[Report on Oxygen-Acetylene Welding and Brazing in Automotive Repairs]
[From the U.S. Government Publishing Office, www.gpo.gov]

Report on
OXYGEN-ACETYLENE WELDING AND BRAZING IN AUTOMOTIVE REPAIRS
Submitted to maintenance section
OFFICE OF DEFENSE TRANSPORTATION
by MAINTENANCE METHODS COORDINATING COMNÏfeEE OF TRANSPORTATION AND MAINTENANCE ACTIVITY SOCIETY OF AUTOMOTIVE ENGINEERS, INC.
U. S. GOVERNMENT PRINTING OFFICE - WASHINGTON - 1945
For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 10 cents
SAE Maintenance Methods Coordinating Committee
W. J. Cumming, Chairman, Chief, Maintenance Section, Office of Defense Transportation.
E.	P. Gohn, Vice-Chairman, Automotive Test Engineer, The Atlantic Refining Company.
E.	N. Hatch, Senior Mechanical Engineer, New York City Transit System.
M. E. Nuttila, Superintendent, Motor Vehicles, Cities Service Oil Company.
C.	W. Laurie, Manager, Automotive Transportation Dept., The Atlantic Refining Company.
S. B. Shaw, Automotive Engineer, Pacific Gas & Electric Company.
W. A. Taussig,- Automotive Engineer, Burlington Transportation Company.
E. W. Templin, Automotive Engineer, Los Angeles Bureau of Power & Light.
D.	K. Wilson, Superintendent, Automotive Equipment, New York Power & Light Corporation.
A. M. Wolf, Automotive Consultant.
Subcommittee On "Welding In Maintenance”
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Major E. C. Wood, Chairman, Div. Supt., Transportation, Pacific Gas & Electric Company.
Floyd Clothier, Shop Foreman, Los Angeles Bureau of Water Works & Supply.
H. J. Fox, Master Mechanic, Consolidated Rock Company.
Frank Gill, Motor Mechanic, Gilmore Oil Company.
Fred Grohs, Field Service Engineer, Victor Equipment Company.
Charles Hudson, Automotive Engineer, Tennessee Valley Authority.
W. W. Mills, President, Mirocol Alloys Company.
L. E. McKibben, Superintendent of Shops, Lang Transportation Company.
F. C. Patton, Manager, Los Angeles Motor Coach Lines.
W. E. Powelson, Master Mechanic, Los Angeles County Fire Dept.
W. R. Smith, Welding Engineer, Lincoln Electric Company.
E.	W. Templin, Project Chairman
OXYGEN-ACETYLENE WELDING AND BRAZING IN AUTOMOTIVE REPAIRS
Welding is a general term which applies to a number of processes by which metals are joined together.
Fusion welding refers to processes in which the joint surfaces of the metals to be joined are heated to the molten state and the joint is completed without the application of mechanical blows or pressure. Welding in the automotive repair industry is, to a great extent, fusion welding and is generally performed with either the oxygen-acetylene torch or with the \ electric arc. Usually additional metal is added to the joint in automotive repair welding work.
Brazing is a type of gas welding process in which a nonferrous metal or alloy, other than one of the tin-lead solders, is used as the filler metal and the joint is made without melting the base metals to be joined. (See figures 1, 2 and 3.)
It is the purpose of this report to describe oxygen-acetylene welding and brazing as a method for the reclaiming and renewal of used automotive parts. Welding has been generally successful when the proper techniques have been used. The information given is based, as far as possible, upon successful American truck-fleet maintenance experience. The report explains the method, describes the required equipment, discusses the desirable qualifications of the operators, and outlines briefly the techniques and costs involved in completing repairs in a number of typical cases.
Information is included regarding new techniques for which experience is limited but which have promise of being important to fleet operators, especially under emergency conditions.
i. « Fusion welding with the electric arc is discussed in a companion booklet entitled, “Electric Arc Welding in Automotive Repairs.”
For the benefit of beginners in welding, a partial list of references is given at the end of the booklet.
OXYACETYLENE WELDING
Oxyacetylene welding is a form of fusion weldingi The heat required is supplied by a high-temperature flame produced by burning a mixture of oxygen and acetylene gases. The two gases are mixed in the proper proportions in a welding blowpipe or torch which is designed to give the operator complete control of the welding flame.
Acetylene is almost universally used as the combustible gas in welding because the combustion of a mixture of nearly equal volumes of oxygen and acetylene produces a flame having a temperature far higher than that of any other known gas flame. The temperature of the oxyacetylene flame, approximately .6000° F., is so far above the melting point of all commercial metals that it provides a means for the rapid localized melting that is essential in welding. The oxyacetylene flame is used also for preheating, cutting, shaping, and flame machining of ferrous metals and as a convenient source of localized heat for a wide variety of operations such as hard-facing, flame-hardening, flame-softening, and flame-descaling.
Fundamentally, oxyacetylene welding may be considered as the process of bringing two pieces of metal together and melting the edges in contact by manipulating the oxyacetylene flame produced at the tip of the welding blowpipe or torch.
In actual practice, to assure complete penetration, on other than the thinner sections, the edges of the abutting plates are beveled so that a “vee” is formed and the welding rod is added to fill up the “vee” and join the two pieces.
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Warpage caused by welding can be controlled or reduced by a number of different methods. Welds can be “peened” so as to dissipate welding stresses ■and, if properly done, can overcome severe warpage.
BRAZING
It is possible to produce sound, strong joints in metals without actually melting the base metal. Thus, in brazing, or bronze-welding, the edges of the joint, after thorough cleaning, are simply heated to a dull red heat by the oxyacetylene flame. With the base metal at the proper temperature and with the aid of a suitable flux, molten metal from the brazing rod will unite with the base metal to form a strong bond.
OXYACETYLENE WELDING EQUIPMENT
Oxyacetylene welding and cutting equipment is so inexpensive and useful that every fleet that operates its own shop, small or large, will find its cost a worth while investment. Costs will vary with volume of work, variety of work, etc.
The following costs are representative:
1.	Small-garage, bottled-gas welding outfit with regulators, hose, lighter, goggles, four assorted tips— light-duty only. Cost—$5O-$75.
2.	Small-shop, bottled-gas, welding and cutting combination torch outfit, 4-5 welding tips, cutting attachment, regulators, goggles, lighter, hose, etc. Medium-duty work. Cost—$75-$100.
3.	Medium-duty shop outfit for bottled gas with separate heavy-service cutting torch and welding torch, manifold regulator hook-up to permit cutting and welding simultaneously, tank cart, hose sets, extra tips, cleaners, lighters, etc. Cost—$125-$175.
Due to a scarcity of acetylene cylinders, the War Production Board has made it possible for every repair station, regardless of size, to obtain acetylene generators in which carbide and water are used to produce acetylene gas. The barriers formerly put up by fire departments against the use of generators have now been almost completely removed and no difficulty need be anticipated from this source, but should be investigated locally in each community.
These generators are available in suitable capacities and may be either portable or stationary:
6 lb. Size— 30 cu. ft. of gas—costs approx. $90.	1 small
per charge	torch
25 lb. Size—125 cu. ft. of gas—costs approx. $150.	1 large
per charge	torch
100 lb. Size—500 cu. ft. of gas—costs approx. $375.	5 or 6
per charge	large
torches
OPERATORS (WELDERS)
Welding requires training and skill on the part of the operator. The experience necessary for proficiency in applying the process to different types of work varies. The United States Government recommends 200 hours of welding practice for beginners in work similar to that required in the shipbuilding industry. Experience has shown that 200 to 300 hours of welding practice, plus a study of metals, is sufficient to enable the welder to accomplish satisfactory results in the reclaiming and renewal of automotive parts.
Castings of iron and aluminum require different techniques from mild steel, but a welder who can successfully weld mild steel can, with proper procedure outlined for him, be entrusted with other metals and more complicated parts.
PARTS REPAIRABLE BY WELDING
Fleet operators report successful experience' in reclaiming and renewal by welding processes the following lists of automotive parts:
By Gas-Welding
aluminum castings anchor plates axle housings battery parts bearing housings bell housings bodies brackets brake drums bumpers bushings cabs
clutch parts control rods crankcases cylinder blocks cylinder heads door handles door hinges
door locks exhaust pipes fans fenders
fender brackets fifth wheels frames
front axles gasoline pumps gasoline tanks gears
gear covers gear shift levers grilles
hood parts housings iron castings manifolds motor supports
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oil pang	step plates
propeller shafts	tail gates
radiators	tie rods
rims	tire chains
rollers	tools
seat frames	torque tubes
shafts	transmission cases
sheet-metal parts	transmission shafts
shock-absorber links	valve covers
speedometer cables	wheels
spring hangers	water pump
spring leaves	wheel bushings
spring shackles	wheel hubs
	By Brazing
armature shafts	gear-shift levers
axle housings	generator pulleys
bearing seats	manifolds
bearing surfaces	oil pans
bell cranks	pistons
brake cams	propeller shafts
brake drums	pump shafts
brake levers	rims
brake pedals	spring hangers
brake pins	spring shackles
brake shafts	stud holes
brake ratchets	studs
brake shoes	thrust plates
bumpers	tie rods
bushings	tools
castings	torque tubes
clevises	transmission covers
clutch parts	universal joints
clutch plates	valve seats
cylinder heads	water pumps
differential carriers	wheel hubs
differential cases	worn holes
door plates	Worn gears
flywheel faces	worn shafts
gears (light-duty)	
COSTS OF WELD REPAIRS
Costs for repairs by welding of automotive parts are almost always well within the cost of replacement. Typical job-shop prices on cylinderhead reclaiming are: (Prices are based on conditions existing in midyear 1943 on the eastern and western seaboards.)
Ford V-8 Aluminum ..................................$ 7.00
1932 Chevrolet ..................................... 7.50
1933-34 Chevrolet ..........................f....... 9.00
1935-41 Chevrolet .............:................... 10.00
Caterpillar Tractor RD8 ..............*............ 50.00
Caterpillar Tractor RD7 ........................... 40.00
Farmall-International Tractor...................... 15.00
AC Tractor GMC Diesel Engine ...................... 12.00
CAUSES OF WELD TROUBLES
The automotive repair welder’s job is not easy because of the variety of materials and shapes which he is called upon to repair. Only by the correct analysis and handling of all the factors present in a given job can good welds be made. When weld failures result, the following items should be rechecked with reference to the welding methods used :
Improper kind of welding rod
Improper size of welding rod
Improper preparation of weld joint
a.	bevel too narrow
b.	bevel not spaced properly
c.	work not thoroughly cleaned
Insufficient preheating
Excessive preheating
Incomplete slag removal
Overheating the weld area
Excessive weld metal
Oversized tack welds
Improper welding sequence
Improper clamping of parts
Improper manipulation of welding rod
Poor root penetration
Improper flux
Too rapid cooling
Unsuitable gas pressures
Incorrect flame
AUTOMOTIVE WELDING REPAIR JOBS
Many of the automotive parts listed earlier as repairable by welding are of simple design and the welding techniques required for their repair are usually covered in welding instruction courses. A number of automotive parts, however, are more difficult rèpair problems, either because of their complex structure or because of their chemical composition and the heat treatment required.
In order to show how oxyacetylene welding can be used to repair the more complex automotive parts, typical jobs using gas welding are described in detail. The examples cover the principles and techniques involved in the most difficult automotive welding repair jobs. The welder can apply the principles and methods outlined to other parts having complex structures and made of similar metals.
PREHEATING
The term preheating applies to the preliminary heating of the base pieces before welding. The purpose of preheating is to prevent residual strains and
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cracking breaks which might be caused by unequal or localized expansion of the metal when the edges of the pieces are suddenly raised to welding heat and then quickly cooled.
Preheating is usually required on cast-iroq and aluminum castings and on many hardened steel parts. The larger the part and the more complex the design, the greater the need for preheating, especially if the weld is extensive. Small, simple pieces requiring small welds frequently can be welded without preheating. However, if cracks or breaks develop in the welded pieces which were not preheated, preheating should be considered on subsequent jobs as a way of eliminating this type of failure.
It is essential in preheating that the pieces be well supported to preyent sagging and to keep the pieces in correct alignment.
Preheating can be accomplished by different methods. The choice of methods will depend upon the size of the piece and the frequency with which the same type of welding job is performed by a shop.
Many shops have found it worth while to construct gas heated ovens of a size to just contain the pieces to be welded. These ovens are usually made of sheet iron and are equipped with removable covers or doors, so that only the portion of the piece to be welded need be uncovered and the welding done in the preheating oven.
Where the oven is not constructed with welding openings, it is best to cover the entire piece to be welded with sheet asbestos paper before the piece is placed in the oven. Then, just before welding, and after the piece has been removed from the oven, the asbestos paper can be torn away at the area to be welded. In this way, the balance of the piece is protected against drafts and too rapid cooling.
In the case of large pieces, such as complete engine castings and cylinder blocks which are only occasionally welded in a shop, a charcoal oven may be found to be the simplest way of preheating the casting. The casting should be firmly supported on a number of firebricks laid on a firebrick platform. A rough firebrick wall can then be built around the casting and arranged with several holes around the bottom edge to admit air for combustion. The furnace is then partially filled with charcoal
below and around the casting. After the charcoal is ignited at several places, it will burn with a soft slow even heat which will not injure the casting. A slow fire should be used in order to heat initially the casting throughout. Charcoal should be added to the top as needed and the top of the furnace covered with sheet iron or asbestos. The temperature of the furnace should be controlled by covering or uncovering the air inlet holes and by controlling the draft with the cover over the top of the furnace. In using the charcoal type of furnace, special attention must be given to ventilation in the shop as dangerous amounts of carbon monoxide gas are produced by slow burning charcoal.
Where the pieces are small, they can sometimes be preheated satisfactorily by playing the oxyacetylene flame over the piece until its temperature is raised to a satisfactory preheating point.
Preheating temperatures above 750° F., can be estimated, after considerable practice, from the color or appearance of the metal. In the table below are given color descriptions and their corresponding approximate temperatures.
Color	Degrees F.
Faint red, visible in dark................... 750
Faint red .................................   900
Blood red ...................................1050
Dark cherry ................................ 1175
Medium cherry ...............................1250
Cherry or full red ........................  1375
Bright red ..............................    1550
Salmon ................................      1650
Orange ....................................  1725
Lemon .......................................1825
Light yellow ................................1975
White heat ..................................2200
Preheating temperatures below 750° F., can be estimated by other methods. If pyrometer equipment is available, it can be used to measure temperatures.
The end of a bar of 50-50 solder can be rubbed on the surface of a piece being heated. When the solder begins to mark the metal, the temperature is about 300° to 325° F. When the end of the bar of solder begins to melt, the temperature of the metal is between 400° and 500° F.
Dry sawdust’ chars at about 600° F. A pine^, stick rubbed on a casting will show a char mark at about 700° F.
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There are also available on the market wax crayon sticks, known as “tempil” sticks, which come in different grades for different temperatures between . 100° and 1000° F. In use, the appropriate grade * of crayon stick is rubbed on the surface of the metal being heated. When the end of the crayon stick just melts enough to mark the metal, the indicated temperature has been reached. The crayon stick should be applied at short intervals while the part is being heated, otherwise misleading indications may be obtained.
When a piece which is to be preheated has finished surfaces which are not a part of the area to be welded, it is usually desirable to coat such finished surfaces to protect the finish against pitting or etching in the preheating furnace. Pastes made of lampblack and adhesive, known as carbon pastes, are available from welding supply dealers. Other ready-mixed, proprietary compounds are also available for use in coating surfaces. Directions for the use of the various coating pastes are usually given on the package.
SLOW COOLING AND POST HEATING
Proper cooling is frequently very important for obtaining satisfactory welding repair jobs. The rate of cooling will depend upon the kind of material used and the size and complexity of the piece. Small pieces will frequently cool satisfactorily if merely laid in the open air. As the size of the piece increases, it is necessary to guard against unequal or too rapid cooling of the piece.
Slow cooling is frequently accomplished by replacing the piece in the furnace and slowly reducing the heat, allowing the piece to cool with the furnace. Some shops have found it preferable to bury the welded pieces in dry sand, powdered asbestos or other proprietary materials and permit the piece to cool slowly while buried for a period of 24 hours or longer. -
If the repair weld is such that cracks develop during cooling, it is frequently helpful to reheat the piece to the preheated temperature, and hold it at this temperature for a short time so that the internal strains may be relieved and then permit the piece to cool down slowly from its reheat temperature.
In welding cast iron, slow cooling and sometimes
reheating is especially desirable. The slow cooling permits any excess carbon in the weld metal to precipitate out in the form of graphitic flakes, with the result that the weld is softer and easier to machine.
SIZE OF FLAME
The size or capacity of the flame produced' by an oxyacetylene torch depends upon the size of the torch tip selected. With certain torches it is sometimes necessary to change other parts of the torch when the tip size is changed. It is advisable to follow the manufacturer’s instructions regarding specific makes of torches in this respect.
The temperature of the different sized flames is about the same, varying from 5700° to 6300° F. The amount of heat produced, however, depends upon the size of tip used. The larger the tip, the greater the volume of heat available for welding. The larger tips consume more bxygen and acetylene so that the selection of a tip for any job depends upon the size of the weld to be made, to some extent upon the size of the piece, and the rate at which the operator can proceed with the weld- Using too large a tip on a small job may not only waste oxygen and acetylene but may make the work more difficult because too large an area may be heated and melted. On the other hand, using too small a tip may cause poor welds because the base metal is not properly melted and fused into the weld metal. Suggestions are given in the job sheets as to suitable tip sizes.
Torch manufacturers use different code numbers to indicate the sizes of their welding cutting tips. Almost all tips, however' approximate closely the size of numbered drills. Numbered drills are an easy shop method of identifying the tips of various manufacturers. In the job sheets, suitable tip sizes are indicated by numbered drill sizes.
In the table below are given the numbered drill sizes which most closely approximate the tips made by the various torch manufacturers. With the aid of this table, even worn or used tips can be classified for shop use. In the table are shown the approximate settings for the oxygen and acetylene regulators for the different sized tips, as well as the approximate oxygen and acetylene consumption for each tip size.
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WELDING TIP CHART
Drill size of tip	Regulated Acetylene	Pressure, p.s.i. Oxygen	Gas consumption, cu. ft. per hour for neutral flame	
			Acetylene	Oxygen
74		p.s.i. 1.0	p.s.i. 1.0	cu. ft. 1.0	cu. ft. 1.1
69		1.0	1.0	2.0	2.2
64		2.0	2.0	4.8	5.3
57		3.0	3.0	8.8	9.7
55		4.0	4.0	15.9	17.5
52		5.0	5.0	24.8	27.3
49		6.0	6.0	31.6	34.8
45		7.0	7.0	38.7	42.6
42	.1	■.	7.0	7.0	60.0	66.0
37		8.0	8.0	72.0	86.0
30		9.0	9.0	88.0	105.0
25		10.0	10.0	122.0	146.0
20		12.0	12.0	156.0	187.0
TYPE OF FLAME
There are four types of flames used in oxyacetylene welding. All four of these flames can be obtained from any oxyacetylene torch. As a general rule, these different flames are produced by slight adjustments of the valves on the torch; however, with large tips it may be necessary to change the regulator adjustments.
The various flames are pictured in color in some manufacturers’ instruction manuals and the novice welder should refer to these pictures in his early practice. The use of the four types of flames are briefly described below.
The neutral flame is used for most welding.
The oxidizing flame is produced when there is an excess of oxygen in the flame. The oxidizing flame is not used in welding but is a common cause of poor welds and for this reason it is included in the nomenclature of welding. The oxidizing flame produces excessive foaming and sparking of the metal and produces excessive amounts of oxide in the weld. A slightly oxidizing flame is frequently used in brazing.
The reducing flame is produced by a slight excess of acetylene in the flame. The reducing flame is used in certain kinds of welding, especially when it is desired to produce very soft welds. Aluminum should generally be welded with a neutral flame, slightly on the reducing side.
The carburizing flame is produced by a greater
excess of acetylene in the flame than was used in the reducing flame. With the carburizing flame, carbon from the acetylene may enter the metal and produce hard spots in the weld. The carburizing flame is sometimes used in hard surfacing as here 4 the action of the flame supplements the hard surfacing process.
WELDING ROD
The composition of the welding rod, used to supply filler metal in making welds, is an important factor in obtaining good welds. While the composition of the welding rod selected depends on the composition of the base metal to be welded, this does not mean that the composition of the welding rod is in all cases the same as that of the base metal. The alloys composing the base metal or the original heat treatment also have an effect on the quality of the weld. For example, ordinary gray cast iron is best welded with a cast-iron rod which is high in silicon; while alloy cast irons, such as are used in some truck engine blocks, require a cast-iron rod containing molybdenum and nickel; and malleable iron, which is a heat-treated form of white cast iron does not weld satisfactorily. Similar variations occur with different types of steel and other metals.
Welding rod manufacturers make many types and compositions of welding rod in order to supply suitable rods for each type of metal. Due to the number of types of rods and the number of manufacturers, the specific code numbers of various rods cannot be given in the job sheets. The manufacturer of welding rod should be consulted regarding the correct rod of his make for the specific welding job to be done.
Stocks of welding rods should be kept carefully separated in the shop as nothing is so likely to produce poor welds as the use of an incorrect rod.
WELDING FLUX
A flux is a fusible material used to dissolve and prevent the formation of oxides, nitrides, or other undesirable inclusions formed in welding.
Fluxes are made by many manufacturers under many trade names. The selection of a flux depends upon the composition of the base metal to be welded. “ The manufacturer of the flux should be consulted
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in regard to the proper type of fluxes for a specific welding job. In general, it may be said that there are no satisfactory fluxes which can be used universally on all metals.
F In the shop, fluxes should not be mixed up and the containers should be kept clean so that the contents can be correctly identified.
IDENTIFICATION OF METALS
The composition of any metal to be welded or brazed should be identified as accurately as possible in order that the best welding rod and welding flux can be selected for the job. Information regarding
OXYGEN-ACETYLENE
Engine Cylinder Blocks
Job: To repair cracks or breaks in water jacket or other portion of block casting.
Material : Cast iron.
Preparation: Clean oil and dirt thoroughly from crack and area adjoining crack. Solvents or alkali solutions should be used to remove all traces of oil or grease. All breaks should be located and marked with a center punch. The cracks should be “veed” out with a chisel and a hammer to as near 90 degrees as possible. The cylinder walls should be covered with a light coating of carbon paste to prevent damage to surfaces during preheating.
Welding Rod: Cast-iron welding rod—3/16 inch size.
Flux: Cast-iron flux.
Welding Tip Size: Medium, ranging from 30- to 45-drill size.
Flame: Neutral.
Preheat: In a preheating surface, heat the entire casting to dull, cherry red. Bring up the temperature slowly so as to prevent the development of local stresses during the preheating and to insure that all parts are at same temperature.
Welding Procedure: When the casting has reached a dull, cherry red throughout, tear a small opening in the asbestos paper covering and proceed. If the break is long, a continuous weld should not ' be made, unless it can be completed at an opening in the casting, such as, water port or plug, an
the composition of a part or piece usually is available from the part manufacturer. If time does not permit the obtaining of such information from the manufacturer, many metals and compositions can be identified by the “spark” test.
A portion of the broken piece is held against a high-speed power grinder in such a way as to produce a stream of sparks which can be observed. The sparks from various metals have different appearances and with practice the spark streams can be identified. A chart is given on page 14 which shows the typical shape and appearance of the sparks from a number of metals.
WELDING REPAIR JOBS
edge, or a corner. If such an ending to the weld cannot be made, it is wise to weld the crack in steps. Weld about 2 inches, then skip about 2 inches, and so on, returning later to finish the parts that have been skipped.
When the welding has been completed, the ‘casting should be examined carefully while hot to see that there are no additional cracks.
Treatment After Welding: If no cracks are found, the casting should be covered so that a slow, gradual cooling rate may be maintained.
Check head surfaces and bearing mounts for alignment and overall length. If not found true, as a general rule a few thousandths have to be machined off of the gasket surface to make the head true and the bearing mounts may have to be brazed to the proper alignment.
Aluminum Engine Crankcase
Job: To repair cracks or breaks in cast-aluminum crankcase.
Material: Cast-aluminum alloy.
Aluminum has several properties which must be understood in order to do successful welding repair work. It conducts heat very rapidly and has a low melting point, melting before it shows a red heat in daylight. Aluminum is also weak when hot, so aluminum castings should always be supported in such a way that they will not collapse or sag during preheating or welding. Molten aluminum oxidizes very rapidly, the oxide
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forming a thick, heavy scum over the surface of the metal. Excess oxide may be removed during welding either by the use of flux or by scraping with a steel paddle or puddling rod formed by heating and flattening a ^-inch steel welding rod. Preparation : Thoroughly *clean the crankcase.
The metal on the surface near the break should be lightly filed to remove any dirt that may remain on the casing.
Next, the broken pieces should be fitted into place, carefully lined up and lightly clamped with C-clamps. Do not clamp too tightly as this may cause a break during heating.
Welding Rod: 5-percent silicon aluminum, 3/16 inch size.
Flux: A good, aluminum flux (most fluxes have instructions on jar for proper mixing).
Welding Tip Size: Medium small, ranging from 53- to 56-drill size.
Flame: Neutral or slightly reducing.
Preheat: Use preheating furnace, blocking the casting in such a position that the fracture is as nearly horizontal as possible. Heat slowly until the casting is just hot enough to melt solder or char sawdust. Care must be taken not to overheat. The metal should feel soft when scraped with the puddling rod.
Welding Procedure: Have a steel puddling rod and sufficient rod and flux at hand. Remove the asbestos paper covering over the section to be welded. Heat the metal at the middle of the break and work toward one end. Keep the flame moving, as aluminum melts easily and does not show color. When the metal is soft, use a puddling rod to scrape out a “vee” about 2 inches long.
When the “vee” has been scraped out almost to the bottom of the section, begin adding the welding rod. (This cannot be added by adding the rod to the puddle of molten metal as in steel or cast-iron welding). Hold the rod in the flame near the base metal and it will quickly begin to run into the prepared channel. When a little puddle has been formed, put the welding rod into it with a rubbing motion of the rod. Be sure to get to the bottom of the “vee” and up both sides. This-breaks up a thin coating of oxide which forms almost instantly and allows the added
metal to form a true weld with the sides of the joint.
When the 2-inch section is finished, reheat it carefully until soft, and smooth it down with the puddling rod.
Continue by “veeing,” welding and smoothing, in 2-inch sections.
Treatment After Welding: Bring the casting up to the same heat as obtained when weld was started; allow to cool in furnace. Finish the weld by filing off any projections that might interfere with use.
Figure 1. Broken Crankshaft.
Automotive Leaf Spring
(Emergency Recommendation)
Job: To weld a broken spring leaf.
Material: Carbon steel and alloy steel.
Preparation : Clean thoroughly. Grind the broken spring leaf to a 90-degree “vee” on both sides, that is, for. a double “vee” weld. Line the pieces _ up and tack-weld each edge so that the leaf will stay fairly straight while welding. See that the
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Figure 2. Crankshaft welded.
leaf has the right curve in it at this time, as shaping after the weld is complete is not desirable.
Welding Rod: Alloy steel rod, %-inch size.
Carbon 0.30 to 0.40 percent.
Manganese 0.50 to 0.80 percent.
Silicon 0.20 percent to maximum.
Chromium 0.50 to 0.75 percent.
Nickel 1.00 to 1.50 percent.
Tip Size: Medium small, 53- to 56-drill size.
Flame: Neutral. (Care should be taken not to use an oxidizing flame.)
Preheat: The leaf should be brought to a red heat
throughout the entire area where the weld is to be made. Approximately 1325° F.
Welding Procedure: Weld across the “vee,” completing the “vee” on the one side. Before welding the other side, be sure the leaf is hot all the way across the second “vee.” Weld the second “vee” and allow the leaf to cool without covering, away from drafts.
Treatment After Welding. When the weld is cool, reheat the leaf to a cherry red (1325° F.) about 2 inches each way from the weld and allow the leaf to cool without covering, away from drafts. After following this welding procedure, the spring leaf may be heat-treated to its original hardness.
Automotive Bumpers and Brackets
Job: To repair broken bumper bars and brackets.
Material: 0.75 to 0.90 percent carbon steel (spring steel).
Preparation: Clean thoroughly. “Vee” each side, leaving contact points for proper alignment. Tack weld lightly on each side.
Welding Rod: High tensile alloy, steel rod. %-inch size.
Welding Tip Size: Medium small, 53- to 56-drill size.
Flame: Neutral. (Care must be taken not to use an oxidizing flame.)
Preheat: Area to be welded should be brought to a cherry red.
Welding Procedure: Weld up the “vee,” keeping
Figure 3. “Close«Up” of weld.
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the weld as flush as possible. Repeat this operation on the other side.
If it is possible to reinforce the weld with a bar-set behind or in front of the bumper bar or bracket, overlapping the weld, it is desirable to do so. This reinforcement may be made of any mild steel and should be welded with the alloy steel welding rod along the top and bottom edges of the bar but not at the ends.
Fuel Tanks
Job: To repair leaks in automotive fuel tanks.
The repair of fuel tanks is another phase of welding work which, although no different from other sheet-metal work, demands the utmost caution. The tank should always be removed from the car and the following safety precautions observed before starting work:
1.	Used tanks must be thoroughly cleaned by circulation of hot water mixed with an alkaline cleansing agent such as commercial metal cleaning compounds, washing soda, lye soap, or caustic soda. (Caustic soda must be used with caution to avoid injury to skin.) Use piece of brass chain to help removal of gum scale or other material sticking to interior surface of tank.
2.	Tanks must be thoroughly rinsed with fresh water and dried at a temperature not to exceed 212° F. for a period of from 4 to 12 hours. This aids the removal of remainder of inflammable material from crevices and seams of tanks. Any old applied metal patches should be given special attention to drive out any fuel caught under patch.
3.	Before starting repair work, tank must be thoroughly rinsed with carbon tetrachloride to prevent explosive gas mixtures from forming. This treatment should be repeated if much work is to be done on tank.
4.	Keep open flame, lights, flashlights, or tools that produce sparks away from vicinity of tank until operation No. 3 has been completed. Welder should keep his head and arms as far away as possible from head of the tank when welding.
BRAZING
By means of brazing, sometimes called brazewelding or bronze-welding, strong joints can be made in cast iron, malleable iron, steel, wrought
iron, copper, brass, bronze and other metals. Practically all commercial metals, except^ those which have melting points lower than that of the brazing rod used, can be brazed. This process is used for repairing parts made of such commercial metals and for building up worn surfaces.
The process of brazing is based upon the fact that molten bronze will form a strong bond with metal surfaces which are clean and properly fluxed, and which have been heated to the proper temperature. In brazing metals with higher melting points than bronze, it is not necessary to melt the base metal. Thus, the weld will progress more rapidly than it could if fusion of the base metal -were required. Castings, with a few exceptions, can be braze-welded without extensive preheating. Frequently, repairs can be made in place without dismantling.
A general technique for brazing which covers many of the simpler jobs is outlined here. Essentially the same technique applies to any metals which are to be brazed. Success in brazing is largely dependent upon the use of good quality, suitable bronze rod and flux. The surface of the metal must be clean, fluxed and heated to the proper temperature to obtain a strong bond between bronze and the base metal.
Thoroughly clean thfe metal in the vicinity of the part to be welded by chipping or grinding. In the case of a fracture, “vee” the edges of the break. When it is necessary to obtain full strength of the joint, it is advisable to “vee” up to 120° included angle. Place the parts in the proper position for joining, using clamps or jigs if necessary to hold the parts in correct alignment.
For most automotive work, the welding torch will furnish all the heat required to bring the parts to the proper temperature for brazing.
When parts are in position for brazing, play a slightly oxidizing flame on the metal. The flame should be directed in a circular fashion for some distance around the starting point of the braze, expanding the metal slowly and bringing it gradually up to the desired temperature. This is just below a red heat or when the metal commences to glow. This is the ideal temperature for brazing r and the metal temperature should not be allowed to fluctuate. If the metal becomes too hot, the
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brazing rod metal tends to boil and form into drops * which roll off as fast as the rod is added. If the metal is too cold, the brazing does not form as strong a bond with the surface of the metal as it should.
When the metal begins to glow, heat the end of the brazing rod in the torch flame and dip the Kot end in the flux so that sufficient flux will adhere to the rod. Then, melt the end of fluxed rod on to the heated spot on the metal. With the metal at the proper temperature, the molten bronze will flow in a thin layer and spread out over the heated
area. This flow will be like water, spreading out over a clean, damp surface, and will not have the appearance of water on a greasy surface. This operation is known as “tinning” and is a vitally important factor in brazing as it provides the strong bond between the bronze and the base metal.
After the “tinning” operation has been completed, more bronze rod can be added rapidly and the “vee” or surface quickly built up.
It is advantageous for a braze-weld to cool slowly while protected from drafts. No stress should be put on a brazed joint until it has completely cooled.
OXYACETYLENE BRAZING REPAIR JOBS
Engine Valve Seats
Job: To rebuild worn engine valve seats.
Material: Cast iron.
Preparation: Remove cylinder block from chassis. Clean thoroughly. Counterbore the valve seats so that when the bronze seat is built and machined to size, the amount of bronze surrounding the finished valve seat will be about 1/32 inch too small for valves (up to 1^ inch O.D.), and 1/16 inch too small for larger valves. It is < important that the counterbore remove any part of the old seat in case the valve has worn into the block. Cover cylinder walls with light coat of carbon paste.
Welding Rod: Bronze, 5/32 inch diameter, of suitable quality.
Flux: Good, cast-iron brazing flux.
Welding Tip Size: Medium, ranging from 30- to 45-drill size.
Flame: Use a slightly oxidizing flame.
Preheat: Using preheat furnace, heat casting to a glowing heat. Support casting carefully to prevent distortion or sagging of block.
Procedure: Remove the asbestos cover over the first valve seat to be built up. Apply the bronze rod around the inner edge of the seat at the bottom, forming a ridge of bronze sufficient to keep the further application of the filler metal from running down into the cylinder port.
Then, build up the whole seat sufficiently to ¡9 allow for the machining operation in the same way as all other brazing operations. The built-> up valve seat should not be less than 3/32 inch
in thickness on small valves and 1/8 to 5/32 inch on large ones.
Treatment After Welding: A gradual cooling rate should be maintained. Check bearing mounts and head surfaces for alignment. On large blocks, 5-inch bore or greater, it is sometimes necessary to rebore.
Engine Cylinder Block
Job: To repair cracks or breaks in an engine cylinder block.
Material: Cast iron.
Preparations The location of the break and the skill of the operator are the factors which determine whether the cylinder block should be removed from the chassis for bronze-welding. Cracks in cylinder blocks are of several types. Perhaps the easiest to repair are cracks which occur in the water jacket. In addition, cracks occur in the corners of the block, in the bottom part of the block and in the cast-iron arms which are a part of some engines. For the latter type of break, it is always necessary to take the block out of the car because even though no preheating is done, it would be impossible to support the block in line when it is under stress.
If the block is left in the vehicle, special care should be taken to protect all other parts from damage which might be caused from the acetylene flame. A stiff paint made from asbestos fiber cement and water should be generously used to cover parts.
All gasoline should be drained from the gas lines,
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Figure 4.	Figure 5.
vacuum tank, gas pump and carburetor. All wiring, oil and gas lines, and other parts of the ignition and lubricating systems, should be protected with asbestos paper.
The water-circulation system should be drained well below the level of the crack, and the cooling system vented so that no pressure will be built up. It is advisable to run the car or truck a few minutes with the cooling system empty in order to preheat the casting slightly. Care should be taken not to overheat the engine. The crack should be chipped out within 1/16 inch of the bottom to form approximately a 45-degree “vee.” Flux: Good, cast-iron brazing flux.
Welding Rod: Bronze, 5/32 inch diameter, of suitable quality.
Tip Size: Medium small, ranging from 53- to 56-drill size.
Flame: Use a slightly oxidizing flame.
Preheat: Play the torch flame on the metal around the break, bringing it gradually up to the proper heat.
Procedure : Start the braze well beyond the visible ends of the fracture. If the break extends into the valve ports or to any other edge of the casting, braze toward this point. In other cases, braze from the ends of the crack toward the middle, and from the end of any small branch cracks toward central point. The braze should be completed in one operation if possible. Braze should be finished at about the middle of the crack unless the break extends to the edge of the
casting, in which case the braze should end at that point.
Treatment After Brazing: Cover the finished braze with a piece of asbestos paper and allow to cool gradually. Figures 4 and 5 show a rather badly broken up cylinder block that has been repaired by bronze-welding.
Automotive Bumpers and Brackets
Job: To repair broken bumper bars and brackets.
Material: 0.75 to 0.90 percent carbon steel (spring steel).
Preparation: Clean thoroughly. “Veeing” is not necessary on light bumpers. Make bronze tack welds at both ends of the joint, making sure to keep in proper alignment.
Flux: Good brazing flux.
Welding Rod: Plain, bronze rod, suitable quality.
Tip Size: Medium small, 30- to 45-drill size. Flame: Use a slightly oxidizing flame.
Preheat: Heat the area to be bronze-welded to a glowing heat.
Procedure: “Tin” area of break and complete repair using regular brazing procedure. When this operation is complete, take three 5/16 x 2 inch steel welding rods and braze them on to reinforce the joint.
Hammer-Struck Tools
Job: To “safe-end” hammer-struck shop tools.# (See figure 6.) The “safe-ending” procedure is simple, quick and economical, and can be used
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for all types of chisels and similar struck tools. The procedure is equally applicable to old or new tools and can be repeated as often as necessary during the life of the tool. In actual use, the struck ends of safe-end chisels have outlived those of untreated new chisels about three to one without showing any appreciable signs of mushrooming, cracking or spalling.
Material: Steel, carbon, or alloy.
Preparation : Grind off any upset or mushroomed corner and undercut slightly as shown in illustration. Clean thoroughly.
Welding Rod: Good manganese bronze.
Procedure: Conventional brazing methods for brazing on steel can be followed in applying and building up the bronze striker surface on the tool head.
ligure 6. Bronze-Welded "Struck Tools” to prevent sparks.
PARTIAL LIST OF REFERENCES
“HARD-SURFACING, APPLICATIONS AND TECHNIQUES.” Maintenance Section, Highway Transport Department, Office of Defense Transportation, Washington 25, D. C.
“RECONDITIONING BRAKE DRUMS.” Maintenance Section, Highway Transport Department, Office of Defense Transportation, Washington 25, D. C.
“ELECTRIC ARC WELDING IN AUTOMOTIVE REPAIRS.” Maintenance Section, Highway Transport Department, Office of Defense Transportation, Washington 25, D. C.
“DEFINITIONS OF WELDING TERMS AND MASTER CHART OF WELDING PROCESSES.” American Welding Society, 1942. 33 West 39th Street, New York 18, N. Y. $0.40.
S.A.E. HANDBOOK, SOCIETY OF AUTOMOTIVE ENGINEERS. 29 West 39th Street, New York 18, N. Y. $5.
“WELDING.” War Department Manual No. T.
M. 1-430, 1942, 180 pg. Superintendent of Documents, Government Printing Office, Washington 25, D.C. $0.30.
Pamphlets published by manufacturers of welding equipment and welding supplies, describing the following:
a.	Composition and preferred use of various welding rods.
b.	Composition and preferred use of various welding and brazing fluxes.
c.	Instructions regarding adjustment, use and repair of welding equipment for assistance of beginning welders.
Note. ODT-SAE booklets can also be purchased in quantity from the Superintendent of Documents, Government Printing Office, Washington 25, D. C.
♦
U. S. GOVERNMENT PRINTING OFFICE: 1945-653743
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4	_ nV
......‘Identifying Metals by Spark Testing
Spark tests should be made on a high speed power grinder, and the specimen should be held so that the sparks will be given off horizontally. For most accurate results, the sparks should be examined against a dark background, preferably in a dark comer of the shop.
The color, shape, average length, and activity of the sparks are details which are characteristics of the material tested. Spark testing can be a very accurate method of identifying metals but it requires considerable practice and experience to become an expert. Several common sparks are given in the table. If the operator learns the technique for identifying these metals readily, he will soon be able to expand his experience to include others by observation and comparison with the sparks from known samples.
* These data apply also to cast steel
•*Spark shown is for stainless steel
♦••Monel metal spark is very similar to nickel