Chip removal has improved production efficiency exponentially, and a moving nozzle has changed the common sense of metal working

Machined components

Programmable coolant systems: Wavy Nozzle

Waste particles produced during metal cutting work are called chips. These chips have a significant effect on product quality and work efficiency. It is not an exaggeration to say that the production of metal components struggles against these chips. MinebeaMitsumi, a global leader of in-house metal working as well, has developed a revolutionary device called "Wavy Nozzle". The product is designed to greatly improve the chip-removal rate, leading to an excellent solution to a long-standing issue faced by component manufacturers.

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"Wavy Nozzle" is registered trademark of MinebeaMitsumi Inc.
Japan trademark registration number: 5645210.

Handling of chips is the key to quality improvement

"Increasing Yield improvement" - this is a long-standing issue faced by component manufacturers. There are a number of factors that may affect the yield, and particularly, the chips produced during metal working have a large effect on the yield rate.

Metal chips sometimes get entangled around components or tool edges, and this may lead to a stoppage of machines to remove the chips, and also chips may damage components and degrade their quality. The removal of chips is directly linked to a reduction in machining time and to the defect rate.

Deterioration in quality, Breakage of machine tool, Increase in working hours

Problems arising from chips

Thus, some machine tools have a device to remove chips by spraying oil from a nozzle, typically called a coolant. However, many conventional nozzles are of a fixed type, and they are not able to remove chips sufficiently. Also, the nozzle angle frequently needs to be manually adjusted depending on the material or processing method. Therefore, the chip removal rate and the effort of adjustment have been the issues to be resolved; especially for companies like MinebeaMitsumi, whose monthly mass-production volume exceeds a hundred million units of components. In such a case, a defect rate of 1% can equate to a million units of components, which proves to be very costly.

Moving nozzle changes the common sense of metal working

Right from the start, MinebeaMitsumi prided itself on its high yield rate in component machining with their mass-production in excess of a hundred million units of components per month; however, a defect rate of even 1% may have a large effect. MinebeaMitsumi's commitment to precision has led to a particular solution. It was the idea that a moving nozzle could inject coolant to remove chips more easily. The project was initiated based on a concept of developing a product to most effectively remove chips during manufacturing. MinebeaMitsumi combined the know-how and technologies among multiple business units to launch a new product called "Wavy Nozzle."

A new idea of guiding chips

As indicated by its name, "Wavy Nozzle" continuously injects a coolant at its target position via programmed actuation. The idea of guiding chips in one direction and preventing them from getting entangled, instead of blowing chips off by spraying a coolant at high pressure like conventional removal devices, was an unprecedented one.
After installing the device on a trial basis in our process for producing hard disk components, significant results were achieved. The occurrence rate of defective items (defect rate), which had been around 1%, was improved to 0.02%.

Sweeping-out movement prevents chips from getting entangled

Conceptual image of operation of "Wavy Nozzle"

The shape and weight of chips vary depending on the details or raw materials of the cutting process. The movement of Wavy Nozzle can be selected from three modes so that it can support any machining work.
Particularly, KICK mode is a function that can change the speed of the nozzle during reciprocation, which is unique to MinebeaMitsumi. The movement of the nozzle is controlled by using our stepping motor that offers accurate positional control.

In addition, we have introduced a teaching play-back system in which we can move the nozzle manually while visually checking the situation using a dedicated controller, and then such movement can be stored on an electronic substrate of the device's main body. The technologies fostered through our manufacturing of electronic devices have also been utilized in these functions. Normally, various components need to be developed and purchased to move the nozzle; however, MinebeaMitsumi, which produces a great variety of precision components in house, was able to realize a moving nozzle by combining existing products and newly developed dedicated substrates.

Operation using the dedicated controller (option) is available

Achieving both space saving and high versatility

Conventional chip-removal methods typically require injecting coolant at high pressure to blow off the chips. On the other hand, Wavy Nozzle, which "guides" chips, does not require high pressure coolant, nor does it require a compressor to be installed, thus saving space. It also contains a feature that allows it to be used for delicate precision machined components, as produced by MinebeaMitsumi and others, because of its low injection pressure.
Moreover, because of its compact design, the unit does not require special equipment, and due to its superior versatility, can easily be installed on new or existing machinery. The intention of the compact design and high versatility was to target chip removal.
However, after initially offering to the market, MinebeaMitsumi has received unearthed and unexpected multiple application uses outside of the initial scope from our customers.

Applying our own products and technologies has produced an innovative product

The product that is essential for oscillating the nozzle of Wavy Nozzle freely is MinebeaMitsumi's stepping motor. A stepping motor, which offers accurate positional control, handles the following movement of the nozzle corresponding to the machining work. In addition, the motor enables the device to be operated at a fixed speed. Minimal acceleration and deceleration at the beginning of movement adds up to a smooth nozzle motion. It can be said that the stepping motor is one of the main keys to bringing about the realization of Wavy Nozzle.

MinebeaMitsumi's stepping motor that controls the nozzle movement

About 80% of the parts of "Wavy Nozzle" are manufactured in house

For the development of Wavy Nozzle, not only the stepping motor, but also a wide variety of our products and technologies have been introduced. A high in-house production rate of about 80% has been achieved by integrating the products and technologies of MinebeaMitsumi. Resin-molding, one of the core technologies within MinebeaMitsumi, is used for the body case; the electronic substrate that controls complicated movement is produced in-house within our Electronic Devices Division; and our Bearing Division produces the ball bearings that support smooth and accurate motor movement.

Thorough removal of chips increases production efficiency exponentially

Although Wavy Nozzle is a very simple device that supports chip removal, it brings immeasurable benefits. It significantly contributes to an increase in component accuracy and production efficiency, while reducing operation man-hours of engineers. We have taken a fresh approach to increasing the production yield, a long-standing issue faced by component manufacturers. In addition, the point that a new product has been created by combining our own products and technologies also makes the device a very MinebeaMitsumi-like product. Wavy Nozzle has made engineers in component manufacturers say, "That is exactly what we wanted!" Without a doubt, the product is fashioned after MinebeaMitsumi's concept of "exploiting the full potential of Monozukuri (manufacturing) in the world."

NG (defect) rate in appearance inspection due to the reduction of damage to the product

* Cutting process: Product: Roller, Material: SUS416: Results of appearance inspection for 3,500 pieces

Frequency of machine stoppage for chip removal

* Cutting process: Product: Shaft, Material: SUS316 The frequency of machine stoppage is monitored for 18 days

Frequency of manual chip-removal work after machining

* Cutting process: Product: Shaft, Material: SUS303: Times that there are chip residues on the product

Interview : Unearthing new market needs from the site of Monozukuri - Karuizawa Plant, Machining Assembly Business Unit

In MinebeaMitsumi's Mechanical Assembly Business Unit that machines and assembles precision components, improving the yield rate was an urgent need. Although our yield rate had initially been rather high, in order to improve it, we learned by trial and error which led us to the idea of a device that waves its nozzle. After the device was introduced into our production line, the results were better than expected, firmly convincing us that the product with which we, professionals of ultra-precision machining, were satisfied and could absolutely change the concept of "Monozukuri" (manufacturing) in the world.
What surprised us after we had launched the device were the needs of customers. We have received a number of inquiries about its use and intended purpose that we had not envisioned. This experience made us more aware of the high versatility of Wavy Nozzle. The content of business will change as the world's needs change. MinebeaMitsumi will continue to produce products that will lead to new solutions based on market needs, and to support "Monozukuri" (manufacturing) in the world.

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