Mold manufacturing includes the steps of design, machining, assembly/finishing, and quality check. In the design step, drawings are made based on the product shape and specifications, and in machining step the product shape is cut from a metal block according to that design drawing. In the finishing step, final adjustments are made to improve the precision. Finally, products formed with the mold are inspected to check the product quality.

Of the people working on the development of simultaneous 5-axis machining, Koji Yokoi was responsible for machining, assembly, and finishing work on the mold manufacturing floor. At that time, Japan had only manufacturers who made 3-axis machines, and so to select machinery Yokoi traveled to Germany where there were many skilled technicians. In Germany, technicians maintain high skill levels with the national “Meister system,” and so there is a high demand for machining of parts with complex shapes that require higher levels of skill than in other countries. Machine tool manufacturers also led in 5-axis machining technology. With a thorough commitment to selecting machines suited to mold machining, we focused on building a 5-axis machining system.
Yokoi also worked on the software side. Even with a high-performance machine, the machine’s full possibilities will not will not be achieved without an appropriate program to serve as its brain. To complete Toyoda Gosei’s 5-axis machining system, Yokoi tried to build into the software the cutting techniques that craftsmen had cultivated over many years. However, it was not easy to digitize the master craftsmanship that humans perform with intuition and skill. Machine and cutting tool manufacturers cooperated in repeated cutting trials with changed conditions, including the cutting tool used, number of cutting passes, and cutting angle, to derive a way of cutting that approached that of a master craftsman. These efforts led to achieving a simultaneous 5-axis machining system. Toyoda Gosei was the first in the world to achieve simultaneous 5-axis machining in the machining of large molds for front grilles. This achievement and efforts in training workers and other areas were recognized, and Yokoi was certified as a “Contemporary Master Craftsman” by the nation in 2024.

At Toyoda Gosei, 5-axis machining technology is evolving and “nano-processing” technology, which enables machining of finer sections, is being introduced. These machines can cut thicknesses of one ten-thousandth of a human hair, and so are used in mold manufacturing for products that require fine surface machining.
One of those products is the “millimeter-wave compatible emblem” that is transparent to the millimeter-wave radar that supports automobile sensing functions. Even the slightest unevenness, which cannot be detected with the naked eye or touch, affects performance and so more precise machining is required to raise this performance even further.
With advances in autonomous driving in the coming years, many sensors will be installed in the front portion of vehicles. Toyoda Gosei views mold machining technology as a promising technology that will support the manufacturing of these next-generation automotive parts.