32 n ROBOTICS AND AUTOMATED MANUFACTURING February 2024 www.drivesncontrols.com Five two-arm cobots free 11 workers for other roles Japan’s SUS Corporation manufactures aluminium products, machinery and equipment for factory automation, control and structural applications. Since October 2022, SUS has been using cobots (collaborative robots) to make parts for one of its main products – a range of aluminium pipes and connecting components known as the GF (Green Frame) series. It consists of various diameters of extruded metal frames with railtype protrusions down four sides. These protrusions are gripped by connectors which are then tightened, resulting in a structure that is easy to assemble and adjust. The frames can be made into almost any structure, from workbenches and storage systems to children’s toys. Over 20 years, the GF family has grown to include more than 40 frame types and 1,000 related parts, oering an alternative to conventional aluminium frames. The die-cast aluminium“multi-connectors”for 28mm outer frames, are available in an inner and outer types, consisting of two separate parts assembled using bolts. SUS makes around round 800,000 of these connectors every month – until 2014, at a factory in Thailand. It then decided to return the production in Japan to improve quality, cut lead times, and develop its production technology. The move would also help it to deal better with uctuations in demand, and the risks associated with overseas production. A particular challenge was the manual nature of the production process. With one worker needed for each assembly machine, achieving the monthly production volume of 800,000 pieces required 11 people each working on a machine full-time. Due to the monotonous and repetitive nature of loading and unloading the machines, SUS was nding it dicult to recruit, train and retain workers. There was also signicant uctuation in production volumes due to the varying skill levels of the workers, and the company was not achieving its target of one million pieces per month. It was clear that automation could help resolve these challenges, but there were also several diculties in putting it to practical use. One was the unique spiral shape of the inner connectors, designed to maximise strength when the parts are combined. This requires a subtle twisting motion to pre-assemble the parts before feeding them into the assembly machine. Another challenge was the need to accommodate dierent types of products in the future. SUS also wanted an accurate estimate of the eect that introducing automation would have so it could make an informed investment decision. It consulted with ABB to help answer these questions and, as a result, opted for the company’s YuMi dual-armed collaborative robot. The cobot is supplied with parts by two rotary feeders. It picks up the parts with each arm, places them on jigs, and pre-assembles the divided parts into an assembly machine. The cobot’s two arms, each with seven axes, oer exibility and there is no need for safety fences. The project started by testing the cobot at an ABB application centre in Japan, using jigs to calibrate the YuMi. This conrmed that the cobot could combine the parts with the necessary twisting action. To guide the development, CAD data for the assembly machines and parts feeders were imported into ABB’s RobotStudio simulation software. A virtual model was created of the system layout, allowing developers to optimise the operation and verify that the cobot could achieve the target production volumes. To adjust the program precisely and obtain accurate production volume forecasts virtually, it is essential to achieve an accurate match between the virtual robot and the actual installation, including changes in behaviour under load conditions. This was achieved using RobotStudio’s virtual robot controller technology, which operates the virtual robot using the same calculations as the actual machine. The software also created simulation videos for the SUS’internal approval process. The programs created during verication were also used for the cobots on the real production line. “With the introduction of YuMi, it was clear that we would be able to generate sucient prots,”says Nobuyuki Osada, SUS’director of design and development.“We are now able to stabilise production volumes, which used to vary depending on the skill level of the operators, and we can forecast and adjust production more accurately.” Based on the ROI estimates from the preliminary validation, SUS decided to invest in ve automation modules, each incorporating a YuMi cobot. “The automation has freed the 11 workers engaged in feeding operations from monotonous repetitive tasks and has allowed them to be reassigned to more rewarding tasks such as operation management,”reports Akihiro Taki, manager of the diecasting team in the Shizuoka Manufacturing Group.“The new system has also made it possible to operate at night with fewer workers, with the number of dedicated assembly machines in operation reduced from 11 to ve. The time required to feed a assembly machine has been reduced from 5 to 4.5 seconds. Similarly, the production volume of each machine has increased from 5,000 to 6,000 sets in 8h – a 20% increase in productivity, allowing SUS to respond exibly to uctuations in production volume. The investment is expected to pay for itself in about two years. SUS is achieving its production targets using only 50–60% of its maximum capacity, giving room to scale up production if needed. The company is now looking at adding further cells for other types of products and automating other processes. n See video at https://youtu.be/q4S-m1kpfFc A Japanese manufacturer of aluminium pro les has installed an array of two-armed cobots to perform a monotonous assembly task that was previously done by hand. In doing so, it has achieved a 20% increase in productivity, and is predicting a two-year payback. One of the ve two-armed cobots that SUS is using to pre-assemble parts for its aluminium frame system
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