Fully automated inspection of catheters
A manufacturer of medical catheters has successfully automated the inspection of its 2-material, 2-shot molded products. Two Stäubli TX2-60L six-axis robots are responsible for the handling of the catheters after inspection. They do so with a high degree of precision and in compliance with stringent hygiene standards.
In the healthcare industry, there are many single-use devices made from plastics which have to be manufactured in compliance with strict hygiene standards. One such product is catheters. A major European supplier of these devices has now teamed up with MGS Mfg. Group to mold the catheters. The company operates several cleanroom production sites worldwide for healthcare customers, including a cleanroom molding factory in Ireland. This is where the catheters are made.
All catheters are subjected to visual inspection. This was previously performed manually by no fewer than 30 employees. It was very difficult to recruit skilled workers in these numbers, and the quality of the inspection process varied from operator to operator. This was clearly a task that required automation. MGS used their in-house-expertise to develop two automated inspection and sorting cells.
Inspection by four cameras – processing and sorting by robots
Molded catheters are deposited into a hopper at the input side of the cell. The catheters are then dispensed into a vibratory feeder system, where they are oriented correctly and delivered into a servo escapement which separates eight catheters at a time for pickup by a servo transfer robotic arm. The handling unit guides the catheters past all four image processing systems. The cameras detect defects on all sides such as blowholes, sink marks and contamination by foreign particles.
Once the inspection is complete, a Stäubli TX2-60L removes the eight catheters from the transfer system and discards the ones that have failed the test. Products that have passed inspection are layer-packed into the final reusable packaging. The end-of-arm tooling on the robot features an eight-position gripper assembly that can individually select and release the catheter as required. Each of the two cells can inspect, sort and package over 50 catheters a minute.
One common programming platform for robot and cell
In designing the cell, the MGS engineers set flexibility as a priority. For example, no tooling change is required when switching between variants. Furthermore, the system was designed to minimize changeover time. All process changes are handled electronically when the user selects a new program via the machine HMI.
The robot in each of the two cells is linked to an EtherNet/IP network and features an Allen-Bradley CompactLogix 5380 controller. This integration of software into a single programming platform saves time and money. The tool that enables integration of the robot into the control platform of the complete cell is Stäubli’s unique uniVAL plc robot control solution. This real-time interface allows the CompactLogix controller to drive the robot using simplified function blocks.
Other factors that make the TX2 robot the obvious choice for this application include its hygienic design, compact dimensions and exemplary repeatability of ± 0.03 mm.