.
With the integration of machining by geometrically defined cutting edges, the range of application of the Ri machine type could be substantially increased. Depending on the machine configuration, the following machining processes can be implemented in only one set-up:
Within the 280° swivel range, the turret can be positioned in 1° increments, in a very precise and also reproducible way.
The positioning is hydraulically powered, and a Hirth coupling gives repeatability of the highest precision. On request, it is possible to have NC controlled positioning. The turret can be fitted with up to five tool stations, specially equipped for grinding or hard turning and milling application, with the possibility of automatic tool changing.
The automatic machining processes are implemented by a Siemens Sinumerik 840 D control. The standard Siemens software is supplemented by the KEHREN-WOP-Software (Workshop Oriented Programming). This features for example reading of CAD data for contour grinding - ready to use without further corrections.
An adaptive speed control allows grinding process times to be reduced: The feed is controlled by the spindle load; thus process times without work piece contact, for example during jig grinding, can be minimized.
Dressing cycles can be selected by program or manually at any time. For conventional grinding wheels, single or multiple grain diamonds are normally utilized for dressing. Using a dressing spindle, fitted with diamond wheel, contour dressing is possible for conventional grinding wheels and for CBN wheels. In this process, an axially parallel, orthogonal or angulate position towards the tool axis can be chosen for the driven dressing tool. With all procedures, the required forms and contours can be realized.
By compensating dressing infeed and wheel wear, parts can be machined in series and without measuring, in repeatable tolerances of less than 0.01 mm.
However, when implementing the optional Renishaw in process measurement system with probe together with a calibration unit, much closer tolerances can be achieved. The measurement system can be used for gauging all machining surfaces.
The measuring data can be read into the NC control and necessary corrections can be realized.
Remarkable features of KEHREN Ri Vertical grinding centres:
To increase productivity, all Ri grinding centres can be equipped with two rotary tables.
For all Ri grinding centres a wear-less direct drivein the X-axis is available, providing excellent machining and measuring accuracy.
The product lines Ri 6 to Ri 12 can be equipped with an optional Y-axis as side support for horizontal machining.
All product lines can be delivered in standard or in grindturn design. The grindturn design includes a
turning tool adapter instead of a grinding spindle. The machine can also be equipped with a chip conveyor.
Various tool changing systems are available for all product lines.
Today, complete work piece machining has become an important feature.
The following operations can be machined in only one set-up:
All diameters and faces can be measured automatically by an optionally integrated measuring unit. For noncircular and jig grinding, this measuring unit can also be used for the localisation of a work Piece.
KEHREN portal type grinding machines extend the Ri product line:
To increase productivity, all portal type grinding centres can be equipped with two rotary tables, if requested in differing designs.
For all grinding centres in portal design, a wear-less direct drive in the X- and Y-axis is available, providing excellent machining and measuring accuracy.
Various tool changing systems are available for all product lines.
Today, complete work piece machining has become an important feature.
The following operations can be machined in only one set-up:
With the optionally integrated measuring unit, all diameters and faces can be measured automatically. In noncircular and jig grinding applications, this measuring unit can also be used for work Piece localisation.
In general, all grinding centres in portal design are built according to customer‘s requirements. Other than the new RP 8 model, for which a standard is defined.
Our new vertical grinding centre RP 8 in portal design is notable for its compact design and the following properties:
Various tool changing systems are available for the RP 8 model.
Today, complete work piece machining has become an important feature.
The following operations can be machined in only one set-up:
All diameters and faces can be measured automatically by an optionally integrated measuring unit. For noncircular and jig grinding, this measuring unit can also be used for the localisation of a work Piece.
KEHREN RS machines are notable for:
Whenever good stock removal performances and flatness are required, RS machines are an economic choice, as in most cases it is not necessary to pre-machine the work piece.
KEHREN D machines are notable for:
If good stock removal performances and surface finish are required, RS machines are an economic choice, as in most cases it is not necessary to pre-machine the work piece.
By using surface grinders with two rotary tables, cycle times of batch products can be reduced by up to 50 %, when setting during main time.
KEHREN RW machines are notable for:
RW machines are an economic choice, if good surface finish and close tolerances are required on large annular parts or on small parts which can be mulitply loaded on the rotary table.
The RW models with table diameter 600 and 800 mm are also available with two rotary tables.
From now on, KEHREN grinding spindles for all machine models are available, with excellent performance data and manufacturing properties.
All spindles are – like our machines – MADE IN GERMANY