Lubrication HandbookSemi-synthetics Synthetics
Corrosion Inhibitors Antifoamants Demulsifiers
6. Soluble Oils, Semi-synthetics, Synthetics C. Sump Fluids
MISCELLANEOUS INFORMATION
THEORY OF LUBRICATION
When one rough metal block is pushed across a second rough metal
block, microscopic peaks on the block surface interfere with the
sliding action and cause a form of solid friction. Sliding two
smooth surfaces against each other causes weld- ing-a second form
of solid friction.
Friction can be reduced by employing smooth surfaces that keep
interference friction low, and by choosing dissimilar metals that
will reduce metal- to-metal welding.
Surfaces designed to allow relative movement between components
while providing support, or
guiding movements, are subject to friction and wear. Wear can be
essentially eliminated and friction can be controlled to the point
where it presents little problem.
Hydrodynamic lubrication shows a continuous film of fluid lubricant
separating the surfaces; the relative surface movement has created
an oil wedge that sup- polts the upper component.
The lubricant used should have the proper viscosi- ty, or
resistance to flow, so it has sufficient "body or "thickness" to
resist being squeezed-out while being thin enough to prevent
excessive fluid friction.
Looking at a simple journal-bearing, we see that JOUrnal rotation
causes the formation Of a lubricant wedge just like the flat
surfaces shown earlier. The pressure generated by this wedge
reaches a maximum at the point where the lubricant film is
thinnest; pressure is lowest at the bearing edges and at the
bearing inlets and outlets.
All full-time lubricants involve the lubricant wedge and pressure
build-up.
Some surfaces are so highly loaded that the lubricant film is
interrupted, requiring "extreme pressure" (EP) lubrication. Mixed
film lubrication, involving monomolecular films and frequent metal-
to-metal contact, generally provides low-friction sliding and
controlled wear of the metal. As this film is constantly removed by
the continuing contact, thesurfaces are eaten away, but at a
tolerable rate,
Lubricant wedgessupporf bearing pressures. avoiding catastrophic
wear that would occur with
EFFORT b b b
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LUBRICANT TYPES
There are four basic types of metalworking lubricants used in metal
forming and metal cutting operations. They include: Straight Oils,
Soluble Oils, Semi- synthetics and Synthetics.
STRAIGHT OILS Straight oils have been around the longest. They
include mineral oils,
napthenic and paraffinic oils and vegetable oils such as lard and
castor oil. To the baseoils, additives are often blended to improve
EP, anti-weld, etc. They typically offer excellent lubricating
properties with only minimal heat-transfer or "cooling."
SOLUBLE OILS Soluble oils were developed to offer the lubricating
properties of oils with the
cooling properties of water. Soluble oils perform well on ferrous
and non-ferrous metal. One drawback of soluble oils is their
tendency for biodegradation.
SEMI-SYNTHETICS Semi-synthetics are basically water solutions with
small amounts of oil
microemulsified for improved lubricity while offering the cooling
properties and cleanliness of synthetics.
SYNTHETICS Synthetics are non-petroleum-based materials which offer
varying degrees of
lubricity with excellent cooling and cleanliness. Synthetics are
preferred because they are biodegradeable, less likely to become
rancid and generally do not cause dermatitis. They also make
filtering and recycling an easier possibility.
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L UBRICANT ADDITIVES
Most high quality lubricants contain additives. Some of the more
common additives, the reason for their use, their function and the
way they enhance performance include:
Emulsifiers TYPE
pH/Alkalinity Buffers
Corrosion Inhibitors
-
REASON FOR USE HOW THEY WORK ADVERSE EFFECTS Hold lubricant and
water Polar-type compounds Reduces oxidation re- together in
soluble oils line up at the lubdwater and semi-synthetics.
interfaces providing of anti-wear, EP, oili-
solubility bridges between the fluid and water.
sistance. Fights activity
Modify friction, reduce Form bonds with rubbing Promote oil
oxidation, ~~~~
wear, prevent galling surfaces that provide foaming, emulsion and
seizing. supplemental "wear tendencies. Thermal
surfaces." The key is stability is weakened. "control," not
elimination.
line materials having a low cause skin irritation pK, value require
large and soft metal attack. amounts of acid contami- Too low pH
results in inants or decomposition bioactivity and rust. to
neutralize them.
Prevent oxidation of Polar-type compounds Reduce oxidation resis-
machine surfaces, tools react with, or are absorb- tance in lube,
tendency and work pieces. ed on, metal surfaces. to emulsify, may
leave
sticky residues.
~
Maintain sufficient Larger amounts of alka- Too high pH can
alkalinity to retard biode- gradation and corrosion.
Ensure rapid collapse of Attracted to lube/air inter- Silicone
types promote large air bubbles. Prevent faces; lowers surface air
entrapment. Others excessive lubricant oxida- tension of air
bubbles increase emulsion ten- tion. causing quick break.
dency.
Encourage rejection of React with polar emulsi- Demulsification
must tramp oils. fiers at oillwater inter- be controlled to
avoid
face, breaking solubility breaking the solubility - bridge between
oil and water causing separation.
bridge between the lube and the water.
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LIMITS OF ACTIVITY Different emulsifier packages must be used for
each base lube.
Heat (metal-to-metal contact) is needed. Notable properties are
obtained with one EP additive.
Affected by some water sources, concentration fluctuation and
contami- nants.
Most require direct contact for effectiveness. They deplete and
must be replaced.
Some lube additives or contaminants render anti-foams
ineffective.
Some weakly emulsified lube may also be separated out. Avoid over
treatment.
They're consumed or decomposed. Must be replenished regularly. Most
work at pH 8.8-9.2. Resistant strain can develop if
undertreated.
TYPICAL COMPOUNDS Metal sulfonates, glycols, ethoxylated phenols,
alcohols or acids, napthenic acids.
OilinessIfatty acids, amides, esters & soaps.
Antiwear=phosphates, lead, sulfur, chlorine, polyalkaline
glycols.
Amines, caustics, carbonates.
Silicone polymers, methyl acrylic polymers, stearates.
Cationics, polymers.
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Stamping
Tapping
Threading
Turning
A machining process where a cutting tool having multiple transverse
cutting edges is pushed or pulled through a hole or over a surface
to remove metal by axial cutting.
A high speed method of gathering metal in certain sections along
lengths of bar, rod or wire by causing the metal to flow between
the dies without preheating the metal. This process is used to make
fasteners, ie. bolts, screws, nails, etc. The initial operation
forms the head which is the essential part of the fastener.
An efficient and economical method of cutting a hole in solid
metal. A drill for cutting metal is a rotary end-cutting tool with
one or more flutes to promote chip removal and the admission of
cutting fluid.
A forming technique where steady compressive forces on unheated
steel cause its controlled flow into a die.
The removal of small chips of metal from the workpiece by the
mechanical action of irregularly shaped grains imbedded into a
grinding wheel.
An abrasive machining process designed to improve bore geometry and
surface finish.
The shearing of holes in sheet metal with a punch and die.
The process of forming strip metal into channels, moldings,
architectural sections and similar parts through the use of dies or
forming roles.
The process used to cut lines of letters, figures and decorations
on smooth metal surfaces. The impact of a punch with comparatively
sharp projecting outlines impresses the characters into the surface
of the metal. Stamping is also used when referring to various
press-forming operations, ie. coining, embossing, blanking and
pressing.
The machining process for making internal threads. A tap is a
cylindrical or conical thread-cutting tool having threads of a
desired form on the periphery. Combining rotary with axial motion,
the tap cuts or forms the internal thread.
Cutting external threads on cylindrical or tapered surfaces.
Generating external surfaces of revolution by the action of a
cutting tool on a rotating workpiece, usually in a lathe.
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GRACE METAL WORKING FLUIDS
A. Daracool740 Light to medium duty synthetic for ferrous machining
and grinding (No CI, P, S).
Medium to heavy duty synthetic for ferrous and limited non-ferrous
machining and grinding (No CI, P, S).
Heavy duty synthetic for ferrous and non-ferrous machining and
grinding (No CI, P, S).
Universal synthetic machining fluid for aluminum, copper, steel,
stainless and titanium (No CI, P, S).
Semi-synthetic for multimetal machining and grinding (No CI, P,
S).
B. Daracool745
Coolant
Coolant Coolant
Nickel, Hi Alloy, 1000 Steel, Inconel, Monel.
Milling
B C D C D
B C D C D
B C D C D
Deep Drilling
Gear Cutting
Grinding: Surface Centerless Threading FormlCrush Blanchard Style
I.D. O.D.
I FERROUS AND NON-FERROUS METALS
Low Stock HI Stock Removal - Removal A B C-D A B C D A B C D A B C
D C D C D B C D B C D A B C D A B C D B C D B C D D D
A = Daracool740 B = Datacool745 C = Daracool N-733 D =
Daracool706LF
Aluminum
Coolant
B C D
B C D I B C D I B C D
C D I B C D I D
B C D I B C D I B C D
B C D I B C D I B C D
I 1 50 Rockwell ‘C and Below ~ I
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B C D B C D D
B C D B C D D
B C D B C D D
Low Stock Removal B C D B C D C D C D A B C D B C D B C D
Hi Stock Removal B C D B C D C D B C D A B C D B C D B C D
PHYSICAL r m m The common tests used to check lubricant quality and
finished lubricant properties include:
A. Cutting Oils
Viscosity The force required None to shear the fluid.
Fluid flowing through an orifice.
Viscosity Index (VI) The change of viscosity Lube VI varies with
with temperature. base composition. temps. (usually 100/
Ratio of vis at two
210°F).
Specific Gravity Weight per unit volume. Lube gravity varies with
Hydrometer; base composition. Picnometer
Flash Point Related to oil vapor Lower explosive limit of Passing a
lighted flame pressure. an oil/air mix. over a liquid heated at
a
constant rate, recording the first surface flash.
Falex Bearing load and None resulting wear produced by extreme
pressure forces.
A prescribed load is applied to a metal pin, allowing wear to be
measured.
Units
Non-dimensional
API degree; Sp. Gr.; Ib/gal.
"F Cleveland Open Cup (COC); Tag Closed Cup (TCC); Pensky-Mattins
Closed Cup (PMCC)
PSI Load; Torque; Finish
Property
Solubility
Chemical
Acid, base buffering.
How Measured units
Good, fair, poor rating. Graduated cylinder, visual after 24
hours.
PH
Acidity or alkalinity of a solution.
The velocity of light in air: velocity of light in coolant fluid
ratio.
High turbulance systems require low foaming properties.
Meter, paper. 0-1 4
Coolant concentration. Refractometer. "Brix
Foam None Blender agitation, Inches initial foam; collapse rate in
seconds.
Swarf Effect Coolant ability to sink swarf so it can be carried out
on a conveyor or shoveled out.
Coolant ability to reject tramD oil.
None Blender agitation. Visual observation- float or sink.
Demulsification
Blender agitation. Visual rejection or emulsification.
Coolant ability to retard metal oxidation of the machine table,
tool and workpiece.
Same as under A
Rate: Excellent, Good, Fair and Poor.
Falex
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C. Sump Fluids
An indication of how acid or alkaline the sump solution is on a
scale of 0-14. For coolant sumps it is important to have pH as high
as possible to retard microbial growth, yet low enough so it will
not harm operator hands or attack soft metal such as aluminum.
Method: pH meter or pH paper. Recommended range = 8.8-9.2.
Treatment: Daraguard 88.
DH
Concentration A measure of product in the sump fluid. Although the
laboratory uses refractive index, titration, FTlR and Hyamine
titration depending on the type of solution involved, refractometer
measurement is most convenient for field use. Recommended range =
58% (may vary from 3% in some grinders to 18% for some tapping
operations).
Free Oil
Total Oil
Note: Alkalinity buffers, corrosion inhibitors and preservaties are
formulated in for optimum performance at 5.8% dilutions. Low
concentrations will have substandard protection whereas high
concentrations may result in operator irritation.
Also known as tramp oil, this is all oil not emulsified or weakly
emulsified in the sump fluid. Free oil floats on the coolant
surface and should be kept to a minimum by skimming, suction or
filtration. Method: Graduated cylinder or centrifugation.
Recommended limits: Less than 3%. Treatment: Skim, suction, filter.
To enhance demulsification of tramp oil use Daraguard CP according
to directions.
The total amount of oil in the sump including coolant (if petroleum
based) and tramp oil-both emulsified and not emulsified. Method:
Acid splitlcentrifu- gation or acid splitlhot water bath.
Recommendation: Keep oil contamination (not contributed by the
coolant) to a minimum. Treatment: Daraguard CP.
The amount of particulate matter suspended in the coolant. High
level can adversely affect finish. Method: Centrifiugation or
Graduated Cylinder. Rec ommendation: Keep to a minimum-less than
1%. Treatment: Filtration.
Conductivity A measure of electrolyte material in the sump. This
material can cause corrosion and can also be a food source for
microbes. Method: Conductivity Meter. Recommended Range: 600-3000
umhos/cm. Treatment: Filter or bleed off at 10.25%.
Same as under B. Method: Cast Iron Chip Test. Recommended Range:
Excellent to Fair-watch; Poor-treat. Treatment: Adjust
concentration to 5-8 %; add Daracool 88.
Corrosion Inhibition
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BacteridMold Microbial activity in a sump fluid. Method: Bio
paddles. Recommended Range: Bacteria-less than 1 06, mold
(fungudyeast) nil. Treatment: Adjust concentration with product or
water. Adjust pH with Daraguard 88. Add Olin Triadine 10 at
2mllgal. (repeat in 48-72 hrs as needed.)
Color
Smell
Color additives are added to concentrates as part of the
formulation for aesthetic reasons. Once in the sump, the color of
the working fluid allows some conclusions related to its
condition:
Microemulsions or Solutions Emulsions
are often chocolate or tan.
In operation: Opalescent (tramp-oil) Yellowish (tramp oil)
Brownish Grey-brown (rust from iron particles)
Grey-grey/brown (abrasives)
(rust from iron particles) Grey-blue (bacteria)
The smell of a working fluid compared to the smell of a freshly
prepared fluid can give indication of changes during its use:
Odor Cause
cheese, musty fungus/mold putrid, rotten bacteria paint (vinyl
acetate) some kind of bacteria ammonia some kind of bacteria other
possible contamination
by extraneous chemicals
MISCELLANEOUS INFORMATION
Misting Synthetic solutions have reduced tendency to be misted,
whether by mechanical
devices, by spray or fogging nozzles, or impingement onto rapidly
moving surfaces due to viscoelasticity evidenced by a tendency for
the liquid to form long filaments rather than round droplets.
This also enhances their filterability.
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CHEMICAL HANDLING AND STORAGE
Omadine containing lubricants and additives are packaged in plastic
or lined steel containers to avoid formation and precipitation of
ferric omadine in the drum.
All triazine containing lubricants and additives must be stored at
tempera- tures less than 110°F. The biocide can start to decompose
at temperatures above 11 5°F.
For best results store all lubricants out of direct sunlight at
temperatures between 40-1 10°F. If contents freeze, ensure complete
thaw and remix before any contents are removed from the
container.
Any unused lubricant should be stored in a manner to minimize
contamina- tion, loss, misapplication or weather hazard.
For best results use only Grace Metalworking Fluids according to
product sheet directions.
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