TECHNICAL INFORMATION
906 Stand: 07/2011
Metalworking Fluids –
Maintenance and Monitoring
FUCHS EUROPE SCHMIERSTOFFE GMBH Postfach 10 11 62
68145 Mannheim
Telefon: 06 21-37 01-0
ISO/TS 16949:2009
DIN EN ISO 14001:2004
BS OHSAS 18001:2007
REG.NR. 2476
2
FUCHS TECHNICAL INFORMATION 906
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
Technical Information 906
Metalworking Fluids – Maintenance and Monitoring
Contents
1.
Metalworking fluids (MWF) – Definition
Seite 4
2.
Storage of metalworking fluids
Seite 4
2.1.
Neat metalworking fluids
Seite 4
2.2.
Water-miscible metalworking fluids
Seite 4
3.
Use of water-miscible metalworking fluids
Seite 5
3.1.
Mixing guidelines
Seite 5
3.1.1.Water
Seite 5
3.1.2.
Mixing of water-miscible metalworking fluids
Seite 5
4.
Monitoring of metalworking fluids
Seite 6
4.1.
Water-miscible metalworking fluids
Seite 6
4.1.2.
Testing methods for water-miscible metalworking fluids
4.1.2.1. On-site testing
Seite 6
Seite 7-10
4.1.2.2. Monitoring schedule and documentation
Seite 10
4.1.2.3. Storing test documentation
Seite 10
4.1.2.4. Solving water-miscible metalworking fluid problems
Seite 11
4.1.2.5. Common practical problems, causes and solutions
Seite 12
4.2.
Neat metalworking fluids
Seite 13
4.2.1.
Testing methods for neat metalworking fluids
Seite 14
4.2.1.1. Common problems and solutions
Seite 15
5.
Maintenance of metalworking fluids
Seite 16
5.1.
System cleaners for water-miscible metalworking fluids
Seite 16
5.2.
Maintenance products for water-miscible metalworking fluids
Seite 16
5.3.
De-foaming agents
Seite 16
5.4.
Other service products
Seite 16
5.5.
Precautionary measures
Seite 17
6.
Maintenance equipment for metalworking fluid systems
Seite 17
6.1.
Separating solids
Seite 17
6.2.Filtration
Seite 18
6.3.
Tramp oil separation
Seite 18
6.4.
Simultaneous separation of tramp oils and solids
Seite 19
6.5.
Mobile maintenance / cleaning units
Seite 19
7.
Disposal of metalworking fluids
Seite 20
7.1.
Disposal of neat metalworking fluids
Seite 20
7.2.
Disposal of water-miscible metalworking fluids
Seite 20
7.3.
Statutory requirements – Waste types and codes
Seite 21
3
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
FUCHS TECHNICAL INFORMATION 906
DIN Classification of metalworking fluids
Metalworking fluids: Classification according to DIN 51 385
0
Metalworking fluid
S
1
Neat metalworking fluid
SN
2
Water-miscible metalworking fluid
SE
2.1
Emulsifiable metalworking fluid
SEM
2.2
Water-soluble metalworking fluid
SES
3
Water-mixed metalworking fluid
EW
3.1
Metalworking fluid emulsion (oil in water emulsion)
SEMW
3.2
Metalworking fluid solution
SESW
1. Metalworking Fluids – Definition
2. Storage of Metalworking Fluids
The primary functions of metalworking fluids are to
reduce the friction between the tool and the material
being cut, to dissipate the heat created and to
transport chips and swarf away from the cutting zone.
2.1. Neat metalworking fluids
Secondary requirements include; corrosion protection
for the machine and components, controlling foaming,
low evaporation and misting, good skin compatibility,
high flash point and high stability.
Neat metalworking fluids can be stored for 2 to 3 years
with no loss of quality. Storage temperature should be
between 5 and max. 40 °C. If stored outdoors, water
can enter drums through the drum bungs when they
“breathe”. As a result, drums stored outdoors should
be placed horizontally or covered with a waterproof
sheet.
2.2. Water-miscible metalworking fluids
As a rule, water-miscible metalworking fluid concentrates should only be stored for 6 months.
The containers should be clean and sealed to hinder
the ingress of water as described in Section 2.1. Storage
temperature should never fall below 5 °C or exceed 40
°C. For optimum mixing with water, the temperature of
the concentrate should be between 15 and 20 °C.
If the metalworking fluid concentrates are kept in storage tanks, these should be inspected for cleanliness at
regular intervals and cleaned if necessary.
Galvanized pipes or containers are not suitable for
water-miscible metalworking fluid concentrates.
4
FUCHS TECHNICAL INFORMATION 906
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
3. Use of Water-Miscible Metalworking Fluids
3.1. Mixing Guidelines
Water-miscible metalworking fluid concentrates are
normally diluted to 3 - 20 % with water as recommended in the corresponding Product Information. During
mixing, the following should be observed:
3.1.1. Water
The quality of the mixing water is of decisive
importance to the characteristics of the metalworking
fluid emulsion.
According to German TRGS 611, the water should have
a nitrate content of less than 50 mg/l. If drinking water
is used, this threshold will be met.
Water hardness in German °dH determines, among
others, the foaming behaviour of a metalworking fluid
emulsion. If under 8 °dH (140 ppm CaCo3), severe foaming can occur during mixing. Water hardness well
over 20 °dH (350 ppm CaCo3) can lead to a precipitation of lime soaps, corrosion protection deteriorates, stability deteriorates and salts can form on machine elements after prolonged use. The optimum hardness of
mixing water is between 10 and 15 °dH (175 - 265 ppm
CaCo3).
3.1.2. Mixing of water-miscible metalworking
fluids
If emusifiable metalworking fluids are mixed by hand,
care should be taken that the metalworking fluid concentrate is mixed into water until the desired concentration is achieved. Smaller quantities can be mixed in
a separate, clean container. The final concentration
should be checked with a refractometer.
Larger quantities of metalworking fluid emulsions are
best prepared with mechanized mixing apparatus.
Such machinery can be built-in or simply attached to
the drum or container. Make sure that a back-flow
valve is installed in the drinking water feed pipe to
stop water being forced back into the drinking water
circuit (DIN 1988, Part 4). Even if the final concentration can be pre-set on automatic mixing apparatus, a
refractometer should still be used for a final check and
the emulsion adjusted as necessary. A product-specific
refractometer as described in the Product Information
should be used.
Water which is too soft can be “hardened” by the addition of, for example, calcium acetate and excessively
hard water can be “softened“ by adding de-ionized
water.
The chloride content of the mixing water should also
not exceed 30 mg/l because otherwise corrosion can
occur on the machine and components. Analytical data
of the water can be obtained from the local water supplier.
If water from wells is used which is not subject to drinking water regulations, ensure that the bacterial count
is less than 103; higher values can lead to the increased
risk of bacteriological attack.
To avoid mixing problems, the temperature of the
mixing water must not be less than 10 °C.
Motorpiston
Powered
piston:
Clear
water
Metering
piston
Mixed metalworking
fluid:
Water
+ % concentrate
Metering
adjustment (%)
Concentrate
inlet
5
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
FUCHS TECHNICAL INFORMATION 906
Analysis
Method
Recommended Frequency
Appearance and odour
Visual and sensory
daily
pH Value
Electrometrically DIN 51 369, pH swabs
at least weekly – TRGS 611
Metalworking fluid concentration
Refractometer titration, acid precipitating
part, DIN 51 368
daily, minimum weekly
Nitrite content
Test swabs, photometry
weekly, TRGS 611
Bacteriological count, fungi, yeasts
Dip-Slide-Method
6
FUCHS TECHNICAL INFORMATION 906
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
4.1.2.1 On-site testing
The following describes a number of practical
on-site tests:
• Visual checks
In the forefront are two important checks which should
be performed daily. The first is a basic prerequisite for
the reliable use of metalworking fluids and refers to
checking the level of fluid in the tank. As machining
centers can still be found which run on too little metalworking fluid, fluid pumps often draw air and the
result is foaming of the emulsion. This can cause subsequent problems. One possibility could be inadequate heat dissipation from the cutting zone and thus poor
cutting performance (scorching during grinding) or
reduced tool life.
In another test, the colour and the degree of emulsion
dispersion should be evaluated on a daily basis. Optical
changes to the metalworking fluid are often an indication of changes to the condition of the metalworking
fluid. These require targeted countermeasures which
must naturally include finding the cause. In its normal
condition, an emulsion must not display any oil separation or thickening.
• pH value measurement
A pH value measurement should be performed at least
once a week. The simplest method is to use test strips
which change colour according to the pH value. As
with all test strips, these should have a best-by date. If
the test strips are too old, they can provide inaccurate
results due to colour fading or distortions.
An important aspect of using test strips is the correct
procedure. The test strip should be dipped into clean
emulsion and not through floating tramp oil because this can lead to measurement errors. Furthermore,
the evaluation time should be observed, i.e. the elapsed
time after which the colour of the strip should be recorded. The advantages of this test method are its speed
and its simplicity without the need for additional reagents. It is also highly reliable insofar as practically no
procedural errors can be made.
As evaluation it is often difficult in the fluid tank, an
emulsion sample can be taken in a transparent glass or
plastic beaker and left to settle for a few hours. Normally, the concentration of the emulsion measured
with a handheld refractometer should be the nearly identical immediately after the sample is taken and
after 8 hours. If the emulsion is unstable the first and
second measurements differ sharply.
Changes to the metalworking fluid can have many
causes and are usually identified by the monitoring
measures listed below.
7
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
FUCHS TECHNICAL INFORMATION 906
An alternative to the test strip method but somewhat more accurate and more expensive is an electrical
pH tester. Regardless of whether a battery-powered
pocket version or a laboratory version, both require
careful handling and maintenance of the pH measurement electrode as well as routine re-calibration.
When measuring with a pH electrode, care should be
taken that the “measuring head” (diaphragm) is not
covered with a film of tramp oil as this will lead to inaccuracies.
An important aspect of pH value measurements and
their documentation is determining any pH value
trends over the life of an emulsion to enable remedial
action to be taken in good time.
• Concentration measurements
Concentration should be measured at least once a
week but if the emulsion volume is very small or if
highly stressed with high drag-out rates, then daily.
Some very simple and cost-effective methods are
available. A concentration measuring tool which no
machining workshop should be without is a hand-held
refractometer.
• Hand-held refractometer
This involves an investment of about EUR 200. Together
with the metalworking fluid-specific refractometer factor which is given the fluid’s Product Information, the
concentration is determined via the shift in refracted
light through the medium. This is shown as the partition between a clear blue-grey and clear bright zone.
The value taken from the scale must be multiplied by
the metalworking fluid-specific refractometer factor.
This gives the concentration of the emulsion in %.
Prior to concentration measurements being performed,
the zero-point of the refractometer must be set with
pure water. Furthermore, a dirty, tramp oil-contaminated or unstable emulsion can diffuse the colour separation mentioned above and thus lead to inaccuracies.
Concentration
Value x refractometer
factor
Konzentration == Ablesung
x Refraktometerfaktor
Value: 5,0
5.0
Ablesung:
Refractometer factor: 1,4
1.4
Refraktometerfaktor:
Concentration: 7.0
%
Konzentration:
7,0%
8
FUCHS TECHNICAL INFORMATION 906
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
• Nitrite content
Clear partition:
Value x factor*,
e.g. 5 x 1.4 = 7 %
Out-of-focus partition:
Value x factor – 0.2*,
e.g. 5 x 1.2 = 6 %
Blurred partition:
Value x factor- 0.4*,
e.g. 5 x 1.0 = 5 %
* e.g. Refractometer factor 1.4
• Digital hand-held refractometer
As opposed to a traditional hand-held refractometer,
a digital refractomer is an opto-electric device. Only a
few drops of the emulsion are necessary to determine
the concentration. The measurement only takes a few
seconds and the concentration is shown directly on the
display in %.
Another parameter of metalworking fluid monitoring
is nitrite content.
Nitrite content should be measured on a weekly basis
to avoid exposing employees to hazardous nitrosamine contamination. Nitrite is a reaction component
which can form carcinogenic nitrosamines with secondary amines. Nitrite can originate from the nitrate in
the mixing water but is not a component of the metalworking fluid concentrate. As metalworking fluids containing secondary amines are banned, these reaction
components (such as diethanolamine) which can form
nitrosamines can be largely ignored. However, the contamination of an emulsion via dragged-in or other
media can never be fully excluded.
Measurements by the BIA (German Institute for Occupational Health and Safety) have shown that observance of the <20 ppm nitrite concentration threshold
offers adequate safety because the permissible MAK
(Maximum Workplace Concentration) value of 5 ppm
nitroso-diethanolamine in the emulsion is not reached.
Values of over 20 ppm should initiate an investigation into the cause. If a source of contamination is found
(such as quenching salts), this must be eliminated.
Further measures to reduce nitrite could be exchanging the metalworking emulsion or exchanging certain
parts. Practical experience has shown that the effectiveness of suitable inhibitors is adequate for nitrite concentrations up to about 80 mg/l. Even higher nitrite
concentrations require individual analysis.
• Nitrate content
As nitrite, as already mentioned, can be formed from
the nitrite in the water used to mix the emulsion, this
must also be checked at regular intervals. Corresponding test strips are also available. According to drinking water regulations, a maximum nitrate content of
50 ppm is permissible. But as a rule, nitrate values are
at the lower end of the 10-20 ppm range. However, in
agricultural areas where intensive farming is practiced,
concentrations of over 20 ppm can be found.
9
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
FUCHS TECHNICAL INFORMATION 906
Nitrate measurements need not be performed on a
weekly basis. However, it is recommended that the
values are checked every 6 months or obtained from
the local water supplier and then recorded. Apart from
the simple visual evaluation of the test strips, it is also
possible to evaluate the test strips automatically with a
Reflectoquant system. This is a particularly interesting
option when a large number of individually-filled
machines need to be monitored.
• Water hardness
Another check which can be of particular benefit to
individually-filled machines which need regular topping-up but which is not absolutely necessary is determining the hardness of the water.
This test is also recommended if the mixing water is
drawn directly from a well.
Here again, simple-to-use and cheap water hardness
test strips are available to check if the emulsion water
gets harder. Evaporation losses in particular can lead to
very hard water.
The influence of water hardness on the stability of the
emulsion, i.e. the charge structure in an emulsion’s
micelles is generally seen as uncritical for the majority of today’s metalworking fluids. The greater problem
is that excess water hardness can cause deposits and
gumming in machines which, in turn, generates high
cleaning costs. All in all, emulsion life can suffer from
excess water hardness. However, excess water hardness
has a much more serious effect on corrosion protection
which ceases to be optimum and especially when the
concentration drops off, can lead to expensive rectification work on corroded components.
Even if water hardness monitoring and the possibility of topping-up with de-ionized water eliminates a
potential source of failure, these measures can also
significantly increase the life of an emulsion.
4.1.2.2. Monitoring schedule and documentation
A monitoring schedule should form the basis of all
checks and tests and contain information about the test
performed, the test method, the testing intervals, corresponding measures and even metalworking fluid-specific data.
Documentation of the monitoring data is best realized
on-site with a so-called machine card.
This allows the development of the tested parameters
to be viewed at a glance and emulsion condition can be
quickly determined.
The results can also be presented more elegantly with
corresponding software which is normally made available by the metalworking fluid manufacturers.
4.1.2.3. Storing test documentation
A company must ensure that the test results and any
maintenance measures are recorded in a hardcopy log
or in a PC file. These records must be kept for a minimum of three years.
10
FUCHS TECHNICAL INFORMATION 906
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
Example of monitoring schedule
Emulsion mixed
in 07.2011
Test acc. to
Measurement in
Tolerance
range
Sample date
Sample no.
System: Mayfran 60 m3
Metalworking fluid: ECOCOOL 2215 BF
07.01.
21.01
04.02.
18.02.
04.03.
18.03.
02.04.
15.04.
13242/1
13320/1
13388/1
13461/1
13535/1
13613/2
13680/1
13759/1
12,0
12,6
12,0
12,8
11,9
12,9
12,1
12,1
0,2
0,2
0,2
0,2
0,2
0,2
0,2
0,2
Conc. Oil
DIN 51368
%
10-14
Floating oil
FLV-F-11
%
<1
Conc. Refractometer
FLV-T-05
%
10-14
12,0
12,8
12,0
12,0
10,6
11,0
11,0
11,6
Conc. Titration
FLV-K-21
%
<14
13,7
9,2
12,3
13,2
12,6
11,8
11,8
12,8
pH value
DIN 51369
Reserve alkalinity
FLV-A-11
ml 0,1 N HCL
<150
Bacterial
FLV-G-04
10^/ml
<104
Fungi/Yeasts
FLV-G-04
10^/ml
neg./<103
Degree of corrosion
DIN 51360/T2
Electrical conductivity
DIN 51412/T1
mS/cm
Nitrite
FLV-N-02
mg/kg
Chloride
FLV-C-08
mg/l
Water hardness
FLV-W-08
°d
8,6-9,2
9,1
9,2
9,2
9,2
8,9
9,2
9,2
9,2
134,0
125,0
118,0
127,0
124,0
116,0
118,0
124,0
<3
<3
<3
<3
3
<3
<3
4
neg./<3
neg./<3
neg./<3
neg./<3
pos./<3
pos./<3
neg./<3
neg./<3
0
0
0
0
0
0
0
0
2,5-5
2,55
2,94
2,75
2,94
2,68
3,02
2,9
3,12
<20
5,0
5,0
5,0
10,0
5,0
10,0
10,0
10,0
50-250
104,0
97,0
104,0
109,0
104,0
107,0
109,0
196,0
20-100
20
22
24
22
23
23
22
24
2-0
4.1.2.4.Solving water-miscible metalworking fluid problems
Deviation
Possible problem
Action to be taken
pH value too low
Corrosion, instability
Add metalworking fluid concentrate or pH
value-increasing addtitive
pH value too high
Nonferrous metal corrosion, skin problems
Check and if necessary reduce concentration,
eliminate drag-in of alkaline cleaners
Water too hard
Unstable emulsion, deposits
Mix emulsion with de-ionized water, add
emulsifiers
Concentration too high
Skin problems, foaming problems
Reduce concentration by adding 0.5 % emulsion or water
Concentration too low
Instability, corrosion, tool life problems, quality problems
Add metalworking fluid concentrate until correct concentration is reached
Chloride value too high
Corrosion problems
Mix emulsion with de-ionized water and eliminate drag-in on components
Bacterial count too high
Odour, low pH value, skin problems
Add suitable bactericide after consulting the
manufacturer
Yeast attack
Filtration problems, clogged circuits
Add suitable fungicide after consulting the
manufacturer
Nitrite content >20 ppm
Change metalworking fluid
Eliminate source of contamination, e.g. quenching salts
Conductivity too high
Instability, corrosion
Find cause: Water too hard?, Magnesium?,
Dragged-in quenchants?, Add de-ionized
water
Emulsion too dirty
Poor machining results
Improve filtration
11
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
FUCHS TECHNICAL INFORMATION 906
4.1.2.5.Common practical problems, causes and solutions
Foaming – Causes
Water too soft
Air ingress
Microbiological contamination
Drag-out of defoamers
Dragged-in tramp oil
Excess concentration
Check fluid level and
circulation pump. Circulation too high,
tank too small
Circulate ambient air
and emulsion. Check
pH value and concentration
Add defoamer
Remove tramp oils
regularly
Reduce concentration
to correct level with
0.5 % emulsion
Solutions
Increase water hardness
Filtration problems – Causes
Poor filter cake formation
Fungi levels
Calcium soaps
Tramp oils
Add fungicide. Mechanical cleaning. Centrifuge filter
Check water hardness, Adjust
concentration with de-ionized
water
Remove tramp oils with skimmer
or separator. Check compatibility
with machine oils
Solutions
Add wetting agent
Strong odours - Causes
Highly contaminated
emulsion
Long machine downtime
Inadequate ventilation of the circulating
system
Contamination with
cigarette ends and
scraps of food
Inadequate concentration
pH value too low
Circulate and vent
Instruct personnel
accordingly
Check and adjust
concentration. Add
bactericide if necessary
Rectify pH value deviations
Solutions
Check and/or improve Circulate and vent
cleaning system
12
FUCHS TECHNICAL INFORMATION 906
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
4.1.2.5.Common practical problems, causes and solutions
System deposits - Causes
Dragged-in tramp
oil
Dragged-in cleaners or corrosion
preventives
Ageing
Inadequate cleaning
Microbiological
decomposition
products
Concentration too
high / too low
Incompatibility
with machine oils
Eliminate cause.
Fully or partly
change emulsion
Change emulsion. Adjust system
temperature to
under 30 °C
Remove deposits. Optimize filtration
Use bactericides
or fungicides
before changing
system cleaner.
Mechanical cleaning
Adjust concentration and check
regularly
Use compatible slideway oils,
hydraulic oils and
metalworking fluids (System products)
Solutions
Remove tramp
oils with skimmer
or separator
4.2. Neat Metalworking Fluids
Neat and water-miscible metalworking fluids are based
on low-aromatic mineral oils, white oils, synthetic oils
or vegetable-based synthetic esters. To improve their
application characteristics, special corrosion inhibitors,
anti-misting agents, EP and anti-wear additives, emulsifiers, wetting agents, etc. are added.
As opposed to water-miscible metalworking fluids,
neat metalworking oils have an almost infinite service
life if well maintained. Bacteriological attacks do not
occur because the oils contain no water.
The operating temperatures of metalworking oil baths
should be under 40 °C and ideally under 30 °C.
Solid impurities should be continuously removed by a
filtering system. A disadvantage of neat metalworking
oils is the irreversible mixing with leaked hydraulic,
spindle and slideway oils. For this reason, it is preferable to use compatible fluid families or multifunctional
oils.
13
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
FUCHS TECHNICAL INFORMATION 906
4.2.1. Testing methods for neat metalworking fluids
Analysis
Method
Indicates
Appearance and odour
Visual and sensory
Contamination, Dragged-in substances
Viscosity
DIN 51 562
Dragged-in tramp oils , Ageing
Water content
Karl-Fischer
Dragged-in emulsions or cleaners,
Water ingress via coolers, etc.
Solid impurities
Over 0.45 %, Filters according to DIN
51592, Particle counters, etc
Degree of contamination
Saponification number
DIN 51 559
Additive condition
Tramp oil
Neutralization number
DIN 51 558
Ageing, Additive level
Density
DIN 51 757
Dragged-in tramp oils
Air release
DIN 51 381
FLV-S 11*
Cooling capacity
Dragged-in substances
Four-ball welding test
DIN 51 550, Part 2
EP additive level
Reichert Wear Test
FLV-R 3*
Anti-Wear additive levels
Foaming
FLV-S 11*
ASTM D 892
Foaming characteristics, Additive
levels
Brugger value
FLV-B 8*
EP and Anti-Wear additive levels
Metal content
ICP, RFA, AAS, DIN 51 391
Additive level, Solid or dissolved contaminants
Flash point
DIN ISO 2592
Dragged-in solvents
Corrosion protection
Copper strip test DIN EN ISO 2160,
Steel rod test DIN ISO 7120
Establishing corrosion protection,
Dragged-in substances
Evaporation losses
DIN 51 581, Part 1 or Part 2
Evaporation loss
Oil Mist Index
Misting properties, FLV-O 02*
Misting behaviour
Colour
DIN ISO 2049
Ageing, Contamination, Dragged-in
tramp oil
* FUCHS EUROPE SCHMIERSTOFFE GMBH test procedure
14
FUCHS TECHNICAL INFORMATION 906
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
4.2.1.1.Common problems and solutions
Foaming - Cause
Fluid flow too fast
Mixing with tramp oils (corrosion
preventives, hydraulic oils)
Dragged-in water-miscible metalworking fluids
Nozzle positioning incorrect or
not enough settling time
Solution
Increase size of tank
Eliminate cause. Use multifunctio- Wash and dry components
nal oils or fluid families
Improve nozzle positioning. Optimize vessels.
Belt filter gumming due to
dragged-in water-miscible metalworking fluids
Water in the oil
Swelling of filter materials, Oil not
compatible with filtering materials
Avoid drag-in by separation or
washing
Remove water with centrifuge or
multiple filtering with diatomite /
cellulose
Use of diatomite or suitable cellulose
Filtration problems – Causes
Viscosity too high.
Flow rate falls
Solution
Eliminate tramp oil influence
Poor machining quality / tool life – Causes
Contamination too great
Excessive tramp oil drag-in, diluti- Dragged-in water
on of additives
Temperature too high
Use fluid families or multifunctio- Use centrifuge or filter with cellunal oils, add additive concentrates lose or diatomite. Adjust additive
after analysis, alter viscosity after level after analysis
consulting the manufacturer
Add cooling to the fluid circuit.
Increase tank volume
Solution
Optimize filtration, Clean system
High emissions / Serious evaporation and misting – Causes
Neat oil additive level insufficient
for the process
Fluid flow rate too low
Metalworking fluid circuit defective
Drag-in of low-boiling-point oils
such as washing emulsions or
hydrocarbon-based cleaners
Optimize nozzle geometry and
positioning
Eliminate the source of draggedin tramp oils
Solution
Restore correct additive level after Increase pump capacity, increase
consulting manufacturer. Select a tank volume
more suitable oil
15
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
FUCHS TECHNICAL INFORMATION 906
5. Maintenance of Metalworking
Fluids
5.1 System cleaners for water-miscible
metalworking fluids
The thorough cleaning and disinfection of the metalworking fluid system plays a decisive role in how long a
water-miscible metalworking fluid can be used. Only if
a sensible combination of system cleaning and disinfection will ensure long product life.
Although metalworking fluid tanks, chip conveyors and
machining enclosures can be cleaned with steam cleaners, the mechanical cleaning of fluid circuits is very difficult. And systems cleaned in this way are far from disinfected.
Inaccessible areas can be cleaned and disinfected with
system cleaners. The special wetting agents in these
products ensure that the cleaner reaches very small crevice in the system. These dislodge stubborn deposits,
fungi and bacteria growths from surfaces. The built-in
emulsifiers disperse floating oil and keep dislodged dirt
in suspension. The micro-biocides in system cleaners do
the disinfecting.
Care must be taken that system cleaners are used at the
correct concentration for the right length of time. The
manufacturer’s recommendations must be observed.
The following procedure is well established:
• Add system cleaner to the water-miscible
metalworking fluid before draining the system
• Circulate for 8 to 24 hours
• Drain fluid tank
• Mechanical cleaning of the fluid tanks and chip
convey
• orsFlush system with fresh emulsion
• Pump empty
• Re-fill metalworking fluid system.
At this point, the fungus problem needs to be mentioned. In some cases, fungi have been found in systems
after system cleaners have been used. One problem can
be fungus-based bio-films which are not fully dislodged by the cleaners and whose spores can immediately
contaminate a fresh emulsion. In such cases, it is recommended that, after consultation with the metalworking
fluid manufacturer, the new emulsion is repeatedly treated with special fungicides.
5.2 Maintenance products for water-miscible
metalworking fluids
A number of water-miscible metalworking fluids contain nitrogen-based compounds which offer a source of
nutrition for bacteria and are thus contaminated with
microorganisms throughout the life of the emulsion.
Microorganisms can significantly reduce the life of a
metalworking fluid. Most metalworking fluids contain
agents which hinder the growth of microorganisms.
During the life of an emulsion, it may be necessary to
restore the effectiveness of these agents.
When using such maintenance products, it is important to make sure that the right effective bandwidth
and application concentration are used. The exact procedure should be performed by trained operatives after
an prior examination of the emulsion. Manufacturers
recommendations concerning the handling of these
substances must be observed.
Bactericides:
Maintenance products to combat bacteria.
Fungicides:
Maintenance products to combat fungi.
Biocides:
Maintenance products to combat bacteria and fungi.
5.3 De-foaming agents
The use of de-foaming agents is only recommended
when the cause of foaming is not known or known but
impossible to eliminate in the short term such as fluctuating water quality, dragged-in pollutants resulting
from changes to the process parameters, changes to
the metalworking fluid, etc.
De-foaming agents should be mixed thoroughly into
the metalworking fluid. The de-foamer should also not
be added to the system up-stream of the filtering unit
because the agents may be get filtered out prematurely.
The application concentrations recommended by the
manufacturer must be observed. Excess dosages can be
counterproductive insofar as they detrimentally influence the fluid’s air release properties and thus help stabilize any existing foam.
Before adding to water-miscible metalworking fluids,
the de-foaming agents should be diluted with water
and then mixed into the fluid circuit. This procedure
ensures optimum effectivity because the de-foaming
agents spread through the system more rapidly.
5.4 Other service products
These include all special products which, in agreement
with the metalworking fluid manufacturers, are designed to generate specific additional benefits for the
operators such as machining performance enhancers,
pH value boosters, corrosion protection improvers, etc.
16
FUCHS TECHNICAL INFORMATION 906
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
5.5 Precautionary measures
The reduction and simplification of metalworking fluid
maintenance can already be influenced at the machine
procurement stage.
Just simple engineering design measures, which in most
cases generate no or insignificant additional costs, can
effectively reduce and simplify monitoring and maintenance procedures during later use.
Type of metalworking fluid
The decision regarding which type of metalworking
fluid will be ultimately used must be taken with care.
The key point is not which manufacturer will supply the
fluid but whether it will be a neat metalworking oil
or a water-miscible fluid. This decision determines
the cost and complexity of later monitoring and maintenance.
Size of the metalworking fluid circuit
Adequate metalworking fluid volume is a decisive criteria for the subsequent foam-free operation of machine
tools. Recommendations concerning fluid volumes can
be found in VDI Guideline 3035 and should be observed
for best results.
Settling tanks for the metalworking fluid
Water-miscible metalworking fluid systems should be
fitted with auxiliary settling vessels where tramp oils
can rise to the surface of the metalworking fluid prior
to being removed or skimmed.
Inside walls of metalworking fluid tanks
The inside walls of tanks, vessels and circuitry should
not be painted, coated or galvanized because such surface treatments can be attacked, dislodged or dissolved
and then cause filter problems.
Location of the metalworking fluid tank
Already at the machine procurement stage, careful
planning should ensure that the metalworking fluid
tanks, vessels and pumps are located in such a way as
to allow easy access for future monitoring and maintenance work.
6. Maintenance Equipment for
Metalworking Fluid Systems
VDI Guideline 3397, Sheet 2 provides a comprehensive
overview of the different maintenance equipment
available. The suitability of each system depends on the
machining process in question and must be decided on
a case-by-case basis. Generally speaking, all are designed to remove contaminants such as metal particles,
grinding abrasion, etc. from the metalworking fluid.
6.1 Separating solids
An overview of the most commonly-used equipment to remove solids
Equipment
Effectiveness
Cost and complexity
Belt filters
Medium / High
Low
Pre-coat filters (mainly for mineral oil-free
emulsions and oils)
High
High
Magnetic separators
Medium
Low
Sedimentation tanks
Medium
Low
Drum or edge filters
High
Medium
Hydrocyclones
Medium
Low
17
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
FUCHS TECHNICAL INFORMATION 906
6.3.1 Oil skimmers
6.4.3 Flotation equipment
A number of techniques are available for the removal of tramp oils. Relative simple and economical are
belt, disk or tube skimmers. The separated oil floating
on an emulsion adheres, for example, to a disk rotating
semi-submerged in the emulsion and is removed with
wipers. Such systems necessitate a settling vessel for the
metalworking fluid emulsion. Turbulence allows the
tramp oil to be mixed with the emulsion and skimmer
efficiency falls. Another option would be to activate
skimmers during machine down-time.
The metalworking fluid is pumped into a separate vessel where it is aerated with a battery of fine nozzles.
These air bubbles rise to the surface. Apart from any
oil, these bubbles also transport fine solid impurities
such as graphite. The upper part of the fluid is then
drained whereby larger particles must be removed by
an up-stream filter.
6.3.2 Coalescence separators
After the contaminated emulsion is pumped into the
inclined plate clarifier, the fluid flows over a series of
inclined plates.
Gravitational and coalescence effects cause the tramp
oil droplets formed to rise up to the bottom surface of
the plates where they are skimmed-off. The sold impurities coagulate and slide down into the slurry tank
from which they can be removed.
The metalworking fluid is pumped out of the main circuit into an auxiliary vessel where it can settle. Nonemulsified oil droplets converge and rise to the surface of the fluid where they are removed. There are a
number of different designs available on the market,
either built-in or as mobile units whereby mobile units
are best suited to individually-filled machines.
6.3.3 Two-phase separators
In two-phase separators, the metalworking fluid is
rapidly accelerated. As a result of their different densities, the emulsion and any tramp oils present are separated. However, in emulsions with coarse dispersions,
there is a danger of emulsion leaning, i.e. some metalworking fluid components may get separated out
along with tramp oils. As a result, on-site trials should
be conducted first. The relatively high initial investment costs are only worthwhile when the mobile separators are used for a large machine shop or as a by-pass
separator for a central system.
6.4 Simultaneous separation of tramp oils
and solids
6.4.1 Three-phase separators
Three-phase separators are a further refinement of the
two-phase separators described above whereby the
third phase is solid impurities. In the case of non-selfcleaning separators, the separated particles collect on
the outer wall where they have to be removed manually. In self-cleaning separators, these particles are automatically centrifuged out.
6.4.2 Sedimentation vessels with oil skimmers
These are a combination of the above-described procedures. Such apparatus can be used a mobile unit or be
built into individually filled machines.
6.4.4 Inclined Plate Clarifiers
(Three-phase separators)
The cleaning or separating effect depends on the spacing and incline of the plates as well as the flow rate.
The extracted slurry is normally very wet and must be
dewatered prior to disposal.
6.5 Mobile maintenance / cleaning units
For a large number of individually filled machines, it
can be economical to use mobile maintenance units. In
principle, these are flexible maintenance units based
on traditional filtering techniques such as belt and
cartridge filters but also centrifugal separators which
can be used for all the machines in a machine shop.
Such mobile units can be used continuously as by-pass
filters but also as discontinuously during the down-time
of machining centers. When using these systems, attention should be paid to hygiene. Emulsion maintenance
units should be cleaned regularly and treated with biocides if necessary. Especially in the case of discontinuous operation, the uncontrolled spread of bacteria and
yeasts can pose a problem.
Is maintenance worthwhile?
Monitoring and maintenance contributes to increasing
the service life of a metalworking fluid and thus reduced consumption and less waste. Apart from longer
tool life and better component quality (surface finish
and accuracy), monitoring and maintaining the metalworking fluid protects the health and safety of machine shop personnel.
The overall cost reductions achieved contribute to the
competitiveness and thus long-term future of companies.
19
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
FUCHS TECHNICAL INFORMATION 906
7. Disposal of metalworking fluids
7.1. Disposal of neat metalworking fluids
If suitably monitored and maintained, neat metalworking oils have a very long service life. In spite of good
maintenance, it is sometimes necessary to dispose of a
fluid ahead of schedule. The following illustrates some
such reasons:
- Mixing with other substances
- Presence of cleaners or water-miscible emulsions
- Excess contamination with solids
- Ageing due to oxidation at excessive system
temperatures
7.2. Disposal of water-miscible metalworking
fluids
Water-miscible metalworking fluids are diluted from
concentrates with water and then used as metalworking fluid emulsions or solutions in machine tools. If,
over the course of their service life, certain application
criteria cease to be fulfilled or other reasons prevent
the fluid for being further used, the metalworking fluid
must be treated. The application criteria depend on the
process and the demands. If these criteria are no longer fulfilled, the operator must decide if a water-miscible metalworking fluid has reached the end of its useful life and must be disposed-of. The following shows
some application criteria which can lead to disposal:
- pH value too high or too low
- Water too hard
- Excess contamination with solids
- Poor foaming behaviour
- Excessive bacteriological or fungal contamination
- Excess tramp oil contamination
- Phase separation
- General contamination with other substances, etc.
Unusable or used
water-miscible
metalworking fluids
Unusable or used
neat metalworking fluids
Treatment
Oil phase
Water phase
Substance recycling
Waste
Waste Incineration
Waste water
Disposal
Process water
(circuit)
VDI 3397, Sheet 3
20
FUCHS TECHNICAL INFORMATION 906
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
7.3. Statutory requirements
Water-miscible metalworking fluids are not included in
the waste oil definition.
A large number of provisions and laws regulate the disposal of metalworking fluids. Of particular significance
is legislation concerning water and waste disposal. The
disposal of metalworking fluids is based on the fundamentals of recycling which are an integral part of European waste legislation.
According to the legislation concerning the implementation of the European Waste Directive, used and unusable metalworking fluids are classified as wastes which
require particular attention. Metalworking fluid waste
substances are classified for disposal by the provisions
concerning the disposal of wastes which require particular attention. As a result, metalworking fluid wastes
must be provided with the corresponding waste code.
sind.
Waste oil provisions regulate the allocation of used and
unusable metalworking fluids. Neat metalworking oils
are allocated to Waste Oil Category 2.
Waste types and codes
Description
Examples
Identification letter
(acc. To DIN 51385)
Machining oils (drilling, cutting
and grinding oils)
Used and unusable neat metalSN
working oils, unusable water-mis- SEM
cible metalworking fluids (no oilwater mixtures)
Waste code
120106 (Containing halogens)
120107 (Free of halogens)
Synthetic machining oils
Used and unusable finishing and
(synthetic coolants and lubricants) lapping oils
SES
120110
Machining oils (honing oils)
Unbrauchbare und verbrauchte
Finish- und Läppöle
SN
120106 (Containing halogens)
120107 (Free of halogens)
Biogenic oils
Used and unusable vegetable oils
SN
130207
Drilling and grinding emulsions,
emulsion mixtures
Used and unusable metalworking
fluid emulsions
SEMW
120108 (Containing halogens)
120109 (Free of halogens)
Other oil-water mixtures
Used and unusable metalworking
fluid emulsions
SESW
120108 (Containing halogens)
120109 (Free of halogens)
Membrane filter residues, evaporation residues
130505
Source: European Waste Directive
21
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
FUCHS TECHNICAL INFORMATION 906
References:
BGR 143 ( bisher ZH 1/248) Regeln für Sicherheit und Umgangsschutz beim Umgang mit Kühlschmierstoffen; 1999
TRGS 611 Verwendungsbeschränkungen für wassermischbare bzw. wassergemischte Kühlschmierstoffe bei deren Einsatz Nitrosamine entstehen können.
DIN 51385 - Schmierstoffe, Kühlschmierstoffe, Begriffe; 1991
DIN 51369 - Prüfung von Kühlschmierstoffen, Bestimmung des pH - Wertes des
Kühlschmierstoffes; 1981
DIN 51360- 2 Prüfung von Kühlschmierstoffen, Bestimmung von Korrosionsschutzeigenschaften vom
wassermischbaren Kühlschmierstoff; Späne/ Filterpapier Verfahren; 1981
VDI 3035 Anforderungen an Werkzeugmaschinen, Fertigungsanlagen und periphere Einrichtungen beim
Einsatz von Kühlschmierstoffen; 1997
VDI 3397 Blatt 1 Kühlschmierstoffe für spanende und umformende Verfahren; 20 07
VDI 3397 Blatt 2 Pflege von Kühlschmierstoffen für die Metallbe- und Verarbeitung. Maßnahmen zur
Qualitätserhaltung, Abfall und Abwasserverminderung; 2005
VDI 3397 Blatt 3 Entsorgung von Kühlschmierstoffen; 2008
22
FUCHS TECHNICAL INFORMATION 906
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
Notes:
23
While the information and figures given here are typical of current production and
confirm to specification, minor variations may occur. No warranty expressed or implied
is given concerning the accuracy of the information or the suitability of the products.
(Date: 07/2011)
FUCHS TECHNICAL INFORMATION 906
FUCHS EUROPE SCHMIERSTOFFE GMBH
Friesenheimer Straße 19
68169 Mannheim
Phone: 0621 3701-0
Fax:
0621 3701-570
E-Mail: zentrale@fuchs-europe.de
www.fuchs-europe.de
07/2011 2.5
Contact: