Machinery''''s Handbook 2th Episode 4 Part 7 docx

The mini-mum requirements for tensile strength in pounds, for briquettes one square inch in cross-section, should be as follows: For cement 24 hours old in moist air, 175 pounds.. For ce

No Square Cube Sq Root Cube Root Reciprocal No.

No Square Cube Sq Root Cube Root Reciprocal No.

No Square Cube Sq Root Cube Root Reciprocal No.

No Square Cube Sq Root Cube Root Reciprocal No.

No Square Cube Sq Root Cube Root Reciprocal No.

No Square Cube Sq Root Cube Root Reciprocal No.

No Square Cube Sq Root Cube Root Reciprocal No.

No Square Cube Sq Root Cube Root Reciprocal No.

No Square Cube Sq Root Cube Root Reciprocal No.

Multiplication Table for Common Fractions and Whole Numbers From 1 to 9

Surface Area and Volume of Spheres From 1⁄64 to 14 3⁄4

* The figures given in the table can be used for English and Metric (SI) units

d = diameter Surface = πd2 Volume = πd3 ÷ 6

Dia Surface Volume Dia Surface Volume Dia Surface Volume

Dia Surface Volume Dia Surface Volume Dia Surface Volume

Dia Surface Volume Dia Surface Volume Dia Surface Volume

Circumferences and Areas of Circles From 1⁄64 to 9 7⁄8

Diameter Circumference Area Diameter Circumference Area Diameter Circumference Area

Diameter Circumference Area Diameter Circumference Area Diameter Circumference Area

Diameter Circumference Area Diameter Circumference Area Diameter Circumference Area

Diameter Circumference Area Diameter Circumference Area Diameter Circumference Area

Diameter Circumference Area Diameter Circumference Area Diameter Circumference Area

Diameter Circumference Area Diameter Circumference Area Diameter Circumference Area

Diameter Circumference Area Diameter Circumference Area Diameter Circumference Area

Diameter Circumference Area Diameter Circumfernce Area Diameter Circumfernce Area

meter Circum-

meter Circum-

meter Circum-

meter Circum- ference Area

Table of Decimal Equivalents, Squares, Cubes, Square Roots, Cube Roots, and Logarithms of Fractions from 1⁄64 to 1, by 64ths

Cement

The cements used in concrete construction are classified as:

1) Portland cements

2) Natural cements

3) Pozzuolanic, pozzuolan, or slag cements

These different classes are all hydraulic cements as they will set or harden under water.When the powdered cement is mixed with water to a plastic condition, the cement sets orsolidifies as the result of chemical action After the preliminary hardening or initial set, thecement slowly increases in strength, the increase extending over months or years

Portland Cement.— Portland and natural cements are the kinds most commonly used.

Portland cement should be used for all structures which must withstand stresses and formasonry that is either under water or heavily exposed to water or the weather According

to the specifications of the American Society for Testing Materials, the specific gravity ofPortland cement must be not less than 8:1 If the tested cement is below this requirement Asecond test should be made on a sample ignited at a low red heat The ignited cementshould not lose more than four per cent of its weight A satisfactory Portland cement mustnot develop initial set in less than 30 minutes; it must not develop hard set in less than 1hour; but the time required for developing hard set must not exceed 10 hours The mini-mum requirements for tensile strength in pounds, for briquettes one square inch in cross-section, should be as follows:

For cement 24 hours old in moist air, 175 pounds

For cement 7 days old, one day in moist air and six days in water, 500 pounds.For cement 28 days old, one day in moist air and 27 days in water, 600 pounds.For one part of cement and three parts of standard Ottawa sand, 7 days old, one day inmoist air and six days in water, 200 pounds

For one part of cement and three parts of standard Ottawa sand, 28 days old, one day inmoist air and 27 days in water, 275 pounds

The cements must under no circumstances show a decrease in strength during the timeperiods specified

Natural Cement.—Natural cement is used in mortar for ordinary brick work and stone

masonry, street sub-pavements, as a backing or filling for massive concrete or stonemasonry, and for similar purposes Natural cement does not develop its strength as quicklyand is not as uniform in composition as Portland cement It should not be used for columns,beams, floors or any structural members which must withstand considerable stress Natu-ral cement is also unsuitable for work that is exposed to water Foundations which are sub-jected to moderate compressive stresses may be made of natural cement, which is alsosatisfactory for massive masonry where weight rather than strength is the essential feature The American Society for Testing Materials gives the following specifications for natu-ral cement: An initial set must not develop in less than 10 minutes, and the hard set must notdevelop in less than 30 minutes, but must develop in less than three hours The minimumrequirements for tensile strength in pounds, for briquettes one inch in cross-section, are asfollows:

For natural cement 24 hours old in moist air, 75 pounds

For natural cement 7 days old, one day in moist air and six days in water, 150 pounds.For natural cement 28 days old, one day in moist air and 27 days in water, 250 pounds.For one part of cement and three parts of standard Ottawa sand, 7 days old, one day inmoist air and six days in water, 50 pounds

For one part of cement and three parts of standard Ottawa sand, 28 days old, one day inmoist air and 27 days in water, 125 pounds

stantly exposed to fresh or salt water and for drains, sewers, foundation work underground,etc It is not suitable where masonry is exposed to dry air for long periods Pozzuolaniccement sets slowly but its strength increases considerably with age While this cement isrelatively cheap, it is not as strong, uniform, or reliable as Portland and natural cements,and is not used extensively.

Concrete Concrete.—The principal ingredients of concrete are the matrix or mortar and the “coarse

aggregate.” The matrix consists of cement and sand mixed with water, and the coarse

aggregate is usually broken stone or gravel What is known as rubble concrete or

cyclo-pean masonry contains large stones which are used for reducing the cost of massive damsand walls These rubble stones may vary from a few per cent to over one-half the volume.When concrete without much strength but light in weight is required, cinders may be used.This cinder concrete is porous and is used for light floor construction or fire-proofing

Concrete Mixtures.—In the mixing of concrete, it is desirable to use as little cement as is

consistent with the required strength, because the cement is much more expensive than theother ingredients The proportioning of the ingredients is usually by volume and mixturesare generally designated by giving the amount of each ingredient in a fixed order, as 1 : 2:

5, the first figure indicating the amount of cement by volume, the second the amount ofsand, and the third the amount of broken stone or gravel

For ordinary machine foundations, retaining walls, bridge abutments, and piers exposed

to the air, a 1 : 21⁄2 : 5 concrete is satisfactory; and for ordinary foundations, heavy walls,etc., a lean mixture of 1 : 3 : 6 may be used For reinforced floors, beams, columns, andarches, as well as for machine foundations which are subjected to vibration, a 1 : 2 : 4 con-crete is generally used This composition is also employed when concrete is used underwater For water tanks and similar structures subjected to considerable pressure andrequired to be water-tight, mixtures rich in cement and composed of either 1 : 1 : 2 or 1 : 11⁄2:

3 concrete are used Portland cement should preferably be used in concrete construction

Sand, Gravel, and Stone for Concrete.—The sand used must be free from dust, loam,

vegetable, or other organic matter; it should pass, when dry, through a screen with holes of

1⁄4-inch mesh The gravel should consist of clean pebbles free from foreign matter andshould be of such coarseness that it will not pass through a screen of 1⁄4-inch mesh Gravelcontaining loam or clay should be washed by a hose before mixing The broken stoneshould be of a hard and durable kind, such as granite or limestone This stone should passthrough a 21⁄2-inch screen

Amount of Water for Mixing Concrete.—The amount of water required to combine

chemically with cement is about 16 per cent by weight, but in mixing concrete a greateramount than this must be used, because of losses and the difficulty of uniformly distribut-ing the water In hot weather more water is required than in cool weather because of the lossdue to evaporation The same applies when absorbent sand is used, or when the concrete isnot rammed tightly An excess of water is not desirable, because this excess will flow awayand carry some of the cement with it The water must be free from oils, acids, and impuri-ties that would prevent a proper chemical combination with the cement It is important tomix the ingredients thoroughly Lime cement, sand and stone should be mixed while dry,preferably using a machine Enough water should then be added to produce a mixturewhich will flow readily and fill different parts of the form

Reinforced Concrete.—Concrete reinforced with steel is widely used, especially where

the concrete must resist tensile as well as compressive stresses This reinforcement may be

in the form of round bars twisted square bars, corrugated bars, expanded metal, steel mesh,

or wire fabric The proportions for reinforced concrete structures are usually 1 : 2 : 4, or 1

lateral spacing between reinforcement bars should not be less than three times the bardiameter from center to center, with a clear space between the bars of at least one inch Thedistance from the side of a beam to the center of the nearest bar should be not less than twodiameters.

Strength of Concrete.—The strength varies greatly depending upon the quality and

pro-portions of the ingredients and the care in mixing and depositing in the forms The pressive strength of concrete which, after having been mixed and laid, has set 28 days,varies from 1000 to 3300 pounds per square inch, according to the mixture used If made inthe proportion 1 : 3 : 6, using soft limestone and sandstone a compressive strength of only

com-1000 pounds per square inch may be expected, whereas a mixture of 1 : 1 : 2, made with softlimestone and sandstone, will show a strength of 2200 pounds per square inch A mixture

of 1 : 3 : 6, made from granite or trap rock, will have a compressive strength of 1400 poundsper square inch, while a mixture of 1 : 1 : 2, made from granite or trap rock, will have astrength of 3300 pounds per square inch Other mixtures will have values between thosegiven The richer in cement in proportion to sand, gravel, and stone, the stronger will be theconcrete The strongest concretes are also obtained by using granite or trap rock Amedium strength is obtained by using gravel, hard limestone, or hard sandstone, whereasthe least strength is obtained by using soft limestone or sandstone Concrete may also bemixed with cinders, but, in this case, very inferior strength is obtained; the richest mixtureswill only give a strength of about 800 pounds per square inch

Durability of Concrete in Sea Water.—Experiments have been made to determine the

durability of different mixtures of concrete when exposed to sea water It has been foundthat the mixtures that give the best results are those that are richest in cement Mixtures of

1 : 1 : 2, for example, will give much better results than mixtures of 1 : 3 : 6 Also, very wetmixtures seem to give better results than those that are comparatively dry when deposited

It has also been found that, in order to insure the permanence of Portland cement concrete

in sea water, the cement must contain as little lime and alumina as possible and must also

be free from sulfates, and the proportion of sand and stones in the concrete must be suchthat the structure is practically non-porous Natural cement should never be used for con-crete exposed to sea water

Waterproofing Concrete.—Several formulas for making concrete waterproof have been

successfully used but some of them are too expensive for general application One of thesimplest, cheapest, and most effective is that developed by the U.S Geological Survey Aheavy residual mineral oil of 0.93 specific gravity, mixed with Portland cement, makes itwaterproof and does not weaken when the concrete consists of, say, cement, 1 part, sand, 3parts, and oil, not more than 10 per cent, by weight, of the cement Concrete mixed with oilrequires about fifty per cent longer time to set hard, and the compressive strength is slightlydecreased but not seriously The bond or grip of oil concrete on steel is much decreasedwhen plain bars are used, but formed bars, wire mesh, or expanded metal act as effectively

in it as in ordinary concrete

Resistance to Acids and Oils.—Concrete of a good quality, that has thoroughly

hard-ened, resists the action of acids and mineral oils as well as other building materials, butvegetable oils containing fatty acids produce injurious effects by combining with the lime

in the cement and causing disintegration of the concrete

Lutes and Cements

Luting and cementing materials for various purposes in the laboratory and shops may beclassified as follows: water- and steam-proof; oil-proof; acid-proof; proof to hydrocarbongases; chlorine-proof; elastic; general purposes; marine glue; gaskets; machinists; leather(belting); crucible; iron; and stone

foundations, brick, wood, etc., are often of use to engineers Asphalt only partly dissolves

in petroleum naphtha, but when heated in a steam-jacketed kettle and not thinned out toomuch, a mixture of the two may be obtained in which the part of the asphalt not dissolved

is held in suspension Asphalt is entirely soluble in benzol or toluol, which are about thecheapest solvents for all the constituents of asphalt Tar and pitch are sometimes used inthis connection, but tar contains water, light oils and free carbon, and does not wear as well

as good refined asphalt; pitch also contains free carbon, which is sometimes objectionablewhen it is thinned out with a solvent Asphalt alone is somewhat pervious to water, but itcan be improved in this respect by adding about one-fourth its weight of paraffin; it is alsowell to add a little boiled linseed oil For thicker compositions, where body is required,asbestos, stone powder, cement, etc., may be added as filters Lutes of linseed oil thickenedwith clay, asbestos, red or white lead, etc., arc waterproof if made thick enough These aremuch used for steam joints Flaxseed meal made into a paste with water is often service-able, the oil contained serving as a binder as the water evaporates

Oil-proof Cements.—The well-known “hektograph composition” is the most useful lute

for small leaks, etc It consists of the following ingredients: Good glue or gelatin, 2 parts;glycerin, 1 part; water, 7 parts This preparation is applied warm and stiffens quickly oncooling Another very useful composition is a stiff paste of molasses and flour Anotherpreparation, impervious to oil vapors, is the “flaxseed poultice,” mentioned in the preced-ing paragraph, which is proof to oil vapors One of the strongest cements, and one which isreally oil-proof, waterproof and acid-proof, is a stiff paste of glycerin and litharge Theseform a chemical combination which sets in a few minutes If a little water is added, it setsmore slowly, which is often an advantage This cement is mixed when required for use Amixture of plaster-of-paris and water is useful, and it is sometimes advantageous to mixstraw or hair with it A solution of silicate of soda made into a stiff paste with carbonate oflime gets hard in six to eight hours

Acid-proof Cements.—The asphalt compositions already mentioned, compositions of

melted sulphur with fillers of stone powder, cement, sand, etc., may be used, and also thefollowing, which withstands hydrochloric acid vapors: rosin, 1 part; sulphur, 1 part; fire-clay, 2 parts The lute composed of boiled linseed oil and fireclay acts well with most acidvapors The composition of glycerin and litharge previously referred to is useful in thisconnection, especially when made up according to the following formula: Litharge, 80pounds; red lead, 8 pounds; “flock” asbestos, 10 pounds It should be fed into a mixer, alittle at a time, with small quantities of boiled oil (about six quarts of oil being used) Sock-ets in 3-inch pipes carrying nitric acid, calked with this preparation, showed no leaks innine months

A particularly useful cement for withstanding acid vapors, which is tough and elastic, iscomposed of crude rubber, cut fine, 1 part; linseed oil, boiled, 4 parts; fireclay, 6 parts Therubber is dissolved in carbon disulphide to the consistency of molasses and is then mixedwith the oil Other acid-proof cements are as follows: “Black putty” made by carefullymixing equal portions of china-clay, gas-tar and linseed oil The china-clay must be welldried by placing it over a boiler or by other means Barytes cement is composed of pure,finely ground sulfate of barium, and is made into a putty with a solution of silicate of soda.This sets very hard when moderately heated, and is then proof against acids The gravity ofthe silicate of soda should be between 1.2 and 1.4, 24 degrees to 42 degrees Baume If toothin, it does not hold; and when thicker than 1.4, it expands and breaks

Gasket Compositions.—Almost any cementing substance may be used with rings of

asbestos, etc., for gaskets, but some are especially adapted for the purpose Asphalt, tar,petroleum residuum and soft or hard pitch are recommended Silicate of soda is much used,and is sometimes advantageously mixed with casein, fine sand, clay, carbonate of lime,caustic lime, magnesia, oxides of heavy metals, such as lead, zinc, iron and powdered

soda, asbestos and slaked lime; silicate of soda and fine sand; silicate of soda and fireclay.

Machinists Cements.—These are also known as red and white leads The red lead is often

diluted with an equal bulk of silica or other inert substance to make it less powdery Thebest way to do this is to add rubber or gutta-percha to the oil as follows: Linseed oil, 6 parts,

by weight; rubber or gutta-percha, 1 part by weight The rubber or gutta-percha is solved in sufficient carbon disulphide to give it the consistency of molasses, mixed withthe oil, and left exposed to the air for about twenty-four hours The red lead is then mixed

dis-to a putty Oxide of iron makes a less brittle cement than red lead

Leather Cements.—a) Equal parts of good hide glue and American isinglass, softened in

water for ten hours and then boiled with pure tannin until the whole mass is sticky The face of the joint should be roughened and the cement applied hot

sur-b) 1 pound of finely shredded gutta-percha digested over a water-bath with 10 pounds ofbenzol, until dissolved, and 12 pounds of linseed oil varnish stirred in

c) 7 1⁄2 pounds of finely shredded india-rubber is completely dissolved in 10 pounds ofcarbon disulphide by treating while hot; 1 pound of shellac and 1 pound of turpentine areadded, and the hot solution heated until the two latter ingredients are also dissolved.d) another leather cement is as follows: gutta-percha, 8 ounces; pitch, 1 ounce; shellac, 1ounce; sweet oil, 1 ounce These are melted together

e) still another is as follows: fish glue is soaked in water twenty-four hours, allowed todrain for a like period, boiled well, and a previously melted mixture of 2 ounces of rosinand 1⁄2 ounce of boiled oil is added to every two pounds of glue solution

Iron and Stone Cements.—When finely divided iron, such as filings or cast iron borings

that have been powdered, is mixed with an oxidizing agent, such as manganese dioxide, or

a substance electro-negative to iron, such as sulphur, in a good conducting solution like salt

or sal-ammoniac, galvanic action sets in very rapidly and the iron swells, by forming ironoxide, and cements the mass together It is best diluted with Portland cement, the propor-tions being as follows: iron filings, 40 parts; manganese dioxide or flowers of sulphur, 10parts; sal-ammoniac, 1 part; Portland cement, 23 to 40 parts; water to form a paste A hardstone-like composition is made as follows: zinc oxide, 2 parts; zinc chloride, 1 part; water

to make a paste Magnesium oxide and chloride may also be used in like proportions.When used in considerable quantity, this cement is mixed with powdered stone, for rea-sons of economy, the proportions depending upon the character of the work

Cement Proof to Hydrocarbon Gases.—Compositions of plaster and cement, the

former setting more quickly, are used; also compositions of casein, such as finely dered casein, 2 parts; fresh slaked lime, 50 parts; fine sand, 50 parts Water is added, whenused, to form a thick mass Various mixtures of silicate of soda are employed in which thethick silicate is absorbed in some inert material such as clay, sand or asbestos

pow-Cements Proof to Chlorine.—The best and only reliable compositions are a few made

with Portland cement, and the following is used for electrolytic and chemical plants: dered glass, 1 part; Portland cement, 1 part; silicate of soda, 1 part; a small amount of pow-dered slate This lute withstands acids and alkalies, as well as the influences of chlorine.Linseed oil made into a paste with fireclay serves for a time

pow-Elastic Cements.—The various cements containing rubber are elastic, if the rubber is in a

predominating amount; many containing boiled linseed oil and the hektograph tion already mentioned are quite elastic The rubber and linseed-oil cement, given in Acid- proof Cements on page 2906, is very tough and useful for nearly all purposes except whenoil vapors are to be confined The most useful single rubber lute is probably the so-calledHart’s india-rubber cement Equal parts of raw linseed oil and pure masticated rubber aredigested together by heating, and this mixture is made into a stiff putty with fine “paperstock” asbestos It is more convenient, however, to dissolve the rubber first in carbon dis-ulphide, and, after mixing the oil with it, to let the solvent evaporate spontaneously

composi-mings, hair, broken stone, etc., and used according to temperature strain and other tions, is one of the most useful preparations for general purposes A putty of flour andmolasses is a good composition to keep in a works ready for quick application whenneeded It serves, for a time, almost any purpose at moderate temperatures Casein compo-sitions have great strength the white of an egg made into a paste with slaked lime is strongand efficient, but must be used promptly on account of its quick setting qualities.

condi-Marine Glue.—This can be purchased almost as cheaply as made It consists of crude

rub-ber, 1 part; shellac, 2 parts; pitch, 3 parts The rubber must first be dissolved in carbon ulphide or turpentine before mixing with the heated combination of the other twoingredients

dis-Acid-proof Lining.—A lining for protecting tanks from the influence of acids is made

from a mixture consisting of 75 parts (by weight), of pitch; 9 parts plaster-of-paris; 9 partsochre; 15 parts beeswax; and 3 parts litharge The tanks are covered on the inside with athick coat of this mixture

Cements for Pipe Joints.—A strong cement which is oil-proof, waterproof, and

acid-proof, consists of a stiff paste of glycerin and litharge These form a chemical combinationwhich sets in a few minutes If a little water is added, it sets more slowly, which is often anadvantage This cement is mixed when required for use

Mixture for Threaded Pipe Joints: A good material to apply to pipe threads before

mak-ing up the joints, in order to obtain a tight joint that will resist the action of gases or liquids,

is made of red lead mixed with pure boiled linseed oil This mixture has been widely usedand is very satisfactory It should have a heavy fluid-like consistency, and if applied to aclean, well-cut thread will give an excellent joint

Shellac for Pipe Connections: Shellac has proved to be a very satisfactory substitute for

lead in sealing air and gas pipe connections It is applied with a brush to the joints and ens very rapidly, and being brittle, the pipes can be readily disconnected

hard-Graphic, Litharge, Chalk Cement: A good cement for use in making steam pipe joints is

made in the following manner: Grind and wash in clean cold water 15 parts of chalk and 50parts of graphite; mix the two together thoroughly and allow to dry When dry regrind to afine powder, to which add 20 parts of ground litharge and mix to a stiff paste with 15 parts

of boiled linseed oil The preparation may be set aside for future use, as it will remain tic for a long time if placed in a cool place It is applied to the joint packing as any ordinarycement

plas-White and Red Lead Mixture: Mix in ordinary white lead, enough powdered red lead to

make a paste the consistency of putty Spread this mixture on the joint, and when it ens, the joint will be water tight This mixture was used on stand-pipe flanges after testingall kinds of rubber gaskets without success The mixture hardened and made a tight joint,never leaking afterward

hard-Adhesives Adhesives Bonding.—By strict definition, an adhesive is any substance that fastens or

bonds materials to be joined (adherends) by means of surface attachment However,besides bonding a joint, an adhesive may serve as a seal against attack by or passage of for-eign materials When an adhesive performs both bonding and sealing functions, it is usu-ally called an adhesive sealant

Where the design of an assembly permits, bonding with adhesives can replace bolting,welding, and riveting When considering other fastening methods for thin cross-sections,the joint loads might be of such an unacceptable concentration that adhesives bonding mayprovide the only viable alternative Properly designed adhesive joints can minimize oreliminate irregularities and breaks in the contour of an assembly Adhesives can also serve

galvanic corrosion when two dissimilar metals such as aluminum and magnesium arejoined together Conversely, adhesive products are available which also conduct electric-ity.

An adhesive can be classified as structural or non-structural Agreement is not universal

on the exact separation between both classifications But, in a general way, an adhesive can

be considered structural when it is capable of supporting heavy loads; non-structural when

it cannot Most adhesives are found in liquid, paste, or granular form, though film and ric-backed tape varieties are available Adhesive formulations are applied by brush, roller,trowel, or spatula If application surfaces are particularly large or if high rates of produc-tion are required, power-fed flow guns, brushes, or sprays can be used

fab-The hot-melt adhesives are relatively new to the assembly field In general, they permitfastening speeds that are much greater than water- or solvent-based adhesives Supplied insolid form, the hot-melts liquefy when heated After application, they cool quickly, solidi-fying and forming the adhesive bond They have been used successfully for a wide variety

of adherends, and can greatly reduce the need for clamping and lengths of time for curingstorage

If an adhesive bonding agent is to give the best results, time restrictions recommended bythe manufacturer, such as shelf life and working life must be observed The shelf life isconsidered as the period of time an adhesive can be stored after its manufacture Working

or “pot” life is the span of time between the mixing or making ready of an adhesive, on thejob, and when it is no longer usable

The actual performance of an adhesive-bonded joint depends on a wide range of factors,many of them quite complex They include: the size and nature of the applied loads; envi-ronmental conditions such as moisture or contact with other fluids or vapors; the nature ofprior surface treatment of adherends; temperatures, pressures and curing times in the bond-ing process

A great number of adhesives, under various brand names, may be available for a lar bonding task However, there can be substantial differences in the cost of purchase anddifficulties in application Therefore, it is always best to check with manufacturers’ infor-mation before making a proper choice Also, testing under conditions approximating thoserequired of the assembly in service will help assure that joints meet expected performance.Though not meant to be all-inclusive, the information which follows correlates classes ofadherends and some successful adhesive compositions from the many that can be readilypurchased

particu-Bonding Metal: Epoxy resin adhesives perform well in bonding metallic adherends One

type of epoxy formulation is a two-part adhesive which can be applied at room ture It takes, however, seven days at room temperature for full curing, achieving shearstrengths as high as 2500 psi (17.2 MPa) Curing times for this adhesive can be greatlyaccelerated by elevating the bonding temperature For example, curing takes only one hour

tempera-at 160°F (71°C)

A structural adhesive-filler is available for metals which is composed of aluminum der and epoxy resin It is made ready by adding a catalyst to the base components, and can

pow-be used to repair structural defects At a temperature of 140°F (60°C) it cures in

approxi-mately one hour Depending on service temperatures and design of the joint, this filler is capable of withstanding flexural stresses above 10,000 psi (69 MPa), tension above5,000 psi (34 MPa), and compression over 30,000 psi (207 MPa)

adhesive-Many non-structural adhesives for metal-to-metal bonding are also suitable for fasteningcombinations of types of materials Polysulfide, neoprene, or rubber-based adhesives areused to bond metal foils Ethylene cellulose cements, available in a selection of colors, areused to plug machined recesses in metal surfaces, such as with screw insets They hardenwithin 24 hours Other, stronger adhesive fillers are available for the non-structural patch-

that combines powdered iron with water-activated binding agents The consistency of theprepared mix is such that it can be applied with a trowel and sets within 24 hours at roomtemperature The filler comes in types that can be applied to both dry and wet castings, and

is able to resist the quick changes of temperature during quenching operations.Polyester cement can replace lead and other fillers for dents and openings in sheet metal.One type, used successfully on truck and auto bodies, is a two-part cement consisting of apaste resin that can be combined with a paste or powder extender It is brushed or trowelled

on, and is ready for finishing operations in one hour

Adhesives can be used for both structural and non-structural applications which combinemetals with non-metals Structural polyester-based adhesives can bond reinforced plasticlaminates to metal surfaces One type has produced joints, between glass reinforced epoxyand stainless steel, that have tensile strengths of over 3000 psi (21 MPa) Elevated temper-ature service is not recommended for this adhesive However, it is easily brushed on andbonds under slight pressure at room temperature, requiring several days for curing Thecuring process accelerates when heat is added in a controlled environment, but thereresults a moderate reduction in tensile strength

Low-density epoxy adhesives are successful in structurally adhering light plastics, such

as polyurethane foam, to various metals Applied by brush or spatula, the bonds curewithin 24 hours at room temperatures

Metals can be bonded structurally to wood with a liquid adhesive made up of neopreneand synthetic resin For the best surface coverage, the adhesive should be applied in a min-imum of two coats The joints formed are capable of reaching shear stresses of 125 psi, andcan gain an additional 25 percent in shear strength with the passage of time This adhesivealso serves as a strong, general purpose bonding agent for other adherend combinations,including fabrics and ceramics

For bonding strengths in shear over 500 psi (3.4 MPa) and at service temperaturesslightly above 160°F (71°C), one- and two-part powder and jelly forms of metal-to-wood

types are available

Besides epoxy formulations, there are general purpose rubber, cellulose, and vinyl sives suitable for the non-structural bonding of metals to other adherends, which includeglass and leather These adhesives, however, are not limited only to applications in whichone of the adherends is metal The vinyl and cellulose types have similar bonding proper-ties, however the vinyls are less flammable and are weaker in resistance to moisture thanthe comparable cellulosics Rubber-based adhesives, in turn, have good resistance to mois-ture and lubricating oil They can form non-structural bonds between metal and rubber.One manufacturer has produced an acrylic-based adhesive that is highly suitable for rap-idly bonding metal with other adherends at room temperature For some applications it can

adhe-be used as a structural adhesive, in the absence of moisture and high temperature It cureswithin 24 hours and can be purchased in small bottles with dispenser tips

A two-part epoxy adhesive is commercially available for non-structural bonding ofjoints or for patchwork in which one of the adherends is metal Supplied in small tubes, itperforms well even when temperatures vary between −50° to 200°F (−46° to 93°C) How-

ever, it is not recommended for use on assemblies that may experience heavy vibrations

Bonding Plastic: Depending on the type of resin compound used in its manufacture, a

plastic material can be classified as one of two types: a thermoplastic or a thermoset.Thermoplastic materials have the capability of being repeatedly softened by heat andhardened by cooling Common thermoplastics are nylon, polyethylene, acetal, polycar-bonate, polyvinyl chloride, cellulose nitrate and cellulose acetate Also, solvents can easilydissolve a number of thermoplastic materials Because of these physical and chemicalcharacteristics of thermoplastics, heat or solvent welding may in many instances offer abetter bonding alternative than adhesives