Cobots aid metal workers in Japan

| Manufacturing

YuMi collaborative robots are being used in production cells for the assembly of aluminium profiles

Japanese aluminium producer supplements dwindling workforce with automation in the form of collaborative robotics

Headquartered in Shizuoka, Japan, SUS Corporation (SUS) is a large, global manufacturer of aluminium profiles. With operations in 16 countries, the company designs, develops, manufactures, and sells a range of aluminium products, machinery and equipment for factory automation, control products, and aluminium structural materials.

Recently, the company has been struggling to find staff who are willing to carry out the monotonous and repetitive tasks involved in the assembly process. Variations in operator skills have also resulted in production falling below the company’s desired target of one million pieces per month.

Robots in Production

SUS has been using robots since October last year to make one of its main products, a range of aluminium pipes and connecting components known as the GF, or Green Frame, series. The GF series consists of various diameters of extruded metal frames, each featuring rail-type protrusions down four sides. These protrusions are gripped from the outside by connector parts which are then tightened, resulting in a structure that is extremely easy to assemble and adjust. Using the connectors, frames can be made into almost any structure.

The range includes more than 40 frame types and over 1,000 related parts, the most common of which is the “multi-connector” made of die-cast aluminium, which consists of two separate parts assembled with bolts. The total monthly production volume of these multi-connectors is approximately 800,000 units.

Reshoring places strain on workforce

SUS had been manufacturing these components at its Lamphun Factory in Thailand but as it expanded its sales channels around the world, it made the decision to return to domestic production of key components to improve quality, reduce lead times and develop its production technology. This would also help it to better deal with demand fluctuations and the various risks associated with overseas production.

However, this onshoring wasn’t without its challenges and one particular challenge was the manual nature of the production process. With one worker required for every assembly machine, achieving a monthly production volume of 800,000 pieces needed 11 assembly machines with 11 people working on them full-time. Due to the extremely monotonous and repetitive nature of loading and unloading the machines, the company was finding it difficult to recruit, train and retain workers. There was also significant fluctuation in production volumes due to the varying skill levels of the workers.

It was clear that automation could help resolve these challenges, but there were also several difficulties in putting it to practical use. One of these was the unique spiral shape of the inner-type connector, which is designed to maximize strength when the divided parts are combined. This requires a subtle twisting motion when pre-assembling the divided parts before feeding them into the assembly machine.

Robotics Meets the Challenge

Another challenge was the need to accommodate different types of products in the future. SUS also required an accurate preliminary estimate of the effect that introducing automation would have so it could make an informed investment decision on the development of an approach.

As a result of consultations, the company decided to focus on the YuMi, a dual-armed collaborative robot from ABB.

Using the robot, the automated assembly cell in which the YuMi Cobot is supplied with parts by two rotary feeders placed behind it. The YuMi picks the parts with each arm, places them on jigs, and preassembles the divided parts into an assembly machine. Because YuMi has two arms installed on a compact body and eliminates the need for safety fences, it offers much greater flexibility.

Simulation, Testing & Verification

The project started with a simple assembly test of the YuMi at ABB’s Local Application Centre in East Japan. A simple work environment and jigs were created to calibrate YuMi. By taking advantage of the flexibility of the 7 axes on one arm, it was confirmed that YuMi could combine parts with the necessary twisting action without any problems.

To help guide 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 actual system layout, allowing developers to optimise the operation and verify production capacity. As a result, it was found that YuMi could achieve the target production volume. The operation of YuMi at different heights was also verified during the simulation, helping to determine the optimal height at which the load is lowest for both arm movements and at which it is easiest to demonstrate its capabilities.

To precisely adjust the program and obtain accurate production volume forecasts in a virtual space, it is essential to achieve a highly accurate match between the actual robot and the virtual robot, including changes in behaviour under load conditions. This was achieved by RobotStudio’s unique virtual robot controller technology, which operates the virtual robot using the same calculations as the actual robot. The software also enabled simulation videos to be created for the customer’s internal approval process, with the programs created during verification also being used as the basic programs for the YuMi robots in the real production line.

“With the introduction of YuMi, 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,” says Nobuyuki Osada, SUS’ Director of Design and Development.

Based on the outcome of the testing and simulation processes, as well as the ROI estimates, SUS decided to invest in five automation modules, each incorporating one YuMi collaborative robot.

“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. 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 five,” says Akihiro Taki, Team Manager, Die-casting Team, Shizuoka Manufacturing Group.

In the current production facilities, YuMi has achieved SUS Corporation’s production targets using only 50 to 60 percent of its maximum capacity, giving extra room to scale up production if needed. SUS engineers made the final adjustments based on the program developed in RobotStudio suite, which has a level of usability that will be important for flexible modifications and future expansion.

Jonathan Newell
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