If there is one word to describe the most important attribute of industrial motion cables today, it would probably be flexibility. Flexible cables allow for more compact designs and more cycles than ever before. Similarly, VFDs and other automation systems requiring tight bending radii are looking for smaller cables that can withstand high speeds.
David Sedivy, senior product manager, and Tim Hannigan, cable engineer, at TPC Wire & Cable Corp., Macedonia, Ohio, said that in their most recent custom applications, flexibility has been one of the most requested qualities. And when they talk about flexibility, Sedivy said, it’s not just in bending radius, but also the cables’ ability to function in extreme temperatures, corrosive environments and applications with high tension.
“You want the cable to be able to have a life, and ensure that it’s not going to destroy itself in the flexing environment,” said Hannigan. “One of the things that we’ve been able to do is use insulation systems that can withstand multiple repeated flexing cycles that you don’t need a real thick wall on. You can use a thin wall so it reduces the size. Any time you can reduce the size of the cable and offer a more flexible product, you’re going to extend its life.”
General Cable’s Steve Wetzel, advanced engineer, Mining & VFD Products, and Josh Smith, market development manager, Industrial Automation, both agree with Hannigan, adding that the design and construction of Variable Frequency Drive (VFD) cables have evolved over the last few years.
“Today’s VFD cables are available in flexible constructions with copper braid shields that have tight bending radii for easy installation, and armored constructions using a continuously corrugated welded aluminum shield (CCW),” they said.
Running at high speeds
The higher speeds and accelerations of machine systems can put a lot of undue stress on cables, causing them to fail. Newer VFD cables are designed to withstand these extra stresses.
“Automated systems are getting quicker and smaller, so the need for high tech cables that can accommodate these changes have been key,” said Rich Buchicchio, national sales and marketing manager for Cicoil.
Neal Allen, key account and industry manger, HELUKABEL USA, agreed, adding that the VFD and servomotor market tends to push the capabilities of the cables used to drive them.
“High acceleration and increased motor accuracy place greater requirements on the cable components. The flat tape and silicon-encased products have been used for more than 30 years, specifically in the material handling (wafer industry) where linear motors required low-moment, low-profile cable tracks,” Allen said. “These applications can see 40 to 60 million cycles over the life of a cable, which, in some cases, occurs in just one year.”
Rick Orsini, product manager at SAB North America, added that not only must these industrial motion cables be able to handle faster motor speeds, they themselves must also provide faster communication speeds.
“One area that is, and will be changing in the future, related to industrial automation is the transfer of data. This is brought on by the advances in microprocessor speeds and the ability for machines to move faster,” Orsini said. “Because the microprocessor’s scan time is faster, the data transfer in the cables must keep pace. Big changes are coming in the way of Ethernet communications on the factory floor and in other areas, such as agriculture and motor vehicles.”
In addition, hybrid servocable designs combining both power and feedback into one cable are becoming more prevalent in efforts to reduce size, said Allen.
For example, Buchicchio said Cicoil dealt with a medical application where personnel incorporated multiple wires, tubing and cables into one flat profile. “The new cable allowed our customer to get a finished, plug-n-play cable, which eliminated the cable track (noise and particulates), increased cable flex life, eliminated downtime, allowed equipment size to be reduced with a tighter bend radius cable and contributed to significant cost savings,” he said.
Customers are looking for cables that are easy to install and can handle tight bends. As more and more equipment is found in factories, there is less and less room for these cables. The overall flexibility of VFD cable is a key concern of drive manufacturers.