Rare Earth NdFeB Countersunk Block Magnet For Sale

These magnets have a countersunk central hole on the front (magnetic) face of the magnet.

A pack of 1 - 20mm dia x 7mm thick x 4mm c/sink N42 Neodymium Pot Magnet. The NORTH pole is on the centre of the front face and the SOUTH is on the outer edge around it (both poles are on the same face). These Magnets are plated with 3 layers of protective coatings - Nickel + Copper + Nickel (Ni-Cu-Ni).

Each magnet can support a steel weight of up to 7.5kg vertically from the magnetic face when in flush contact with a mild steel surface of equal thickness to the magnet. Each magnet can also support up to 1.5kgs in a shear position before beginning to slide down a steel surface under the same conditions. These magnets can be fixed in place using a 4mm c/s Screw and have a maximum operating temperature of 80 degrees C  

What is pot magnets?

Pot magnets are made up of magnets (NdFeB, SmCo, AlNiCo or Hard Ferrite) and other spare parts, such as metal, plastic, rubber and other components. Sometimes Pot magnets can meet some special requirements while a single magnet can not do. In the meantime, using pot magnets can save more cost than just using magnets and gain the same purpose.

How to choose a pot magnet?

The basic principle of the holding or pot magnet is to direct and concentrate the flux from both magnetic poles to one active face. This is usually achieved with steel pole pieces or a steel-backing cup.

The standard selection can be broken down into three material types and there is a great variety of systems available. The following data should act as a simple guide:

1) Sintered Ferrite, this material offers a good performance from an inexpensive magnet, however, they tend to be bulky and are not always suitable where space is an important factor. The steel parts are plated & the Ferrite is inert thus corrosion is limited. Maximum operating temperature is +120 degree Celsius.

2) Cast AlNiCo, offers a better holding force than Ferrite systems and is the only pot magnet that can be heated to extreme temperatures. However, the high cost of the Cobalt content in the cast magnet makes the price prohibitive unless the application requires temperatures over +120 degree Celsius up to a maximum of +500 degree Celsius .

3) Rare Earth Samarium & Neodymium, pots and assemblies can offer up to eleven times the performance of a Ferrite system in a comparable size. Applications tend to be specialized engineering projects where performance and available space are key factors. Maximum operating temperatures are +60 degree Celsius C for the Neodymium and +150 degree Celsius  - +250 degree Celsius C for the Samarium depending on the design configuration.

When considering your selection, please be aware of the following factors: The stated Kg Pull (holding/gripping force) is based on the magnets retaining force against a direct pull when offered to a clean ground mild steel surface with a minimum thickness of 6mm. Painted or un-ground surfaces will reduce this force, assemblies working in shear will support approximately 1/3 of the stated value.

PCT:130c ,humidity 100%,vapor pressure 2.7 bar.20 days,average low weight loss less than 2 mg/cm2

Common Applications :

Sensors   Linear actuators   Microphone assemblies    Magnetic separators   DC and servo motors   Speakers   Printers   Magnetic hooksComputer rigid disc drives   Beam controls   Intelligent toys   MRI/NMR

We are specialized in producing NdFeB Magnet over many years,We guarantee the best price based on the same quality and service. Our finance conditiearon and industrial reputation are excellent.

Testing Center

We are ISO/TS16949:2002 certified and well implement all procedures strictly under control. Problem preventive actions and quality assurance are preoperly combined with special inspection for all procedures from raw material purchasing ,outside cooperating part manufacturing,inside manufacturing to shipping . We also install a complete set of physical and chemical test equipment to make sure that all our products are manufactured and shipped under strictly quality control .

Salt Spray Test :

Mainly test the surface treatment against the corrosion.  Usually the tested samples will be  continuous sprayed 24 hours in the 35℃ temperature to see if there is any rust appearance on the surface. 

Projection Instrument:

Mainly test the magnets with irregular shapes such as arc segments and any other irregular-shaped parts to see if their dimensions meet the customers' requirements or not.  

PCT Instrument:

Mainly test the magnets to prevent against corrosion on the high temperature and high atmospheric pressure . Usually the test condition is 120℃ temperature and 2 atmospheric pressure .

Heat& Humidity Instrument:

Mainly test the magnet to against corrosion on certain temperature and humidity . Usually the test condition is 80℃ temperature and 90%+/-3% humidity

Hysteresgraph:

Mainly test the magnetic characteristics of the magnet, including Residual (Br ), Coercive(Hcb) . Intrinsic  Coercive(Hcj), Max. Energy product(BH max) and any other related magnetic parameters. 

HSMAG Magnets has been supplying high quality Neodymium Magnets to customers for about 20 years.

Super Magnet

Made of neodymium, the most powerful magnet material in the world

Great for projects that require extreme strength in a small size

Permanent magnetism guaranteed

Not for children