Most cable is not designed for repeated bending, twisting and movement stresses. Repeated flexing can eventually ‘work harden’ the conductor cores to the point of failure. This same process can easily be demonstrated by bending an ordinary paper clip back and forth. Initially, it is flexible and bends easily, but after a short time it ‘work hardens’ and breaks. Similarly, the friction arising between various parts of a moving cable can generate enough heat to cause the outer jacket to fail. 

Industry standards for cables tend to ignore these failure mechanisms; the focus being more on EMC safety and standards and directives such as UL, CSA and VDE. It is therefore left up to the cable manufacturers to devise their own set of tests to give some level of confidence to their customers that the cables can endure the millions of flex cycles. 

As a manufacturer of cable carriers and continuous-flex cables, igus tests as many different types of cable carriers and cables for automated machinery as possible. At the company-owned technical R&D test centre in Cologne, Germany, numerous tests are carried out concurrently under the most demanding conditions. Every year more than 1 million electrical tests and 2 billion test cycles are carried out in the igus test labs, with the resultant data regularly being added into a master database. This extensive, current data pool provides precise, reliable information on the actual service life of these components and is also the basis for new igus product developments such as the chainflex M range.

The current range of chainflex cables is guaranteed for 5 million double strokes in constantly moving energy chain applications. The new chainflex M range, on the other hand, is designed for less demanding applications where reliability is still important but the required cycle life is much lower.

Typical applications for the chainflex M range are tools and jigs, packaging machines, some machine tools, and in theatres. Covering all types of cables from control, motor, servo and measuring cables through to data and bus cables, the chainflex M range has undergone the same demanding in-house tests as standard chainflex for wear, chemical resistance, and flexing performance in energy chains. It is also UL/CSA certified.

All cable families in the chainflex M range cost 20 to 30% less than the standard chainflex ranges, and are guaranteed to last one million cycles of service life, which I believe is unique at this price point. With no cutting costs and no minimum order quantities, the chainflex M provides a very cost-efficient solution for energy chain applications that do not require a very high cycle rate.

In saying that, the igus test lab has already subjected power cables from the chainflex M range to an endurance test in e-chains. Testing was performed on a 5m length of cable with travel lengths of 2.1m and speeds of 3m/s with stop/go accelerations of 12m/s2. A visual inspection and measurement of the ohm resistance were performed after 1,448,335 double strokes – all parameters of the intact cable were normal. 

The test data that igus has collected over the last 20 years for energy chains, cables and pre-harnessed systems is described in such detail that igus simply guarantees that its products, when properly specified, will work without a problem.