MachiningMachining CenterMachines are alive:
hone your five senses to respond
to their changes

Whether engine parts for sports cars,
banknote printing machines,
or large diameter pipes for oil fields …

Selected as a certified Master Craftsman by Aichi Prefecture (called the "Manufacturing Kingdom" in Japan) in 2017, Katsumi Sumitaku has been handling an array of difficult machining since joining Okuma in 1983.
In his first work assignment, he learned the principles, concepts, and basic techniques of metal working while operating general-purpose boring machines. It was a workplace in which he saw a steady stream of work coming in that involved difficult-to-cut parts, such as parts processing for rotary knitting machines produced by Okuma at that time. These parts had special shapes that could not be handled by machining centers.
Mr. Sumitaku continued to hone his machining and other skills after that and was involved in the manufacture of banknote production equipment that required rigorous dimensional accuracy and in the manufacture of milling machines for large-diameter pipes used in U.S. oil fields. To put this into perspective, the machining accuracy required at that time for a headstock with an inner diameter of 930 mm was strict, with perpendicularity and roundness tolerances of only 3 μm.
He also struggled with other parts that had strict thread misalignment tolerances of within 1 μm despite them being small parts, and he was later told that they were parts of machines for manufacturing engine parts for the world's finest sports cars. That manufacturer still uses Okuma grinders to machine certain critical parts. These achievements have attracted attention from FI racing engineers, and Okuma's machines are used to machine engine parts for race cars that contend over the boundaries of speed.

Transfer of know-how from the machine shop to design and bringing design knowledge to the machine shop

At Okuma, monozukuri is achieved through close cooperation between the product development and design department and manufacturing department such as parts machining and assembly. This is a corporate culture that has been cultivated traditionally and passed down from one generation to another to this day.
Based on his own experience, Mr. Sumitaku says, "Based on my many years of machining experience, it is possible to read drawings and see how changing certain points results in improvements, such as preventing vibration or making assembly easier while maintaining rigidity. Providing feedback to the design department is also an important role for us. On the other hand, the machine shop can acquire knowledge and wisdom through exchanges with the design department and further improve our skills." For example, cavities in certain spots may resonate when cutting workpieces. In addition, attachments of double-column machining centers (5-face machining centers), which can switch between more than 100 different spindle heads, may cause vibration when machining curved or inclined surfaces if there are any spots where the rigidity is insufficient. These observations are proffered to the design section at drawing review meetings and/or in the prototyping stage to ensure that we thoroughly adhere to the fundamental principles of Okuma machines: high rigidity and high accuracy.
Because we consistently do this throughout the entire process in Japan, from development to shipping, we are able to confidently deliver the highest level of products to our customers.