Filtration 2017-08-31T09:06:03+00:00

Clean coolant is critical to the process…


Clean coolant is critical to the process of components as it supports a good surface finish, maintains the life of the pumps, provides uniform flow and pressures of fluids.

The following factors can affect the filtration process when it comes to grinding:

  • Wheel grit size and how it fractures giving a final size.
  • Ratio between metal removal rate and abrasive used.
  • Type of dressing the machine uses for wheel conditioning.

Fluid delivery

Various features of the process require different delivery.
Pumps come in different sizes in terms of delivery and pressure.
In a given process the following pumps may be required:

  • 300 litre/min at 10 bar
  • 150 litre/min at 4 bar
  • 50 litre/min at 1 bar
  • 80 Litre /min at 70 bar

Often more than one machine may need to be connected to a system this may result in one system requiring 20 plus pumps due to the process.


This part of the process is all to often overlooked.

Water quality varies across the country so this should be taken into account. Hard water when mixed with a cutting fluid can make soap which will coat a filter and therefore impede the filtration process.

For water based coolant, 95% of the content is water so this has to be considered.
Due to evaporation a lower level of concentration maybe required along with de- mineralised water.
Pumping fluid can change the fluid character including adding air.


If the process needs to be kept at a constant temperature then refrigeration can play a major part and the following factors need to be accounted for:

  • Machine spindle power will add heat to the fluid.
  • Cutting process will added heat to the fluid.
  • Pumps delivering fluid will add heat.
  • Part stability due to different temperatures needs to be taken into account and the system may need to work on fixed or ambient tracking.
  • How well the fluid will react to chilling or heating.
  • The chilling process can be by drop in chillers or heat exchangers.

Fluid Requirements

Fluids come in two basic forms, water based or oil based, in the metal cutting process. For other processes such as Zinc Phosphating, the fluid is of a different base.
For water based fluids there maybe a turnover ratio of 5 to 7 times per hour the higher the pressure generally the volume of coolant needs to be greater. For oil this could go up to 10 times per hour.
The cutting process can not only add particles to be filtered out but air entrainment which needs to be considered when specifying the pumps.
The filter will need to take into account these challenges.


Please contact Alastair for more information