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by Dom Ruggeri

April 2001:


My first experience with metalworking fluid additives came at the hands of a chemist named Carl.  Back in the early eighties, when I was much younger and fresh out of school, I worked for a medium sized formulating house and additive supplier.  Carl and I arrived one morning and as we enjoyed a morning cup of coffee, talking about the football game or some such trivial pursuit, the plant manager came running into the laboratory.  He was beside himself.  “ Number 3 reactor is rumbling and shaking from side to side,” he said franticly.  He ran out of the laboratory back toward number 3 reactor.  I followed.

I will admit that if I knew then what I know now, I probably would have gotten into my car and quickly drove as far away from that plant as possible.  Here is why, number 3 reactor was a glass lined 5000-gallon reactor capable of pulling a huge vacuum.  Should this reactor blow the last place one wants to be is in the same room.

Carl followed behind us at his normal speed.  Carl’s body was 70 years old, while his brain was about 35.  We arrived in the reactor room and yes, reactor 3 was behaving as we expected, rumbling and shaking.  I had no clue as what to do so I turned to Carl; he was swaying at the same rate as the reactor, calmly watching its every move.  Finally he yells "Knock the jazz off"; the reactor stops dead, and Carl turns and walks out. 

When we reached the lab I asked how he stopped that reactor. His reply was as amazing as his feat of moments ago; ten percent knowledge ninety percent theatrics packaging is everything.  He also explained that as I grew and learned such things would not be beyond me.

As I said in last month’s article when I first began in this business a synthetic was a metalworking fluid where all the components are water-soluble. Many coolant suppliers will tout these fluids as the cure all for certain machining problems, and in many applications this special type of fluid will perform very well. However, they are not suited for all machine shop applications.

On the surface these fluids would appear to be easy to formulate, and in fact, in many instances they are.  So let’s look at a typical formulation:



Non-ferrous inhibitor   

0.25 – 0.50% (depending on activity)

Lubrication Package   

10 – 25%

Corrosion Inhibitor Package   

5 – 10%

High HLB Surfactant (detergent package)   

2 – 5%

Biocide Package   

0.5 – 3.5%

Note Well: The high HLB (Hydrophil Lypophil Balance) surfactant is necessary to keep the machining area clean and prevent chip and gum build up.

Depending on the application, the actual formulation may be more or less complex but the above components will be present in one form or another. The types and manufacturers of specific additives are as many and as varied as the stars; each claiming that their material is the best (sound familiar?). So how does a formulator choose?  By experience and by analyzing the specific customer’s needs.

Advantages to using a Solution Synthetic:

These fluids due to the detergent package will run very clean, further they will keep the machines clean as well.

No Emulsion Related Problems: Since all components are water soluble, there is no oil phase to separate. Therefore, maintenance is not as critical as with emulsifiable metalworking fluids.

Although any metalworking fluid is a gourmet feast for a microbe, solution synthetics tend to be more Bioresistant then emulsifiable coolants

Disadvantages to Using a Solution Synthetic
System preparation: You cannot convert from an emulsifiable fluid to a solution synthetic without making some system modifications (consult your coolant supplier for clarification on these modifications).

Since this class of products has a detergent additive package, copious quantities of foam can be generated. Thus, requiring the post addition of an antifoam, an added expense

The additive packages made designed for this class of products are costly therefore; this cost must be passed along.

As I said at the beginning packaging is everything and many coolant salesman will tout their line of solution synthetics as the cure for all system problems. Unfortunately, this is not always the case:
       Solution synthetics do not always do well on heavy machining operations.
       A system may be incompatible due to engineering or other reasons with a solution synthetic

Waste Treatment
I saved this as a separate topic since this is on everyone’s top ten list of coolant requirements.  Emulsifiable coolants will waste treat using classical waste treatment methods such as splitting the emulsion skimming off the oil etc.  Solution synthetics are not that easy because the traditional waste treatment methods do not work well.  For example, if you emulsify tramp oil into an emulsion system, and waste treat the coolant tramp oil mixture, you can be sure the tramp oil will split with the oil phase of the coolant.  However, if there is a component that is undesirable in a solution synthetic fluid, one cannot split this component using traditional waste treatment methods.  In short a new method must be developed or the spent coolant must be hauled away for disposal.  Quite an expense considering the fluid can be up to 95% water.   

In closing, if used correctly in a system, a solution synthetic can be a true cost savings.  However, this class of metalworking fluids is not for all operations.  As I always say, consult with your coolant supplier for the appropriate coolant recommendation.  As always if I can be of any help please feel free to e-mail me at the magazine.

All Best