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Magnetic Filter

Get the magnetic attraction!

Our Magnetic Filters remove particles and contaminants from process fluids such as cooling lubricants, washing and cooling water or fuels at low cost and without consumables.

How does magnetic filtration work?

Highly effective neodymium magnets generate a magnetic field that attracts dirt particles made of iron, steel and, in some cases, stainless steel, carbide and corundum. Due to the special flow design, the cleaned liquid flow through the inlet port, after which it evenly flows around a series of magnetic bars. This makes it possible to filter out even the finest particles below 1 µm.

You do not need any additional consumables or operating energy to run our Magnetic Filters. In addition, there is hardly any pressure loss when operating the magnetic filter. Even when the filter rods are full, the liquid can pass through the filter without any additional pressure. Apart from occasional cleaning of the magnetic rods, no further maintenance is required.

The advantages at a glance:

  • Filter even the smallest particles down to a size of 1 µm.
  • You do not need any additional consumables to use our magnets.
  • Achieve a better surface quality as well as an optimal grinding pattern thanks to the clean cooling lubricant!
  • Increase the lifetime of your machines and tools.
  • Significantly increase the service life for cooling lubricant.
  • Reduce your disposal costs by being able to reuse fluids more often.
  • You do not have to worry about energy costs or losses. Only semi-automatic or fully automatic magnetic filters need a little extra energy.
Reinigung von Prozessflüssigkeiten dank FRIESS Magnetfiltration
Magnetic Filter CC
Magnetic Filter that can be cleaned while closed.
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Dank Magnetfilter Partikel ohne Verbrauchsmaterialien entfernen
Self-cleaning Magnetic Filter SMF
Magnetic filter that is cleaned semi-automatically.
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Selbstreinigender Magnetfilter von FRIESS
Self-cleaning magnetic filter ASMF
The fully automatic magnetic filter. Cleaning at the push of a button.
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Reinigung auf Knopfdruck dank vollautomatischem Magnetfilter
Magnetic Filter FMF
Removes iron, steel and stainless steel particles from all types of process fluids.
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FRIESS Magnetfilter FMF
Magnetic Grid FMG
Filters particles from cooling lubricant, cutting oils and grinding oils.
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Magnetgitter FMG von FRIESS

Application examples

prepare cooling-lubricants
Prepare cooling lubricants

Many manufacturing companies rely on coolant in their manufacturing processes. These coolants decrease the heat generated by friction in machining processes and also ...

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Magnetic Filter Cleans Coolant
Magnetic Filter Cleans Coolant ...

A manufacturer of automotive components uses different grinding machines in order to grind parts for steering systems.

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Magnetic Filters Reduce the Bacterial Count in Cooling Lubricant
Magnetic Filters Reduce the ...

Casting iron parts are regularly machined at a production company. The chips produced in the process are flushed out of the machine by the cooling lubricant. Large chips

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Semisolid sludge separated by magnetic roll
FRIESS self-cleaning magnetic filter

In the Chinese plant of a big Japanese car manufacturer two honing machines are used in order to machine engine housings.

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in order to monitor the magnetic filter system
Automating and Improving Filtration ...

A metalworking company operates a washing machine in which hydraulic parts made from cast iron are washed to remove oil and grease as well as particle contamination ...

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Basics of Magnetic Filtration

Magnetic filters are capable of removing ferritic particles from process fluids such as cooling water, emulsions, grinding oil and washing water, etc. The basis of a magnetic filter is the magnetic field force. The magnetic field force exerts a force on ferritic particles, such as iron, steel, carbide, stainless steel, etc.

Different materials are used for permanent magnets. Commonly used are magnets made from AlNiCo, ceramics or rare earths. Taking into account the special application limits, magnets made of rare earths (neodymium magnets) offer the highest flux density and thus the greatest attraction for dirt particles. A disadvantage is that the material is very susceptible to corrosion and must therefore always be protected by a coating or stainless steel housing. Furthermore, most neodymium magnets are only temperature resistant up to max. 80 °C. In continuous use, the max. temperature should be limited to approx. 60 °C.

Magnetic Roll versus Magnetic Filter

Magnetic roll

Both systems are based on magnets, but work differently.  Both fall under the category of magnetic separators. In a magnetic roll, the liquid gets washed over the rotating magnet. The magnetizable particles stick to the magnet. The magnet continues to rotate with the particles on it  and the particles are removed with a scraper. The now clean magnet continues to rotate and the fluid is cleaned of the ferritic particles. The field force of the magnet is usually between 2500 and 3500 gauss.

Magnetic filter

A magnetic filter has no moving parts. The liquid flows through the inlet, flows around the magnet in the housing, and flows back into the system through the outlet, while the particles are attracted. The particles must be removed manually after a while. The field strength of the magnet is usually above 10,000 gauss.

Magnetic rolls offer the advantage that they clean themselves and do not require any supervision or labor. However, the magnetic filter can remove much smaller particles from the liquid because the magnetic rod is stronger than that of a magnetic roller.

Therefore, the two systems perform different tasks: A magnetic roll serves as a pre-filter, continuously removing ferritic particles down to 20µm in size. There is no labor involved and no expendable materials are used. A magnetic filter is a filter that can remove all ferritic particles, even down to 1µm. Thus, this is intended, among other things, for ultra-fine filtration, but can also perform the task of the magnetic roll, if one is willing to invest the labour to clean it.

FRIESS GmbH – Manufacturer of Magnetic Filters

FRIESS has been developing solutions to optimize the cleaning of process fluids for 50 years. As a manufacturer of magnetic filter systems, we ensure long-lasting use of oils and less wear on machines and components. In this way, we combine significant cost savings, sustainability and environmental protection.

Buying a Magnetic Filter – important facts

Before using a magnetic filter, it is important to establish the performance characteristics and physical requirements. The following points should be considered:

  • Properties of the liquid to be cleaned
  • Flow rate
  • Temperature
  • Operating pressure in bar
  • Inlet and outlet size

In considering this, the purchase of a magnetic filtration system for your oil quickly becomes an effective economic advantage. The most significant advantages are the longer service life of the oil and reduced maintenance due to failures or wear.

Integration and Maintenance of a Magnetic Separator

Magnetic filters can be installed either as in-line or bypass filters in a process. The optimal operation for the filter is if it is operated in a bypass connection. Then the operating conditions can be designed exactly for the filter and optimum results can be achieved. As an in-line filter, magnetic filters can serve as pump protection. In such an application, however, the care of the liquid is no longer the priority.

Magnetic Filters – Economic Efficiency and Environmental Protection

Reduce Operating and Investment Costs

Magnetic filters only require maintenance when they are cleaned. Otherwise, there is no need for maintenance. Only automated systems that clean themselves require occasional spare parts.

This is how you protect the environment:

Even a small amount of waste oil pollutes large quantities of water. By reducing the amount of oil that needs to be replaced by up to 90 percent, you significantly reduce the burden on the environment. With magnetic filtration, you are helping to actively promote sustainability and environmental protection.


In which applications can a magnetic filter be used?

A magnetic filter can be used in all processes in which ferritic particles occur. The machining of steel or stainless steel covers a large part of the application areas with its different manufacturing processes. This includes machining, honing, lapping, eroding, grinding, etc.

Washing and cleaning processes also often accumulate ferritic particles that can be found in the washing fluid. Magnetic filters can remove these. These processes are found in machining, surface treatment and electroplating, as well as painting.

What are the benefits of a magnetic filter?

Removing ferritic particles results in different benefits depending on the application. In metalworking, a clean fluid protects your tools and improves workpiece quality or reduces defective products that do not meet quality standards. In cooling lubricant or emulsion, removing particles slows down the formation of bacteria in the fluid. In washing processes, the washing liquid remains unsaturated for longer and can thus deliver the optimum washing result for longer. More details and further applications can be found in our case studies.

We would be happy to advise you on your application.

What happens to the removed particles?

If the process only produces magnetizable particles that are pure by type, the particles represent a reusable raw material depending on the liquid content of the magnetic sludge. Depending on internal processes, the particles can be reused within the company or returned to the manufacturing process via your disposal company. This is not only efficient and resource-saving, but potentially good for your wallet. Details on requirements and payments must be clarified with your disposal company.

Is it better to use a magnetic filter or a magnetic roll?

That depends on the process. If you have a very large amount of fairly coarse ferritic particles, a magnetic roll may be sufficient, as they can remove particles larger than 20µm, depending on the model. However, if you are concerned with ultra-fine filtration, a magnetic filter is the right choice.

We will be happy to assist you in making the correct selection. As a rough guide, we have listed the processes in which the respective device is usually used.

Range of application of a magnetic filter:

  • Grinding
  • Honing
  • EDM
  • Milling
  • Rolling
  • Cast steel machining
  • Washing

Range of application of a magnetic roll:

  • Milling
  • pre-filtering
  • mechanical processing

Which magnets are used?

Neodymium magnets are generally used in magnetic filters. These magnets are the only ones strong enough to remove particles from liquid.

What is the service life of the magnets?

Neodymium magnets are permanent magnets. This means that they do not depend on external influences to generate the magnetic field. Thus, the magnetic field is permanent unless the magnet is damaged or destroyed. So you can expect lasting performance from your magnetic filters.

Are there any differences between a magnetite filter and a magnetic filter?

Magnetite filters are primarily installed in heating systems where the so-called magnetite is formed. Magnetite is formed by rusting and corrosion in pipelines and is highly magnetic. Therefore, magnetite filters use a magnet to filter out the magnetite.

Magnetic filters, on the other hand, are not just focused on such a specialized application, but are much more widely applicable. Especially since they are also suitable for much larger systems.

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