Pot magnets

Pot magnets – General properties

Goudsmit has been supplying magnets for a wide range of applications since 1954. Customers from the automotive industry to electronics expect Elektrokul A/S and Goudsmit to deliver the most suitable magnets for their applications. The wide range of Neoflux (Nd-Fe-B), Ferrite, Samarium-Cobalt, Alnico and pot electromagnets can often provide you with finished products ready to use.

At Goudsmit’s high-tech laboratories, measurements and research are carried out daily. We use the latest and best computer and special equipment, such as Helmholtz-coil and Permagraph, to measure the quality of the magnets with great accuracy. This is one of the reasons why Goudsmit can guarantee quality in accordance with the ISO 9001 standard.

This technical competence, as well as advice from staff and high-tech equipment, is the basis for the perfect product. A product that will meet your needs. Elektrokul A/S, together with Goudsmit, would like to advise you and we guarantee you the best.

Pot magnets in general.

With Pot magnets, you can place ferrite magnet equipment in the right place quickly and easily. Thanks to its construction, this type of magnet has only 1 surface that is magnetic. In other words, all other surfaces are not magnetic. This type of construction prevents the magnetic field from spreading. The result is that other parts of the equipment, or machine parts that are close by, are not magnetized.

Magnetic fields and strength.

The diagram shows the strength and direction of the magnetic field. It shows target values for the permanent magnet. By adding, for example, a steel plate or a U-profile, the magnetic values can be increased. The thickness of the steel elements, the volume of the magnets and the construction play a role here.

Possibilities for changes and additions in the design.

The wide range of different models means there is always a suitable pot magnet for your application. You need to consider the following: high pot magnets made of rare materials in a sandwich shape cannot be pressed directly into iron. The special construction can cause a magnetic short circuit; this means a clear decrease in attraction force.

The tensile force shown in the tables has been measured under optimal conditions. This can be achieved when the pot magnet is placed upright on smooth polished mild iron or steel surfaces 37.5 mm thick. If the surface of the pot magnet poles is dirty or the surface is not smooth enough, it will greatly reduce the attraction force. Figure 3 shows the decrease in attraction force if there is air gap.

Clean pole surfaces and smooth working tools are therefore good to have to ensure optimal tensile force of the pot magnet.

Pot magnets always retain their magnetic force. Only increased temperature and external magnetic fields can decrease their magnetic force. The following tables show the possible decreases in magnetic force in different situations.

Please ask us for advice on the magnet if it will be exposed to varying force fields or high temperatures for periods of time. We are happy to advise you on the installation of the magnets and how to choose the right pot magnet, or if the pot magnet needs a special surface treatment, which among other things is especially suitable for the chemical industry.

Figure 1

Different mixes have an influence on the attractiveness due to the permeability of the mixed material. The magnetic attraction decreases in proportion to the carbon content of the mixed material, the higher the carbon content the lower the attraction.

Figure 2

The magnetic force decreases as the surface roughness of the workpiece increases.

Figure 3

The attraction force decreases in proportion to the size of the air gap.
Non-magnetic material between the magnet and the workpiece has the same effect as the air gap.

Alnico pot magnets

Alnico pot magnets are placed in a steel pot, with a non-magnetized material (brass or aluminum) in between. These pot magnets can be used at temperatures up to 450 degrees C. There is then a 30 to 40% reduction in magnetic force.
However, this is not permanent and the force is restored as soon as the pot magnet is cooled down to room temperature.

Ceramic pot magnets

Ceramic pot magnets are also equipped with a steel pot to protect the magnetic field. They require very little construction height and therefore have many structural advantages. Ceramic pot magnets can be used at temperatures up to 200 degrees C.
There is then a 30 to 40% reduction in magnetic force.
However, this is not permanent and is restored as soon as the pot magnet cools down to room temperature.

Samarium-cobalt pot magnets.

Although Samarium-Cobalt magnets have a steel pot, it does not protect against a radiation of the magnetic force. Therefore, Samarium-Cobalt magnets should not be built into steel structures without care. A condition for building in steel is that the distance between the steel element and the pot magnet must be between 1.5 and 6 mm, depending on the size of the pot magnet.

Samarium-Cobalt pot magnets can be used up to temperatures of 200 degrees C, after which the magnetic force decreases by 15-20%. However, it will be restored as soon as the temperature is back down to normal room temperature.

The magnetic force of Samarium-Cobalt pot magnets is about 5 times higher than a ceramic pot magnet. They are also more resistant to strong, varying fields. Samarium-Cobalt magnets are often used in spot welding machines and in very small machines that require strong attraction force.
You can recognize Samarium-Cobalt pot magnets by their white color on the magnetic side.

Neoflux pot magnets.

Neoflux pot magnets are made of neodymium-iron-boron mix. The magnetic force of Neoflux pot magnets is – at room temperature – 7 times higher than ceramic pot magnets. These magnets have a soft iron case that provides them with a magnetic shield. To prevent rust, the attraction surface of Neoflux magnets has a protective coating.

Neoflux cylindrical and flat pot magnets can be used up to temperatures of 80 degrees C. At temperatures above this, the magnetic force decreases by 15 – 20%. It is not permanent and will recover at normal room temperature. Under no circumstances should these Neoflux magnets be pressed directly into iron. This causes a magnetic short circuit which reduces the attraction force.
The table shows the distance between the iron wall, the bottom edge and the outline.
To achieve an optimal attraction force, it must be observed.
You can recognize Neoflux pot magnets by its blue color on the magnetic side.

Adhesive electromagnets.

The design and function of adhesive electromagnets is basically the same as pot magnets. The advantage of adhesive electromagnets is that they can be switched on. When the adhesive magnet is switched on, the magnet will attract the workpiece. When the magnet is turned off, it will let go of the workpiece. Adhesive electromagnets can be used to attract or position an object for a short period of time or if you need a strong magnet. The magnet has a hole on the back that can be used for mounting.

Individual and specially made magnets.

Together with Goudsmit, Elektrokul A/S is a good partner in many different applications, thanks to different disciplines, as well as well-trained and competent employees. This applies not only to standard work, but also to many customer-oriented solutions. Elektrokul A/S, together with Goudsmit Magnetic Supplies, can both design and deliver according to the customer’s needs.
Customers’ ideas are worked through in detail by well-trained and competent professionals in the relevant system. It uses the latest and greatest CAD-CAM equipment (including a Flux3D simulation package) and an advanced production management system.

Permanent adhesive electromagnets.

The permanent adhesive electromagnet is known as a “safety magnet”. The magnet works opposite to the adhesive electromagnet. The item remains in place when the magnet is switched off.
The permanent adhesive electromagnet is often used when longer adhesive periods are needed and when the magnet only needs to be switched on for shorter periods or once in a while, such as transportation equipment or lifting equipment.

Power supplies.

A 24 volt DC electromagnet needs power! Elektrokul A/S and Goudsmit Magnetic Supplies have 2 types (maximum 23 Watt and maximum 70 Watt) available directly from stock. Goudsmit also produces custom-made power systems for all volts and power up to 150 A, with and without power failure safety.

Ultra flat adhesive electromagnets.

Ultra flat adhesive electromagnets can be switched on and off just like standard adhesive electromagnets. When the magnet is turned on, it attracts ferrite magnetic articles. When the magnet is switched off, it releases the workpiece. The ultra flat adhesive magnet is primarily used for lifting and positioning thin steel plates. The extremely flat design makes the magnet ideal for places where space is at a premium.

Product range box.

What’s new! Elektrokul A/S can now supply a mixed range of pot magnets in a handy plastic box. This handy storage system makes pot magnets a valuable aid for tool manufacturers and design engineers.
The storage system also provides a clear overview of the range specifically aimed at the user.

Pot Magnets – Safety instruction

Things to remember!
Anyone working with magnetic material should read the following and do as recommended. If you are not careful when working with permanent magnets, it can cause serious injury. Both the attracting and repelling force of the magnet can be dangerous.

• The magnets should slide apart so your fingers don’t get between them. It will also prevent the surface finish on Neoflux magnets from being damaged. Always wear gloves if possible.
• It is highly recommended to use safety glasses and/or other safety equipment when working with magnets.
• Watch out! Neoflux magnets should never be processed in an environment where there is a risk of explosion because sparks may occur.
• Neoflux magnets should always be moistened before and after machining to prevent spontaneous combustion of the parts being machined. Therefore: Always use cooling water during machining.
• Powder and other parts that have been processed must be hermetically sealed in containers after processing to prevent spontaneous combustion.
• Always unpack magnets well away from iron objects.
• The magnets must be kept well away from objects containing electronic information, such as credit cards, tapes, floppy disks, and from electronic equipment such as hearing aids, pacemakers, measuring and regulating instruments, computer machines and watches, which can be affected or (permanently) damaged by the extreme and strong magnetic fields.

Radiation and maximum temperature for use

• Permanent pot magnets must not be exposed to radioactive and gamma radiation for extended periods. This decreases their magnetic force.
• Maximum temperature for use is as follows:

Effects on the human body

• There are no known negative effects from contact with magnetic material. People who are allergic to ceramic and metal materials may experience a similar reaction if they come into contact with magnetic material.