What are motors used in vacuums? Examples of applications and benefits explained

1. What is a vacuum?

A vacuum is a state of space filled with a gas at a pressure lower than normal atmospheric pressure. Vacuums play an important role in many fields, including science, engineering, and medicine.

In science, it is used in the study of atoms and molecules.
In engineering, vacuum is used to manufacture materials such as semiconductors and solar cells, and to manufacture electronic components.
In the medical field, vacuum is used for tissue research, blood and tissue preservation, and sterilization of surgical instruments.

Vacuum Type

Absolute Vacuum

Vacuum is also an important concept in physics. In classical theory, an absolute vacuum is a state in which there are absolutely no molecules in space. Although outer space is said to be a vacuum, in reality there are trace amounts of molecules in space, so it is merely a hypothetical state and does not actually exist.

Negative pressure

Negative pressure is a state where the air pressure is lower than the standard atmospheric pressure on Earth (near sea level = 1 atmosphere). The JIS (Japanese Industrial Standards) defines four stages of vacuum: low vacuum, medium vacuum, high vacuum, and ultra-high vacuum.

• Low vacuum: Used as vacuum packing, for example in the manufacture of vacuum tubes and electronic components.
• Medium vacuum: Used in the manufacture of materials for semiconductors, solar cells, etc.
• High vacuum: Used to manufacture devices such as lasers and electron microscopes.
• Ultra-high vacuum: Used for atomic and molecular research, etc.

2. What applications require a vacuum environment?

So far we have been explaining about vacuum, but motors are used in devices that take advantage of this vacuum environment and in devices used in outer space.

Example 1: Case of vacuum thin film forming equipment

Vacuum thin-film deposition equipment is used to deposit thin films of metals, ceramics, semiconductors, organic materials, and more.
Thin films are used in a variety of applications, including semiconductor devices, solar cells, displays, and optical devices.

The reason why a vacuum environment is required in vacuum thin-film deposition equipment is to remove air molecules that interfere with the movement of atoms and molecules necessary for thin-film growth.
In a vacuum environment, the low air pressure means that atoms and molecules are less likely to collide with each other, which makes it easier for them to stick to the desired location, resulting in the formation of uniform, high-quality thin films.

Examples of applications for vacuum thin film deposition equipment

• Semiconductor devices such as transistors, diodes, and capacitors (for improved performance and miniaturization)
• Solar cells (to convert sunlight into electricity)
• Displays such as LCDs and OLEDs (to improve image quality and make them thinner)
• Optical devices such as lasers and optical fibers (for improved performance and miniaturization)
• Energy devices such as solar cells, fuel cells, and light-emitting diodes (LEDs) (to improve performance and efficiency)
• Protective coatings for metals, ceramics, plastics, and other materials (to protect against abrasion, corrosion, and ultraviolet light)
• Decorative coatings on glass, plastics, metals, and other materials (to add beauty, durability, or function)

Example 2: Vacuum metallurgy equipment case

Vacuum metallurgy equipment is a device for melting and solidifying metals in a vacuum.

The reason why a vacuum environment is required in metallurgical equipment is:
"By removing impurities from the air, it is possible to suppress the oxidation of metals and the introduction of impurities."
"In a vacuum, the solidification rate of metal increases, making it possible to manufacture metal products with fine and uniform crystal grains."
"The bubbles that form during solidification become smaller, improving the strength of the metal and its quality."
This is because of the benefits it offers.

Examples of vacuum metallurgy equipment applications

• High quality steel manufacturing
• High temperature alloy manufacturing
• Semiconductor Materials Manufacturing
• Magnetic Materials
• Manufacturing of superconducting materials

Example 3: Accelerator case

An accelerator is a device that gives energy to particles such as electrons and protons and accelerates them to high speeds.
Accelerators must operate in a vacuum environment because particles inside the accelerator lose energy when they collide with air molecules.

In a vacuum environment, collisions between the particles and air molecules can be avoided and the particles can be accelerated to high speeds.
Accelerators are used for research in a wide range of fields, including physics, chemistry, biology, and medicine.

It is also used in medical diagnosis and radiation therapy, and is useful in everyday life in applications such as particle beam therapy.

Examples of vacuum metallurgy equipment applications

• Study of the structure of matter
• Development of new materials
• Medical Diagnosis
• Radiation therapy
• Nuclear Fusion Research

Example 4: Use of motors in space

In space, motors are used to operate many pieces of equipment on satellites and spacecraft.

Examples of space applications

• Robotic Arm:
  It is controlled by motors and can remotely perform operations such as grabbing and releasing objects outside the spacecraft.
• antenna:
  They are used by satellites and spacecraft to communicate with Earth and other spacecraft. They use motors to orient satellites and spacecraft so that they can communicate correctly with Earth and other spacecraft.
• Solar Array:
  It is used to power satellites and spacecraft. It is controlled by a motor to point it towards the sun so that it can capture as much sunlight as possible.
• Thruster:
  These thrusters are used to control the orbit of satellites and spacecraft. These thrusters consist of nozzles driven by motors.
  When the motor drives the nozzle, high-pressure gas is ejected from the nozzle, which provides thrust to the satellite or spacecraft, accelerating it.
• Reaction Wheel:
  It plays an important role in attitude control and orbital control, and is made up of a series of wheels rotated by a motor. Satellites and spacecraft require precise attitude control.
  For example, if a spacecraft needs to point in a particular direction, rotating a part of the reaction wheel can control the rotational movement of the craft. It is also used for fine adjustments in orbit or to move to a specific position.

These are just a few examples, but motors are essential devices for the operation of spacecraft and artificial satellites. They perform precise operations while maintaining reliability even in harsh environments, and play an essential role in the success of a mission.

3. What are the advantages of using a vacuum motor?

​Previously, when using a motor to move an object in a vacuum environment, a vacuum introducer (rotary introducer) was used to transmit the movement of an external motor into a vacuum chamber (a space that maintains a vacuum state).
However, the vacuum introduction machine required a large amount of space, which posed a problem.

Vacuum motors can be installed and used directly in a vacuum environment, eliminating the need for a vacuum introducer and allowing the equipment to be made more compact.

4. Precautions when using motors in a vacuum

Now, we will explain the precautions to take when using motors under vacuum conditions.

Risk of rising temperatures

When electricity is passed through the motor windings, the temperature of the windings rises. In the atmosphere, the heat escapes through air convection, but in a vacuum, where there is no air, the temperature rises significantly. For this reason, measures to prevent heat generation are important.

SANYO DENKI CO., LTD. 's vacuum stepping motors

• Made of high temperature resistant material (can be used continuously at 200℃).

Risk of outgassing

Lubricating oils and cooling oils evaporate in a vacuum. If the evaporating oil diffuses into the vacuum, it will adhere to the surfaces of the vacuum pump and vacuum chamber, leading to reduced performance.
Also, if the lubricating oil evaporates, it will no longer be able to maintain lubrication on the surfaces of components such as bearings and gears.

Furthermore, in standard motors, the flanges and end brackets are made by die casting (a technique in which molten non-ferrous alloys are injected into a mold at high pressure to form a product), but this method leaves tiny air bubbles on the surface, which can lead to outgassing.

SANYO DENKI CO., LTD. 's vacuum stepping motors

• No rust-preventive oil is used as in standard motors.
• We do not use paints or solvents that cause outgassing.
• Before assembly, the parts are baked to remove as much outgassing as possible, and then cleaned before assembly.
  (Baking is a process in which gas molecules, including moisture, are removed by heating the surface.)
• The flanges and end brackets are not die-cast, but are machined from solid aluminum.
• The ball bearings use vacuum grease, which is less likely to evaporate.

Furthermore, when used in ultra-high vacuum environments, we customize the bearings by using solid lubrication (only coating on the inner ring, outer ring, and ball of the ball bearing).

Motor Reliability

Motor failure in a vacuum environment can cause serious problems, especially in applications where repair or replacement is difficult and extremely high reliability is required.

SANYO DENKI CO., LTD. 's vacuum stepping motors

• The thermal expansion coefficient of each component is taken into consideration. For example, materials with similar thermal expansion coefficients are used for the stator and flange, enabling assembly precision to be maintained even at high temperatures.

Motor Efficiency

In a vacuum environment, it is important for motors to produce high torque with as little power as possible, since heat does not easily escape. Therefore, it is necessary to select a highly efficient motor.

SANYO DENKI CO., LTD. 's vacuum stepping motors

• The design is to minimize losses due to winding current.
• The design minimizes losses that occur in the motor core.

5. Introduction of SANYO DENKI CO., LTD. 's vacuum stepping motors (2-phase and 5-phase)

Features

• This stepping motor can be operated directly in a vacuum environment without the need for a vacuum introducer.
• This actuator is suitable for vacuum environments and allows for easy high-precision positioning control.
• It can be customized to suit a wide range of environmental pressures, from low vacuum to ultra-high vacuum.
• The heat resistance temperature is 200℃.

Usable pressure guideline

Applications

Semiconductor manufacturing equipment, electron microscopes, accelerators, synchrotron radiation analyzers, spacecraft robot arms, etc.

Motor Size

42 mm to 86 mm
We can provide fully customized motors to suit your needs. Please feel free to contact us for more information.

Customizability

The vacuum usage environment varies from customer to customer.
At SANYO DENKI CO., LTD., we can provide a wide range of customizations to meet your needs. Please feel free to contact us for more information.

Examples of SANYO DENKI CO., LTD. 's customization projects:

• Semiconductor wafer inspection equipment/Cable material customization
• Robot arm for space station/fully customized
• Vacuum deposition equipment/Customization to geared stepping motors
• Customization for electron microscopes/geared stepping motors
• Nuclear power-related equipment/Radiation-compatible customization for stepping motors
• Liquid crystal sputtering equipment/Customization to geared stepping motors, etc.

In cooperation with: SANYO DENKI CO., LTD. Servo Systems Division Servo System Business Group, Sales Division, Design Department 1

release date: 2023-06-01 00:00