Sub-micron precision machining technology

It has achieved precision machining technology that has a high global market share of hard disk drive motors

It is the backbone technology that supports the manufacturing business of the Japan Electricity Group.

The Japan Electricity Group manufactures motors, sensors, fans, blowers, pumps, and other products, and products that require special precision are motors for hard disk drives and related parts. Among them, Japan Electronics Co., Ltd., which has built up advanced processing technology over many years, uses its own manufacturing equipment and inspection equipment in its production line for parts used in hydraulic bearings, from micron-level accuracy to sub-micron-level accuracy.

For example, DVD and BD (Blu-ray Disc) have strict specifications for each of them, and as long as they meet their specifications, they can be used as products, and they do not need to have more than a certain level of performance. However, unlike DVDs and BDs, hard drives are constantly evolving in pursuit of high-capacity, high-speed burning/reading. More than half a century has passed since the advent of hard drives in 1956, and this trend of high-capacity, high-speed burning/reading has not stopped for a moment, and it is still moving forward today.

As a technology that enables high-capacity, high-speed burning/reading, the innovation of magnetic heads and magnetic recording methods has attracted attention, and in fact, the mechanisms that make up hard disk drives have also contributed greatly to the evolution of hard disk drives. Hydraulic bearings are one of them. The innovation of the magnetic head and magnetic recording method has made it possible to record at high speed in fine fields, and the vibration of roller bearings has become an obstacle to recording and reading, which has led to the introduction of hydraulic bearings.

Sub-micron precision machining technology

With the development of hard disk drives in the direction of high-capacity, high-speed burning/reading, the market has put forward higher requirements for precision machining technology for such products, so the new generation of products to replace ball bearings - hydraulic bearings has been introduced.

Although the principle of a hydraulic bearing, which is caused by a herringbone groove engraved into the bearing and supported by the dynamic pressure of oil, is simple, it requires very advanced processing technology to realize this simple principle. For example, the tolerance of the diameter accuracy of the shaft is ±1.5 μm, and the management of the shaft diameter within the production hall should be controlled within the range of ±0.5 μm. The clearance between the shaft and the bearing is 1 μm, and the surface roughness varies depending on the model, but in the most stringent cases, the diameter is 0.02 μm. Although the bearing needs to form a human-shaped groove that generates hydraulic pressure, the electrolytic processing machine that forms the groove is original to Japan Den, and the electrodes used in the processing are also produced in-house.

Tens of millions of extremely high-precision products like these are produced every month at Japan Denco, and the background is Japan Denko's extremely high-precision processing technology.

The dimensional accuracy of the bearing, the roughness of the surface, and the size of the groove are all managed in the micron and sub-micron ranges

In recent years, in order to improve the performance of hard disk drives, new products have been introduced that charge helium into hard disk drives. This product also makes full use of Japan's technology. Since the inside of a helium-filled hard drive is completely sealed, it is required to eliminate residual gases other than helium. In addition, since the gap between the disk and the head of the latest products is less than 2 nm, the gas mixture must be kept to a minimum. In order to reduce residual gases and mixtures to a minimum, repeated cleaning and baking are required at all stages of the production process to keep the product clean. Choose a detergent that does not harm the product and has no residue, and wash it with purified water. The temperature during baking, the heating time, and the layout of the oven are also based on the experience and know-how that Japan Dec has cultivated over a long period of time. Currently, the factory maintains a level of 100 levels of cleanliness in the factory, but as part of the production process, it is also being planned to increase the level of cleanliness to class 10, and the level is gradually being reached as that of semiconductors is being improved.

In order to achieve helium-filled hard drives, they need to be cleaned and baked to reduce residual gases and mixtures to a minimum. In some manufacturing processes, we are also planning to raise the dust-free level to Class 10, which is equivalent to that of semiconductor manufacturing plants

Sub-micron precision machining technology

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