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hp tooling 2019 #1

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The journal of hp tooling is an english, global publication on all aspects of high precision tools, accessories and their applications.

materials LACH DIAMANT

materials LACH DIAMANT looks back on 95 years Poly – poly – or what? How new super hard cutting materials revolutionized machining Horst Lach, managing director and CEO of LACH DIAMANT agreed to write an ongoing series of articles about the development of diamond and CBN tools and grinding wheels in modern industries. Horst Lach is known as a true industry veteran, and we are excited to have this pioneer of technology share some insights from 58 years of professional experience in the diamond tool business. In this part of this (almost) historical review, Horst Lach looks back to the time between April 26 th and May 4 th of 1973 when new super hard cutting materials revolutionized machining: The introduction of our Borazon CBN grinding wheel was still in full swing when I received information from General Electric in 1972 that a new cutting material would be coming soon. What could it be? Naturally all of us were curious! The Hanover Trade Show would start on April 26 th , 1973. A new cutting material meant another chance to showcase another innovation, like Borazon, as one of the first com- The world’s first presentation of a PCD turning steel during turning aluminium part with a simulated interrupted cut panies, or the first, worldwide. After successfully introducing the new abrasive “Borazon”, I expected prefer - ential treatment compared to other competitors. Answers to my requests for first samples or test materials were delayed. It was already March 1973. Despite the secrecy of General Electric, I managed to pick up on two little clues: “Compact and poly”! Poly – poly – or what? I was fascinated by the possibilities that seemed to open up on an almost daily basis in regard to the new Borazon CBN grinding wheels. At first I thought that “compact and poly” might refer to compressed cubic boron nitride. That would have been great for LACH DIAMANT since we already had a lot of experience with the Borazon CBN grinding wheel: Grinding of high-alloyed hardened steel and HSS; compact CBN; turning instead of grinding, fantastic! As it happened, we then also received a request from DEW. They wanted to know whether LACH DIAMANT could offer any tools for machining DEW’s “Ferrotitanit”. This new and compact CBN material was so exciting for DEW’s management that two of their directors paid us a visit only a few days later. They must have been very disappointed when I had to tell them, about three weeks later, that we would use not a CBN material but a polycrystalline block of synthetic diamonds. “PCD”, polycrystalline diamond, was born! To be honest, I was a bit disappointed too, at first. Disappointed, but then … Compact CBN would have been something to work with immediately. But a “diamond block” as substitute for natural diamonds? At the time, in April 1973, we employed about 20 grinders for natural diamond for the production and service of natural turning diamonds for customers like Bosch, AEG, Siemens, Menke and others. Should we now switch completely to synthetic diamond blocks? We would have to find new customers in order to stay profitable. But how and where? At the time, the only way to find new potential customers was via the ABC of German Industries, a handbook of national companies. Successful polycrystalline diamond tools of the first hours – examples (1973 - 1974) I found one Swiss commutator manu facturer and the name “Kautt & Bux”. I called them and found out something surprising: commutators are not turned, but ground in a very time-consuming procedure. At least that was the case in 1973. I spontaneously explained that they could save several minutes of grinding time if they would instead replace this pro cedure with turning with the new PCD turning steel; they were impressed and pro mised to visit our stand at the Hanover Trade Show. At this point, my sug ges tions were only of a theoretical nature, since we did not have the ma terial yet. But in the 18 no. 1, April 2019

materials hope of a timely delivery for the production of the first PCD turning steel, we planned to set up a Weiler turning machine at our stand in order to do a demo presentation on it. After General Electric had published the first announcements that the new material would allow even for interrupted aluminium cutting, we decided to demonstrate with a “blemished” aluminium round part with several cross bores. Natural diamonds are the hardest of all materials, however very sensitive to shock, especially during interrupted cuts! However, the new material promised not be affected by this… Three critical days Finally, the long-awaited PCD material arrived as 90° and 60° segments which had apparently been cut out from a 3.2 mm blank. The visible PCD diamond layer was about 0.3 - 0.4 mm thick and connected via a carbide support so that the cutting edge could be further manipulated by soldering. It was now Friday – exactly three business days before the start of the Hanover Trade Show on April 26 th , 1973. I proudly presented the first PCD to Kurt Wagner, manager of our grinding shop and a highly talented diamond grinder who had mastered his art as a diamond specialist at a Swiss manufacturer for diamond tools. First PCD tools used in production of copper commutators at Kautt & Bux After careful inspection and several grinding attempts on a cast grinding wheel that was apparently used for natural diamonds and coa ted with diamond dust, he announced: “Sir, usu ally we do everything, but this stuff is so beast ly – there is nothing we can do!” I thought, that this was probably the end of it. There were few other grinding options. But then I thought of our Simon steel grinding machine (L15). We had purchased it for our coope ration with Simon, Neu-Isenburg, a distributor of resin and metal bond diamond wheels. I suggested: “Try it with the Simon machine, with the cup wheel!” And to our great astonishment, the very first grinding attempt with a re sin bond diamond grinding wheel proved already to be very promi sing. How ever, we still had to spend se veral hours to get the desired cutting geometry. Right at the start of the trade show, at 9 AM, our dri ver, Mr. Barmus, arrived at our stand and deli vered the first PCD tool which would later be known un der the trademarked name “dreborid”. The driver delivered ad di - tion al tur ning steel, on Wednesday and Thurs day, until we explained to him that “this stuff will hold long enough, we do Selection of polycrystalline diamonds (development status approx. 1982) not need any more tools.” Our visi tors could hardly believe that this “little diamond cutting edge” could machine the perforated aluminium turned part without any “rumbling”. We became more and more confident and increased the feed with every attempt up to the maximal edge width. We only succeeded to “kill” our PCD cutting edge on the very last day – it could not cut an (empty) piccolo bottle which we had boastingly inserted. By the way, the technicians of Kautt & Bux were there as well and very excited about the demonstrations. A first key custo mer for serial use of dreborid PCD tools was found – so Kautt & Bux can boast to be the first company world wide using po ly crystalline dia monds in pro duc tion. This was a stroke of luck for LACH DIAMANT because in the pro cess of turning the surface of cop per collectors, we al so learned how po lycrystalline dia monds can be suc cessful ly used with other com po site materials. Success followed success – a new era of machining of non-ferrous metals and plastics had begun.* Horst Lach * This “poly – poly – or what?” series will be continued with further highlights in hpt 2/2019. further information: www.lach-diamant.de no. 1, April 2019 19

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