Everything runs smoothly here


A report by REGO-FIX AG

In order to machine parts made of titanium, cobalt-chrome, and steel alloys with a high five-axis precision, the contract manufacturer Kreyenberg in Norderstedt primarily clamps small-diameter long protruding tools with the powRgrip® clamping system from REGO-FIX. This is the only way the tools run with sufficient precision to avoid breaking or premature wear.

As Clemens Kreyenberg reports, customers increasingly expect maximum flexibility from a contract manufacturer. Single pieces and small batches can be produced in no time at all. According to the entrepreneur, this can only be achieved with innovative technologies such as five-axis machining centers. They have to work extremely reliably. “Due to the increasing shortage of skilled workers, we are being forced to automate to a large extent. But this can only be achieved if the production process is reliable and only a few interventions by specialist personnel are required,” continues Clemens Kreyenberg.

Versatile Contract Manufacturer
With around 200 specialists currently working at two production sites in Norderstedt and Henstedt, the contract manufacturer is active in a wide range of industries. At the Henstedt site, the company has concentrated processing aluminum components. The processes there are largely automated. At the company headquarters in Norderstedt, on the other hand, the specialists manufacture for machine, tool and mold making and, above all, for medical technology. “Implants and some surgical instruments account for around 50 percent of the contract orders for our production here in Norderstedt. Approximately 90 percent of these are implants,” explains Clemens Kreyenberg. In addition, the company also manufactures components for measurement and drive technology, fitting and assembling them into assembly groups and complete devices, including for medical technology.

Five-Axis Milling Now Standard
In order to work efficiently, the contract manufacturer now has several five-axis machining centers. Clemens Kreyenberg says: “These machines allow us to completely finish even complex components by clamping no more than twice. This ensures short processing times. This way, we create the flexibility that is absolutely essential today.” In addition, due to the increasing number of components with three-dimensionally curved surfaces and geometries that can be machined at any angle, five-axis milling is unavoidable. All geometries can be fully machined with just one or two clampings. However, five-axis machining often requires long protruding tools. Only with them can the geometries be achieved. This applies, for example, to the milling of deep pockets as well as drilling and thread milling in openings and pockets. Tools have to be clamped in slender, extended tool-holder. However, this is proving to be difficult. With the usual shrink-fit chucks, even small-diameter tools can only be clamped to a limited extent, as Clemens Kreyenberg reports. He goes on to explain: “Above all, the exact concentricity of cantilever tools cannot be maintained with shrink-fit chucks. However, tools that are not running smoothly do not work reliably. Their results are inaccurate and create an insufficient surface quality. They also wear out prematurely.”

Mechanical-Hydraulic Clamping Better Than Shrinking
The production engineers in Norderstedt came into contact with Hermann Meyer when they were looking for suitable, highly precise running clamping systems especially for cantilever tools. He is one of the owners and CEO of MMI Meyer und Münster GmbH in Verden. The trading company is a regional partner of the Swiss clamping technology manufacturer REGO-FIX AG, based in Tenniken. Hermann Meyer presented the hydraulic-mechanical clamping system powRgrip® and initially gave the specialists at the contract manufacturer a PGU9500 clamping unit and an initial selection of collets and tool-holders for a few weeks. “After just a few weeks, we were completely convinced,” reports Florian Bodenstab, programmer and machine operator, about the test run.
Since then, the production engineers in Norderstedt have been using the innovative REGO-FIX clamping system for five-axis milling, especially for small-diameter tools. They have confirmed that drilling and milling tools clamped with powRgrip® have significantly improved concentricity accuracy. As a result, the tools have up to 20 percent longer service lives. In addition, even with very long, slim tool-holders, it is possible to drill small holes to an accuracy of a few μm in diameter and roundness. With the powRgrip® clamping system, tool-holders of up to 400 mm in length can be easily realized. PG10 collets and milling and drilling tools clamped in them run concentricly to an accuracy of 3 to 5 μm. As a result, the clamping system powRgrip® at the contract manufacturer Kreyenberg proves to be considerably better than the previously usual tool clamping with shrink-fit chucks.

Optimal Clamping over the Long Term
In addition, the specialists in Norderstedt emphasize that the collet clamps of the powRgrip® clamping system reliably clamp over a large number of clamping processes with constant clamping forces and holding torques. As Hermann Meyer explains, hydraulic-mechanical clamping preserves the material properties of chucks and shanks of extensions and tools. Heat input and alternating heating and cooling are eliminated. This also shortens the time it takes to clamp tools. With the powRgrip® clamping system, the exact clamping force is specified by the PGU9500 clamping unit. On the clamping adapter, the clamping device detects the size of the collet and automatically sets the corresponding pressing pressure. This is confirmed by Vincent Schmidt, who is responsible for preparing the clamping, measuring, and presetting of the tools. With powRgrip®, tools can be clamped reliably with repeatable precision at all times with the optimum clamping forces.

Continuously Expand Applications
Based on their positive experience, the production engineers in Norderstedt are using the REGO-FIX clamping system for an increasing number of machining centers. “Especially when clamping small tools that protrude with corresponding extensions, we do not see any alternatives to the powRgrip® clamping system today,” emphasizes Clemens Kreyenberg, adding: “In terms of process reliability, ease of use, and the concentricity of the clamped tools, the clamping system is significantly better than all other conventional systems. This is why the powRgrip® clamping system is the first choice for us, especially when machining difficult materials. This particularly applies to medical technology components. We have to meet special requirements for these. This means that we manufacture reliably with the highest precision and high surface quality. In addition, validated processes have to be traceable.” The powRgrip® clamping system also supports the contract manufacturers with the latter. The PGU9500 clamping unit monitors and stores the parameters of all clamping processes, such as the time of the clamping process, the inserted adapters and collets, and the clamping pressure. This information is therefore available for documentation if required.

Over 100 Years of Mechanical Production
Today’s contract manufacturer Kreyenberg goes back to a mechanical workshop that had existed in Riga in Latvia since the 1920s. In 1952 Artur Klemens Kreyenberg founded his one-man business A.K. Kreyenberg in Harksheide (now part of Norderstedt) as a service center for cameras and microscopes as well as a precision engineering workshop. From the 1970s onward, the company focused on plastic injection molding as well as tool and mold making. In addition, it was increasingly active as a manufacturing company for contract orders for precision engineering. This laid the foundation for the strong growth in the following years. In 1993, Clemens Kreyenberg, grandson of the company founder, took over the company and expanded it into today’s contract manufacturer with over 200 employees. Since the turn of the millennium, the company has continued to grow by acquiring sheet metal processors, and mold and tool manufacturers. It is certified according to ISO 13485 as a supplier for medical technology. Clemens Kreyenberg’s three sons now work for the company. As Clemens Kreyenberg emphasizes, the line of succession is thus clearly and reliably regulated. At Kreyenberg, special attention is paid to the training and promotion of skilled workers. Every year, the contract manufacturer trains around 20 to 30 young people to become specialists in metal and plastics technology.

Reliable: When clamping end mills for circumferential milling, the powRgrip® clamping system from REGO-FIX reliably generates high clamping forces and holding torques that prevent axial pull out.

Completely from scratch: At the contract manufacturer Kreyenberg, the production engineers process five-axis machine complex components made of steel alloys that are difficult to machine, including for medical technology and tool and mold making.

Concentric: Long protruding tools can be clamped quickly, easily, and reliably with the powRgrip® clamping system.

Convinced: Vincent Schmidt, who works in tool preparation, appreciates the ease of use of the PGU9500 clamping unit for the repeatable clamping of tools, even ones with a long projection.


Trust all around: When it comes to five-axis milling, Florian Bodenstab can rely on the fact that the drilling and milling tools with the powRgrip® clamping system are reliably and precisely clamped in all directions.

Have made the right decision: Hermann Meyer (left) from regional partner MMI Meyer + Münster GmbH in Verden in conversation with division manager Jan Bakowski (middle) and machine operator Florian Bodenstab about the advantages of the powRgrip® clamping system from REGO-FIX.

Picture credit: Konrad Mücke / REGO-FIX


Contact person:
Obermattweg 60
4456 Tenniken
Tel.: 061-976-14-66

Kreyenberg GmbH
Oststrasse 51–53
22844 Norderstedt, Germany
Tel. 040-521-9670
www.kreyenberg.eu (in German)

Swiss Machining