Recently we completed an interesting project that began as a standard palletizing robot project but ended up as something much more complex, with much more value-added and much more interesting from an engineering point of view.
The customer has state-of-the-art manufacturing installation for high-quality thermoplastic road marking paint. It is a powder substance that is packaged in 20 kg plastic bags. The packaging and the palletizing of the bags were becoming a serious bottleneck in the manufacturing process. The reason was that it was all done manually.
An employee had to take an empty bag and hold it under the transport screw through which the powder was pouring. He had to hold the bag straight while it was being filled. Furthermore, he also had to lean forward as the bagging hopper is positioned relatively low from the factory floor. In terms of ergonomics, this is a very bad position. When the bag was full, the operator had to lift the bag and seal it with a heat-sealing machine. Finally, he was ready to manually palletize the bag. This process was being repeated several hundred more times per day.
The job was physically very demanding. Not surprisingly, the factory had difficulties in finding and retaining employees for this job position. Therefore, our customer was looking for a solution with an industrial robot.
The standard approach to designing a robotized solution for such a manufacturing process is to create series of mechanisms that take care of each step in the process:
Usually, in such systems, an industrial robot is used just for the pelletizing step. All the rest is done with additional hardware – manipulators, transporting systems, conveyors etc. This is expensive to build, expensive and difficult to maintain in the long run and needs significant floor space. The advantage of such a system is that it can achieve faster cycle times. Also, the robotic solution in such a system is simpler and more straightforward.
The other less sophisticated option would be to use a robot just the palletizing and keep the operator doing the rest. In such an approach, the capital costs will be lower, but it will not offer a good return on investment, as the operator would be as busy as before and cannot perform other tasks. Furthermore, he will be a little bit relieved of the physically demanding palletizing, but he will still have to stand in un-ergonomic positions while bagging. Last, but not least, this solution would also require significant floor space as the operator has to be standing at a safe distance from the robot.
We did not like either of the standard solutions as they are either very expensive and demand a lot of space, or have a bad return on investment. We started asking ourselves – is there is a better way? Is it possible to do all those steps in the process with the industrial robot that we have selected? After all, the FANUC M-710iC/70 is a very powerful machine. It has a reach of 2050mm, very good flexibility due to its 6 axes of freedom, it can lift up to 70 kg, it is fast and very precise, with repeatability of just ± 0.04mm.
Another big factor was that the bagging cycle time of the upstream production is 25 kg/min. So, we had enough time to perform all of those 6 tasks with just one robot and with minimum additional mechanisms. This would be the best solution. It will be less expensive than a complex packaging and palletizing line, with a more compact size, easier to maintain and with the ability to work autonomously. Then the operator would be free to do other more value-adding tasks. Furthermore, when the operators were filling big bags, the robot could just move to the side and not interfere with the process.
The biggest challenge for our team in Siviko with this project was to create a complex gripper that can do all the tasks. It would pick up plastic bags, open them, hold them while they were filling in, at the same time check their weight and thus control the dosing of the filling machine, close and seal them via heat sealing, and finally palletize the bags.
Innovating is a painful process as it contains many risks. However, it is essential if one is to achieve much better results than what the standard solutions offer. So, after hundreds of hours spent on engineering, and trial and error we created a completely original design of a gripper and a complete robotized solution that we have not seen elsewhere.
In manufacturing, it is even more important to achieve a high level of reliability. We achieved it with our robotic solution. It was very easy for the operators to understand what the working process is and they knew how to control it. With this peace of mind, they could focus on the more interesting job and leave the robot to do the boring and physically demanding work.
The customer was also very happy, as he solved a big bottleneck problem for his production. Now all the packaging and palletizing was fully automated. It was also cheaper than a standard solution due to our novel approach. It is also easier to maintain as there are fewer mechanisms that can fail. It had a very small footprint and was a perfect fit for a manufacturing process that was making both 20 kg bags and big bags.