Robotic platforms abound in Cartesian setups, delta subtypes, and six-axis selective-compliance-articulated robot arms (SCARAs). They’re more common than ever for machining, packaging, palleting, machine tending, welding, and assembly. But no matter the application, the robot morphology must match the task at hand.
Case study: Quadrupled production capacity with collaborative robots
Contract manufacturer Dynamic Group had difficulty staffing injection-molding production and wanted to employ their labor force with less menial tasks, so recently bought three collaborative robot arms from Universal Robots.
One robot picks and places frames to hold pieces and transport them to a trimming fixture. Then the robot places the parts in front of an operator for further handling before he or she pushes a button to reactivate the cycle. The setup makes medical-device pieces that are heat sensitive, so cycle times must be consistent from part to part. Before, Dynamic Group was having trouble making one good part with manual labor, especially with various shifts tending the machine cycle differently.
“Universal Robots’ UR10 robot arm gave us a consistent cycle,” said CEO Joe McGillivray. We went from having three operators on a single shift to running three shifts per day with just one operator. So we essentially quadrupled production capacity and scrap went from significant to near zero.”
The second injection-molding application uses a traditional Cartesian robot that drops a molded piece down a slide where the UR robot picks it up and places it in a degating fixture … then palletizes the part on a table in front of an inspector. The old setup had parts fall onto a conveyor, which sometimes caused damage unless the operator caught them before they unloaded. The new setup lets the inspector walk away to do other things and come back at will.
A third robot works on a kitting application. Using a vacuum gripper, a UR10 picks up a clamshell (the bottom part of a plastic box) then loads sterile wipes and saline solution into it before putting the container on a conveyor. Before the UR10, Dynamic Group tasked six to seven employees at once to do kit assembly.
“Our return on investment was less than two months, and we can quickly adapt the robots to other products,” said McGillivray.
He assumed Dynamic Group would need an expensive programmer or engineer to install the robots. “I’m not an engineer but within an hour of delivery, I had them setup and running test tasks,” said McGillivray. “Their user interface made them easy to program — so my initial assumptions about investment and extra hires were completely wrong.”
It took Travis Oksendahl, automation engineer at Dynamic Group, about two days to get the robots programmed once the cell was setup.
“Compared to traditional robots, the UR robots are easier to teach and program from drag-and-drop applications. In Teach Mode one simply grabs the robot arm and move it. Once points are set, simply hit play and the robot runs through these.”
All three UR robot models (UR3, UR5 and UR10) use technology that measures electrical current in the joints to determine force and movement. If the robot arm measures a force exceeding programmed force (down to 50 N in the UR3) it automatically stops.
“When Universal Robots distributor Braas Co. first showed me the robot, I asked them to pummel me with it. They wrote a program that let me walk in its way. It didn’t hurt, sensed me immediately, and stopped just like I’d want,” added McGillivray.
Having robots take over tasks previously handled by employees didn’t lead to staff layoffs. “We needed to make better use of our team, so instead of using our employees as labor, we needed to use their brains. That’s what Universal Robots helped us do.” The injection molder is now training employees to operate and program the UR robots. McGillivray and his team are also working on getting more UR robots into their production — including a UR with a structured lighting system for doing micron-level inspection 360° around a part.
Robot I/Os (and ease of access to them) allow quick tool changes, which serve the manufacturer’s high-mix low-volume situation.