Proper maintenance ofwater-miscible metalworking fluids
during production stops.
Blaser Swisslube
Customer ServiceProper maintenance of water-miscible metalworking fluids during production stops

blaser.com 31.03.2020

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Overview of recommendations to keep water-miscible
metalworking fluids healthy during production stops
Concentration

Circulation

Skimmer

Chip conveyor

Keep theconcentration atminimum 8%. This will
ensure sufficient pH
buffer for stability.

Plan for daily
circulation of emulsion
in tank for minimum
30 minutes.

Keep the skimmer
running during standstill. If you don’t havea skimmer,
periodically remove
tramp oil manually.

Run the chip
conveyors daily –before starting
circulation – toremove thesedimented chips/
microchips which
settle at the bottom ofthe tank.

pH value
Make sure the pH
remains within therecommended range.

Proper maintenance of water-miscible metalworking fluids during production stops

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Equipment for coolant monitoring
Required equipment for checking the vital parameters of your water-miscible
metalworking fluid:
Concentration checkwith refractometer

pH check with pHstrips

Hardness check withhardness strips(optional)

Nitrite strips forGermany

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Check concentration
Why testing concentration?

How to measure

For long-term stability of the emulsion,
the correct concentration is key.

1) Calibrate the refractometer with water.
The reading must be 0.

The concentration tells us whether
sufficient stabilizer, pH booster and othercomponents are present.

2) Apply a drop of emulsion to therefractometer.
3) Read the line in the refractometer.
4) Multiply the reading by the productspecific factor.
5) Record the value on the monitoringsheet.
6) Rinse and clean the refractometer.

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Proper maintenance of water-miscible metalworking fluids during production stops

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Contamination can influence refractometer reading
Emulsion contaminated with tramp oil shows a diffuse reading.
A properly mixed, fresh emulsion shows a sharp line.

Fresh and clean emulsion

Contaminated emulsion

Highly contaminatedor unstable emulsion

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Proper maintenance of water-miscible metalworking fluids during production stops

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Check pH value
Why testing pH value?

How to measure

The pH tells us how “healthy” an emulsion
is. Low pH is a first sign for a reduced
quality of the emulsion.

1) Dip the pH strip into the cleanemulsion.

What is the normal pH range for anemulsion?
The pH of used emulsions is between 8.7
and 9.4 for most Blaser coolants.

3) Record the value on the monitoring
sheet.

2) Compare the color with the color scaleon the box.

(See also instructions on the box)

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Proper maintenance of water-miscible metalworking fluids during production stops

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Consequences of pH that is too high or too low• More aggressive to skinpH high> 9.4• Staining on aluminum surfaces• Higher foam tendency• More aggressive to paint and plastic

pH okay
8.7 – 9.4

• Bad smell
pH low< 8.7• Corrosion (ferro-corrosion in machines)• Loss of stability• High bacteria / bio-film formation

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Proper maintenance of water-miscible metalworking fluids during production stops

blaser.com 31.03.2020

8Check smell and appearance
The smell should remain neutral. A badsmell is often a sign that the emulsion isoff balance.

The appearance gives you good
information about the stability of theemulsion.

Bad smell may also occur if the emulsion
has been stagnant for a while. In this casea 30 min. circulation may help.

• A consistent appearance is a good signfor a stable emulsion.
• Visual changes in color or the formationof a floating layer must be considered asa first sign of an unstable emulsion.
Record changes on the monitoring sheet.

Proper maintenance of water-miscible metalworking fluids during production stops

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9Additional/optional checks
Emulsion hardness

How to measure

In some systems it may be helpful tocheck the hardness level.

1) Dip the hardness strip into theemulsion (remove any floating layer ifnecessary).

The correct hardness level ensures good
foam control and prevents the emulsion
from splitting (in case the hardness
accumulates too fast).

2) Wait for 1 minute and compare thereading with the color scale on the box.
Nitrite (Germany only)
In Germany it is requested to check theNitrite level (TRGS 611).
Check Nitrite with the Nitrite strips andrecord on the monitoring sheet.

Proper maintenance of water-miscible metalworking fluids during production stops

blaser.com 31.03.2020

Record measurements in monitoring sheet
It is strongly recommended to record measurements
In case of issues, the monitoring sheet can be exchanged and discussed withyour Blaser specialist.
Important: When pH or concentration drops, contact your Blaser representative.

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Proper maintenance of water-miscible metalworking fluids during production stops

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Frequency of monitoring
The frequency depends on the size of the sump. Big central systems need a higher
monitoring frequency than stand-alone tanks.
Parameter

Central systems

Machines withstand-alone tanks

Concentration

daily

weeklypH valuedaily

weeklySmell and appearance

daily

daily (when producing)

Nitrite (Germany only)

weeklyweekly11

Proper maintenance of water-miscible metalworking fluids during production stops

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Remove tramp oil
Floating tramp oil on the coolant surface
may lead to anaerobic conditions in thetank.
Especially when the coolant is not
circulating, tramp oil may slowly float tothe surface.
Keep the skimmer running during standstill. If you don’t have a skimmer,
periodically remove tramp oil manually.

With and without skimmer

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Proper maintenance of water-miscible metalworking fluids during production stops

Remove chips and microchips
Chips and microchips sediment at thebottom of the tank, especially when thecoolant is not circulating.
This creates anaerobic conditions andsometimes even galvanic corrosion (chips
are made of different metal than the tank).
Removing the sediments from the bottomof the tank may keep long-term stability
and prevent bad smell.

blaser.com 31.03.2020

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Proper maintenance of water-miscible metalworking fluids during production stops

blaser.com 31.03.2020

No waste in the metalworking fluid
Keep the coolant tank clean. Contaminated fluids may lose stability and quality.

cigarettes
left overs
coffeefloor cleaner
candy

No!

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Proper maintenance of water-miscible metalworking fluids during production stops

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Contact your Blaser representative.

blaser.com 31.03.202015