Precision Fluids FAQ

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Q: How do I mix water extendable coolant?

A: Both water and concentrate should be at room temperature. Big differences lead to instability of the resulting mix. The coolant concentrate must be added to the water while continually stirring, never vice versa. The use of an automatic mixer is strongly recommended.


Q: What are the possible reasons for foam problems with water soluble coolants?

A: There are several reasons for foam problems. The emulsion is instable due to incorrect mixing or from bacterial attack. The coolant sump is too small or not filled to an appropriate level, giving the entrapped air not enough time to dissipate. The pump is sucking air. Cavitating. The concentration is too high. Contamination with surfactants, e.g. from machine cleaners. Incorrect product selection for the existing water quality.


Q: Why do emulsions sometimes have a "Monday Morning" smell?

A: This smell is caused by microbial attack of the emulsion by bacteria, yeast, and fungi. Reasons for the attack are:

  • Reduced biostability due to low concentration
  • Tramp oil on the surface of the emulsion and poor aeration promote the growth of anaerobic bacteria.
  • Instable emulsions (see item 1) have low bio resistance.
  • The mixing water has microbial contamination.
  • The machines and systems have not been cleaned before the refill.


Q: Why can water miscible fluids lose their corrosion protection performance?

A: The concentration is too low. Salts accumulate due to top up with hard water. The emulsion is unstable due to wrong mixing. The pH has fallen due to biological attack. Tramp oil may give the wrong concentration readings.


Q: What are emulsifiers?

A: Emulsifiers are chemical molecules which allow the stable distribution of oil droplets in water. There are 3 main groups which can be classified by their polarity:

  1. Anionic (Potassium or sodium soaps, Amine compounds, and Sulphonates)
  2. Nonionic (Ethoxylated fatty alcohols, fatty acids, and fatty amides)
  3. Cationic (Quaternary Ammonuim Compounds) are rarely used in water soluble coolants


Q: Is there a fire risk associated with the use of neat cutting oils?

A: Yes, all mineral oils, as well as vegetable oils or esters, have an explosion range. For mineral oils it is commonly between 0.6 and 6.5vol.%. Within this range there is a danger of explosion if there is an ignition source, such as broken tools. The mix of oil and air in a machine tool should be kept either below 0.6 vol.% by using a local exhaust ventilation (LEV) unit or above the upper explosion limit by heavy flooding. As the flashpoint of neat cutting oils is mostly far above 100, this value usually has a smaller impact when fire occurs.


Q: When do you use water soluble coolant, and when do you use the neat cutting oils?

A: Water soluble coolants have four times higher cooling power compared to neat oils and are used when cooling is the major demand. Neat oils have the advantage of higher lubrication power.


Q: What are multi-functional oils?

A: Multi-functional oils are coolants. The coolant concentrate is also suitable for hydraulic, spindle, and slideway lubrication. Multi-functional oils can be used undiluted or as a water soluble coolant. Contamination of the coolant by tramp oils, is no longer a problem.


Q: What are the five main factors that influence the performance of a soluble oil?

A: Here are the five:

  1. The water quality
  2. Tramp oil
  3. Microbiological attack (bacteria, yeast, and fungi)
  4. Chemical reaction with the machined material
  5. The temperature being too high or too low