Unexplained holes in a wide-spiral wire link belt presented our customer, his furnace maker and us with a seemingly unsolvable puzzle. But as is so often the case, the solution was quite obvious – and therefore easy to miss.
"In 2001, the phone rang. One of our overseas customers had a problem. The wire link belt made by us and used by the customer had given up the ghost much sooner than was usual. It quickly became clear that there had to be a good reason for that."
These reasons, as the skilled mechanical engineer Peter Hluchnik, who took the call at the time, suspected, had nothing to do with the actual wire link belt itself. He knows what he is talking about: Peter Hluchnik has been working for HEIN, LEHMANN for many years as a sales engineer in the conveyor belt department. He has managed numerous projects and has accumulated a wealth of experience.
"Our customer uses the wire link belt to dry mineral wool. This is something of a death warrant for belts: all the fluid is pressed from the already very difficult material at a very high pressure. Of course, this is a strain on the belt on which the mineral wool lies, resulting in a very high degree of wear and tear. The wire link belt had worked well for the customer's production up to that point. But then the production conditions changed a lot – in terms of increased production and an increase in product density."
The changed production conditions left no doubt: the wire link belt being used had to be reinforced – it needed to be harder, and quickly. Where others are reduced to frowning when faced with a problem, we at HEIN, LEHMANN go looking for solutions. We followed up with the customer, a detailed questionnaire on all conditions of use for the belt was prepared – and the Design, Engineering and Laboratory departments got ready to face the challenge.
"But that was back in 2001. Just like the new millennium, the technical innovation of the time, the internet, was still in its infancy. And 'infancy' then meant mainly 56k modems in the phone jacks. It was the same for us. So, we needed plenty of patience to receive photos of the plant from overseas. In fact, a video showing the machine in action overwhelmed our network. You can't really imagine things like that happening anymore today."
A thorough investigation and analysis into the underlying causes began once all the data had been transferred. To reinforce a wire link belt, it was necessary to determine its weakest areas first.
"At the high load due to the increase in production, it was the discs that got the brunt of it – small plates between the slats used to protect the slot. These discs were the weakest link because they were made of unhardened steel. The next weak point was the slats themselves. They were hardened, but not enough. All this had been perfectly appropriate before – but now there was a problem."
Weakness number three involved the cross braces, which had been soldered with normal solder so far. So, this was the challenge for the HEIN, LEHMANN team: How can these three parts of the material be strengthened without changing the wire link belt as a whole?
"Now it was time to head to the laboratory. Our customer's problem posed an exciting challenge for us! How could we improve our product for tougher conditions – that is, how to invent a version 2.0 of our wire link belt?"
The solution after brainstorming and tests in terms of concept, laboratory, and technology:
"For the discs, we used a different hardening process with full hardening. This wasn't possible for the slats, because they would have broken. The method of the hour was carbonization. We were able to achieve a higher degree of hardness by treating the surface. Finally, we turned our attention to the cross braces. Welding is not an option with spring steel – so we had to keep soldering. We put aside the regular solder and used more robust silver solder instead. This created a new problem: Too much silver solder came out of the threads of the nuts."
This called for finer threads. The considerations eventually led to what is known as the Whitworth thread. Unfortunately, it was not widely used yet – and was nowhere to be found.
"That's why we had no choice but to make these nuts ourselves. But that was an advantage for us. We were able to build these directly according to our ideas – and it became a kind of disc into which the fine thread was cut."
The new wire link belt '2.0' developed with all these measures was put to an endurance test – and passed with flying colors.
"This project forced us to think a bit outside the box. We had to find the solution that would do the trick. Cooperation between the Laboratory, Engineering and Design departments played a major role here. This great teamwork is what allowed us to succeed."
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