The application of Mitsubishi Electric’s e-F@ctory concept at its Kani manufacturing facility in Japan has delivered hugely beneficial outcomes, with the productivity of each square metre of production space increased through greater utilisation.
Part of its Nagoya Works, Mitsubishi’s Kani factory, which produces motor starters and contactors, was facing a number of significant challenges, not least the sheer number of product variations and possible configurations in its product range – some 14,000 in fact. Customer demand for greater choice had diluted the volumes of each particular product, despite overall product quantities increasing substantially.
Manual production at Kani had given way to totally automated assembly lines, which were ideal for mass production with few product variations where high yields could be realised at high speed. However, many individual components were required in stock and ready for the manufacturing process – without which the lines would not be able to run for any appreciable length of time.
For various reasons, substantial numbers of assembly lines had been optimised to produce a limited range of products, and these would stand still when components ran out. In such a scenario it became difficult and uneconomical to produce small batches.
The solution was to employ engineering know-how built up over many years and combine this with a vision of integrated manufacturing – known as the Mitsubishi Electric e-F@ctory concept. In tandem, existing technology and third-party relationships were utilised through the e-F@ctory Alliance, CLPA and other collaborative engineering groups. Put simply, the objective was to perfect the ‘art of manufacturing’ – or ‘monozukuri’, as it is known in Japan.
The major challenge was to find the root cause of any inconsistencies. This involved several approaches, from analysing existing data or collecting new data sets for fresh eyes to review, to looking for links between data that on the surface could appear unlinked. This factor is related to the first principles of Industry 4.0.
Studying existing processes, as well as the methodology, revealed that natural, normal, organic growth in the production process had inadvertently led to inefficiencies. Resolving this issue at Kani led to a re-evaluation of the need of 100% automated lines, which were not necessarily the most efficient. Restoring some human elements could potentially reduce manufacturing anomalies.
Further observations revealed that the automated parts feeding of some larger components not only created bottlenecks but led to the parts feeders consuming large volumes of space. This could result in minor damage to components – not enough to cause an issue, but enough that engineers were dissatisfied with the quality level being achieved.
Conversely, automation of some tasks which had, in the past, seemed impossible, now looked possible through a combination of technologies. An example of this thinking concerned the misalignment of certain screws during the assembly process. The automation system, unaware of the misalignment, would try to insert the screw and cause damage to the entrance of the hole.
Two technologies helped to overcome this problem: the automatic alignment of robots; and combining rotational drives for inserting screws using torque sensors. As a result, the hole can now be located easily and aligned correctly every time. Moreover, the torque sensor confirms the absence of misalignment and that the screw is tightened to the correct level. The increased use of vision systems, checking for correct assembly and alignment, has also helped to increase the number of right-first-time products.
A further, simpler idea was to etch a matrix code on the body of each product and track it through the various stages. Now, as the product arrives at a workstation, its code is read and the appropriate processes and parts applied. At the end of the manufacturing cycle, each product then has a traceable manufacturing history, making it possible to track the history of individual issues.
By redesigning the process and reintegrating the human element, a single line occupying some 280sqm has been reduced to a cell of just 44.1sqm. This 84% reduction means the productivity of each square metre of production hall has been increased through greater utilisation. Even though a single new cell cannot produce the same volume and speed of units as the original fully automated line, it is now possible to deploy up to 6.3 cells in the same space. In turn, total productivity density is much higher thanks to three key factors: a wider variety of products can be manufactured in smaller batches; one stoppage does not halt the whole of production; and the total number of production lines has increased.
The end result, much to the satisfaction of the team at Kani, is effective optimisation of both machine and human resources, as well as the production process and space – a true productivity gain. Mitsubishi Electric’s e-F@ctory concept shows how manufacturers can achieve their own smart factory concepts.