Collaborative Robots Deliver Flexibility to Shop Floor

Editor's Note: Watch a YouTube video at the bottom of this story that shows how two UR5 robots working in tandem use vision guidance to pick blanks off a conveyor for CNC milling.

 

In the 1990s, Task Force Tips, a manufacturer of firefighting equipment, started integrating robots with its machine tools. These robots, however, were dedicated to working only on one machine and could not be redeployed to other tasks. In need of more flexibility on the shop floor, the company installed four collaborative robots from Universal Robots USA Inc. (East Setauket, New York). Not only did these robots pay for themselves in just 34 days, they also improved product quality.

CEO Stewart McMillan still remembers his father looking at him and asking, “Are you sure about this?” when the family-owned company located in Valparaiso, Indiana, bought its first CNC machine 40 years ago. “It was a huge step, but giving people the proper tools to do their jobs is essential to being productive,” Mr. McMillan says.

That line of thinking helped him recognize that the shop’s robots had limited capabilities because of their dedication to just one machine. “So, what happens is the machine wears out first, and now you have a $100,000 robot that you cannot do anything with,” Mr. McMillan explains.

After hearing about collaborative robots that could be used in a much more flexible manner, the company decided to explore the technology by getting a Universal Robots demo in the shop. According to Production Supervisor Cory Mack, his colleagues were trying to program it and make it work within minutes of its arrival.

“The Universal Robot is so simple and non-intimidating that our programmers were already in the mindset of ‘I don’t need any guidance; I can do this on my own.’ It was almost like a PlayStation video game, where they could pick up the controller and figure it out without reading the rules to the game,” he says.

This led Task Force Tips to install one UR10 robot and two UR5 robots to tend CNC machines. Another UR5 is mounted to a table on wheels and moved between tasks. The UR robots can work collaboratively right alongside employees due to a built-in safety feature that causes them to automatically stop operating when they encounter obstacles in their route—a scenario Mr. McMillan calls “a fundamental paradigm shift.” In the past, a major impediment to using robots was the required security fencing around the machine, he says. With the UR robots, all the guarding is unnecessary. Employees can roll the table with the robot right up to a machine and teach it to load parts in a matter of minutes.

This is especially useful for the production-cell layout at Task Force Tips, where operators run multiple machines simultaneously around the clock. Since acquiring the robots, staffing requirements have decreased from seven to three operators, because it only takes about one hour per operator shift to operate the robot, which includes laying out parts and staging the robot, Mr. Mack says. This translates to 21 hours of unassisted run time for the robot. In just 34 days, it pays for itself, he says. As an additional benefit, the robot saves seven hours each shift for a machine operator to do something else productive. No automation solution has resulted in layoffs, just optimized production.

In application, the two UR5 robots working in tandem have helped optimize hose coupling production in a two-machine cell. As blanks arrive on an inbound conveyor, the first robot uses vision guidance to identify and pick up the blanks before inserting them into the first milling machine. The robot then takes out a half-machined part and hands it over to the other UR5. The second robot inserts that part into the second CNC machine, takes out the complete-machined part and places it on the outbound conveyor. From there, an operator places the parts onto anodizing racks, completing the cycle.

The process looks very impressive, but it is deceivingly easy to do, says Automation Specialist Adam Hessling. With a background in CNC programming and no specific robotic-programming experience, he was able to use Universal Robots’ support website to put together the two-robot machining cell that produces hose couplings. No external help was necessary. “If you understand basic logic, you can do an unbelievable amount with Universal Robots,” he says.

Both the robot hand-off and the vision guidance use the Modbus communication protocol registers in the UR robots’ controllers. Mr. Hessling says that Modbus made communication between the two robots easy. Through the touchscreen that comes with each robot, he set the waypoints that he wants the robots to move through, and the two robots confirm back and forth to each other that they are where they are supposed to be, he says.

According to Mr. Hessling, he has the option to have discreet inputs and outputs such as those of a normal programmable logic controller, or he could use register values, which is what he used for the vision-guidance camera’s coordinates. Since Modbus registers what it can output, he says he sent the coordinates to the Modbus registers in the Universal Robot’s controller. This generated the parts’ waypoints and directed the robot there. No scripting was involved. In fact, Mr. Hessling says it was a very clean installation. “All of the communication we did was through our computer network; nothing is actually hardwired together.”

During production, when the UR5 places the unmachined part in the lathe, the robot’s force detection identifies if the part is misshapen, has burrs or if there are chips in the chuck jaws. For example, when the robot tries to reach the set waypoint for placement and there is an obstruction that causes the force on the end of the arm to exceed 50 newtons (which Mr. Hessling programmed as the threshold), it applies an air blast to clean away the debris. If this does not clear the debris after several attempts, the robot tells the machine to execute a chuck-wash cycle, which uses the machine’s high-pressure coolant system to dislodge the debris from the chuck jaws. If the part still can’t load after the coolant wash, a popup appears on the robot’s touchscreen, instructing the operator to clear any debris from the chuck jaws and press “continue.” If the issue persists, another popup halts the program entirely. The operator can then diagnose the problem, fix it and restart production.

According to Mr. Hessling, the robot fixes a “failure-to-load” issue about three or four times an hour, which helps eliminate downtime. The operator needs only to intervene about once per shift, sometimes not at all, he says, explaining that the robots are not at fault; it is just the nature of the chips created from machining aluminum.

Freeing personnel from machine tending has also played an important role in increased product quality. Mr. Mack says that when employees are not worried about keeping a machine running, they have more time to visually inspect the machined products. “Part quality has really gone to a whole other level with the UR robot in place, while allowing our personnel to come up with new ideas and better ways to improve our production,” he says.

Mr. McMillan agrees: “When you set people loose with a way to reduce the mundane labor in their daily job, they find those ways. There have been multiple days in which I’ve come in and seen the robot somewhere else in the shop that surprised to me. I do not see our possibilities being limited on places we can use these.”

The next UR robot application at will likely be at a deburring station within the CNC machining cell where parts are currently being hand-deburred. The company is also looking at potential robot use for packing and shipping parts, as well as with its laser machines.