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Getting Automation Cables Right

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As smart automation grows, the need for specialized cables grows, whether they’re connecting robots or motion and motor systems.

Even with the ubiquity of wireless connectivity, cables still provide a steadfast thread connecting advanced manufacturing. The role of cables is critical. As technology becomes increasingly integrated, the need for effective cables grows as well.

In manufacturing, cables are essential for the delivery of electricity to machinery and transporting digital information from machine to machine and to control systems. Cables are also needed to connect different parts of a machine, from a robot arm to the base and brains of the robot. Cables are essential to ensure the safety of workers while creating streamlined forms of communication between control systems and robots.

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The issues involved in getting the right cable include mechanical elements are well as electrical elements. “Users are looking for a cable management system. They have a system or process and they need to provide electrical connectivity when the axes are moving,” Don Nester, a product manager at Igus, told Design News. “They need a product that functions electrically and mechanically. The cables could be used for power, data, fiber optics, or networking.”

Ultimately the goal of the cable is to continue functioning no matter what strain it may experience or what amount of flex may be involved. “There are many types of electrical systems – cameras, cutting tools – we need to power up these applications and provide a solution where we eliminate downtime caused by cable failures,” said Nester. “Customers ask how long the cable will last in their applications. Through testing, we’ve been able to come up with lifecycle predictions. We do two billion cycles of testing each year so we can determine how long a cable will last.”

The Need for Predictable Flexibility

With motion control systems and robotics, cables are attached to machines that may be in constant movement. So, cable flexibility becomes a big issue. “The flex life of the cable is a major concern. Automation systems require high mechanical flex. A machine that’s expected to last 10 years may have 10 million cycles,” said Nester. “Cable designs have to combine manufacturing techniques and materials that produce a cable with good continuous flex properties. A cable may need to bend 2.5 times its diameter and last 40 million cycles.”

With automated systems proliferating, manufacturers have a greater need for a wider range of cables. “American manufacturing is coming back, and it’s more automated now. That means more robots. Plus, the machines moving faster,” said Nester. “We’re seeing smaller form motors and faster machines. We have more control over them, and that alone has made manufacturing faster. Cables for robotics need to withstand twisting, liner torsion, and multi-axes. Given that need, some cables are designed just for robots.”

Cable Material Matters

Automation has increased the need for specialized cables the need to withstand harsh conditions over long periods of time. That has produced the need for new cable materials. “To determine the right cable, you make a choice between reducing cost or increasing flex life. To increase flex life, you have to introduce materials that can meet the cost while meeting the demands,” said Nester. “Some cables need to be oil resistant. We work with an alloy rather than copper, and we’ve tested it for 3 to 5 years.”

Changes in motor technology have also forced changes in cable materials. “Cables for variable frequency drives have to have low capacitance. Reducing the size of the motor is great, and the connector also has to be smaller. Now there’s more plastic,” said Nester. “In the past, the motor was a heat sink. With a smaller motor that’s more plastic, the heat sink isn’t there. So, the cable works as the heat sink. The cable has to be designed to accommodate the temperature or you have a problem. We added insulation and tested that for three to five years.”

Nester noted that Igus is eating its own dogfood. The company is using much of the same equipment its customers are using. “We’re using robots and try-flex energy chains in our manufacturing. We use robots in hazardous environments. They have to be resident to solvents and flex,” said Nester. “We have some applications for AVG (automatic guided vehicles) forklift handling packaging. That industry has blown up with Amazon and other distribution. They have driven automation with the ends of conveyors and robots. Some of our biggest customers are in those systems.”

Materials have to be developed for differing types of cable movement. “We classify three types of movement, linter, torsion, and mufti-axis. A cable for linear should never be used for a torsion application. From the outside, they look similar, but the materials used are very different for torsion versus linear,” said Nester.

Managing the Motion and the Energy Chain

In a constantly moving automation system, multiple cables may be needed. Energy chains have been developed to contain the cables and manage the movement. “The energy chain manages the media, the cables, and hoses,” said Nester. “The energy chain manages cables as well as managing the movement of the cables. It may require 500-meter travel, or it may be a short-chain handling a machine with 100 million cycles a year. There are different energy chains to meet these differing needs.”

In order to create cables that can predictably withstand harsh conditions and constant movement, Igus tests for failure. “As part of testing, we try to destroy cables all day. We’ve learned that the energy chain will extend the life of the cable by offering strain relief or spacing of cables,” said Nester. “These considerations are basic, but they are commonly skipped. If you don’t have an energy chain, you’re going to have to cobble something together.”

 Rob Spiegel has covered manufacturing for 19 years, 17 of them for Design News. Other topics he has covered include automation, supply chain technology, alternative energy, and cybersecurity. For 10 years, he was the owner and publisher of the food magazine Chile Pepper.

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