Lighter, smoother and more reliable

At the waste-processing facility (see ‘Mechanical Biological Separation’), municipal solid waste is handled by two overhead cranes equipped with scrap grippers. The cranes were installed in 2004 and equipped with a festoon cable system for the power supply, which needed to be quite bulky given the 116-metre travelling stroke of the cranes. “Unfortunately we ran into problems with it after just a few years,” says Geert Van den Broeck. “The festoon cables and trolleys suffered frequent damage in the heavy operating conditions, especially with the high speed of 2.5 m/s and frequent and abrupt accelerations and decelerations. This very often resulted in cracking to the cables and trolleys colliding at high speed, so we regularly needed to install spare cables and trolleys, leading to unplanned production downtimes.”

Putting an end to uncertainty

Subsequent improvement projects did not solve the problem. “I remember that in 2010 we replaced the entire system, using alternative components and an improved detailed design,” explains Van den Broeck. “But the problem reappeared in 2012 and increasingly risked jeopardising our service. Don’t forget that our waste treatment process should rigorously keep up with the flow of waste, otherwise we’re in the headlines! Eventually we opted to circulate a Request for Proposal to crane suppliers to put an end to the uncertainty.”

A cable chain for high speed applications

The request produced only a handful of proposals, and most of them were barely adequate. “They said they would over-dimension the system with thicker cables, larger trolleys and increased cable bending radiuses,” says Van den Broeck. “But that wouldn’t do, because it wouldn’t eliminate the danger of collisions and would lead to an unacceptable increase in weight. But then TCS came up with the idea of a cable chain, a solution widely used in production machinery but not so common in cranes. They recommended one of the newest IGUS products, which is capable of handling the high speed and acceleration rates we have here.”

Reduced installation time

The cable chain system proved to be a smart option in many ways. Van den Broeck: “First and foremost, it’s much more reliable than a festoon, because the cables are embedded in a plastic gear, which runs smoothly within a cable gutter. And then it’s so much lighter, because cable length is reduced by about two thirds.”

Installation was a real challenge, however. “The problem was that we operate 24/7 and cannot afford a long standstill, given the continuous supply of municipal waste,” says Van den Broeck. “But TCS was able to reduce installation time in a number of ways, for example by carrying out preliminary activities during production. And their combined expertise in cranes and steel construction came in handy to speed up the whole process.”