Jun 19, 2015 —

It usually takes five days from when a dentist sends an impression of a patient’s teeth to the lab, until the finished crown returns.

The UR5 robot arm, source Universal Robots Denmark

The UR5 robot arm, source Universal Robots Denmark

June 2015

Challenges and Needs: A process, that Glidewell Dental Laboratories wanted to optimize. David Leeson, engineering manager at Glidewell, had his eyes on Universal Robots’ collaborative robot arms as he researched potential automation solutions:

“I had followed the collaborative robot development for a while, and hearing that the UR robots were used at BMW was a vote of confidence in this new type of robot. I finally got to play around with a UR5 at Automate 2013 and realized it was a real industrial piece of machinery and not just a toy,” says Leeson, who bought the first UR5 robot in 2012 and is now waiting for the seventh to be delivered.

Robot Tasks: The UR5 robot picks a crown to be milled from dispensers with blanks in 16 different shades. The UR5 places the blank in the milling lathe, picks it back out and places it on a conveyor after the 10 minute milling cycle. A vision camera monitoring the dispensers with shades communicates with the robot. If a dispenser is empty or jammed, the vision guidance enables the robot to work on a crown in a different shade, ensuring continued production while an operator can be alerted to fix the dispenser issue.
Since the milling cycle is 10 minutes, it was not feasible for Glidewell to have an operator stationed at the machine to manually load and unload each blank. Instead, the lab inserted the crowns in batches of 15 each which only needed to be done every two hours.
“But now with the UR robot, we can insert each blank immediately into the mill when we receive the CAD scan without waiting for 15 cases to arrive, having the operator nest them into the 15 piece block,” explained Leeson.

Achieving a dynamic, single part flow with the UR5 robot has cut the production cycle time from 28 to 17 hours. “That is less time that our customers are waiting and it has efficiency benefits throughout our process,” says the engineering manager. The optimized production cycle also means that Glidewell can save two operators per shift in the milling room.

“We run a 24/7 operation and. The robot has freed our employees up to focus and improve on handling the complex tasks which also improves our overall product quality,” says Leeson. “We will likely get 3-4 more UR robots in the near future. The only limiting factor right now is that we need more blocks for the individual crowns. As soon as we have those, we’ll get more robots to handle the one crown one batch process. We’re also looking into automating other steps in our production where we see the UR robots playing a key role.”

Selected Robots and Parts: Seven UR5 robots equipped with SMC grippers with SS fingers made in house.

Implementation and Training: Automation engineer Daniel Phee had not worked with collaborative robots before and was surprised at how easy it was to program the robot: “The interface on the touch screen makes it very easy to program the robot. I used a combination of the teach method and my own script. I really liked how reliable the UR robot is, you don’t have to worry about maintenance and we have had no big operation issues come up.”

The teach method allows the user to simply grab the robot arm and move it through the way points in the desired task. It took Glidewell about 5-6 months to fully integrate the first application, but this was mostly down to building custom milling machines and working with heavy IT infrastructure. “But after this it was easy. With the next robots, it only took us 2-3 days to install the complete system,” says Daniel Phee. David Leeson was struck by the fact that interfacing with external equipment was a native capability of the UR robots.

“We wanted to use TCP/IP to easily work with inexpensive, non-industrial hardware instead of having to buy Modbus or something costly like that. As a result, we’ve got simple integration with a machine vision that we did all the coding in-house for while avoiding having to buy a proprietary expensive system.”

Results & Advantages: Production cycle time has now been reduced from 27 hours to 18 hours

As a result, Glidewell saves two milling operators per shift. They have been allocated to more complex tasks, ensuring increased product quality. Seamless integration with external machinery means that Glidewell could easily integrate machine vision in the application. Force-sensing enables the UR5 robot to operate with no safety fencing, saving Glidewell both space and the cost of having to build a large enclosure for the robot. Having the collaborative robot work next to employees heightens the awareness of human interaction and the benefits of gradual transition from manual to automated processes, making the robot seem “less threatening” to employees.

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