Recently I entered our stainless-steel tube processing area, which looks completely different from the way it did 10 years ago. The entire room used to be filled with people who were running machines, inspecting components, and working on changeovers. The company was a different place back then and was only starting to embrace automated work cells. Fast forward to today. When I walked into that room, I was greeted by one of our setup technicians sitting on a chair in the corner. I joked with him, “Don’t you have any work to do?” He replied, “Take a look around, you see all those green lights? If they are green, then I am doing my job.” There was no one else in the room but us, yet all of the machines were running. That was a powerful moment for me, and it was then that I realized we had transitioned almost every processing machine in that room to some form of automation.
Designed for Automation
One of the initiatives that has helped us to use robotic automation on our production lines successfully has been to develop our process and tooling in a semi-automated state prior to full robotic integration. These initial cells are designed for future automation from the start but built in a way that allows a person to safely complete the work in a manual state. Once stability is proven, a pre-built robotic work cell is married up to the machine. This technique has been employed by MICRO many times with a great deal of success. Most recently, we were able to efficiently integrate robotic automation into a multistage tube forming and swaging process. This included a six-axis robot, automated belt fed component rack loader and finished parts tote exchange system, all integrated in two weeks’ time, right on our production floor.
The grinding and processing of medical sharps is another area ideally suited to robotic automation. Typically, these components are very delicate, high-volume components that are best handled by robotic cells. Protecting operators from sticks and protecting the sharps from damage are two of the main areas of concern that use of robotics can address. Secondarily, the throughput requirements and strict quality and cleanliness standards are what drive the use of automation. Six-axis robotics have been integrated to several of grinding cells where strips of sharps are loaded into various fixtures for sharpening and deburring. The accuracy required to place these components and the tight tolerances associated with the operation would never be achievable with human hands.
Selective Compliance Assembly Robot Arms
Vision inspection and packaging of sharps is also an area where robotics continues to play an important role. Not only do we leverage several highly accurate, cleanroom certified six-axis robots, but we are now integrating compact, lower cost, and higher speed SCARA (selective compliance assembly robot arm) robots. These are starting to replace traditional cartesian-based linear actuators in a number of applications. Their size and rapid acceleration rates have made them perfect additions to some of our needle packaging, inspection, and singulation machines.
There are even applications where one SCARA will hand off a strip of components to another so each can continue concurrent tasks in different areas of the work cell. We have really seen the benefit of these in packaging applications. SCARAs tend to have lower payload capacities when compared with traditional six-axis robotic arms, but this is of little concern when handling needles and sharps. Their mechanical rigidity and simplicity in design allow us to package components with great speed and precision into various shapes and sizes of vacuum formed plastic trays. Packaging consistently is critically important for downstream automated processes for our customers and their suppliers. This is a competency developed over the years through many collaborative efforts to yield the most efficient packaging with the highest density of components that still meets both our automation needs and those of our downstream partners.
The pad printing process is one area where we have leveraged robotics to handle a variety of operations in one integrated cell. The tubing components that are printed in this cell are extremely delicate components and therefore subject to scratching. This, in combination with the high throughput required for the product line, made it an ideal candidate for robotic automation. This cell uses a six-axis robot in combination with a series of actuators to pick from rack, verify orientation using integrated IR vision software, and then load that component into the printer.
The benefit here is in both cycle time and accuracy. The system can calculate the radial orientation from randomly loaded components in milliseconds and translate that to dynamic code that provides the exact coordinate to load a tube on an alignment pin with 0.002 in. of clearance every time. There is no scratching of the tube surface, and no ink from an operator’s hands being mistakenly deposited on the OD. Tubes are then unloaded, inspected with additional vision sensors utilizing OCR technology (optical character recognition) to verify the readability of text, and scored to determine acceptance. In the final production phase, the tubes are inspected for straightness and placed onto an exit conveyor for packaging.
Stainless steel support tubes for new medical devices have continued to evolve over the years with more and more complex design. This led the company, in collaboration with one of our partners, to design a flexible four-axis laser cutter capable of handling various input lengths, diameters, and thickness tubes.
This system utilized a series of vision cameras to orient the tube based on a preformed shape, as well as to locate the start of the CNC laser cutting program on every component. We have since implemented a number of these machines and as the component volumes grew, so did the need for an automated solution. The initial solution was an excellent opportunity based on product mix to dedicate one robotic system to serve two machines. This was achieved with a six-axis robot that replicated the exact movements of an operator’s hand to remove the finished part and in the same motion insert the blank tube through the machine’s rotary actuator. These two cells became one, and after integration, the machines were each running unattended for four hours straight without stopping. This, of course, not only increased our efficiency but also reduced cosmetic defects and reduced our frequency of in-process inspections.
Based on the success of this initial robotic implementation, we decided to integrate an additional machine with an even more dynamic approach for component flexibility. The next cell was designed to handle different families of components, including different combinations of diameters and lengths. The challenge that existed here was the need to verify that the components that were loaded manually to rack matched the cutting program as intended. This was achieved by leveraging the flexibility of the robot and integrating simple vision sensors outside the cutting area that the robot would place the component in front of, just like a person using their eyes to check. We also integrated sensors to the gripper that could verify the diameter and confirm that it had the correct tube based on how far its fingers closed. Due to all of these inputs, we were able to utilize an automated solution in a high product mix environment. This allowed us to gain the benefits of reduced labor without sacrificing any efficiency associated with lengthy changeover.
New initiatives are currently in development at the company to leverage the latest in 3D scanning technology integrated with robotics. 3D dynamic picking of randomly oriented components from a bin is a very difficult problem to tackle for any automated system. Traditionally, this has been handled with the use of feeder bowls to orient components, but that process requires components to meet a strict set of criteria in order to work properly. Bin picking is the exact opposite. The only criteria is simply that the component is visible, and the robot can calculate a path to retrieve it in the most efficient way possible.
This has great potential to further increase the benefits from an automated cell because it does not require any form of operator racking or staging of components for processing. Components can be loosely transported between work cells in inexpensive and simple totes. The benefits are clear and will soon be integrated on our floor to handle a variety of different shape and size stainless steel tubing products, all within one flexible work cell and with no changeover required.
This article was written by Steven Jacobsen, Manager of Process Development Engineering, MICRO, Somerset, NJ. For more information, visit here .