Mitsubishi Corp's 'Mill-Box' Adopted for Zenitaka Gumi's Construction of New Meiji Plant, Reducing Workload by 50% Through Mill Sheet DX

Mitsubishi Corporation's Material Solutions Group, Industrial Materials DX Team (hereafter, Mitsubishi Corp) announces that its cloud-based mill sheet electronic management system, 'Mill-Box,' has been implemented in the construction of the Meiji Co., Ltd. (tentative name) Kanagawa New Plant, undertaken by The Zenitaka Corporation (hereafter, Zenitaka Gumi).

This has significantly reduced the time spent on organizing and verifying mill sheets, a task that used to take two to three days per month. It enables immediate identification of missing documents and automates the creation of inspection paperwork, cutting the on-site workload by more than 50%.

Background

On large-scale construction sites, vast quantities of steel materials are used daily, generating a massive volume of documents to certify their quality. Traditionally, these mill sheets were managed on paper, requiring manual, one-by-one visual checks to aggregate weights by rebar diameter and manufacturer and to cross-reference with rebar tags from processing companies. This process was a significant burden, often taking two to three days a month just for organizing and checking hundreds to thousands of mill sheets, impacting on-site productivity.

Adoption Initiative

The impetus for Zenitaka Gumi to consider adopting Mill-Box came when the Deputy Head of the Architectural Division suggested, 'Let's just try it on-site.' This move, initiated voluntarily from an awareness of site-level issues rather than a top-down directive, aligned with the company-wide DX promotion policy (aiming for a 30% reduction in work hours and a 30% increase in productivity by March 2028) and evolved into a full-scale implementation study.

> 'Rather than comparing it with other services, it was a proactive decision to first try to streamline operations at the construction phase, as part of the company's overall DX promotion.' (Mr. Kurokawa & Mr. Kojima, Zenitaka Gumi)

The final decision for adoption was based on a rigorous cost-benefit analysis by the site manager. By converting the implementation cost over the entire construction period into labor costs, they concluded, 'If we can save a few days of organization work per month, it's well worth it.' In practice, the billing amount remained within expectations, and they felt confident about expanding it to other sites.

> 'Converting the implementation cost over the construction period to labor costs, it was about the cost of one site employee for just under two months. We judged that this would be easily recoverable by saving a few days of organization work per month. The actual charges did not exceed our expectations, giving us the feeling that we could deploy this at other sites.' (Mr. Ochi, Zenitaka Gumi)

Implementation Effects

- Work time reduced by over 50%. A task that took 2-3 days per month now takes a few hours. - Uncollected mill sheets are visible at a glance, enabling early detection of omissions. - An intuitive screen that anyone can operate eliminates task dependency on specific individuals.

After implementing Mill-Box, on-site operations changed significantly. The most notable effect was the reduction in work time. The task of organizing and verifying mill sheets, which previously took two to three days a month, became much more efficient by switching to a scan-centric operation.

> 'When we asked another site, they said they felt the organization work was reduced by over 50%. The work that used to take 2-3 days a month can now be done mainly by scanning, which has been a great relief mentally.' (Mr. Yonekura, Zenitaka Gumi)

Furthermore, being able to manage the collection status of mill sheets on a single screen has made it possible to track omissions in real-time, which were previously easy to overlook. During inspections, responses have become smoother as necessary documents can be instantly retrieved on-screen.

> 'On the screen, you can see at a glance which mill sheets are uncollected, so we no longer worry about omissions. During inspections, we used to struggle to find documents in paper files, but now we can check them immediately on a PC screen. The operation is intuitive and easy to understand, and it's great that work errors are less likely to occur regardless of who does it.' (Ms. Tanaka, Zenitaka Gumi)

Summary and Future Outlook

Zenitaka Gumi highly values the effects of Mill-Box, having presented a case study of its use at an internal technical presentation, and plans to continue its company-wide rollout.

In the future, they hope to expand electronic management to all materials handled on-site, such as steel frames and ready-mixed concrete delivery slips, and look forward to a system where everything is connected automatically from image recognition to list generation.

> 'Ideally, in the future, all materials we handle on-site, like steel frames and ready-mixed concrete slips, could be managed electronically, with a fully automated process from image recognition to listing.' (Mr. Kurokawa & Mr. Ochi, Zenitaka Gumi)

Mill-Box continues to evolve based on real feedback from the field. We will continue to reflect site feedback into the product, supporting the creation of a mill sheet management system that facilitates collaboration among stakeholders in steel distribution—including construction companies, trading firms, manufacturers, and inspection agencies—thereby contributing to the productivity improvement of the entire industry.