Ralf Kahlen, Managing Director of Dohlen & Krott Werkzeugbau, didn't take the decision lightly. The decision to invest in a new machining center was preceded by an intensive benchmarking process, including a visit to Fehlmann in Switzerland. Factors such as vertical integration, quality, spare parts availability, staff competence and willingness to innovate were convincing. 

Kahlen had already been inclined towards the VERSA 645 linear: "Fehlmann had mentioned two well-known customers in Holland. I visited these companies and discussed their experiences with these machining centers. I was really impressed by the parts they produced. But also in comparison with other machine manufacturers, my decision was quickly made. Our space is limited, and any other machining center would have been too large for our existing product portfolio. Energy efficiency is also an issue for us. And, of course, it was the precision that no other machine could achieve.

In Baesweiler, tolerances are at 5 µm and surface finishes at Rz 0.8, even without climate control. This is why the High Precision Package option was chosen. Alain Strebel, Sales Manager at Fehlmann, explains: "We still scrape the contact surfaces of the linear guides, have a geometric precision protocol, and check the positioning accuracy in all axes according to ISO 230/2. We set even tighter tolerances for both measurements. Peter Potjans, Fehlmann Sales Engineer, North Rhine-Westphalia (NRW), adds: " We deliberately milled the test component for Dohlen & Krott several times without climate control. As a result, the finished parts were consistently within the tolerances of +/- 3 µm." 


A good feeling from a business point of view as well 
Dohlen & Krott is committed to milling because 98 percent of the parts are polished in the cavity area. An eroded structure is not necessarily seen as an advantage. With the arrival of the VERSA 645 linear in October 2022, it is now possible to deliver parts to the polisher with almost final quality.

The advantages of the VERSA 645 linear described by Fehlmann are fully confirmed by Ralf Kahlen. This starts with the work area, which is freely accessible from the front for setup work and process monitoring. Automation can be easily added. In Baesweiler, the VERSA 645 linear machining center is already prepared for Erowa automation. Although the VERSA 645 linear is also used for contract manufacturing (25 to 30 percent), future automation will be used exclusively for multi-cavity machining (up to 96 cavities). 

The linear drives also allow high accelerations and dynamics. However, dynamics play only a minor role at Dohlen & Krott, because the toolmaking industry is not looking for seconds. According to Kahlen, "If I have a good feeling about such an investment, it's not about the second or the price. Ultimately, I have to think about my customers' products. And if I can produce precision and quality quickly and easily, as with the Fehlmann, that is also an economic advantage.

Another economic advantage is that a complete product range was transferred from another machine to the VERSA 645 linear. Process reliability was a high priority for Dohlen & Krott right from the start. Especially since the machining center processes a wide range of materials, starting with M 330, through alloys and heavy metals, hardening up to HRC 62, and soon also titanium. The machine can run for two days with a correspondingly large tool insert. But even there, accuracy has never been a problem.

Although the products in Baesweiler are the same as before the investment, the required precision and quality can now be produced much faster and more easily. Last but not least, the employees are also enthusiastic about the VERSA 645 linear, especially since the tolerances are becoming increasingly tighter. 


Focus on Dohlen & Krott Werkzeugbau 
Dohlen & Krott is a medium-sized, owner-managed company that has been manufacturing injection molds for demanding injection molded parts in various industries for over 30 years. Dohlen & Krott offers a comprehensive after-sales service for these molds, ranging from spare parts supply and management, maintenance - also within the scope of service contracts - to repair and overhaul. Customers include companies in the automotive, electronics, medical, cosmetics and packaging industries. A second business unit in Baesweiler focuses on contract manufacturing, focusing on individual parts and series production.


Interesting facts 
Dohlen & Krott opted for a tool changer with a chain magazine for 86 tools and the High-Precision Package. The VERSA 645 linear is already considered extremely precise in its standard version, with cooled slide parts and machine structure, and the supported X-axis along the entire length of the machine bed.


By the way 
Ralf Kahlen: "I have my own requirements for such an investment, I simply have to have a good feeling. I'm less interested in technical data, I have to keep an eye on our customers' products."  

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