- 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 main goal was to create a system that would operate at an extremely low tension set point, while automatically handling tubing com
- Allen-Bradley CompactLogix 5370 programmable automation controller (PAC) – uses a common control engine to provide mid-range application control in a small footprint
- Allen-Bradley Kinetix 350 servo drives – provide high-performance, integrated motion. Rockwell Software RSLogix 5000 design
- Rockwell Software RSLogix 5000 design and configuration software – allows developers to create the motion control code in a modular fashion so it can be re-used in similar machines
- EtherNet/IP – provides a single network for easy integration of the HMI, PAC and motion components
- High-performance, integrated-motion package fits in small footprint
- Programming environment provides re-usable code for similar machines
- Identical coding for PAC and servo drives simplifies programming and saves time
- Standard EtherNet/IP network reduces commissioning and debugging time
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 indispensible for treating, repairing and even replacing parts of the human body.
Manufacturers produce microbore tubing in a broad range of sizes for different medical purposes. Whatever the size, microbore tubing requires a rigorously precise and consistent production process. One particularly delicate step occurs at the end, when long sections of newly extruded tubing are wound around spools. By carefully aligning layers around a hard core – just as thread is wound on a sewing spool – manufacturers maintain the tubing's proper shape until it is unwound to make medical products.
Tension is a major quality-control issue in the spooling process. 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. Based in San Francisco, CKC provides custom equipment solutions for clients in the pharmaceutical, medical-device and drug-delivery industries.
“Often, device makers will approach us to provide automated equipment for a new production line, and usually the client is looking to enhance the level of automation on the new line,” said Carl DiPietro, vice president and controls engineering manager at CKC Engineering. “In this case, the client stressed the need for a closed-loop electronic control system to govern its tube-spooling process.”
The application required multi-axis coordinated 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,” DiPietro 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.
DiPietro and his colleagues at CKC had heard about two new offerings from Rockwell Automation, and thought the products might provide the ideal combination for their client.
Even before the Allen-Bradley® Kinetix® 350 single-axis servo drive was available on the market, CKC's managers contacted their Rockwell Automation distributor, Buckles-Smith in California. CKC wanted to hear about the combined capabilities of the Kinetix 350 servo drive with the Allen-Bradley CompactLogix™ 5370 controller.
The consultation with representatives from Buckles-Smith and Rockwell Automation convinced CKC to choose 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 coordinated motion.”
The machine operates via closed-loop tension control using a high-accuracy tension sensor to ensure the tubing is not stretched or flattened during the spooling process. A traverse axis is electronically geared to the operating spool, such that it travels at the correct speed to smoothly lay the tubing, even as the spool speeds up and slows down to maintain the optimal tension. Optical sensors enable the traverse system to detect the edge of the spool and reverse direction – allowing multiple spool sizes to be used interchangeably.
“The Rockwell Automation technology provided the tight integration and communication our application required,” DiPietro explained. “The combination is unique because the drive uses the same programming code as the controller. That single programming platform, Rockwell Software® RSLogix™ 5000, dramatically decreases development and commissioning time.”
The RSLogix 5000 design and configuration software helped the CKC team develop the motion-control code in a modular fashion, so that they could re-use the code in future projects to drastically reduce development time.
EtherNet/IP provides even more simplicity. “The ease of integrating the HMI, PAC and motion components on the single EtherNet/IP network reduced design time and simplified debug,” DiPietro said.
CKC's design 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.
DiPietro believes the new Rockwell Automation products decreased programming and commissioning time by 25 percent. In addition, the component cost was reduced by 25 percent compared to the SERCOS platform.
“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.”