US2921874A

US2921874A - Cold forming lubricant and method of applying same

Info

Publication number: US2921874A
Application number: US710192A
Authority: US
Inventors: William L Kubie
Original assignee: Aluminum Res Corp
Current assignee: Aluminum Res Corp
Priority date: 1958-01-21
Filing date: 1958-01-21
Publication date: 1960-01-19
Anticipated expiration: 1977-01-19

Description

nitecl States Patent COLD FORMING LUBRICANT AND METHOD OF APPLYING SAME No Drawing. Application January 21, 1958 Serial No. 710,192

9 Claims. (Cl. 1486.14)

This invention relates to lubricants to be used on metals during the cold forming thereof and particularly to such lubricants used in the cold extrusion of metals.

In the cold extrusion of relatively malleable metals such as, for example, aluminum, magnesium, copper and other alloys, the reduction and surface ratios attainable is dependent upon the efficiency of the lubricating layer existing between the metal billet and the die surface.

The term freduction and surface ratios refers to the ratio of the cross-sectional areas and the ratio of the surface areas of the metal article after extrusion to the corresponding dimensions of the original metal billet.

Many standard lubricants, such as petroleum oil and greases, may be used to achieve small reduction and surface ratios, i.e., ratios of from 2:1 to 3:1. This is parcularly true when the cross-sectional area of the metal billet, that is, the metal article prior to extrusion, is small. When these ratios approach or exceed 5 to 1 and the cross-sectional area of the metal billet is increased, conventional lubricants break down and fail under the heat and shearing forces occurring during extrusion. In order to achieve higher reduction and surface ratios, efforts have been made to develop new lubricants suitable for use under the conditions found in extrusion. An example of such lubricants are those having a phosphate base. The complex and metastable nature of the phosphate base lubricants makes reproducibility diflicult and the lubricant is frequently marginal if not unsatisfactory. In addition, the use of such phosphate lubricants adversely affect the surface finish of the extruded metal. For example, extruded aluminum tubing to which phosphate base lubricants have been applied has a dull, cloudy and uneven surface finish. As the reduction and surface ratios are increased above approximately 7:1 and the cross-sectional area of the metal billet is increased, the efiiciency of the phosphate lubricant decreases. As a result of lubricant failure, the extruded metal welds itself to the die or tooling, causes excessive wear on the die or tends to cause stick-slip extrusion, giving the resulting extruded product a nonuniform crosssection.

Accordingly, one of the principal objects of the present invention is to provide a lubricant suitable for use in the cold forming of metals which overcomes the above disadvantages.

A further object of the present invention is to provide a lubricant which will allow metals to be extruded at low temperatures and at high reduction and high surface ratios.

A further object of this invention is to provide a lubricant suitable for use at high pressures and high surface temperatures.

A further object is to provide a lubricant which may be applied to a metal billet in a uniform and controllable manner.

A further object of this invention is to provide a method for applying a cold extrusion lubricant to a metal billet. 1

Still another object of this invention is to provide a metal billet suitably lubricated for use in the cold extrusion process.

Other objects and advantages of this invention will be apparent, it is believed, from the following detailed description of a preferred embodiment therof.

Generally, the lubricant, which is the subject of the present invention, is in the form of an emulsion and comprises a mixture of a fatty acid, soap or ester thereof and an organic acid in a selected solvent.

For this purpose of this specification, the term lubricating agent will refer to the fatty acid or derivatives thereof indicated above, and the term reactant will refer to the organic acid.

In order to achieve satisfactory lubrication at high reduction and surface expansion ratios, i.e., 5:1 or more, it is essential that the lubricant adheres firmly to the metal billet, that it maintains its presence on the expanding surface under the conditions found in the cold extrusion process and that it does not adversely affect the surface finish of the extruded article. For the purposes of this specification the terms cold forming and cold extrusion refer to the working of a metal at temperatures'below its recrystallization temperature and include such processes as cold rolling, deep drawing and wire drawing in addition to extrusion. Fatty acids and their esters and metallic soaps, are well known lubricants. However, under the conditions of cold extrusion such compounds are not sutficient by themselves to give satisfactory lubrication. I have determined that by the use of a reactant, a chemical bond is formed between the surface of the metal billet and the lubricant. The exact nature of this bond is not completely understood. However, it may be hypothesized that under the conditions of the process of applying the lubricant to be discussed below, the following reactions occur:

The organic acid in the presence of the selected solvent reacts with the metal billet to form the metal salt of the organic acid. This metal salt in turn reacts with the lubricating agent to form the metal salt of the fatty acid and to reform the organic acid used. Upon heating, the organic acid is driven off, leaving the metal salt of the fatty acid.

Since a stoichiometric excess of fatty' acid is used, there also remains a layer of the unconverted fatty acid. The surface of the metal billet may then be defined as one having a multilayer composition, the first layer being the pure metal, the intermediate layer being the metal salt of the fatty acid used, and the top layer being the lubricating agent. It will be understood that these layers are closely interrelated and theoretically, under what might be termed ionic interaction, are chemically bonded to one another.

'The following equations are illustrative of the nature of the reactions which theoretically take place to form the intermediate layer. For the purpose of this illustration, trichloroacetic acid is chosen as the reactant, RCOOH, a fatty acid, is the lubricating agent, and the metal billet is formed from aluminum.

in OClaCOOH Al Al(COl3COO) A (2) A1(CClaCO0)3 3stearic acid of chemical bond exists between the surface of the metal billet and the lubricant itself.

Because of the chemical as distinguished from the physical nature of the bonding of the lubricant to. the billet, reduction and surface expansion ratios as high as 33 to l have been attained without lubricant failure. It'

has further beenobserved that wear on the, die, has been considerably reduced and. that the use of a lubricant in accordance with this invention results'in an extruded metal product characterized by excellent surface characteristics.

The lubricating agent used, in the cold extrusion lubricant may consist of one or more compounds selected from the group of organic compounds normally considered as fatty acids or the derivatives thereof having the general formula (R COO),,R where n is.1, 2, or. 3. R may be a nonpolar monovalent organic radical-containing 7 or more carbon atoms which. may include a hydroxyl constituent. or which may include a branch carbon chain or a carbon chain interrupted'by an ether linkage. R represents a radical selected from the group consisting of hydrogen, a metal and a saturated hydrocarbon. Generally speaking, depending .on the solvent, any metallic salt may be used as the lubricating agent. However, the sodium and potassium salts of fatty-acids are considered unsatisfactory when water is-used as the solvent. is substantially insoluble in water and, therefore, satisfactory, the sodium and potassium saltsionize and. preferentially attack the metalbillet to form-an alkalimetal salt rather than the acid metal salt. The, presence of the caustic salt considerably reduces the efficiency of the lubricant and I, therefore, prefer to use only solvent insoluble metal salts in the lubricant.

At high reduction and surface expansion ratios the lubricating agent must be saturated to prevent stick-slip phenomena. Compounds wherein the total number of carbon atoms in the R group in the above illustration is less than 7, are normally inoperative because of their volatility under the conditionsof cold extrusion, the lack of an adequate soapy quality, and their general inability I to act as a lubricant. As the reduction-and surface expansion ratios are increased, the length of' the chain in the lubricating agent must be increased, there being 'a direct relation between the length :of the chain'and its ability to act as a lubricant at increasing reduction ratios. While there is theoretically no upper limit to the number of carbon atoms suitable for use 'in'the lubricating agent, practically speaking, compounds wherein R has more than 22 carbon atoms are difficult to obtain-and the increased chain length above that point does not appreciably increase the lubricating ability of the compound.

It has been observed that while the lithiumsalt (2) A boiling point below the glazing temperature, i.e., below the melting point of the lubricating agent.

(3) The temperature of decomposition of the reaction product between the acid and the metal billet is below the glazing temperature. 7

Examples of such acids "are:

Formic Fumaric Maleic Malonic Oxalic Phthalic Salicylic Performic Peracetic Monobromoacetic (XBI'OmOPI'OpiOHiC Monochloroacetic aChloropropionic Dichloroacetic Trichloroacetic and completeness of the lubricant as applied to the metal As indicated in Equation 2 above, the lubricating agent reacts with the acid metal salt to form the fatty acid metal salt and to reform the reactant. Since theiboiling point of the reactant, as will be discussed below, is. lower than the glazing temperature, the reactant is removed from the billet.

Examples of compounds suitable for use as a'lubricating agent are: caprylic, pelargonic, capric, lauric, myristic, palmitic, phenylstearic, arachidic, 'behenic and stearic acids, the corresponding esters and the metallic salts thereof, hydroxystearic acid and similar hydroxy homologs of the acids, esters and salts named, 2-ethyl caprylic acid and similar branch-chain fatty acids, lanolin, beeswax and hydrogenated jojoba oil. Lanolin is a complex mixture of sterolsand sterol esters, beeswax is a mixture of esters of long chain fatty acids and alcohols, and jojoba oil consists mainly of esters composed of C to C acids and 'alcohols.-

The reactantis an organic acid having the following characteristics:

(1) An ionization constant'equal to or greater than 10- i billets a dye may be advantageously used. Further, parting compounds may be included toprevent metalrto-rnetal contact. Finally, since the lubricant is either sprayed or painted onto the metal billet in relatively uneven amounts, a leveling compound may he used to cause the formation of a uniform level coat around the billet.

The wetting agents which may be. incorporated in order to disperse the insoluble soaps, esters and fatty acids in water may be selected from a wide group of commerical compounds and such choice is determined by their'chemical stability, their ability to keep the emulsion dispersed and to keep the tacky point above the operating temperature. Examples of such wetting agents are: a polyoxyalkylene derivative of sorbitan monostearate having a molecular weight of about 1300 (Tween 60, manufactured by Atlas Powder Co.), polyoxyethylene sorbitan monooleate (Tween 80, manufactured by Atlas Powder Co.),. sorbitan monostearate (Span 60, manufactured by Atlas Powder Co.), sorbitan monooleate (Span 80, manufactured by Atlas Powder Co.), oxyethylene'nonylphenol (Tergitol NPX, manufacturedyby Union Carbide Co., composition approximately one mole of oxyethylene per mole of nonylphenol), polyoxyethylene nonylphenol (Tergitol NP14, manufactured by Union Carbide Co., composition approximately 14 molesof oxyethylene per mole of nonylphenol), polyoxyethylene nonylphenol (Tergitol NP35, manufactured by Union Carbide Co., composition approximately 35 moles of oxyethylene per mole of nonylphenol), sulfated castor oil (manufactured by Baker Castor Oil Co.'), alkyl aryl sulfonate (Duponol G, manufactured by-Du'Pont de Nemours '& Co.), alkyl aryl sulfonate (Textilana MW, manufactured by Texti lana Corp), polyoxypropylene glycol (Pluronic L 62, manufactured by Wyandotte Chemicals Corp.'), and fatty alkanolamides (Emcol15100T,.manufactured by Witco Chemical Co.). Other similar wetting agents may be used. a r

Binders suitable for use to control the viscosity of the lubricant are materials such, as gum tragacanth, starch, dextrine, casein, and glue. Other similar thixotropic ma terials may be used. While the useofa. dye is not essential to the lubricant, it may be used advantageously for at least two purposes, first, the final glazed lubricant in the thickness used is transparent and the inclusion of a dye provides a visible film, the relative thickness of 'which can be judged by the intensity of the color; secondly, if the dye chosen acts as a pH indicator, the evolution of acid during the curing operation can be readily followed by the change in color. In, addition, if the dye chosen; is an acid pH indicator,.the acid. concentration can be observed. For example, when trichloroacetic acid is used as the reactant and oil soluble green (No. 3126 distributed by Melford Chemical Co.) was used as the dye, it was observed that during the spraying and drying of the lubricant a magenta color was formed, indicating with this dye a pH of 1. This condition occurred primarily at the surface of the metal indicating a strong concentration of the acid at the place desired. Oil soluble dyes and other dyes which do not participate in the reaction may be used.

Parting copounds well known in the extrusion art to prevent metal-to-metal contact may also be included. Examples of such compounds are talc, mica, graphite, chalk, borax, lithopone, zinc oxide, white lead and polyhydric alcohol esters of bentonite (Bentones, manufactured by National Lead Co.).

As indicated above, in order to achieve a uniform thickness, leveling compounds may be added to the cold extrusion lubricant to eliminate brush strokes and to provide a smooth, level surface. Examples of such compounds are carboxy-methylcellulose, tricresyl phosphate, glycerine, lecithin, ethylene glycol and sorbitan borate.

Although water is satisfactory as a solvent in forming the emulsion, other volatile solvents which do not react with the metal billet or enter into unfavorable side reactions with the other constituents may be used. Examples of such solvents are acetone, methylethyl-ketone, methyl, ethyl, and isopropyl alcohols and kerosene.

The relative proportions of the various constituents included in the cold extrusion lubricant may be varied over a wide range and depend, to a large extent, on the reactivity of the particular metal to be extruded, the pH of the lubricant, the reduction and surface expansion ratio desired and the lubricating qualities of the fatty acids or derivatives thereof used. The effective by weight ratio of lubricating agent to reactant may vary from 100:20 to 100:1. The use of increased amounts of reactant, particularly if the reactant is volatile, does not substantially alfect the efiiciency of the lubricant. Such excess reactant adds nothing to the lubricant and cannot increase the efficiency thereof. If less than the indicated minimum of reactant is used, the intermediate layer will be incomplete and the resulting lubricant will be physically rather than chemically bonded to the metal billet. Based on 100 parts by weight lubricating agent, the following indicates satisfactory by weight ranges for the additional constituents which may be advantageously used in the composition:

The amount of solvent to be used in the compound should be suflicient to have a thin, regularly dispersed solution, preferably in the range of from 400 to 2000 parts solvent to 100 parts lubricating agent. If dye is used, a sufficient quality should be present to adequately color the emulsion.

The metals to which the cold extrusion lubricant may be applied include any metal to which the cold extrusion process is commercially practicable, provided the indicated reactions can occur. Examples of such metals are aluminum, iron, copper, lead, silver, magnesium and the alloys thereof. By the use of this lubricant, reduction and surface expanding ratios from 5 to l, to 33 to l, have been readily achieved.

The process by which the lubricant is applied to the metal billet consists essentially of four steps: cleaning, application, glazin and cooling.

In order to achieve the chemical bond indicated above, it is necessary that the metal billet be chemically clean. The cleaning can be accomplished by etching, the use of suitable solvents or sandblasting. The chemically clean surface is essential for application of the lubricant to the billets where the surface expansion is large. In cases of relatively small surface expansion, sufiicient reaction takes place to maintain the adhesion of the lubricant even though the billets are not clean.

The lubricant may be applied by any of the standard methods of paint application. It is desirable to obtain a uniform coat of controlled thickness. The coating weight will vary according to the material and type of extrusion and may be in the range of from 100 to 6000 milligrams of cured lubricant per square foot.

In order to obtain a smooth, hard coat which will ad here to the billet, the coated billet is heated above the melting point of the lubricant. The temperature is, therefore, dependent on the choice of lubricating agent and may be varied from 200 F. to 500 F. The heating time required depends on the heat capacity and surface to volume ratios of the billet, the heating being continued until the reaction is complete. The heated billet is tacky, or sticky, and it is, therefore, necessary to cool the billet below the tacky point prior to handling. As indicated above, the wetting agent, if used, affects the tacky point. If the billet is tacky at room temperature, too much wetting agent has been included in the emulsion. The above indicated process of forming a coated billet, using the cold extrusion lubricant provides a billet having; a

slippery, smooth, coat of lubricant which adheres firmly,

through chemical reaction, to the metal.

The following are specific examples of the composition of the cold extrusion lubricant, the processby which it is applied to the billet, and the results of the extrusion of coated metal billets at temperatures below the recrystallization temperatures thereof.

In each of the examples given, the materials used are of commercial grade unless otherwise specifically indicated. In the extrusions, a Lake Erie 2500-ton horizontal extrusion press was used.

' in the quantities indicated:

Grams Lithium stearate 570 Zinc stearate 380 Span 60 10 Tween 60 10 Green dye (oil soluble green No. 3126 distributed by Metford Chemical Co.) 2.5 Gum tragacanth 10 Trichloracetic acid To a conventional colloid and blending mill having a 10 gallon vat and a cooling jacket surrounding the vat was added 9 liters of hot water F.). The 10 grams of Span 60 was then added, the solution being continuously agitated by a mechanical mixer. After the Span 60 dissolved, the Tween 60 and green dye were added and allowed to dissolve. To this solution the trichloracetic acid was added and then the gum tragacanth was sprinkled in slowly and allowed to dissolve. The lithium stearate was then added slowly and when the mixture had become homogenous, water was introduced into the cooling jacket to lower the temperature of the solution in the vat. The zinc stearate was then added and the resulting slurry agitated continuously for one and one-half hours to break up the large aggregates and homogenize the mixture. After such agitation, the colloid mill was started to form the final mixture. The use of the colloid mill is particularly advantageous if the lubricant is to be applied to the billets by spray guns, it being my experience that the needle valves of the spray guns become clogged unless the colloidal suspension is finely divided. Any standard colloid mill is satisfactory. The purpose of the milling 'ma lycl f B tube, in passingthrough 7 andcolloiding is merely to-form a homogenous, finely divided colloidal suspension. The emulsion was milled untila finely dispersed emulsionwas formed (approximatelythree-fourthsof an'hou'r) and the finished lubricantcollected" into a storage drum.

Preparation of billets Prior to the, application of? the, lubricant to the billets the exposed'surface areas were cleaned in the following manner: A -hollow. aluminum cylinder (commercial alumihunt with minimrun impurities) 23% inches long having an internal diameter of 4.97 inches and an external diameter of6151 inches was immersed in a concentrated nitricv acid bath at room temperature for one minute, water-rinsed for one minute,washed with 1% caustic soda atflfTSF. forthree minutes, water-rinsed at room temperaturefor, one minute,,washed again with nitric acid for one minute, water rin'se'd at room temperature for one minute, andfinalllthoroughly washed with water having a temperature of 132 F The billet was then air-dried for'two. hours on an inclined ramp, to allow theinterior bore to drain.

Application of lubricant .Thepreparedcold extrusion lubricant was sprayed ontheexternal surfacesoi thecleaned metal billet, using a.. D.e -Vilbiss,.M.B..C. spray gun'with, an FXdype needle valve. The hereof the. billet was sprayedwith a /1 inch by; 3.0. inch extension on the spray gun having a 360 spray-head, The lubricant was supplied to thespray gun froma. 5 gallon pot. The pressure on the lubricant was 50 p.s.i. and the air pressure on the gun'was 60 p.s.i. Spraying was continued until a uniform coat as determinedby clear. color density throughout was obtained.

Spraying wasaccomplished in the following manner. The etched billetfwas loaded on an angle iron track approximately30 feet long. The bore of the billet was sprayed with the extended gun "for approximately 3 /2 seconds. The billet was then placed on a set of rotating wheels to permit rotation ofthe billet, the rate of rotation being adjusted to approximately 7 /2 r.p.rn. The billet was permitted to make two complete revolutions while spraying back and forth for approximately 25 seconds, the

spraying covering the entire external surface. Examination ofwthe resulting coating showed that there was approximately- -1-500milligrarns ofsolvent free lubricant per squarefoot of surface area; The coated billet-was then transported -to an'indirectly-heatedoven. The temperatureof theoven was maintained at 470 F. The billet was placedintheoven'for curing and allowed to cure for 35 minutes. t -was observed that thetemperature of the-billet-intheoven-was-raisedto 400 F. After ,curingthe-billet; was removed from the oven and allowed topool. It'was; noted that the tacky point'was approxithat temperatureathe surface of theqbillet: was smooth, hard, and slippery. The billet was. then ready. for extrusion;

"Extrusion of billet As-indicated above,'a Lake Erie 2500-ton horizontal extrusion press was used. The diehad aminimum bore diameterof 5' inches. The punch head was ground to 0.015 inch smallerthan-the bore diameter. A mandrel having an OD. of 4.910- inches was positioned on the punch The die was preheated'to 145 'F. and the mandrel heated-"to 280 F. The billetwas then'preheated to 220 F., inserted into the press and extruded at a pressure of approximately 950 tons p.s.i. A washing bath was positioned at the exit of the extrusion die through whichthe extruded aluminum tube passed; The the bath was cooled and allowed to p'ass-out onto a'cooling tray. The heel was cut ofi andthe extruded tube allowed to cool. The resulting extrudedproduct was; an aluminum tube having- OD. of 5.000 inches, a mean IiD. of 4910 inches and a mean wall thickness of 0.045 inch; The tube was approximately 32 feet in length and had'a clear, regular surface with a minimum of discoloration and die or extrusion marks. The reduction and surface ratio was determined to be approximately 20 to l.

The following are examples of cold extrusion lubricants which may be prepared and applied to metal billets by the methods shown in Example I. In these examples the quantitiesare indicated in parts by'weight.

EXAMPLE 11 Gum tragacanth 1 Oil soluble green No.'-31'26 0.25 Peracetic acid 10 Water 900 V V EMMPLE 1V Beeswax (yellow) 95 Behenic acid 5 Methoxycellulose 2 Span 60 1 Tween 60 l m-Chloropropionic acid l2 Isopropyl alcohol 300 EXAMPLE V Hydrogenated jojoba oil 95 Arachidic acid 5 Carboxymethylcellulose, 2 Ricinoleate polyoxyethylene ester l Formic acid 5 Mica (300 mesh) 10 Water 300 EXAMPLE VI Zinc hydroxystearate 95 Hydroxystearic acid 5 Monobromacetic acid l2 Ethyl alcohol 900 EXAMPLE VII Zinc palmitate 95 Palmitic acid 5 Maleic acid 11 Alkylaryl sulfonate l Casein 1 Water 900 EXAMPLE VIII Lanolin 30 Lithium stearate 40 Stearic acid 5 Zinc stearate 25 Gum tragacanth 1 Oil soluble green No. 3126 0.25 Tween 60 1 Span 60 l Oxalic acid 12 a mean Water a 900 In the above examples other organic acids having the properties previously indicated may be substituted for the reactant specified.

In addition, other fatty acids, their metallic salts or esters may be substituted for the lubricating agent specified. It is to be understood that as the chain length of the fatty acid or its derivative is decreased, the maximum reduction and surface ratios must be decreased.

In these examples parting compounds, such as talc, mica, graphite, chalk or borax may be included to increase the ease of extrusion particularly when shorter chain lubricating agents are used.

In addition to commercial aluminum, the following alloys of aluminum have been successfully lubricated and extruded using the lubricant and methods indicated in the examples:

It will also be apparent, it is believed, that the lubricant will be satisfactory in cold forming processes other than extrusion such as, for example, cold rolling.

Having fully described my invention, it is to be understood that I do not wish to be limited to the precise details of the examples set forth but my invention is of the full scope of the appended claims.

I claim:

1. A lubricant for use in the cold forming of selected metal billets consisting essentially of: a mixture of a lubricating agent, a reactant, and a solvent; said lubricating agent being a compound having a melting point between 200 F. and 500 F. and having the general structure where n is 1, 2, or 3, R is a monovalent nonpolar organic radical having at least 7 carbon atoms and R is a radical selected from the group consisting of H, metals and saturated hydrocarbons; said reactant being an organic acid having an ionization constant of at least 10* and a boiling point less than the melting point of said lubricating agent, said acid being capable of reacting with the metal in said selected billets to form a reaction product, the temperature of decomposition of said reaction product being less than the melting point of said lubricating agent; the by weight ratio of said reactant to said lubricating agent in said mixture being not less than i to 100; the by weight ratio of solvent to lubricating agent being in the 7 range of from 400:100 to 2000:100.

2. An emulsified lubricant for use in the cold forming of selected metal billets consisting essentially of: a lubrieating agent, a reactant, and water; said lubricating agent being a mixture of at least two compounds selected from the group consisting of fatty acids having more than 7 carbon atoms, the insoluble metal salts and esters thereof; said reactant being an organic acid having an ionization constant of at least 10- and a boiling point less than the melting point of said lubricating agent, said acid being capable of reacting with the metal in said selected billets to form a reaction product, the temperature of decomposition of said reaction product being less than the melting point of said lubricating agent; the by Weight ratio of reactant to lubricating agent being in the range of from 1:100 to 20:100; the by weight ratio of water to 10 lubricating agent being in the range of from 400: to 2000:100.

3. An emulsified lubricant for use in the cold forming of selected metal billets consisting essentially of the following ingredients by weight: a lubricating agent selected from the group consisting of fatty acids having more than 7 carbon atoms, the insoluble metal salts and esters thereof, and mixtures of the acids, esters and salts 100 parts; a reactant, said reactant being an organic acid having an ionization constant of at least 10" and a boiling point less than the melting point of said lubricating agent, said acid being capable of reacting with the metal in said selected billets to form a reaction product, the temperature of decomposition of said reaction product being less than the melting point of said lubricating agent; 1-15 parts; a volatile solvent, 400-2000 parts; a wetting agent, 0.5-5 parts; a binder selected from the group consisting of gum tragacanth, starch, dextrine, casein, and glue, 0.5-5 parts.

4. A coating composition as claimed in claim 3 wherein the lubricating agent is a mixture of lithium stearate and zinc stearate.

5. A coating composition in accordance with claim 3 wherein the reactant is trichloroacetic acid.

6. A method of applying a cold extrusion lubricant to an unformed metal billet, the steps comprising: applying a uniform coating of a lubricant comprising a reactant and a lubricating agent to said billet and heating said billet to a glazing temperature between 200 F. and 500 F., said reactant being an organic acid having an ionization constant of at least 10 and a boiling point less than said glazing temperature, said acid being capable of reacting with the metal in said selected billets to form a reaction product, the temperature of decomposition of said reaction product being less than said glazing temperature; said lubricating agent being a compound having the general structure where n is 1, 2, or 3, R is a monovalent nonpolar organic radical having at least 7 carbon atoms and R is a radical selected from the group consisting of H, metals and saturated hydrocarbons; the by weight ratio of said reactant to said lubricating agent in said lubricant being not less than 1 to 100.

7. A method of applying a cold extrusion lubricant to an unformed metal billet, the steps comprising: cleaning said billet to remove surface impurities therefrom; applying a uniform coating of a lubricant comprising a reactant and a lubricating agent to said billet; heating said billet to a glazing temperature of between 200 F. and 500 F. and cooling said billet to a temperature below 200 F., said reactant being an organic acid having an ionization constant of at least 10- and a boiling point less than said glazing temperature, said acid being capable of reacting with the metal in said selected billets to form a reaction product, the temperature of decomposition of said reaction product being less than said glazing temperature; said lubricating agent being a compound having the general structure (RICOO)1LR2 where n is 1, 2, or 3, R is a monovalent nonpolar organic radical having at least 7 carbon atoms and R is a radical selected from the group consisting of H, metals and saturated hydrocarbons, the by weight ratio of reactant to lubricating agent being in the range of from 1:100 to 152100; the amount of said coating applied to said billet being in the range of from 100 to 6000 milligrams per square foot of surface area.

8. A coated metal article comprising: a metal billet and a thin film covering said billet, the film consisting essentially of the lubricant set forth in claim 2.

9. An emulsified lubricant for use in the cold forming of selected metal billets consisting essentially ofthe fol- 1 1 Iowing'ingredients by weight: a lubricating agent selected from the group of compounds having a melting point between 200" F. and 500 F. and having the general structure 1 where n is 1, 2, or 3, R is a monovalent nonpolar organic radical having at least 7 carbon atoms and R is a radical selected from the group consisting of H, metals and saturated hydrocarbons and mixtures of the acids, esters and salts thereof, 100 parts; a reactant, 1-15 parts, said reactant being an organic acid having an ionization constant of at least 1O- and a boiling point less than the melting point of said lubricating agent, said acid being capableof reacting with the metal in said selected billets to form a reaction product, the temperature of decom- 12 position of said reaction product being less than the melting point of said lubricating agent; a volatile solvent, 400-2000 parts; a Wetting agent, 0.5-5 parts; a binder selected from the group consisting of gum tragacanth, starch, dextrine, casein, and glue, 0.5-5 parts.

References Cited in the file of this patent UNITED STATES PATENTS 2,246,549 Spangler June 24, 1941 2,588,234 Henrichs Mar. 4, 1952 2,849,107 Logue Aug. 26, 1958 FOREIGN PATENTS 29,161 Great Britain of 1913 201,358

Australia Feb. 22, 1956

Claims

1. A LUBRICANT FOR USE IN THE COOL FORMING OF SELECTED METAL BILLETS CONSISTING ESSENTIALLY OF: A MIXTURE OF A LUBRICATING AGENT, A REACTANT, AND A SOLVENT, SAID LUBRICATING AGENT BEING A COMPOUND HAVING A MELTING POINT BETWEEN 200*F. AND 500*F. AND HAVING THE GENERAL STRUCTURE