China Magnets Source Material Limited Customs Motor Magnets for Voice Coil Motor / Actuator in Medical, Semiconductor, Industrial Process, Space Applications

Voice Coil Actuators are Linear DC motors, a simple type of electric motors as well. They consist of 2 separate parts: the magnetic housing and the coil. Motor magnets is the core of structure.

Originally developed for loudspeaker, voice coil actuation technology now provides precise, reliable motion control for a range of medical, semiconductor, industrial process, and space applications.

Especially for medical industry, mission-critical medical devices need small, high-accuracy linear motion control components; voice coil actuators offer a solution.

For example, they are often used to control inhalation and exhalation valves on ventilators. As voice coil motors feature precision, reliability, simple structure and small size, they are pretty match to the demands for life-critical applications in the medical industry.

magnetic assembly for voice coil actuator in medical devices

As the situation with the coronavirus continues to develop globally, the medical ventilators are especially crucial now in treating cases of COVID-19, the disease caused by the novel coronavirus, because critically ill patients often suffer severe respiratory symptoms. Many companies jump in to supply ventilators needed in coronavirus fight now.

Click here to see how we work hard recently to produce voice coil motor/actuator Magnets for Medical Devices Ventilators To Help Fight New Coronavirus In China

China Magnets Source also provide mounting magnets as magnetic headgear clips on oral-nasal mask of ventilator. The magnets allow for quick release and easy application, and can hold mask in place throughout the night.

Permanent Magnets Used on Voice Coil Motors for Ventilator Machine

Magnets, expecially rare earth magnets are high-value accessories for motor. How to choose a magnet for voice coil motor? This question is very important and related to the performance and the production cost of motor. When selecting the material of the voice coil motor magnet, we need to consider factors such as system performance, magnet working environment and cost.

1. Magnet Materials for Voice Coil Motor

Ceramic magnets are popular for use in linear actuators because of low cost, reliable supply, good resistance to demagnetization and reasonable magnetic strength.

If a higher energy material is required, then samarium cobalt or neodymium magnets must be considered.

Neodymium magnet is the strongest magnet in the world and the most widely used type of rare-earth magnet. They have higher remanence, much higher coercivity and energy product, but often lower Curie temperature than other types of magnets. the Curie temperature (°C) ranges 310–370.

At moment, special neodymium magnet alloys that include terbium and dysprosium have been developed that have higher Curie temperature, allowing them to tolerate higher temperatures.

But most of time, motor manufacturers use samarium cobalt magnet as a replacement selection if a higher working temperature is required and no need for too high magnetic energy product (BHmax) of the magnet material.

Samarium–cobalt magnets have maximum energy products (BHmax) that range from 14 megagauss-oersteds (MG·Oe) to 33 MG·Oe. It is similar to neodymium magnet in N35 grade.

In addition to the choice of magnet material, how can the performance of the voice coil motor be improved in the design of the magnet?

Suitable magnet thickness. The larger the thickness of the magnet, the stronger the air gap magnetic field and the larger the motor output.

But generally the motor has a diameter requirement. Under a fixed diameter, the thicker the magnet, the smaller the diameter of the voice coil. Therefore, the thickness of the magnet must be properly selected to make the motor output better.

2. Coating for Voice Coil Motor Magnets

Neodymium magnet has corrosion problems and good surface treatment is a very important factor in showing the quality of magnets.

However samarium–cobalt magnets have a strong resistance to corrosion and oxidation resistance, usually do not need to be coated can be widely used in high temperature and poor working conditions.

voice coil motor ring magnets in the process of plating

ring magnets in the process of plating

All above magnet materials (ferrite, neodymium and smco) are available in bonded form (combined with plastics). Bonded magnet materials can be created through Injection Molded. They can be molded into complex shapes and also molded directly onto components. Bonded magnets can also be created through the process of compression bonding. By this way, they can offer higher magnetic output but are limited to simpler geometries than Injection Molded materials.

3. Voice Coil Motor Magnets Price

If you want to ask the price different on three types magnets, plastic molded magnets have prices and characteristics somewhere between those of the solid sintered very high-energy materials and ceramics.

As neodymium magnet uses relatively low rare earth content (12% by volume) and it is relative abundant of neodymium and iron compared with samarium and cobalt, they make neodymium magnets lower in price than samarium-cobalt magnets.

4. The Shapes of Magnets on Voice Coil Actuator 

According to the external structure, voice coil motors can be divided into five types: cylindrical, rectangular, flat, curved and inner shaft voice coil motors. Different voice coil motors use different shape magnets.

The ring and segment shape magnets are usually used on ring-shaped voice coil motor. And the magnetization pattern of magnet in a cylindrical voice motor is mainly through radial direction.

They are usually built into a ring by a set of diametrically magnetized arc/curved magnets. Radial ring magnet is also available. Compared with arc magnet array, the magnetic field of radially oriented ring magnets is more evenly distributed.

China Magnets Source Material Limited is a professional magnet manufacturer for motor application. What we provide is not merely high quality arc/block/cylinder/wedge shaped motor magnets for voice coil actuators, but radial ring neodymium magnet, hot-pressed plastic ring magnets, and high precise magnetic assembly.

We are also permanent magnet supplier for CERN, click here to read more Rare Earth Magnet of Accelerator For CERN

5. Magnetic Assembly for Voice Coil Actuators

The high-speed precision magnetic rotor is a rotor assembly for the motor of the therapy device and can be used in medicine for the treatment of sleep apnea.

The main characteristics are: high speed and fast response in order to generate continuous and stable pressure and airflow to keep the patient’s airway unobstructed; the noise should be small enough to ensure the patient’s sleep.

  • high corrosion resistanceand good consistency magnetic properties;
  • research on the adhesive force of the glue: unique surface treatment technology improvesthe wettability (surface energy) of the product surface and achieves the adhesive force between the glue and the material;
  • study the effect of the product air gap on the adhesive strength of the glue and also the influence of humidity on the bonding strength to improve the strength of the glue itself;
  • through research and design of self-aligning positioning mechanism to achievecoaxiality 0.03mm bonding technology without the need of traditional machining technology;
  • achieved fully automatic assembly and testing technology.

If you are looking for an exceptional voice coil motor magnet manufacturer that will listen to you and deliver what you expect, email us, we are ready to serve you.

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