Permanent Magnets

PERMANENT MAGNETS

Your source for high-quality, low-cost permanent magnets and magnetic components and assemblies for your OEM electric motor manufacturing.

A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic). These include the elements iron, nickel and cobalt and their alloys, some alloys of rare-earth metals, and some naturally occurring minerals such as lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered magnetic, all other substances respond weakly to a magnetic field, by one of several other types of magnetism.

But in certain materials, called ferromagnets, all the spins and the orbits of the electrons will line up, causing the materials to become magnetic. This would be your normal iron, cobalt, nickel. Permanent magnets are limited by the structure of the material. And the strongest magnetic field of a permanent magnet is about 8,000 gausses.

Types of Permanent Magnets

• Ceramic (Ferrite) Magnets
• Alnico Magnets
• Samarium Cobalt Magnets
• Neodymium Iron Boron Magnets
• Bonded - Injection Molded Magnets
• Flexible Magnets

Ceramic (Ferrite) Magnets

Ceramic, also known as Ferrite, magnets are made of a composite of iron oxide and barium or strontium carbonate. These materials are readily available and at a lower cost than other types of materials used in permanent magnets making it desirable due to the lower cost. Ceramic magnets are made using pressing and sintering. These magnets are brittle and require diamond wheels if grinding is necessary. These magnets are also made in different grades. Ceramic-1 is an isotropic grade with equal magnetic properties in all directions. Ceramic grades 5 and 8 are anisotropic grades. Anisotropic magnets are magnetized in the direction of pressing. The anisotropic method delivers the highest energy product among ceramic magnets at values up to 3.5 MGOe (Mega Gauss Oersted). Ceramic magnets have a good balance of magnetic strength, resistance to demagnetizing and economy. They are the most widely used magnets today.

Alnico Magnets

Alnico magnets are made up of a composite of aluminium, nickel and cobalt with small amounts of other elements added to enhance the properties of the magnet. Alnico magnets have good temperature stability, good resistance to demagnetization due to shock but they are easily demagnetized. Alnico magnets are produced by two typical methods, casting or sintering. Sintering offers superior mechanical characteristics, whereas casting delivers higher energy products (up to 5.5 MGOe) and allows for the design of intricate shapes. Two quite common grades of Alnico magnets are 5 and 8. These are anisotropic grades and provide for a preferred direction of magnetic orientation. Alnico magnets have been replaced in many applications by ceramic and rare earth magnets.

Samarium Cobalt

Samarium cobalt is a type of rare earth magnet material that is highly resistant to oxidation, has a higher magnetic strength and temperature resistance than Alnico or Ceramic material. Introduced to the market in the 1970's, samarium cobalt magnets continue to be used today. Samarium cobalt magnets are divided into two main groups: Sm1Co5 and Sm2Co17 (commonly referred to as 1-5 and 2-17). The energy product range for the 1-5 series is 15 to 22 MGOe, with the 2-17 series falling between 22 and 32 MGOe. These magnets offer the best temperature characteristics of all rare earth magnets and can withstand temperatures up to 300° C. Sintered samarium cobalt magnets are brittle and prone to chipping and cracking and may fracture when exposed to thermal shock. Due to the high cost of the material samarium, samarium cobalt magnets are used for applications where high temperature and corrosion resistance is critical.

Neodymium Iron Boron

Neodymium Iron Boron (NdFeB) is another type of rare earth magnetic material. This material has similar properties as the Samarium Cobalt except that it is more easily oxidized and generally does not have the same temperature resistance. NdFeB magnets also have the highest energy products approaching 50MGOe. These materials are costly and are generally used in very selective applications due to the cost. Cost is also driven by existing intellectual property rights of the developers of this type of magnet. Their high energy products lend themselves to compact designs that result in innovative applications and lower manufacturing costs. NdFeB magnets are highly corrosive. Surface treatments have been developed that allow them to be used in most applications. These treatments include gold, nickel, zinc and tin plating and epoxy resin coating.

Injection Molded

Injection mouldable magnets are a composite of resin and magnetic powders of different materials allowing parts to be made in an injection molding process. Energy products are dependent upon the magnetic powders used in fabrication. The molding process allows for the manufacture of more complex shapes. These magnets are usually lower in magnetic strength as there are limitations to the degree of loading.

Flexible magnets

Flexible magnets are very similar to the injection molded magnets but are produced in flat strips and sheets. These magnets are lower in magnetic strength and very flexible depending on the materials that was used in the compound with the magnetic powders. Vinyl is often used in this type of magnet as the binder.

Magnet Material Comparisons

WORKING TEMPERATURES OF MAGNETS

PERMANENT MAGNETS COMPARISON TABLE

INDUSTRIES AND APPLICATIONS OF MAGNETS

• Automotive Applications

• Home appliances

• Power tools

• Industrial motors and pumps

• EV industries

• Electric and Electronics

• Aeronautical and Marine

• Medical

• Servo Motors
• Miniature brushless DC motors
• Brushless DC motors with Hall sensors
• Brushless motors with thermistors
• Position sensors
• External rotor brushless DC motors
• Hollow shaft brushless DC motors
• Slot less brushless motors
• Ironless brushless DC motors
• DC brush type motors
• Frameless brushless DC motors
• Brush type torque motors
• Harsh environment motors
• Splined motors
• Deep well drilling motors
• Limited rotation torque motors

APPLICATIONS

AUTOMOTIVE	HVAC motors Window wiper motors Window lift motors Sunroof motors Seat adjuster motors Mirror adjuster motors EPS- Electric Power steering motors Washer pump motors Fuel pump motors ABS motors APS/parking Motors Power antenna motors Starter motors Micromotors Sensors
HOME APPLIANCES	FHP motors Mixer motors Brushless DC Motors PMDC Motors Pump Motors Micromotors / DC Motors
INDUSTRIAL MOTORS	DC Motors PMDC motors Step motors Servo motors Traction motors DC generators Ex-proof motors Tacho generators / Actuators

QUALITY

Our stringent quality management ensures product consistency covering all processes from raw material procurement to finished goods production. The products and processes pass through stringent quality tests benchmarked with global standards.

Our manufacturing facilities are ISO 9001:2015 or IATF/TS16949 certified. Our greatest asset is delivering outstanding product quality and first-class service to our customers globally.

PRICE

Our components are efficiently manufactured to give our customers very competitive pricing without compromising product quality.

DELIVERY

We offer warehousing locations across the UK and Europe that are set up for stocking programs and deliveries to match customer specific manufacturing and inventory requirements.

If you would like to know more about our extensive range of permanent magnet products please contact us.

WELCOME TO Motor Components Ltd.

"One-stop Solutions for your OEM electric motor manufacturing!"

"Specialist suppliers of OEM motor components, OEM electric motors"

MOTOR VIDEO HERE We/You can use one of the following videos. We will also use other videos according to products! Motor-Video-1 Motor-Video-2

ALNICO MAGNETS

Excellent Temperature Stability!

Alnico was the strongest permanent magnet available until rare earth magnets were developed.

Alnico magnets, composed of primarily Aluminium (Al), Nickel (Ni), Cobalt (Co), and also sometimes copper, titanium and iron, were developed in the 1940s. This class of magnet remains a preferred material because of its excellent temperature stability, high magnetic flux density, and corrosion resistance. There are plenty of trade names are used for different grades such as Columax, Alcomax 3SC, Alni etc.

The most commonly used grade names are; Alnico 5, Alnico 8, Alnico 9, Alnico 5DG, Alnico5-7, Alnico8HC, Alnico 6, Alnico 2, Alnico3, Alnico 500, Alnico 400, Alnico 600 and Alnico 700, etc.

Alnico magnets are widely used today in applications where strong permanent magnets are needed and/or high temperatures are present, in applications requiring low coercivities (the ability to demagnetize and re-magnetize easily). Also has good resistance to demagnetization from vibration and shock.

The advantages of alnico magnets are high magnetic flux density, low-temperature coefficient of magnetic properties, high mechanical strength, and very stable magnets. Alnico magnets are generally (approx. four times) stronger than regular ferrite (ceramic) magnets, but not as strong as rare-earth magnets, they are also electrically conductive, unlike ceramic/ferrite magnets. Alnico magnets are available in either isotropic or anisotropic versions.

On a cost per pound basis, this material is comparable to the cost of neodymium magnets. However, in most applications, alnico is much less powerful than Neodymium magnets.

However, the coercive force and maximum energy product are not high. They limit their applications in many cases.

There are two production processes used to manufacture Alnico Magnets: casting and sintering, magnetization is possible only in axial direction.

AlNiCo magnets have high remanence, but low coercivity - this fact determines the magnetization direction. Optimal ratio of diameter and length of the magnet is 1:4. Magnetic field of AlNiCo magnets can be weakened by demagnetizing. AlNiCo is a hard material, machining is possible by grinding. Working temparature is between -270°C and +500°C. AlNiCo magnets are resistant against acids and solvents.

The casting process allows the magnet to be manufactured into complex shapes. Sintered Alnico is made from a powdered mixture of ingredients that are pressed into a die under tons of pressure. The Sintering process allows for the magnets to be manufactured to tighter tolerances and higher mechanical strength.

Alnico magnets have high magnetic flux density, high resistance to corrosion and excellent temperature stability. Though the corrosion resistance of alnico is excellent and, in most cases, no surface treatments are required, alnico magnets can be plated for aesthetic applications.

Alnico magnets are widely used in industrial and consumer applications where strong permanent magnets are needed and/or high temperatures are present.

What makes Alnico a preferred magnet material for many manufacturers is its high induction levels with good resistance to demagnetization and stability. This occurs because industrial sintered alnico magnets have a low-temperature coefficient and are produced at an affordable cost.

Advantages of Alnico Magnets

• Excellent temperature stability up to 550°C and retain their magnetic properties up to high temperatures.
• High resistance to acids and other chemicals.
• High residual induction can produce powerful fields in certain configurations.
• Corrosion resident to most chemical and environment.
• When sintering and casting, Alnico magnets can also be manufactured in very complex ways.
• Low-cost Tooling for cast magnets, generally sand moulds are used for the casting process.

Disadvantages of Alnico Magnets

• Alnico materials have low coercivities, so they are easily demagnetized.
• They are relatively costly, as they contain both nickel and cobalt.
• Cast alnicos often have casting pores and voids within them, which can be problematic from an aesthetic point of view, and because large voids may lower expected magnetic flux.

Caution!
Special care should be taken to ensure that these magnets are not subject to adverse repelling fields since these could partially de-magnetize the magnets. If alnicos are partially de-magnetized however, they can be easily re-magnetized.

The lower coercive force of Alnico makes magnetizing a simple matter in most cases. To optimize the performance of Alnico magnets, it is advisable to magnetize the magnet after assembly with other circuit components.

MANUFACTURING PROCESS:

• Cast alnico is produced by conventional foundry methods using resin bonded sand moulds
• Sintered Alnico magnets are formed using powdered metal manufacturing methods. Sintering alnico is suitable for complex geometries.

Most alnico produced is anisotropic, meaning that the magnetic direction of the grains is oriented in one direction.  This orientation is achieved via heat treatment after casting or sintering.  The process involves heating the cast or sintered part above its Curie temperature and then cooling it at a controlled rate in the presence of a strong directional magnetic field.  Final shaping of the alnico materials is achieved by abrasive grinding and cutting where close tolerances are required.

↓

Cast alnico, magnets are produced by conventional foundry methods using resin bonded sand moulds.

Max Working Temperature of AlNiCo ranges from 450°C to 550°C. There are two kinds of AlNiCo, Sintered AlNiCo and Cast AlNiCo. Cast magnets may be manufactured in complex shapes and the mould charge (sand mould) is cheap. But due to the sand mould edges, cast alnico has darkened edges with a slightly rough texture. To get a smooth surface, grounding is needed. Sintered AlNiCo offer slightly lower magnetic properties but better mechanical characteristics.

Most AlNiCo magnet grades are anisotropic (they can only be magnetized in a single axis /direction – they are the more powerful magnet grades of AlNiCo.

The others are isotropic (Lower grade, they can be magnetized in any direction or directions) – but for these types of alnico magnets, magnetic strength is very low but offer more design and performance flexibility.

Available Shapes: blocks, bars, discs, rings, horseshoes, etc.

Sintered Alnico magnets are formed using powdered metal manufacturing methods. Sintering alnico is suitable for complex geometries

Most Alnico magnet grades are anisotropic (they can only be magnetised in a single axis/direction – they are the more powerful magnet grades of Alnico. The others are isotropic (they can be magnetised in any direction or directions) – they are weaker but offer more design and performance flexibility.

There are 29 grades of Alnico (17 cast grades, 10 sintered grades, 2 bonded grades).

Typical composition of Alnico alloy

Alnico Magnets Demagnetization Curve

Anisotropic Alnico Magnets:

Isotropic Alnico Magnets:

↓

↓

Surface Treatments

Alnico magnets do not usually require a surface finish to prevent corrosion. However, this does depend on the grade of Alnico and the chemicals in the environment. Some grades of Alnico contain iron, so may corrode if it is exposed to water or acids.

They can, however, be easily plated using a variety of metals, such as nickel, zinc, chrome or paint

Cast Alnico materials commonly contain casting voids and hairline cracks within the material. Finish machining can expose these voids and hairline cracks.

↓

DESIGN CONSIDERATIONS

Alnico Magnets can be made by both cast and sintered processes. Alnico Magnets have distinct advantages over other varieties of permanent magnets in terms of moderate prices & widest temperature stability. Alnico magnets are coarse-grained and very hard and brittle, therefore they cannot be drilled or machined with conventional methods. Holes are usually cored in at the foundry. Magnets are cast or sintered as closely as possible to required size so that abrasive grinding to finish dimensions and tolerances are minimized.

Alnico parts are not normally used as structural parts. Where a choice exists, select simple shapes. Slots are preferred over holes. Cross-sections of less than 0.125" (3.18 mm) should be avoided. Finished surfaces, when required, may be produced by grinding; however, for many applications, the "as cast" or "as sintered" surface yields a satisfactory result at a significantly lower cost. To facilitate mounting and give adequate protection to the magnet, special assemblies such as rotors and magnetron magnets may be supplied with an aluminium jacket. Additionally, low carbon steel pole pieces may be attached to magnet pole faces by adhesive bonding or with studs or bolts. Plastisol or paint can be applied for an improved appearance.

Available Shapes: blocks, bars, discs, rings, horseshoes, etc.

OPERATING TEMPRERATURES OF MAGNETS

WORKING AND CURIE TEMPRETURES OF MAGNETS

↓

Typical Applications:

Alnico magnets are widely used in industrial and consumer applications where strong permanent magnets are needed and/or high temperatures are present.

Today Alnico magnets are used many applications; most commonly; sensors, position, level, angle and acceleration sensors, instruments, meters, actuators, various types of electric motors, hi-fi/loudspeakers, lock mechanism etc.

We are equipped to manufacture these materials as per customers specifications.
 
If you would like to know more about our extensive range of magnets products please contact us.