OEM delivers high-performance motion solution in small footprint

Microbore tubing is an essential tool in modern medicine. As its name implies, the plastic tubing is tiny in diameter. It’s also flexible and durable — qualities that make it indispensable for treating, repairing and even replacing parts of the human body. Tension is a major quality-control issue in spooling microbe tubing. If the tubing is too taut, the plastic can stretch; if it’s too loose, it can warp. Either effect can ruin the product.

With the need for optimal tension control and several other features firmly in mind, one of the world’s largest medical device companies tapped CKC Engineering to design and develop a custom microbore tubing spooler machine for a new extrusion plant. The client was looking for a closed-loop electronic control system to govern its tube-spooling process.

The application required multi-axis co-ordinated motion, and closed-loop control of the tubing tension by a proportional-integral-derivative (PID) feedback mechanism. Closed-loop control provides far greater accuracy and repeatability than a manual open-loop system, which depends on the operator’s judgment and intuition about how much to adjust the output on a tensioning device.

“The main goal was to create a system that would operate at an extremely low tension set point, while automatically handling tubing coming in at varying speeds and tensions,” Carl DiPietro, vice-president and controls engineering manager at CKC Engineering, explained. “A complicating factor was that the client also wanted two spools in the system, so that the tubing could be quickly switched to an empty spool on the fly.”

Versatility was another requirement. The machine needed to handle more than 100 different extrusions and their specific recipe parameters. It also needed to fit and accurately fill different-sized spools. All these capabilities needed to come in a machine approximately the size of a small refrigerator. That way, operators could move the spooler between extrusion lines and out of the way when they were not using it.

After careful consideration, the company chose offerings from Rockwell Automation — the CompactLogix 5370 controller, along with three Kinetix 350 EtherNet/IP servo drives — as the control platform for the new tubing spooler machine.

“By coupling the Logix controller with the Kinetix 350 drives, we got the high-performance, integrated-motion package we needed in a small footprint,” said DiPietro. “The new products using EtherNet/IP also offer a significant cost savings over the SERCOS platform, which previously was our preferred platform for co-ordinated motion.”

The technologies provided the tight integration and communication CKC’s application required. In fact, CKC’s design, which includes Rockwell’s technology, met all of the client’s needs. The new custom-built tubing spooler accommodates over 100 different extrusions, and enhances the quality and repeatability of the process by accurately controlling the tension.

“The CompactLogix controller, paired with the Kinetix servo drives, gave us all the capabilities the application required,” DiPietro said. “Going forward, this combination gives CKC Engineering a standard platform for any motion control application.”

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