LEONI Cable management system enables top automaker to cut millions in downtime costs

No amount of engineering can completely eliminate production downtime. But when a leading U.S. automaker sought a way to reduce downtime costs ranging from $7,000 to $10,000 per minute at three of its assembly plants, it tapped LEONI engineers for help.

The stoppages arose from the automaker’s robotic flow-drill operations, where 30 industrial robots on a single line joined alloy parts. Flow drilling is a highly effective manufacturing technique that applies friction and heat to punch a hole through two parts and rivet them together in a single step. The automaker found, however, that the feed lines delivering rivets to its robots would occasionally jam. In addition to shutting down operation of the robot, such jams often stopped all production downstream until human operators could clear or replace the line and reset the bot.

Connecting the dots

An on-site inspection by LEONI engineers traced the issue to a confluence of factors. First, as with any robotic system, the repetitive movement of the six-axis arm and end effector caused wear and tear on the cabling and feed tube. Cables were constantly flexing and, in some spots, rubbing against one another and the robotic arm.

LEONI’s team also determined that jams were more frequent when the feed line’s bend radius fell below a certain threshold. “If the tube was bent too tightly, then the rivets wouldn’t flow freely,” explained Jose Carrasco, Technical Sales Engineer for LEONI. “The bend radius threshold varies, but in the case of this application we found it was 10 times the diameter of the tube, which was 23 millimeters. So, it was important to ensure at least 2.3 centimeters of bend radius.”

Addressing these two issues, LEONI determined, would reduce the frequency of jams. But the team noted something else about the automaker’s initial setup. “The application ran cable in a contiguous line without any break points all the way to the tool,” he said. “So, when the line had a jam, it required a lot of time and work to change the whole cabling harness and get production back online.”

Breaking something to fix it

LEONI determined where jams typically occurred in the feedline and, with the customer’s help, identified where break points could be added to segment the line. When a jam occurred, operators would only need to replace the troublesome section. And they could make repairs within 30 minutes rather than the 4–6 hours it had typically taken to change the complete wire harness, which could be in excess of 20 m.

That left the task of minimizing jams. The LEONI team developed a customized hose-and-cable management system — not only for the feed line but for the robotic power and communications cabling as well. The system included custom bracketry designed to minimize wear caused by contact with the robot arm and ensure the feed line’s bend radius remained above the threshold where jams became more common.

Downtime costs slashed

The automaker’s initial setup had experienced about one or two failures per month. LEONI’s solution significantly improved on that. In the months since the new cable management system was installed, the facility’s flow-drill feed lines have experienced zero jams and caused no downtime. Further, should a jam ever occur, the newly segmented feed tube can be fixed in a fraction of the time it took to repair the previous system.

“What separates LEONI is our knowledge of the cables and hoses used in these applications,” said Carrasco. “And the attention we pay to details like the effect of stress and bend radius on performance.”

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