Superior production process combining the strengths of motor design, manufacturing technology and facility development
Motors produced at the Nakatsugawa Works. At front, a motor produced at the Iida Factory. The Nakatsugawa Works has produced ventilators since 1943 and made its 100 millionth product in 2006, produced. The Iida Factory had manufactured more than 40 million as of 2005. The high-quality, highly reliable products that come off these facilities' automated production lines have made Mitsubishi Electric the No. 1 manufacturer for four straight years, as chosen by material and equipment manufacturers, according to a survey by Nikkei Architecture.
minimo was developed by a project team from the Iida Factory at the Nakatsugawa Works. For the project, engineers specializing in motor design, manufacturing technology and facility development gathered at the factory. This concurrent engineering resulted in the development of this product.
The Iida Factory is one of Japan's leading facilities for ventilator production. It manufactures duct ventilators, pipe fans and other models. As competitors shift production overseas, the Nakatsugawa Works has remained focused on production in Japan while pursuing a high market share and customer satisfaction through high-quality products matched to the needs of the Japanese market.
The Iida Factory makes highly competitive products because of its ongoing factory automation. The Nakatsugawa Works can handle production from line design to the design and development of automation equipment and molds. The factory combines these technologies to build automated, high-efficiency, high-precision production lines that cannot be imitated. Product development does not follow a typical pattern of design production. Instead, an automated production line is a prerequisite, and so divisions collaborate to create the optimal motor design, production line configuration and equipment molds. The Company has used this development process for many years. Long before concurrent engineering became widespread, the Nakatsugawa Works applied this approach to product development, a process it terms its DNA.
Technology Development System for minimo
The Nakatsugawa Works' DNA was evident in the development of minimo. To create the ultimate fan motor, top staff members from sales, motor design, manufacturing technologies, facility development and other divisions participated. Also enlisted was the Manufacturing Engineering Center, which provides technical support for all of Mitsubishi Electric's production sites around the country. Highly experienced employees were invited to the Iida Factory. This new team pursued the best product development process by combining and fusing technologies, knowledge, and experience cultivated on the production floor, the front line of product manufacturing.
As the team developed concurrent technology, a key was technical innovations related to integrating design with manufacturing. For example, the motor coil was separated from the insulating framework and insulated after winding the copper wire as densely as possible and inserting other parts. This new technology shattered conventional views about fan motors and is why minimo is compact and efficient. The minimo is the direct result of combining a new manufacturing perspective with motor design. The Nakatsugawa Works is well known for this type of innovation.
Technical innovations went beyond designs. Concurrent engineering resulted in many manufacturing innovations as well. An experienced employee in fan motor design was put in charge of production technology, a move that infused a new perspective. Similarly, staff from the Manufacturing Engineering Center worked closely with team members in charge of facility development and combined their respective expertise. Efforts were made to reduce loss in every process, including the development of a work conveyance system. The team constantly innovated to ensure the best product was manufactured with high-precision efficiency.
minimo: a product of concurrent engineering
Project Members for minimo From left: Deguchi (design leader), Yamaguchi (production technology leader), Kinoshita (project leader), Miyake (production technology development assistance)
Creation Lab located next to the production line
The Iida Creation Lab at the Iida Factory was a key element in the concurrent engineering used to develop minimo. This lab houses parts and components for experiments and product development. It also hosts meetings at which project members exchange ideas.
The Iida Factory is a production site without a formal development division. At the start of the project, space was created next to the factory entrance of the where all development team members could meet. The development site was located within a few steps of the production line to aid in fusing design and production.
Many manufacturing facilities aspire to concurrent engineering, but their actual development process typically involves technology developed separately because of the high degree of specialization required, with regular meetings to coordinate these disparate efforts. In contrast, all team members gather at the Iida Creation Lab to inspect the manufacturing line that will be used and debate how to improve mechanisms and processes. Rather than trying to coordinate their efforts in a meeting room at a later date, the team members meet at the actual production site, making the lab an essential tool for effective concurrent engineering.
Engineers gather in the Creation Lab.
All team discuss ways to create the best product.
Reducing the size of a motor typically reduces its output and power efficiency. Coil innovations provide a way to make a motor compact while maintaining its efficiency.
Primary loss, the major power loss by a motor, refers to power lost due to heat from electrical resistance when current flows through the coil connected to the power source. This loss accounts for around 40% of losses in compact capacitor start motors. To reduce this primary loss, minimo uses concentrated winding in which the copper wire is directly coiled on the stator (the part of the fan motor that does not revolve), which differs from regular distributed winding. As a result, primary power loss from coil resistance is reduced by about half.
A problem with centralized winding, which involves few slots, is that the amount of dead space increases. Dead space is where the copper wire cannot be wound because it is blocked by the framework that insulates the coil. To solve this problem, the framework was separated and the wire was wound around a portion that could not be used previously. Other insulating parts were inserted on the portion that juts out after the coil was wound. The coil space factor (ratio of the space occupied by the copper wire to the area of the slots) was increased 12% over conventional models, which enabled primary loss to be successfully reduced another 20%.
A high-speed, low-shock conveyor. To ensure the high precision required by minimo, the Manufacturing Engineering Center and Facility Development Division worked to develop a conveyor that is smooth, fast and does not jolt parts. Development of this equipment was not outsourced; instead, the production line was built concurrently with the design of minimo.
With conventional models, parts are supplied to the line by a robot that lays them out on a pallet. Switching to a direct-parts supply system made possible by a parts feeder manufactured in-house eliminated the manual laying out process upstream on the line.
The soldering trowel features a new mechanism that lowers the temperature in stand-by mode when the line stops temporarily. Thorough efforts were made to totally rationalize energy efficiency.