Note: Descriptions are shown in the official language in which they were submitted.
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Methods of Working Metal and Compositions Useful
As Working Fluids Therefor
FIELD OF THE INVENTION
This invention relates to methods of working metal, including methods of
forming and cutting metals. More particularly, the present invention relates
to
cooling and lubricating fluids used in conjunction with metal working
operations.
BACKGROUND OF THE INVENTION
Metalworking fluids long have been used in the cutting and abrasive
working of metals. In such operations, including cutting, milling, drilling,
and
grinding, the purpose of the fluid is to lubricate, cool, and to remove fines,
chips
and other particulate waste from the working environment. In addition to
cooling
and lubricating, these fluids also can serve to prevent welding between a work
piece
and tool and can prevent excessively rapid tool wear. See Jean C. Childers,
The
Chemistry of Metalworking Fluids, in METAL-wo~tlcn~1G LUBRICANTS (Jerry P.
Byers ed., 1994).
Metals may also be molded and shaped into a desired form by methods of
forming that are similar in nature to the molding of pottery. Although many in
number and widely varied in particular characteristic, methods of forming
metal
share the common, basic attribute of applying an external force to a metal to
deform
the metal without removing or otherwise cutting or abrading the metal to be
shaped. For a detailed description of the basic metal forming methods see, for
example, Betzalel Avitzur, Metal Forming, in 9 ENCYCLOPEDIA OF PHYSICAL
SCIENCE AND TECHNOLOGY 651-82 (1992).
A fluid ideally suited as a coolant or lubricant for metal and ceramic working
operations must have a high degree of lubricity. Such a fluid also will
possess the
added advantage of being an efficient cooling medium that is environmentally
non-
persistent, is non-corrosive (i.e., is chemically inert), and such an ideal
fluid also
would leave minimal residue on both the working piece or the tool upon which
it is
used.
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Today's state of the art working fluids fall generally into two basic
categories. A first class comprises oils and other organic chemicals that are
derived
principally from petroleum, animal, or plant substances. Such oils commonly
are
used either straight {i.e., without dilution with water) or are compounded
with
various polar or chemically active additives (e.g., sulfurized, chlorinated,
or
phosphated additives). They also are commonly solubilized to form oil-in-water
emulsions. Widely used oils and oil-based substances include the following
general
classes of compounds: saturated and unsaturated aliphatic hydrocarbons such as
n-
decane, dodecane, turpentine oil, and pine oil; naphthalene hydrocarbons;
polyoxyalkylenes such as polyethylene glycol; and aromatic hydrocarbons such
as
cymene. While these oils are widely available and are relatively inexpensive,
their
utility is significantly limited; because they are most often nonvolatile
under the
working conditions of a metalworking operation, they can leave residues on
tools
and working pieces, requiring additional processing at significant cost for
residue
I S removal.
A second class of working fluids for the working of metals and ceranucs
includes chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and
perfluorocarbons (PFCs). Of these three groups of fluids, CFCs are the most
useful
and are historically the most widely employed, see, e.g., U. S. Pat. No.
3,129,182
(McLean), though PFCs have become a viable replacement in recent years for
some
metalworking applications, see, e.g., U.S. Pat. No. 5,676,005 (Balliett).
Typically
used CFCs include trichloromonofluoromethane, 1,1,2-trichloro-1,2,2-
trifluoroethane, 1,1,2,2-tetrachlorodifluoroethane,
tetrachloromonofluoroethane,
and trichlorodifluoroethane. The most useful fluids of this second general
class of
metal working fluids (CFCs & HCFCs) possess more of the characteristics sought
in a cooling fluid, and while they were initially believed to be
environmentally
benign, they are now known to be damaging to the environment; CFCs and HCFCs
are linked to ozone depletion (see, e.g., P. S. Zurer, Looming Ban on
Production of
CFCs, Halons Spurs Switch to Substitutes, Cmvt. & ENG'G NEws, Nov. 15, 1993,
at 12), and PFCs tend to persist in the environment (i.e., they are not
chemically
altered or degraded under ambient environmental conditions).
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SUMMARY OF THE INVENTION
Briefly, in one aspect, this invention provides a method of working metals
and ceramics comprising applying to the metal or ceramic workpiece, either
prior
to, during, or after working, an aqueous emulsion comprising a fluorocarbon
fluid.
In another aspect the invention provides aqueous emulsions comprising
fluorocarbon fluids useful as cooling and lubricating fluids in the working of
metals
and ceramic materials.
The aqueous emulsions of the invention possess a unique balance of
properties that make them well-suited as working fluids for metals and ceramic
materials. These emulsions leave minimal residue on the workpiece, are
environmentally acceptable, and are more effective cooling media than most
neat
fluorinated fluids.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In their most essential aspect, the metal and ceramic working fluids
described by this invention comprise an aqueous emulsion of at least one
fluorocarbon fluid. Such fluorochemical emulsions include those where the
liquid
fluorocarbon comprises the dispersed phase as well as those where the liquid
fluorocarbon comprises the continuous phase (and the water phase is
discontinuous). The emulsions preferably will comprise a continuous phase and
a
discontinuous phase and will yield emulsions milky white in appearance. The
emulsions of the invention are formed by use of one or more surfactants that
are
soluble in at Ieast one phase of the emulsion and that comprise any of a broad
class
of surface-active compounds known to be useful as emulsifying agents.
Liquid fluorocarbons useful in the creation of the emulsions of the invention
include any substantially fluorinated liquid compound. Thus, perfluorinated
liquids,
including perfluorinated hydrocarbons, perfluorinated ethers, and
perfluorinated
amines, partially fluorinated hydrocarbons, partially fluorinated amines, and
partially
fluorinated ethers all find utility in the practice of this invention. The
most useful
liquid fluorocarbons will be those that are suitably volatile at elevated
temperatures
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such that they will evaporate from the surface of the subject metal or ceramic
workpiece with relative ease. Such fluids will, therefore, be those having
boiling
points between about 30 °C and about 250 °C.
Useful perfluorinated liquids typically contain from 5 to 18 carbon atoms
and may optionally contain one or more catenary heteroatoms, such as divalent
oxygen or trivalent nitrogen atoms. The term "perfluorinated liquid" as used
herein
includes organic compounds in which all (or essentially all) of the hydrogen
atoms
are replaced with fluorine atoms. Representative perfluorinated liquids
include
cyclic and non-cyclic perfluoroalkanes, perfluoroamines, perfluoroethers,
perfluorocycloamines, and any mixtures thereof. Specific representative
perfluorinated liquids include the following: perfluoropentane,
perfluorohexane,
perfluoroheptane, perfluorooctane, perfluoromethylcyclohexane,
perfluorotributyl
amine, perfluorotriamyl amine, perfluoro-N-methylmorpholine, perfluoro-N-
ethylmorpholine, perfluoroisopropyl morpholine, perfluoro-N-methyl
pyrrolidine,
perfluoro-1,2-bis(trifluoromethyl)hexafluorocyclobutane, perfluoro-2-
butyltetrahydrofuran, perfluorotriethylamine, perfluorodibutyl ether, and
mixtures of
these and other perfluorinated liquids. Commercially available perfluorinated,
liquids that can be used in this invention include: FluorinertTM FCTM-43
Electronic
Fluid, FluorinertTM FCTM-72 Electronic Fluid, FluorinertTM FCTM-77 Electronic
Fluid, FluorinertTM FCTM-84 Electronic Fluid, FluorinertTM FCTM-87 Electronic
Fluid, Performance FluidTM PF-5060, Performance FluidTM PF-5070, and
Performance FluidTM PF-5052. Some of these liquids are described in
FluorinertTM
Electronic Fluids, product bulletin 98-0211-6086(212)NPI, issued 2/91,
available
from 3M Co., St. Paul, Minn. Other commercially available perfluorinated
liquids
that are considered useful in the present invention include perfluorinated
liquids sold
as GaldenTM LS fluids, KrytoxTM and FlutecTM PP fluids.
Partially fluorinated liquids also may be employed in the emulsions of the
invention. Such liquids, like the above perfluorinated counterparts, typically
contain
from 5 to 18 carbon atoms and may optionally contain one or more catenary
heteroatoms, such as divalent oxygen or trivalent nitrogen atoms. Useful
partially
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fluorinated liquids include cyclic and non-cyclic fluorinated alkanes, amines,
ethers,
cycloamines, and any mixture or mixtures thereof.
A class of hydrofluorocarbon liquids particularly useful to form the
emulsions of the invention comprise fluorinated ethers of the general formula:
(I)
~Rl _O)n-R2
where, in reference to Formula I, n is a number from 1 to 3 inclusive and Rl
and R2
are the same or are different from one another and are selected from the group
consisting of substituted and unsubstituted alkyl, aryl, and alkylaryl groups
and their
derivatives. At least one of RI and R2 cantains at least one fluorine atom,
and at
least one of Rl and R2 contains at least one hydrogen atom. Optionally, one or
both of Ri and R2 may contain one or more catenary or non-catenary
heteroatoms,
such as nitrogen, oxygen, or sulfur. Rr and R2 may also optionally contain one
or
more functional groups, including carbonyl, carboxyl, thin, amino, amide,
ester,
ether, hydroxy, and mercaptan groups. R~ and R2 may also be linear, branched,
or
cyclic, and may contain one or more unsaturated carbon-carbon bonds. Rl or R2
or
both of them optionally may contain one or more chlorine atoms provided that
where such chlorine atoms are present there are at least two hydrogen atoms on
the
Rl or RZ group on which they are present.
Preferably, the cooling and lubricating emulsions of the present invention are
prepared with fluorinated ethers of the formula:
~u)
RIO-R
where, in reference to Formula II above, Rf and R are as defined for R~ and R2
of
Formula I, except that Rf contains at least one fluorine atom, and R contains
no
fluorine atoms. More preferably, R is an acyclic branched or straight chain
alkyl
group, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, i-butyl, or t-
butyl, and Rf
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is preferably a fluorinated derivative of a cyclic or acyclic, branched or
straight
chain alkyl group having from 3 to about 14 carbon atoms, such as n-C4F9-,
i-CaF9-, c-C6Fl-, or (i-C3F~)(n-CaF,)CF-. Rf may optionally contain one or
more
catenary or non-catenary heteroatoms, such as nitrogen, oxygen, or sulfur. Rf
preferably is free of chlorine atoms, but in some preferred embodiments, R
contains
one or more chlorine atoms.
In the most preferred embodiments, Rl and R2, or Rf and R, are chosen so
that the compound has at least three carbon atoms, and the total number of
hydrogen atoms in the compound is at most equal to the number of fluorine
atoms.
Compounds of this type tend to be nonflammable. Representative of this
preferred
class of hydrofluoroethers include C3F70CH3, C3F70C2H5, C4F90CH3,
C4F90CH2Cl, C4F90C2H5, C-C~F13OCH3, c-C~F130C2Hs, C7F1$OCH3,
C7F15OC2H5, CloF2~OCH3, and ClpFZ10C2H5. Blends of one or more fluorinated
ethers are also considered usefi~l in practice of the invention.
Any surface active emulsification agent that will create a stable emulsion of
the fluorinated fluid may be employed to create an aqueous emulsion of the
above
fluorocarbons. Such surfactant compounds span many and diverse chemical
classes
and include many surfactants widely known and used in a variety of
applications,
including specifically those known as emulsifiers for fluorinated fluids.
Useful
emulsifiers may be nonionic, cationic, anionic or amphoteric in nature, though
nonionic emulsifiers generally are preferred for most applications. Among the
specific useful surface-active compounds are biochemical and other naturally
occurnng classes of emulsifiers including lipids, phospholipids, and
lecithins, such as
those described by U.S. Pat. Nos. 4,423,077 (Sloviter), 4,865,836 (Long, Jr.),
and
5,061,484 (Heldebrbrant); fatty acids and tri-, di- and mono-glycerides of
fatty
acids, including those described by U.S. Pat. Nos. 3,962,439 and 4,713,459,
both to
Yokoyama et al.; as well as cholesterols, tocopherols, steroids, albumins,
glycerols,
dextrans, geletin, etc. Also useful are those myriad surface active compounds
described as suitable for emulsification of fluorinated fluids by U.S. Pat.
Nos.
5,011, 713 (Lenti et al.), 5,439,944 (Kaufinan et al.), and 5,562,911
(Brunetta et
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al.), as well as those fluorinated emulsifiers described as usefizl for the
same purpose
by U.S. Pat. Nos. 3,989,843 (Chabert et al.), 4,987,154 (Long et al.), and
5,532,310 (Grenfell et al.), all the above descriptions of which are
incorporated
herein by reference.
Also usefizl as emulsification agents are those fluorinated surface-active
compounds depicted generally by the formula:
~~f)n(Q)x(Z)m
wherein n is 1 or 2, x is 0 or 1, m is 1 or 2, and R'f is a fluorochemical
group
identical to that defined earlier for the fluorochemical treatment except
that most preferably R'f for the fluorochemical surfactant contains only
from about 1 to about 12 carbon atoms. The composition of the
fluorochemical surfactant should contain, relative to the amount of
surfactant solids, at least 5 weight percent, preferably at least about 20
weight percent, of carbon-bound fluorine in the form of said Rfgroup or
groups;
Z is a water-solubilizing polar group containing an anionic, cationic,
nonionic or amphoteric moiety or any combination thereof. Typical
anionic Z groups include C02H, C02M, S03H, S03M, OS03H,
OS03M, OPO(OH)2, and OPO(OM)2, wherein M is a metallic ion, such
as sodium, potassium or calcium, or is ammonium or another such
nitrogen-based ration. Typical cationic Z groups include NH2, NHR,
wherein R is a lower alkyl group, and NR'3A', where R' is a lower alkyl
group or hydrogen and A' is an anion such as chloride, iodide, sulfate,
phosphate, or hydroxide. Representative nonionic Z groups include
polyoxyethylenes (e.g., O(CH2CHZO)7CH3 arid O(CH2CHZO)14H), and
nuxed polyoxyethyiene/polyoxypropylene alcohols and polyols. Typical
amphoteric Z groups include N+(CH3)20-, N+(CH3)2CH2CH2C00- and
N+(CH3)2CH2CH2CH2S03-; and
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Q is a multivalent, generally divalent, linking group such as an alkylene
(e.g.,
ethylene), an arylene (e.g., phenylene), a combination of an alkylene and
an arylene (e.g., xylylene), an oxydialkylene (e.g., CH2CH20CH2CH2),
a thiodialkylene (e.g., CH2CH2SCH2CH2), a sulfonamidoalkylene (e.g.,
S02N(CH2CH3)CHzCH2), a carbonamidoalkylene (e.g.,
CONHCH2CH2CH2), or a sulfonamidodialkylene (e.g.,
CH2CHZS02NHCH2CH2). The Q groups for a specific surfactant will
depend upon the specific reactants used in its preparation. In some
instances, more than one fluorochemical radical may be attached to Q
and, in other instances, a single fluorochemical radical may be attached
by a single linking group to more than one polar solubilizing group. For
the particular case where x is 0, Q is absent and R'f is covalently bonded
to Z which will often be the case when Z is S03M or C02M.
Surfactants corresponding to the above formula are described in U. S. Pat.
No. 2,915,554 to Olson, et al., the disclosure of which is incorporated herein
by
reference.
Many useful emulsification agents are available commercially.
Commercially available nonionic surfactants include those sold under the
PLURONIC tradename (black copolymer's of ethylene oxide and propylene oxide
available from BASF Corp., Performance Chemicals), the BRIJ tradename
(polyethoxylated straight chain alkanols available from ICI Americas, Inc.),
the
TERGITOL tradename (polyethoxylated branched chain alkanols available from
Union Carbide Corp.), the TRITON and IGEPOL tradenames (polyethoxylated
alkyl phenols available from Union Carbide Corp. and Rhone-Poulenc, North
American Chemicals, Surfactants and Specialties, respectively) as well as the
SURFYNOL tradename (acetylenic glycols available from Air Products and
Chemicals, Inc.). Suitable nonionic and ionic surfactants are sold, for
example,
under the tradename FLUORAD by the 3M Company (fluorochemical carboxylic
and sulfonic acid salts}.
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The aqueous emulsions of the invention typically will comprise a minor
amount of the chosen fluorinated liquid, though emulsions comprising more than
50
percent by volume of fluorinated liquid may also prove useful, and it will be
understood that the particular composition of any chosen emulsion will be
selected
according to the particular needs of the metalworking process into which the
emulsions are to be employed and that selection is well within the competence
of
the skilled artisan. The concentration of the emulsifier or emulsifiers within
the
emulsion will be that concentration required to create a stable aqueous
emulsion of
the fluorinated liquid. For the purposes of this invention, an emulsion is
considered
stable when a homogenous mixture is created that remains homogeneous for at
least
five to ten seconds, preferably for more than thirty seconds. It will be
understood,
however, that emulsions employed in metalworking applications typically are
agitated continuously, and the length of time for the dispersion to separate
without
agitation serves here only as a relative measure of the quality of the
emulsion and
not as an absolute measure of its utility. Emulsions that remain dispersed
with
agitation but do not remain stable for long periods of time without agitation
are
nonetheless considered useful and within the scope of the present invention.
The precise concentration of the emulsifier will, of course, depend on the
subject fluorinated fluid and upon the chosen emulsifier but typically will
comprise
between about 0.1 and about 10.0 percent by weight of the aqueous emulsion. It
will be preferred to prepare the emulsion with the lowest operative
concentration of
emulsifier for the given emulsion to reduce the expense of the overall
emulsion as
well as to avoid leaving a significant residue of the emulsifier on the metal
or
ceramic workpiece.
The fluorochemical emulsions of the invention also may contain additives to
make the emulsion more useful in metalworking. Such materials include rust and
corrosion inhibitors, lubricious materials, antioxidants, antibacterial
agents,
defoamers, dyes, freezing point depressants, pH buffers, etc. These additives
may
be soluble in either the continuous or discontinuous phase, and the selection
of
these additives far any given method of cutting, abrasive, or forming metai or
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ceramic working also is well known to the art and is well within the
competence of
the skilled artisan.
Suitable lubricious additives include one or more base oils or synthetic
organic fluids that are soluble in the fluorochemical phase and that optimize
the
S lubricating nature of the composition. The most useful additives are those
that are
volatile under the operating conditions of the metal or ceramic operation into
which
they are employed (with a boiling point <250°C). Useful lubricious
additives
include, for example: saturated and unsaturated aliphatic hydrocarbons such a
n-
decane, dodecane, turpentine oil and pine oil; naphthalenic or aromatic
hydrocarbons such as naphtha and cymene; polyoxyalkylenes such as polyethylene
glycols or polypropylene glycols; thiol esters and other sulfur containing
compounds; and chlorinated hydrocarbons including oligomers of
chlorotrifluoroethylene, chlorinated fluorocarbons, and other chlorine-
containing
compounds. Also useful for such purposes are load resistive additives which
include phosphates, fatty acid esters, fluorochemical acid esters and amides,
alkylene glycol ethers, and alkylene glycol ether esters. These classes of
compounds include trialkyl phosphates, dialkyl hydrogen phosphates; methyl and
ethyl esters of CIO to C2O carboxylic acids; monoethers of mono-, di- and tri-
ethylene or propylene glycols; ester's of monoethers of mono-, di- and tri-
ethylene
or propylene glycols; and the like. Representative load resistive additives
include
triethyl phosphate, dimethyl hydrogen phosphate, ethyl caproate, propylene
glycol
monobutyl ether, and propylene glycol monoethyl ether acetate.
One or more partially fluorinated or perfluorinated additives also may be
added to the fluorochemical emulsions to further optimize the lubricious
properties
of the composition. Such additives typically comprise one or more
perfluoroalkyl
groups coupled to one for more hydrocarbon groups through a functional moiety.
Suitable perfluoroalkyl groups consist of straight-chain and branched,
saturated and
unsaturated Ca-C12 groups, and useful hydrocarbon groups include straight-
chain
and branched, saturated and unsaturated CIO to C3o groups. Suitable functional
linking moieties can be groups comprising one or more heteroatoms such as O,
N,
S, P or functional groups such as -C02-, -C(O)-, -C(O)NR-, S02-, -S03-, -
S02NR.,
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-P04-, -POa-, _p02(R)-, or -POR,R2- where R, Rl, and R2 are hydrogen or short
chain alkyl groups. In addition, perfluoroalkyl groups coupled to -CH20H, -
CH(OH)OH, -CH2NH2, and -C02M where M is H or an suitable cation such as
NHa+ are particularly useful. Fully fluorinated additives such as
polyperfluoroethers
with and without functional end groups (-OH, -C02R, -CH20H, etc.) also can be
used to increase the lubricious properties of the emulsion formulations.
While not wishing to be bound to any specific emulsion formulation or
preparative method, fluorochemical emulsions generally are formulated with a
combination of surfactants, typically where at least one of the surfactants is
soluble
in the aqueous phase and at least one in the fluorochemical phase. The
surfactants
most useful in the fluorochemical phase are nonionic and contain a highly
fluorinated group such as a perfluoroalkyl (CnF2n+1)-, a polyperfluoroalkoxy
[H(OCF2CF2)n]- or H(OCFZOC2F4)n or H[OCF2CF(CF3)J", perfluorosulfonamide
(CnFz"+1SO2NR)-, trihydroperfluoroalkoxy (FiC"FZ"+, CH20)- or the like.
Suitable
water soluble surfactants can be nonionic, anionic, or cationic, and
preferably have
an HLB (hydrophilic/lipophilic balance) of 12 or less. Representative of this
latter
group are polyethoxylated phenols, polyethoxylated alkanols, and polyethylene
oxide/propylene oxide block copolymers. Anionic surfactants can be salts of
fatty
acids, alkyl sulfonic acids, and the like.
The aqueous phase of the emulsions can also optionally contain additives
such as defoamers, corrosion inhibitors, and stabilizers. A buffer salt also
can be
dissolved in the water phase to maintain pH. The fluorochemical phase can
optionally contain lubricious additives, dyes, corrosion inhibitors, or load
resistive
additives.
To prepare the emulsions the water and fluorochemical phases generally are
mixed to form a crude dispersion by physically shaking or vigorous mechanical
agitation in a stirnng vortexing, or mixing apparatus. This crude mixture can
then
be finished with higher shear methods such as homogenation in a
Microfluidizer,
ultrasonicator, or French press.
In a metalworking operation the fluorochemical emulsions of the invention
can be applied in the manner of conventional metalworking fluids. This would
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include flooding, spraying, submersion, etc. of the workpiece while the
tooling cuts,
forms or bends the desired shapes.
The emulsions of the invention may be utilized as working fluids in any
process involving the cutting or abrasive treatment of metals or ceramic
materials or
in any process involving the forming or other deformative working of any metal
suitable to such operations. The most common, representative, processes
involving
the cutting, separation, or abrasive machining of metals include drilling,
cutting,
punching, milling, turning, boring, planing, broaching, reaming, sawing,
polishing,
grinding, tapping, trepanning and the like. The most common, representative,
processes involving the forming metals include: bulk deformation processes
such as
forging, rolling, rod, wire, and tube drawing, thread forming, extrusion, cold
heading, and the Like; and secondary metal forming processes such as deep
drawing,
stretch forming, knurling, spinning, shearing, punching, coining, and the
like.
Metals commonly subjected to cutting and abrasive working and forming
processes include: refractory metals such as tantalum, niobium, molybdenum,
vanadium, tungsten, hafnium, rhenium, titanium; precious metals such as
silver,
gold, and platinum; high temperature metals such as nickel and titanium alloys
and
nickel chromes; and other metals including magnesium, bismuth, aluminum,
copper,
steel (including stainless steels), brass, bronze, and other metal alloys.
The use of aqueous emulsions of a fluorocarbon fluid in such operations acts
to cool the machining environment {i.e., the surface interface between a
workpiece
and a machining tool) by removing heat and particulate matter therefrom, and
also
lubricate machining surfaces to provide a smooth and substantially residue-
free
machined metal surface. In many forming/deformation operations their use can
also
eliminate the necessity of annealing.
EXAMPLES
Emulsion Pre~rraration
For each of the following Examples the emulsions were prepared by
combining the fluorinated compound, the surfactant, water and other additives
in
the proportions detailed below and shaking vigorously for several minutes. The
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crude suspension was then processed with a MicrofluidizerT"' Model 1 I O-T in
a
recycle mode where the processed emulsion was returned to the reservoir
continuously for 15 minutes. Each emulsion was then tested as described below.
The prepared emulsions:
Emulsion 1: 100 mL of C4F90CH3 with 0.1 wt%
CgF»S02N(C2Hs)(CH2CH2O)"CH3, n=7-8, prepared as described in
US 2915554), 400 mL of water with 0.1 wt% Brij 78T"" (available
from ICI America) and 0.01 wt% Antifoam AT"" (available from Dow
Corning) to produce a 20 vol.% aqueous emulsion.
Emulsion 2: 200 mL of C4F90CH3 with 0.1 wt%
CgF~~SO2N(C2Hs)(CH2CH20)"CH3, 300 mL of water with 0.1 wt%
Brij 78T"" and 0.01 wt% Antifoam AT"" to produce a 40 vol.%
aqueous emulsion.
Emulsion 3: 100 mL of C~FISOCH3 with 0.1 wt%
CsFmSOaN(C2Hs)(CH2CH2O)"CH3, 400 mL of water with 0.1 wt%
Brij 78T"" and 0.01 wt% Antifoam AT"" to form a 20 vol% aqueous
emulsion.
Emulsion 4: 100 mL of (C4F9)3N, with 0.1 wt%
CeF1~S02N(C2Hs)(CH2CH~0)"CH3,400 mL of water with 0.1 wt%
Brij 78T"" and 0.01 wt% Antifoam AT"' to form a 20 vol% aqueous
emulsion.
Emulsion 5: 100 mL of C4F90CH3 with 10 wt% dipropylene glycol di-n-propyl
ether.and 0.1 wt% C8F1~S02N(C2Hs)(CHZCH20)"CH3, 400 mL of
water with 0.1 wt% Brij 78T"" and 0.01 wt% Antifoam AT"" to form a
20 vol% aqueous emulsion.
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Examples 1 to 9
Aqueous emulsions of hydrofluoroethers and perfluoroamines (Examples 1
to 5) were tested by drilling 1/2" diameter holes in a 3/4" thick piece of
type 304
stainless steel at a speed of 420 rpm or 55 surface feet per minute (SFM) at a
feed
of 3"/minute using a 0.25" peck program on an Mitsuura MC-600VF CNC drilling
machine. The drill bit was a 2-flute high speed steel (HSS) twist bit (CLE-
Forge).
Three through holes were drilled using each coolant lubricant emulsion which
was
applied from a plastic squeeze bottle at a flow rate of about 40-45 mL/minute.
The
Comparative Examples made use of neat hydrofluoroethers (Comparative Examples
i and 2), neat (CqF9)3N (Comparative Example 3), and a conventional water-
based
coolant lubricant, CimtechT"" 3900, an aqueous hydrocarbon emulsion available
from
Cincinnati Milacron (Comparative Example 4). In Comparative Example 4, the
same experimental procedure was followed using an Excel 510 CNC drilling
machine.
The drill bit was stopped between holes and the temperatures of the drill bit
and the workpiece (in the hole) were determined with a type K thermocouple
fitted
to an Omega (Model H23) meter. A new drill bit was used for each coolant
lubricant tested. The work piece was then cleaned and the surface finish or
roughness of each hole was measured using a Hommel T500 profllometer. Two
passes each of 0.5" length were made on each hole, rotating the workpiece
90°
between passes, and these were averaged over the three holes drilled to
determine
R, and R3Z. Data for each of the coolant lubricants tested are presented in
Table 1.
The numbers in parentheticals represent the standard deviation for each
measurement.
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Table 1
Ezample Coolant) Drill Hole Temp Surface Surface
Lubricant bit (C) Roughness Roughness
temp R~ In R3Z In
(C)
1 Emulsion 37.8 38.5 (2.4)218.2 (52.1)411.9 (44.7)
1 (1.1)
2 Emulsion 42.6 35.0 (2.8)166.7 ( 433.2 (104.9)
2 (4.5) 30.5)
3 Emulsion 32.0 32.5 (5.6)195.5 (23.7)495.9 (45.6)
3 (1.2)
4 Emulsion 34.6 36.8 (1.9)262.0 (90.8)610.8 (209.6)
4 (1.5)
Emulsion 35.3 34.0 (4.6)263.1 (38.5)527.9 (115.0)
5 (3.1)
Comp. CaF90CH3 102 (8) 42 (7) 214.7 (18.7)957.2 (106.8)
1
Comp. C~F~30CH3 67 (3) 40 (3) 247.7 (11.8)1100.4 (96.8)
2
Comp. (C4F9)3N 61 (2) 47 (2) 203.7 (17.5)927.7 (143.6)
3
Comp. CimtechTM 37.6 35.8 (4.7)229.2 (54.2)474.8 (76.2)
4 2700 (1.1)
The emulsion preparations (Examples 1 to 5) all were more effective in
cooling the drill bit and hole than the corresponding neat fluorochemical
fluid
5 (Comparative Examples 1 to 3). These values are also about the same as or
slightly cooler than that found with a commercial water based coolant, Cimtech
3900 (Comparative Example 4). Surface roughness values were similar regardless
of the formulation of the fluid (either neat or emulsified) and about the same
as the
commercial water based coolant.
E.xamnles 6 to 10 and Comparative Examples S-8
These examples show hydrofluoroether and pertluorocarbon emulsions can
act as effective coolant lubricant fluids when used in the formation of
threads in
titanium with a cold forming bit. Holes were drilled in a 314" thick titanium
block in
rows spaced 1 1l2" apart with an 8.8 mm HSS bit using a conventional water
based
coolant {Cimtech 3900} on a Mitsuura MC-600VF CNC drilling machine. After
cleaning and drying the workpiece, these holes were threaded using a 3/8-16
bit
(Chromflo GH 8 HSS) run at 10 SFM. Emulsified hydrofluoroethers {Examples 6
to 8), perfluoroamines (Example 9), and an emulsified mixture of -10 wt
dipropyleneglycol n-propyl ether in C4F90CH3 (Example 10) were applied to the
bit
and the hole from a plastic squeeze bottle at a flow rate of about 40-45
mLlminute.
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Comparative Examples 5 to 7 made use of the neat hydrofluoroethers and
perfluorocarbon fluids and Comparative Example 8 utilized a conventional
tapping
fluid, MolydeeTM (available from Castrol). A new threading bit was used for
each
fluid tested.
Immediately after the bit was withdrawn from the workpiece its temperature
and that of the threaded hole were measured with a type K thermocouple on an
Omega Model HH23 meter applied to the bit tip and the hole thread,
respectively.
These temperatures were recorded and averaged over three separate test
threads.
Maximum load values as indicated on the CNC were also recorded and averaged.
This data are presented in Table 2. The numbers in parentheticals represent
the
standard deviation for each measurement.
Table 2
Example Coolant) Threading bit Hole temp.Machine Load
Lubricant temperature (C) factor (%)
C
6 Emulsion 114.4. (22.8) 62.8 (6.8)95 (5)
1
7 Emulsion 126.4 ( 12.1 71.4 (5.2)84 (2)
2 )
8 Emulsion 68.3 (7.2) 61.8 (3.3)65 (5)
3
9 Emulsion 69.2 (15.5) 55.3 (6.5063 (6)
4
10 Emulsion 107.6 (20.6) 62.6 (4.0)90 (5)
5
Comp. CaF9OCH3 165.7 (14.0) 97.2 (15.5)72 (6)
5
Comp. C~F,30CH3 156.6 (8.8) 84.0 (14.4)75 (0)
6
Comp. (CaF9)sN 151.6 (3.4) 86.7 (14.9)64 (8)
7
Comp. MolydeeTM 125.0 (11.8) 65.1 (6.6)53 (6)
8
The tap and work piece material temperatures found for Examples 6 to 10
{fluorochemical emulsion coolant lubricants) were significantly lower than
when the
neat fluids were applied (Comparative Examples 5 to 8). The commercial tapping
fluid MolydeeTM produced a significantly higher tap temperature along with
significant amounts of smoke. The MolydeeTM tap additionally had a large
amount
of charred residue while the taps from the test emulsions of fluorochemical
fluids
were clean with no residue. The machine load factors observed for emulsified
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fluorochemicals appear to be either unchanged or slightly higher than those
found
with the neat fluorochemicals.
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