Dynamic Group had difficulty staffing its injection moulding production and wanted to better utilise its labour force. Three collaborative robot arms from Universal Robots have taken over repetitive tasks, improving product consistency and increasing production capacity.
Dynamic Programming
The UR robots come with a palletizing feature pre-programmed that Dynamic Group used when the robot places the molded parts on the table in front of the operator. “It was really nice to have the pre-canned program, I only needed to teach the four corner positions and the robot automatically figured the remainder of the positions from there,” says Travis Oksendahl, Dynamic Group’s Automation Engineer
Dynamic Group, a Minnesota-based contract manufacturer, sought to automate repetitive manual tasks after finding employees to fill injection moulding jobs proved challenging. As CEO Joe McGillivray puts it: “We’re lucky to live in a place that has high wages and low unemployment, which is great on a daily basis normally, but it’s difficult for someone who runs a business.”
The collaborative robots are used in three different applications. The first robot tends a complete machine cycle; it picks and places ‘book frames’ that hold pieces to be moulded into the injection moulding machine, transports the units to a trimming fixture, places the part in front of an operator for further handling, and finally pushes a button to activate the cycle again.
This application produces a medical device with parts that are extremely heat sensitive, so cycle times have to be consistent from part to part.
“We were having trouble making one good part with manual labour, let alone the various shifts tending the machine cycle differently,” says McGillivray.
“Universal Robots’ UR10 robot arm gave us a perfectly consistent cycle. We went from having three operators on a single shift to being able to run three shifts per day with just one operator per shift. So we essentially quadrupled our production capacity and our scrap went from significantly high to near zero. It’s been an extremely successful application for us.”
Hand off with cartesian robot
The second injection moulding application uses a traditional cartesian robot that drops a moulded piece down a slide where the Universal Robot (UR) picks it up and places it in a degating fixture, then palletises the part on a table in front of the operator for inspection. Previously, the parts would fall onto a conveyor, which often damaged parts, and the operator had to catch them before they unloaded.
“It was very challenging for the operator to keep up, making sure the parts didn’t fall and trimming them as well, resulting in a lot of ruined parts. Now we still use one operator, but they can be there one quarter of the time they would otherwise,” explains McGillivray.
Payback
The third robot is deployed in a kitting application. Using a vacuum gripper the UR10 picks up a ‘clam shell’, the bottom part of a plastic box. It then places sterile wipes and saline solution into the clam shell, and pushes the loaded shell onto a conveyor. Before the UR10, Dynamic Group used six to seven employees at once to do this kit assembly application.
“It was fast paced and very high volume. It wasn’t sustainable. Now we’re able to run it with as little as two people. Having this type of success out of the gate as first time rookies at this stuff has been phenomenal and totally unexpected. Our return on investment was less than two months, and we can even go further because we’re able to adapt the robots to other products so quickly,” says the CEO.
Robots on wheelsIt took Travis Oksendahl, automation engineer at Dynamic Group, about two days to get the robots programmed once the robotic cell was set up.
The Minneapolis injection moulder is able to quickly redeploy its UR robots to completely new tasks in short order. “All the robots are on bases that we can transport around on wheels and slide from press to press and application to application. The fact that we can quickly reprogram and redeploy these robots enables us to effectively address our high mix/low volume challenge,” said McGillivray.
No safety cages neededThe mobility of the UR robots is in stark contrast to traditional industrial robots that usually stay bolted down in a safety cage. They robots can work collaboratively right alongside Dynamic’s employees due to a built-in safety feature causing the robots to automatically stop operating when they encounter obstacles in their route.
“Our employees are working directly with the robot, there is no fence in between. That’s a huge savings to us on time, needing to manufacture, and costs to manufacture those enclosures and of course floor space. We’re able to fit a lot more automation in a much smaller footprint,” added McGillivray.
Tested robot on own body
All three UR robot models (UR3, UR5 and UR10) utilise a patented technology to measure electrical current in the joints to determine force and movement. If the robot arm measures a force stronger than the amount it is programmed for (can be down to 50 Newton in UR3) it automatically stops.
McGillivray wanted to understand how well the safety features worked on the system so asked for a program to be written that allowed him to walk in its way as it was going back and forth.
“It didn’t hurt, sensed me immediately, and stopped just like I’d want it to,” he said.
No job killer
Having robots take over tasks previously handled by employees did not lead to staff layoffs at Dynamic Group.
“We needed to make better use of the labour we had on hand. Instead of using our employees as labour, we needed to use their brains. That’s what Universal Robots has helped us be able to do. We lowered our labour content per part, and gave people better jobs,” says the injection moulder who is now training employees to operate, install, and program the UR robots.
Future applications
McGillivray and his team are also working on getting more UR robots into production. Next step will be installing the smaller UR3 model directly on presses.
“The UR robots’ number of I/Os and the ease of access to them, makes this relatively simple to do. With quick tool changes we should be able to address our high mix low volume situation extremely well. We’re also looking to integrate a UR with a structured lighting system for doing micron level inspection 360 degrees around a part. That’s a capability we’re anxious to get in place.”