igus is the world’s first manufacturer to receive UL approval for halogen-free TPE cables

Change of perspective: the long service life of the chainflex high-end TPE cables convinced the testers. This is the first time that halogen-free TPE cables have also received UL certification (Photo credit: igus GmbH)

igus is the world’s first manufacturer to receive UL AWM certification from the well-known US organisation, Underwriters Laboratories (UL), for its high-end TPE cables that do not use fire-retardant halogens as additives. This is the first time that the testing organisation has recognised that halogen-free TPE cables can also meet the fire protection requirements in the industry.

UL is one of the most important authorities in the USA in terms of product safety. It has been testing components of machines and systems since 1894 to determine if they are suitable for industrial use. Their seal is one of the prerequisites for a successful market entry in North America.

Fire protection is a key decisive criterion. This is because, according to the US National Fire Protection Association (NFPA), machine fires are the fourth leading cause of fires in industrial environments in the USA, closely followed by fires caused by electrical factors.

“That is why we are particularly pleased that igus has now become the world’s first manufacturer to receive a UL seal for halogen-free TPE cables,” said Rainer Rössel, vice-president and head of the chainflex cables business unit at igus. “The approval demonstrates to our customers that they have the safety aspect with chainflex high-end TPE cables.”

Fire protection can be achieved without halogens

For this certification, the igus engineers had to do a lot of persuading. Up to now, the flame retardancy of cables has been the key factor in obtaining UL certification for fire protection. Approval is therefore only granted to products containing flame retardants such as chlorine, fluorine or bromine. These additives increase the flame retardancy.

However, it has not been taken into account that the flame retardants generally change the chemical structure of the jacket and reduce the mechanical load-bearing capacity. Therefore, igus started much earlier in the process: The company focussed less on preventing a fire from spreading, and more on how the cable itself caused the fire.

The TPE jacket compounds from igus are extremely resistant to mechanical loads and external influences. They can therefore be used in a wide range of applications: in small installation spaces of up to 4xd, on highly dynamic, short travels with accelerations of 100m/s² or on long travels in a temperature range from -35°C to +100°C. At the same time, they are extremely media resistant, even with special organic oils. 

In all of these energy chain applications, the halogen-free TPE jacket compounds from igus minimise premature ageing of the outer jacket by a factor of up to 10 when compared to the same materials containing flame retardants. A decisive cause of fire is reduced. This is because if the jacket does not break the cable, then it cannot cause a fire. In other words, a reduction in the cross section of the cores is impossible due to the non-existent jacket break. This was an argument which finally convinced the UL.

Flame retardancy of TPE cables is no longer the measure of all things

With these measures, igus made a significant contribution to increasing machine safety. The long-term flexural strength and service life of chainflex cables in the e-chain have been proven by numerous practical tests in the in-house igus test laboratory – and not just for TPE cables.

“So far, customers have already had the opportunity to choose from 1,044 chainflex cables with UL approval,” Rössel pointed out. “With the new certification, there are now more than 200 TPE cables, so we can offer an almost complete UL certified product range.”

Customers in Europe benefit from the cables being halogen-free, as do those who build machines for the North American market, where UL certification of the individual components is the required rule.