Going autonomous to speed inspections at Metro Plastics

Officials of Metro Plastics Technologies Inc. wanted to boost automation at its custom injection molding plant in Noblesville, Ind. But since the average production run is short, fixed automation didn't make sense.

"It's very difficult for us to find a payback on some automation possibilities, due to the fact that the product runs are too short. There's no payback," President Ken Hahn said.

So they bought what's known as an autonomous mobile robot from Mobile Industrial Robots. It's a moving cart that shuttles parts around the plant.

Automated guide vehicles have been the standard for plastics processors — usually very big companies — to carry parts and supplies from place to place. They followed a wire track buried in the floor. Some use elaborate conveying systems. The most common method? The good old forklift.

This month, Best Practices takes you to the future — actually right now at Metro Plastics — and a mobile robot that needs no track and is easy to program.

Mobile Industrial Robots, or MiR, is a Danish company that is owned by Teradyne Inc. of North Reading, Mass. Teradyne also owns another automation company from Denmark, that makes the well-known collaborative Universal Robots.

Hahn said Metro Plastics wanted a more efficient way to move boxes of parts around the plant. A fixed conveyor system was one possible solution, but Metro officials wanted something totally flexible to move between the plant's 25 injection molding presses. Like most custom molders, Metro sometimes rearranges machines to make the most efficient production layout. And they buy new machines.

Hahn said the family-owned molder looked at traditional automated guide vehicles, but they were too expensive and company officials thought the buried track would be too disruptive to install and not flexible enough.

Metro Plastics built a new 72,000-square foot factory about a year-and-a half ago. It was time to look at the automation challenge again.

MiR distributor Neff Engineering suggested the mobile industrial robot to Metro Plastics. The molder bought a MiR200, a decision Hahn calls "a no-brainer."

The autonomous cart has built-in sensors and cameras, so it can identify its surroundings and take the most efficient route to its destination, avoiding obstacles and people. There is no need for inflexible wires or sensors.

The first task for the mobile cart was taking boxes of parts from each molding press to the quality department. Metro Plastics does that for every box, running each one through the quality department and into the warehouse. Before getting the MiR200, filled boxes used to stack up at each press until a quality inspector could get there and move the boxes for a quality check. Quality technicians inspect about 10 percent of the molded parts. They also do additional inspection, including metrology tests for one shot's worth of parts, Hahn said.

The MiR200 now handles moving the boxes from press side to the quality department. Initially, Metro Plastics set up the robotic cart to run in a loop around the production floor, stopping at each injection molding machine for 30 seconds to allow operators to load finished boxes of parts. The MiR automatically docks at its charging station until the next run.

The MiR200 can circulate through the whole plant in about 10 minutes.

Before, quality inspector Falicia Roudebush said, it could take several hours to inspect all the boxes on the production floor.

"But the MiR robot brings them back to us every 30 seconds, so once a box is done, we're getting a visual of it right then and there, so if there is a problem we can fix it right then and there," she said.

That's a big advantage. Taking action immediately is better than the alternative, obviously. Also, the people in quality can focus on their jobs instead of spending time walking around the shop floor.

It is also safer, with less traffic in the factory.

"We have no finished product on the production floor, no fork trucks," Hahn said. Large monitors show operators where the robot is and it's next scheduled stop.

If Metro Plastics' first phase is like a bus on a scheduled route, phase two is an on-call, on-demand system like Uber. Each molding press is equipped with an iPad. When a box is finished, the operator touches the tablet to call the robot over, and the box goes on to the quality department.

Metro Plastics' project coordinator, Emma Morris, was a bit skeptical of the ease of the system. But that quickly dissolved when she set up the entire MiR path through the plant in just a few hours. Laser scanners on the robot could see the plant layout, as Morris directed it around the plant.

"To set it up with our production floor, it was as easy as just driving it," she said. "We scanned the production floor in about 30 minutes."

Then Morris used the information to set up the desired stops along the way for the MiR cart. The robot finds its own best route. Remember, it doesn't have to follow any guide wire.

"It has taken some interesting paths to find the way it needs to go," she said.

If Metro Plastics needs to change the route, she can do it with a few mouse clicks.

Future plans call for the MiR to pick up the boxes all on its own, with no need for operator interaction. Powered conveyor belts at each press will allow the robot to pull up to the station and let product roll directly onto the robot.

Mobile Industrial Robots has U.S. sales offices in San Diego and Holbrook, N.Y.

MiR robots have gone into a wide range of applications, including hospitals and a nursing home. But manufacturing is the core market, said Ed Mullen, MiR's vice president of sales for the Americas.

"We're now able to expose the technology to the smaller and medium-sized companies," he said.

Watch Metro Plastics' MiR robot in action.