Everything done right

An interview with Stefan Radke, owner of Schleifzentrum West, in Jülich.

"Everything done right!" is how Stefan Radke, Managing Director of Schleifzentrum WEST, describes his experience with the LH65 Premium from WENZEL.

Christian Klostermann from Klostermann Ingenieurbüro‍ und Vertriebsgesellschaft mbH visited Stefan Radke (SR), owner of Schleifzentrum West, in Jülich. We find ourselves in a special environment, because his grinding center is located in an old farmstead, in the middle of the countryside. Surrounded by meadows and fields, in the middle of a small village, the Radke family's farm smiles at us. From the outside, you can hardly guess what is hidden behind these red brick walls. In this warm atmosphere, Stefan Radke tells us about his experiences with the LH 65 from WENZEL.


Mr. Radke, tell us briefly what your company does.

SR.: We are mainly active in two areas: On the one hand, with the production of special tools and prototypes; on the other hand, with grinding technology - in many variations - of hardened workpieces. In this condition, machining the surfaces in a conventional way is simply not possible due to the hardness of the surfaces. The grinding technology is very demanding and highly precise. This is exactly what we have been dealing with for over three decades.


Which parts do you manufacture and in which end products are they used?

SR: That varies greatly. Sometimes I don't even know what the parts will be used for later, because we have a lot of customers with whom we are only allowed to work under non-disclosure agreements. About 75% of our customers come from research & development and universities. The remaining 25% or so come from the general engineering sector. We also make tools for the pharmaceutical sector. So it can be quite different.


Which measurement tasks are to be solved?

SR.: Our daily measuring tasks lie in the recording of very tight dimensional tolerances as well as all shape and dimensional tolerances.  


What measurement inaccuracies are required?

SR.: The tightest tolerances we work with are well below a hundredth of a millimeter. The measuring machine is always calibrated before the most accurate measurements. The spans when calibrating the SP25 scanning probe are often less than one micrometer, which is very impressive, I think.


We are standing here at a grinding machine and see a grinding wheel with an asymmetrical contour. What is this used for?  

SR.: One of our main competences is profile grinding.

In addition to classic surface grinding (for machining flat surfaces), so-called "profile grinding" can be used to introduce "technically feasible" geometry into grinding wheels in order to machine contours other than flat and level. This is what we call profile grinding, or full-grinding. With an optimum grinding wheel design, this process can also be used to economically machine very delicate and very difficult-to-machine (due to high strength and low thermal conductivity), tough-hard materials such as those found in engine construction (nickel, cobalt and titanium-based alloys, Nimonic, Inconel, Udimet).

This naturally generates enormous temperatures, which must be prevented - because high temperatures also often lead to distortion of components. For deep or full grinding, we automatically switch on a second cooling pump with an additional 40 bar supply pressure. On the one hand, this removes the chips produced during grinding, and on the other hand, it cools the workpiece efficiently. With this enormous cooling capacity, we hardly ever have temperatures above 23° Celsius on the workpieces. 1,700 liters of cooling water are available in a tank. The chips are filtered out in a circulation system and the cooling water is reintroduced into the process under temperature control.


What typical components do you machine? How big and how heavy are they?

SR.: 90% of the components we machine are in a weight range between five and ten kilograms. We can machine components up to a length of 1500mm.


What location did you choose for the LH6-12 from WENZEL ?

SR.: At that time, we built a new measuring room for the measuring machine, which is about 25 square meters in size and, of course, fully air-conditioned.


What criteria were used to select the new measurement system?

SR.: The problem at that time was that we could no longer solve many tasks and serve some requests. I even had to turn down some work because there were contours I couldn't measure. 

The accuracy of the WENZEL measuring machine convinced us. With the standard accuracy class, this is already in a very attractive range. Nevertheless, we decided to go for the "Premium" accuracy class in order to be even more precise.  

I was also concerned that the measurement results could be displayed in a meaningful way. Especially in the case of shape deviations, it is important to see at first glance where these are located. I really liked the "error superimposed display" of the measurement results on the CAD model in WM | Quartis . 

However, it was mainly our customers who motivated us to invest in a high-precision measuring machine. For many years, we have already been grinding the most complex contours in provided workpieces, which we simply could not document in terms of accuracy until now. 

With the introduction of the measuring machine, we were finally able to comprehensively document the high precision of our subcontracting. On the one hand, this has given us confidence, and on the other, it has opened up new customer groups. 

It's impossible to describe what this machine has brought us. Incredible, really incredible! We've always been able to grind quality, but now we can prove it exactly - in black and white. And with a very high degree of accuracy. And when you finally see the result, how well you've ground, it makes me very happy.


Why did you choose a WENZEL machine?

SR.: One of my main customers has been using a large WENZEL gantry measuring machine for more than 20 years. We have often talked about the reliability of this measuring machine. What I also found impressive about the granite-based machine from WENZEL is that all surfaces that require precision are not only ground, but also lapped by hand. 

Of course, we looked at three different manufacturers during the investment phase. We felt particularly well looked after by our responsible sales partner, Klostermann GmbH from Remscheid, and had the machine and software demonstrated intensively in two demonstrations on components we had brought along.

The overall package of high-quality mechanical engineering and easy-to-use software, in addition to the very good customer support, ultimately convinced us.


Looking back at the investment - a little over two years ago you got your new WENZEL measuring machine. How has the arrival of this measuring machine affected your business?

SR.: We have actually gained many new customers because we can now use this machine to document the quality we produce in a meaningful way. For us, having this machine is an absolute competitive advantage. Since the machine has been installed, our clientele has also changed somewhat. We have moved away from the previous standard business towards somewhat more lucrative orders. In the case of machining jobs for research and development departments, we always supply a measurement report with almost 100% of the orders. Complaints have virtually reached zero.


With two employees, you are certainly one of the smallest companies, but you have been very successful for years. What is your "unique selling proposition"? What is your secret recipe?

SR: I don't know (says Radke, with a smirk on his lips). I started my apprenticeship as a toolmaker when I was 15. Now I've been doing nothing but working with tools for 45 years. You've seen it all before, but you're still learning all the time. Materials science is my hobbyhorse. 

Many companies ask me for advice on materials, hardening and annealing processes. Here I am quite experienced and word gets around. That is certainly one of the components. And the fact that I always approach every new task with pleasure is also one of my strengths. In addition, everyone who calls here gets to speak to me personally.


They are also a training company. On the wall we see some certificates. Please correct about your motivation to take young people in hand here.

SWR: I always enjoy accompanying the young people here and getting them excited about the fascination of high-precision metalworking.

In recent years, we have accompanied a total of 6 apprentices. Three of them have become chamber winners in the area of "Best Apprentice in the Apprenticeship Profession "Toolmaker" and "Machinist", in the district of Aachen.

In 2017, we trained the best apprentice from NRW at state level. Mr. Pinkwart congratulated us on this at the time. The WDR also reported on it. This fills us with pride. 

We are still in contact with all the trainees from those days. Some of them still visit regularly two or three times a year. Either for a delicious coffee and a chat. But often they also come with a question or two.


One last question: We are very impressed by the surroundings. In the middle of the countryside, in a well-kept courtyard, grinding technology takes place at a high-end level. Grinding machines and measuring machines are in a fully air-conditioned environment. To be honest... We have never seen a WENZEL measuring machine in such a courtyard setting. How does it all feel to you here and how did it come about? 

SR.: (laughs) Yes, I have truly fulfilled a dream here with my wife. Here with us, the world is still in order. Besides precision grinding, my second passion is horse breeding. I do this on a small scale, not only as far as the horses are concerned, since they are "Icelanders", but with all my heart.

From my production hall, I can look out over the horse pasture. Sometimes you have to hold your breath for a moment because you can hardly believe your luck.  

The yard, which now stands in full splendor, wasfrom less than 5 years ago not yet quite "vivid". The previous owner had no longer cared much. So the lucky coincidence happened that we became aware of this gem. In addition to the Aufbaudes company, I have then together with my wife in the last 3 yearsall once turned upside down. All the effort has been more than worth it. I live and work where others go on vacation.

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