When asked how they envision a robot, most people either think of huge, unwieldy robots working in fenced off areas in large factories. Or, they think of futuristic cyberbots mimicking human behavior.
But somewhere in between these two scenarios lies a new emerging reality — a new class of robots, dubbed “collaborative robots” due to their ability to work directly alongside employees with no safety caging. These kinds of co-bots are poised to bridge the gap between fully-manual assembly and fully-automated manufacturing lines. Nowhere is that more obvious than in the small and medium sized business sector that up until now viewed robot automation as too costly and complex.
Danish gear manufacturer BJ-Gear is a poignant example of this. The company with 80 employees was constantly looking for ways to optimize the production flow through automation while keeping their work force in Denmark. Figure 1
“We were, however, reluctant to acquire robots as the solutions from robot manufactures were so costly that the payback time would be far too long for a small company like ours,” said Bjørn Sommer, plant manager at BJ-Gear.
Lowering The Entry Barrier
With traditional robots, the capital costs for the robots themselves typically account for only 25 to 30 percent of the total system costs. The remaining costs are associated with robot programming, setup, and dedicated, shielded work cells. The collaborative robot arms from Universal Robots changed this notion due to three challenges now addressed — cost, user-friendliness, and applicability.
“The flexible, lightweight UR5 and UR10 robot arms are easily redeployed in various places in production, because they are portable and can run entirely without any safety shield. Our calculations show that the cost of a UR robot will be covered in less than one year,” Sommer said.
Unlike their big brothers working behind glass at automobile plants and other big assembly lines, collaborative robots can work right alongside employees with no fencing due to innovative force-sensing technology enabling the UR-robot to automatically stop operating if it comes into contact with employees.
BJ-Gear purchased their first UR robot back in 2009 with the purpose of optimizing the feeding of raw work pieces into the chamber of a CNC machine followed by the unloading of the finished product at the other end. Figure 2
“We had 3 functional, older machines: A lathe, a cutter and a washing machine. They needed constant manning as it took an employee to feed work pieces into the lathe chamber and subsequently take the processed work pieces and place them in the cutter followed by the washing machine. We could have replaced these machines with a fully automated multitasking machine, however, this would have cost us 15 times more than the robot solution from Universal Robots. It is also a great advantage that the robot needs no safety shield, as this reduces the need for additional installation space,” Sommer said.
Today, it only takes one employee to make sure that the chamber with items at the CNC lathe is full. The conveyor belt and the UR5 robot handle the rest. The setup has enabled BJ-Gear to produce 100 work pieces at a time without human intervention leading to drastically increased production speeds. Today, the same employee is able to handle another production cell and take care of filling and quality control of both cells at one and the same time.
Agile Manufacturing Now Automated
BJ-Gear manufactures either directly following orders or for components for their ”supermarket” enabling the company to assemble, fix and deliver gears on a daily basis.
Every gear size has approximately 100 various combinations and therefore a large number of product variants. The end results are extremely complex high-end products with finer tolerances than most others, offered in small series.
The optimized production means that the company was able to maintain production in a high wage country such as Denmark. Because the lightweight UR robots do not stay bolted down in glass cages but can be moved around the shop floor and quickly reprogrammed, automating the production of smaller volumes with great complexity is now possible.
The UR robots are programmed through the touch screen tablet that comes with the robot or by activating the teach-mode that allows employees to simply take hold of the robot arm to demonstrate the movement they want their new colleague to perform. Figure 3
“The robots are so user-friendly and intuitive to operate that our employees themselves have learnt how to program and adjust the robots for new and other tasks,” Sommer said.
One of the machine operators now promoted to robot programmer is Lars Meldgaard Nielsen.
“Before we got the Universal Robots, I stood eight hours a day at the same machine and didn’t have any other work assignments,” Sommer said. "But the robots have enabled me to be more flexible and take on new tasks. It’s also made it more interesting to come to work as you learn to program the robots, – which is really fun.”
Ergonomic And Quality Benefits In Automated Paint Spraying
After witnessing the successful machine tending installation, BJ-Gear looked at automating the spray painting of their gear wheels. Another UR5 robot was fitted with an ordinary spray gun and now spray paints preassembled gears, creating a more uniform, higher quality of the paint work. The robot is used even on small series down to five work pieces each.
“We could have gone for a decided paint robot to automate our paint work. This, however, would have at least doubled the cost for purchase alone. In addition, it is very important to us that the UR robots are as small and flexible as they are, as this means there is still room to solve special tasks in the same paint booth and to paint special gears manually,” Sommer said.
Before implementing the robot, two employees would carry out the paint work manually. Today, one of the employees has been freed completely to take care of other tasks. And the other employee works in particular with the covering of gears and uncovering following paint. The robot also improves the working environment, as employees spend shorter time in the paint booth.
For Gear Engineer at BJ-Gear, Frits Egelund Jensen, that’s a welcome change:
“Before we had the robots, we hand-painted a lot, which was hard on arms and shoulders, so it’s a good thing that we got the robots,” Sommer said. They have definitely alleviated much of the physical work load. BJ-Gear can choose to either send one production series at a time through the paint application by having the employees place a series of work pieces on the conveyor and simply pressing ‘Play’ on the robot's touchscreen. Or, they can paint various work pieces in random order. This can be done by means of employees placing a chip on the gear which then defines the paint program needed for the item’s size and shape. A chip scanner is installed at the conveyor and the scanner sends a message to the UR5 robot with information about which program to initiate and which color to use. Figure 4
“We can now place gears on the conveyor as soon as they are ready for paint,” Sommer said. “This has further strengthened the production flow and shortened our delivery time.” Sommer said.
Increasing The Payload With UR10
The UR5 robots automating the spray painting and machine tending are named after their payload in kilos (11lbs). When their big brother, the UR10 (payload 22lbs), was introduced in 2012, it was met with excitement at BJ-Gear.
“The UR10 offers more possibilities for automation in a company like ours where a large number of the work pieces weigh more than 5 kilos. The larger robot now feeds a lathe with work pieces that are to become flange fixings. It takes 4.5 minutes to process these pieces in the CNC machine, which can be quite a tedious task for employees to operate,” Sommer said.
The UR10 also has an increased a range of 51.2 inches which is now utilized to handle a wide rack that can contain a large number of pieces at a time.
Looking back at several years of automation with UR robots, Sommer said, "The automated solutions have increased both productivity as well as flexibility at our gear manufacturing company. Thanks to the robots we have been able to create growth without having to employ additional staff. Even in a specialized niche production as ours with a large number of changeovers, I see even more opportunities for the automation of processes. We’re currently considering purchasing an additional UR robot each year for the next five to seven years.”