Fully automatic tube precoat filters


Fully automatic precoat filters are used for the superfine filtration of low viscous oils. The filter plant is a compact installation for the supply of individual machines. The range of filtration is between 1 – 5 µm – corresponding to NAS 8. The regeneration of the filter and cleaning of the filter tubes is carried out automatically.


  • fully automatic mode of operation
  • first-class filtration results
  • small installation space
  • low-maintenance expenditure
  • full-stream filtration
  • dry sludge discharge
  • no use of nonwoven
  • maximum service life of the coolant

mode of operation

The system pump (1) conveyes the clean coolant from the clean liquid tank (2) to the machine tool. The contaminated coolant enters the dirty liquid tank (3) of the precoat filtering installation via inlet channels or lifting stations. The processing cycle of the plant can be subdevided into four steps: 'precoating', 'filtration', 'regeneration' and 'sludge processing'.


The precoating pump (4) conveyes clean coolant out of the filled up precoat container via the forward flow (6) to the filter dome (7) passing the filter tubes (8). The filtering aid which has been filled into the precoat tank (5) by the metering device (9) settles on special steel filter tubes (8) and forms the filtering layer. The coolant is returned to the precoat container (5) via the backflow pipe (10). This “precoating cycle” continues until the whole filtering aid is deposited on the filter tubes (8).


After the precoat process the precoating pump (4) is switched off and the backflow pipe on the precoat-cycle (10) is closed. At the same time the filter pump (11) is switched on and the filtrate backflow pipe (12) is opened. Now, the filter pump (11) conveyes the cleaned coolant via the pipe (13) through the filter dome (7), the coated filter tubes (8) and the filtrate backflow pipe (12) to the clean liquid tank (2) of the installation. The dirt, filtered out of the contaminated coolant, is retained on and in the precoat layer. The differential pressure of the filter dome (7) rises by the increasing clogging-up of the precoat layer. The pressure of the filter dome is supervised by the contact making pressure gauge (14) and initiates the regeneration at an adjustable pressure.


After the regeneration has been initiated by the contact making pressure gauge (14) the filter pump (11) is switched off and the filtrate backflow pipe (12) is closed. Now, the de-sludge stop valve (15) opens and the filter dome (7) is blown off with compressed air (16), opposite to the filtration direction. The blown-off coolant enters the secondary treatment unit (17) together with the used filtering aid and the sludge which has settled down. After the filter dome (7) has been desludged completely the cycle in the precoat filter recommences, starting with the precoat process. The sludge in the secondary treatment unit (17) is dried and dehumidified at the same time of renewed precoating.

sludge processing

In the secondary treatment unit (17) the solid particles are retained and the coolant is recuperated. The dehumidified solid matter is discharged fully automatically into a sludge container (18) whereas the recuperated coolant is returned to the system. The correct choice of the container sizes and the coordination of all pumps guarantees a continuous supply of the machine tools with highly purified coolant during the whole process. Each installation is adapted to the requirements of its user. Optimal operating results are guaranteed by an adequate dimensioning of the installation.

dimensions of a compact installation type AF37 KA/K

volumetric flow: 100l/ min
medium: oil
treatment: honing/ finishing


The standard equipment of a compact installation includes:

  • container, subdevided into dirty liquid, clean liquid and precoat tank, including visual oil-level gauges with integrated switching function
  • filter dome, inspected by the TÜV (German technical supervisory Association) equipped with wire fabric filter tubes (special steel)
  • secondary treatment unit whithout use of nonwoven
  • metering device for filtering aid
  • filter, system and precoating pumps
  • compressed air supervision
  • control cabinet with SPC and luminous circuit diagram
  • transportable sludge container
  • execution according to factory specifications of the customer
  • operating and maintenance manual
  • complete pneumatic installation
  • complete electric installation
  • execution according to the German resources law, including probe approved by the water resources law
  • CE sign
  • commissioning and training of the operators

Optional additional devices

  • magnetic filtering cylinders for the preseparation of coarse ferritic particles, including sludge container
  • immersion recooler
  • oil fume exhaust
  • bag evacuation of the filtering aid (little dust emission)
  • security filter in the system supply pipe
  • lifting station in case of low machine beds and ground level set-up

area of application

Fully automatic precoat filters are used for the superfine filtration of coolants. They ensure an optimal care of the used media, which leads to a high service life of the coolant and optimal processing results. They are proven in several branches of industry such as supferfinishing, microfinishing, finest grinding or other kinds of treatment which require an optimal care of the coolant. Fully automatic compact installations are used for the supply of individual machines and groups of machines. They are also carried out as full-stream installations. Different sizes can be supplied. The standard types cover filtration surfaces up to 10 m². Special constructions are possible within a certain range. Beyond this, central precoat filtering installations can be supplied.

filter types applied by the filter fineness and the specific filter performance:

The specific throughput rates in question are the filter-specific base capacities. They represent reference values for the interested customer. F.E.S. supervises each filter completely from the initial request to the turnkey handover to the future operator. Each filter system is specifically designed and custom-tailored to the case of operation at hand. For this purpose, we utilise our experience values, company-internal laboratory tests and, if necessary, mobile test installations for application 'on location'.

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