Traditionally, plastic medical tubing is manually attached to valves, connectors, catheters, and other devices. But, medical device manufacturers are eager to automate the assembly process. It’s being driven by several trends, such as labor shortages, labor costs, increased levels of quality control and stringent requirements to track production.

“Traceability and increasingly stringent quality requirements have been significant drivers,” says Rush LaSelle, director of worldwide sales and marketing at Adept Technology Inc. “Also, many [assembly] applications are returning to the United States to overcome logistics issues, as well as intellectual property concerns. Manufacturers that are ‘reshoring’ are evaluating automation as a means to help offset the higher costs associated with most U.S. labor markets.”

High volumes also justify investment in automated assembly systems. “This continues to be an active segment of our business,” says Howie Speiden, applications engineering manager at Sortimat Technology, which has built machines to assemble high volume tube assemblies for the past 20 years.

Speiden defines “high volume” as more than 5 million tube sets a year. “High-volume tube assemblies are automated—typically with a dedicated [cam-driven] machine running two or three variables of the tube assembly,” he points out. “Without the volume, it’s difficult to justify [full automation. However], we do receive many inquiries for solutions for lower volume tube set assemblies.”

“Sets typically consist of varying tube lengths joined by fittings with connection components attached to the tube ends,” adds Speiden. “To manufacture efficiently, the set is categorized into segments, which our machines assemble. The segments are then joined, completing the set. To reduce manufacturing costs, we are also receiving inquiries to automate this final assembly step.”

According to Speiden, the biggest challenge to automating the tube set assembly process is handling the varieties of tube assemblies, such as tube length and different fittings, required on a single automation machine.

Robots are one way to address flexibility and quality, while reducing variability in the assembly process. “Robots excel in assembling components within tight tolerances,” claims LaSelle. “Robotics offer greater flexibility than custom-designed assembly machines, [because it] permits frequent product changeover to address the decreased product life cycle [of medical devices].”

“Sortation continues to yield the greatest number of requests [for robotics], as manufacturers typically source tubing externally and therefore have to sort the tubing from the packaging they are shipped within,” adds LaSelle. “Assembly with other components, inspection, kitting and packaging are also areas where [medical device] manufacturers frequently evaluate robotic solutions.”

Robots typically attach plastic medical tubing to an assembly or component with ultrasonic welding, adhesive bonding and mechanical attachment, such as a clamp.

“In the case of ultrasonic welding, the robot will bring the tubing and another component together on a fixture within an ultrasonic welder where the parts are fused,” explains LaSelle. “For adhesive, the dispensing device can be fixed and the part or tube is presented to a dispensing head prior to assembly. Alternatively, the robot can wield the dispensing head and use the robot’s dexterity to dispense the adhesive on the component or tubing.

“The choice between these two methods is typically driven by additional task requirements within the workcell,” LaSelle points out. “[With] mechanical assembly, such as friction, barb or clamp, [robotic applications are] highly dependent on the mechanism used to secure the tubing.”

No matter what type of assembly process is used, LaSalle says detangling, fixturing and reliable picking of tubing pose the greatest challenge when using robots. “[However], vision and other sensory inputs offer solutions to many of these challenges,” he claims.