At REITZ Natursteintechnik, everything revolves around the natural hard stone, granite. In an interview, we talked to manager Christopher Reitz about what the individual steps in component production are in detail.
"From 6mm to 180mm diameter, we drill around 15,000 holes a week." (Christopher Reitz)
Christina: Hello, Christopher! It's so kind of you to take the time to talk to our new REITZ blog. Today I'd like to find out just how a machine component is even made. Is it all automatic? What steps are required?
Christopher Reitz: Well, it starts with the block saw, then we move on to the saw. This is where the materials are cut to size on all sides. The next steps are grinding, drilling, and pulling off by hand – which is also called breaking edges. After gluing the metal inserts, the machine components first go to the measuring room, then to precision assembly, and finally to quality control.
Christina: It sounds like a lot is done by hand; is that right?
Christopher Reitz: No, not quite. The pre-machining is done on the CNC processing machine. The only tasks that are done by hand are the ones from breaking the edges to quality control.
Christina: What are the advantages of CNC production?
Christopher Reitz: You can work around the clock, which minimises errors. In addition to series production, we also produce custom-made items to customer drawings. Every single part is exactly as the customer wants it.
Christina: Let's consider the various steps again now. How do the materials get to you before you start?
Christopher Reitz: The materials are often brought in tranches, cut into plates. On the other hand, the material from South Africa is brought in blocks, and we then cut it to size in Asslar. The workpieces vary greatly in size: from 50 centimetres to 15 metres. The biggest one we have ever made measured 15m x 1.50m x 1m and weighed around 65 tons.
Christina: We talked briefly about the individual steps earlier. Let's start with sawing.
Christopher Reitz: Well, there are actually two steps when sawing. First the raw blocks are cut, which is rather like cutting a slice of bread from a loaf. Then the material goes onto another saw, where the length, width and contours are cut. All of this is done with an accuracy of +/- 2mm. We use diamond tools in this process to cut through the material.
Christina: So you saw first, and then you grind?
Christopher Reitz: Yes, that's right. We have to process the exact areas on the grinding machine, and we achieve this with an accuracy of 10 to 15 micrometres to one metre. The customer provides us with a full set of drawings, which we then work to: 3D models and drawings so everything complies with the REITZ standard at the end. This is also when we create the program and quality acceptance protocol.
Christina: Ah, that's interesting. And then you move on to the drilling, right?
Christopher Reitz: Precisely. The workpiece is now moved from the grinding machine and clamped onto a boring mill. This is where all the holes are drilled using a hollow crown drill that is also set with diamonds. We drill around 15,000 holes a week in diameters ranging from 6 to 180 millimetres.
Christina: And then what happens?
Christopher Reitz: Now it's time for the manual grinders. The item is cleaned and the edges broken so they don't break off when the workpiece is lifted. The edges shouldn't be sharp, either. The metal inserts are glued on by our professionals after the manual grinding process. Then it's on to the measuring room and precision assembly.
Christina: All these steps are done by hand. Is that the only way they can be done?
Christopher Reitz: At the moment, yes. But we also always need to keep an eye on automation. In Hall 6, for instance, you can see a fully automated production setup to industry standard 4.0. Incidentally, this doesn't mean that we're thinking of cutting down on staff. We've put our colleagues' minds at rest on that score. We qualify our staff for higher requirements.
Christina: Ah, I see. Hall 6 is already in operation. Remind me what its advantage was?
Christopher Reitz: The workpiece is fed in as a raw panel, and comes out at the end as a finished product. We saw, grind, mill and drill in just one clamping process, so we can fully process all five sides. Because reclamping always causes errors, and we minimise them in Hall 6.
Christina: Let's talk about the final production step now. This happens in the measuring room, doesn't it?
Christopher Reitz: Yes, it does. This is when superfinishing, precision assembly and quality control happen.
Christina: There's going to be a new blog post about this soon. So be sure to keep listening and watching. As usual, I do have one final question. Could you please sum up the various production steps that you carry out again?
Christopher Reitz: We begin with the CNC machining steps (sawing, grinding, milling and drilling), then finish the items by grinding and drying them, gluing in the metal inserts, precision assembly and quality checks. And incidentally, we develop and construct most of the CNC processing machines ourselves. This shows you just what you can really do with granite – it's a complete processing centre.
Christina: So these are the individual steps in the production of a component at REITZ Natursteintechnik. Many thanks to Christopher Reitz for the fabulous insights.
