See also:

• WELDING (i.e. the action of the verb " to weld," the same word as " to well," to boil or spring up, the history of the word being to boil, to heat to a high degree, to beat heated iron; according to Skeat, who points out that in Swedish the compound verb

WELDING (i.e. the See also:

• ACTION

action of the verb " to weld," the same word as " to well," to See also:

• BOIL

boil or See also:

• SPRING (from " to spring," " to leap or jump up," " burst out," O. Eng., springau, a common Teut. word, cf. Ger. springer, possibly allied to Gr. QnrFpxecOac, to move rapidly)

spring up, the See also:

• HISTORY

history of the word being to boil, to See also:

• HEAT (0. E. haktu, which like " hot," Old Eng. hat, is from the Teutonic type haita, hit, to be hot; cf. Ger. hitze, heiss; Dutch, hitte, heet, &c.)

heat to a high degree, to See also:

• BEAT (a word common in various forms to the Teutonic languages; it is connected with the similar Romanic words derived from the Late Lat. battere)

beat heated See also:

• IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron; according to See also:

• SKEAT, WALTER WILLIAM (1835– )

Skeat, who points out that in See also:

• SWEDISH

Swedish the See also:

• COMPOUND
• COMPOUND (from Lat. componere, to combine or put together)

compound verb  uppvdlla means to See also:

• BOIL

boil, the See also:

• SIMPLE

simple vdlla is only used in the sense of See also:

• WELDING (i.e. the action of the verb " to weld," the same word as " to well," to boil or spring up, the history of the word being to boil, to heat to a high degree, to beat heated iron; according to Skeat, who points out that in Swedish the compound verb

welding), the See also:

• PROCESS

process of uniting metallic surfaces by pressure exercised when they are in a semi-fused See also:

• CONDITION (Lat. condicio, from condicere, to agree upon, arrange; not connected with conditio, from condere, conditum, to put together)

condition . It differs therefore from brazing and soldering, in which See also:

• COLD (in O. Eng. cald and ceald, a word coming ultimately from a root cognate with the Lat. gelu, gelidus, and common in the Teutonic languages, which usually have two distinct forms for the substantive and the adjective, cf. Ger. Kolte, kalt, Dutch koude

cold surfaces are See also:

• UNITED

united by the interposition of a fused metallic cementing material . The conditions in which welding is a suitable process to adopt are stated in the See also:

• ARTICLE (from Lat. articulus, a joint)

article See also:

• FORGING

FORGING . The technique of the See also:

• WORK

work will be considered here . The conditions for successful welding may be summed up as clean metallic surfaces in contact, a suitable temperature and rapid closing of the See also:

• JOINT (through Fr. from Lat. junctum, jungere, to join)

joint . All the See also:

• VARIATIONS
• VARIATIONS, CALCULUS
• VARIATIONS, CALCULUS OF

variations in the forms of welds are either due to See also:

• DIFFERENCES, CALCULUS OF (Theory of Finite Differences)

differences in shapes of material, or to the practice of different craftsmen . The typical weld is the See also:

• SCARF

scarf . If, for instance, a See also:

• BAR
• BAR (0. Fr. barre, Late Lat. barra, origin unknown)
• BAR, CONFEDERATION OF
• BAR, FRANCOIS DE (1538-1606)
• BAR, THE

bar has to be united to another bar or to an See also:

• EYE
• EYE (O. Eng. edge, Ger. Auge; derived from an Indo-European root also seen in Lat. oc-ulus, the organ of vision (q.v.)

eye, the joint is made diagonally (scarfed) because that gives a longer See also:

• SURFACE

surface in contact than a weld at right angles (a See also:

• BUTT
• BUTT, ISAAC (1813-1879)

butt weld), and because the See also:

• HAMMER, FRIEDRICH JULIUS (1810-1862)

hammer can be brought into See also:

• PLAY

play better . Abutting faces for a scarfed joint are made slightly See also:

• CONVEX

convex; the See also:

• OBJECT

object is to force out any See also:

• SCALE
• SCALE (1) A

scale or dirt which might otherwise become entangled in the joint at the moment of closing and which would impair its See also:

• UNION
• UNION (known locally as Union Hill and officially as Town of Union)

union . The ends are upset (enlarged) previous to welding, in See also:

• ORDER
• ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
• ORDER, HOLY

order to give an excess of See also:

• METAL
• METAL (through Fr. from Lat. metallum, mine, quarry, adapted from Gr. µATaXAov, in the same sense, probably connected with ,ueraAAdv, to search after, explore, µeTa, after, aAAos, other)

metal that will permit of slight corrections being effected around the joint (" swaging ") without reducing the See also:

• DIAMETER (from the Cr. &a, through, µErpov, measure)

diameter below that of the See also:

• REMAINDER, REVERSION

remainder of the bar . These principles are seen in other See also:

• JOINTS

joints of diverse types, in the butt, the vee and their modifications . Joint faces must be clean, both chemically, i.e. See also:

• FREE

free from oxides, and mechanically, i.e. free from dust and dirt, else they will not unite .

The first condition is fulfilled by the use of a fluxing See also:

• AGENT (from Lat. agere, to act)

agent, the second by See also:

• ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary precautions . The See also:

• FLUX (Lat. fluxus, a flowing; this being also the meaning of the English term in medicine, &c.)

flux produces with the See also:

• OXIDE

oxide a fluid slag which is squeezed out at the instant of making the weld . The commonest fluxes are See also:

• SAND
• SAND, GEORGE (1804-1876)

sand, used chiefly with wrought See also:

• IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron, and See also:

• BORAX (sodium pyroborate or sodium biborate)

borax, used with See also:

• STEEL, FLORA ANNIE (1847– )

steel; they are dusted over the jcint faces both while in the See also:

• FIRE (in O. Eng. f j'r; the word is common to West German languages, cf. Dutch vuur, Ger. Feuer; the pre-Teutonic form is seen in Sanskrit pu, pavaka, and Gr. irup; the ultimate origin is usually taken to be a root meaning to purify, cf. Lat. purus)

fire and on the See also:

• ANVIL (from Anglo-Saxon anfilt or onfilti, either that on which something is " welded " or " folded," cf. German falzen, to fold, or connected with other Teutonic forms of the word, cf. German amboss, in which case the final syllable is from " beat," and

anvil . See also:

• MECHANICAL

Mechanical cleanliness is ensured by See also:

• HEATING

heating the ends in a clean hollow fire previously prepared, and in brushing off any adherent particles of See also:

• FUEL (O. Fr. feuaile, popular Lat. focalia, from focus, hearth, fire)

fuel before closing the weld . The scarf, the butt and the vee occur in various modifications in all kinds of forgings, but the principles and precautions to be observed are identical in all . But in work involving the use of rolled sections, as angles, See also:

• TEES

tees, channels and joists, important differences occur, because the awkwardness of the shapes to be welded involves cutting and bending and the insertion of See also:

• SEPARATE

separate welding pieces (" gluts ") . Welds are seldom made lengthwise in rolled sections, nor at right angles, because union is effected in such cases by means of riveted joints . But welding is essential in all bending of sections done at See also:

• SHARP, GRANVILLE (1735-1813)
• SHARP, JAMES (1618-1679)
• SHARP, JOHN (1645-1714)
• SHARP, RICHARD (1759-1835)
• SHARP, WILLIAM (1749-1824)
• SHARP, WILLIAM (1856-1905)

sharp angles or to curves of small See also:

• RADIUS

radius . It is necessary, because a broad flange cannot be See also:

• BENT
• BENT (E1. BENI)
• BENT, JAMES THEODORE (1852–1897)

bent sharply; if the See also:

• ATTEMPT (Lat. adtemptare, attentare, to try)

attempt be made when it is on an See also:

• OUTER

outer See also:

• CURVE (Lat. curvus, bent)

curve it is either ruptured or much attenuated, while on an inner curve it is crumpled up . The plater's See also:

• SMITH
• SMITH, ADAM (1723–1790)
• SMITH, ALEXANDER (183o-1867)
• SMITH, ANDREW JACKSON (1815-1897)
• SMITH, CHARLES EMORY (1842–1908)
• SMITH, CHARLES FERGUSON (1807–1862)
• SMITH, CHARLOTTE (1749-1806)
• SMITH, COLVIN (1795—1875)
• SMITH, EDMUND KIRBY (1824-1893)
• SMITH, G
• SMITH, GEORGE (1789-1846)
• SMITH, GEORGE (184o-1876)
• SMITH, GEORGE ADAM (1856- )
• SMITH, GERRIT (1797–1874)
• SMITH, GOLDWIN (1823-191o)
• SMITH, HENRY BOYNTON (1815-1877)
• SMITH, HENRY JOHN STEPHEN (1826-1883)
• SMITH, HENRY PRESERVED (1847– )
• SMITH, JAMES (1775–1839)
• SMITH, JOHN (1579-1631)
• SMITH, JOHN RAPHAEL (1752–1812)
• SMITH, JOSEPH, JR
• SMITH, MORGAN LEWIS (1822–1874)
• SMITH, RICHARD BAIRD (1818-1861)
• SMITH, ROBERT (1689-1768)
• SMITH, SIR HENRY GEORGE WAKELYN
• SMITH, SIR THOMAS (1513-1577)
• SMITH, SIR WILLIAM (1813-1893)
• SMITH, SIR WILLIAM SIDNEY (1764-1840)
• SMITH, SYDNEY (1771-1845)
• SMITH, THOMAS SOUTHWOOD (1788-1861)
• SMITH, WILLIAM (1769-1839)
• SMITH, WILLIAM (c. 1730-1819)
• SMITH, WILLIAM (fl. 1596)
• SMITH, WILLIAM FARRAR (1824—1903)
• SMITH, WILLIAM HENRY (1808—1872)
• SMITH, WILLIAM HENRY (1825—1891)
• SMITH, WILLIAM ROBERTSON (1846-'894)

smith therefore cuts the flanges in both cases, and then bends and welds them . If it is on an inner curve, the joint is a See also:

• LAP

lap weld; if it is on an outer one, a fresh piece or glut is welded in . Gluts of rectangular See also:

• SECTION
• SECTION (Lat. sectio, cutting, secare, to cut)

section are used for cylindrical See also:

• OBJECTS

objects and rings of various sections .

The edges to be united may or may not be scarfed, and the gluts, which are See also:

• PLAIN (O. Fr. plain, from Lat. plenum)

plain bars, are welded against the edges, all being brought to a welding See also:

• HEAT (0. E. haktu, which like " hot," Old Eng. hat, is from the Teutonic type haita, hit, to be hot; cf. Ger. hitze, heiss; Dutch, hitte, heet, &c.)

heat in separate furnaces . The See also:

• FURNACE

furnace tubes of boilers and the See also:

• CROSS

cross tubes are welded in this way, sometimes by See also:

• HAND
• HAND (a word common to Teutonic languages; cf. Ger. Hand, Goth. handus)
• HAND, FERDINAND GOTTHELF (1786-185r)

hand, but often with a See also:

• POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

power hammer, as also are all rings of See also:

• ANGLE (from the Lat. angulus, a corner, a diminutive, of which the primitive form, angus, does not occur in Latin; cognate are the Lat. angere, to compress into a bend or to strangle, and the Gr. ayKOS, a bend; both connected with the Aryan root ank-, to

angle and other sections on the See also:

• VERTICAL (from Lat. vertex, highest point)

vertical See also:

• WEB (a word common to Teutonic languages, cf. Du. webbe, Dan. vaev, Ger. Gewebe, all from the Teutonic wabh—to weave)

web . The temperature for welding is very important . It must be high enough to render the surfaces in contact pasty, but must not be in excess, else the metal will become badly oxidized (burnt) and will not adhere . Iron can be raised to a temperature at which See also:

• MINUTE
• MINUTE (Lat. minutes, small; minuere, to make less)

minute globules melt and fall off, but steel must not be heated nearly so much, and a moderate See also:

• WHITE
• WHITE, ANDREW DICKSON (1832– )
• WHITE, GILBERT (1720–1793)
• WHITE, HENRY KIRKE (1785-1806)
• WHITE, HUGH LAWSON (1773-1840)
• WHITE, JOSEPH BLANCO (1775-1841)
• WHITE, RICHARD GRANT (1822-1885)
• WHITE, ROBERT (1645-1704)
• WHITE, SIR GEORGE STUART (1835– )
• WHITE, SIR THOMAS (1492-1567)
• WHITE, SIR WILLIAM ARTHUR (1824--1891)
• WHITE, SIR WILLIAM HENRY (1845– )
• WHITE, THOMAS (1628-1698)
• WHITE, THOMAS (c. 1550-1624)

white heat must not be exceeded . Welds in steel are not so trustworthy nor so readily made as those in iron . Thermit Welding.—The See also:

• AFFINITY (Lat. affinitas, relationship by marriage, from offinis, bordering on, related to; finis, border, boundary)
• AFFINITY, CHEMICAL

affinity of finely powdered See also:

• ALUMINIUM (symbol Al; atomic weight 27.0)

aluminium for metallic oxides, sulphides, chlorides, &c., may be utilized to effect a reduction of metals with which See also:

• OXYGEN (symbol 0, atomic weight 16)

oxygen, See also:

• SULPHUR

sulphur or See also:

• CHLORINE (symbol Cl, atomic weight 35`46 (0=16)

chlorine combine . C . Vautin in 1894 found that when aluminium in a finely divided See also:

• STATE
• STATE, GREAT OFFICERS OF

state was mixed with such compounds and ignited, an exceedingly high temperature, about 3000° C., was See also:

• DEVELOPED

developed by the rapid oxidation of the aluminium . He found that metals which are ordinarily regarded as infusible were readily reduced, and in a very high degree of purity . These facts were turned to See also:

• PRACTICAL

practical See also:

• ACCOUNT
• ACCOUNT (through O. Fr. acont, Late Lat. comptum, cornputare, to calculate)

account by Dr H . See also:

• GOLDSCHMIDT, HERMANN (1802-1866)

Goldschmidt, who first welded two iron bars by means of molten iron produced by the process, to which the name of " thermit " is now commonly applied .

The method has also been applied to the See also:

• PRODUCTION (Lat. productionem, from producere, to pro-duce)

production of pure metals for alloying purposes, as of See also:

• CHROMIUM (symbol Cr. atomic weight 52.1)

chromium free fromcarbon, used in the manufacture of chrome steel, of pure See also:

• MANGANESE (symbol Mn; atomic weight, 54.93 (0=16)], a metallic chemical element. Its dioxide (pyrolusite)

manganese for manganese steel, of See also:

• MOLYBDENUM [symbol, Mo; atomic weight, 96 (0=16)]

molybdenum, ferro-See also:

• VANADIUM

vanadium, ferro-See also:

• TITANIUM [symbol Ti, atomic weight 48.1 (0 = 16)]

titanium and others used in the manufacture of high See also:

• SPEED, JOHN (1552–1629)

speed steels . Thermit as a welding agent is produced by mixing iron oxides with finely granulated aluminium, in a See also:

• SPECIAL

special crucible lined with See also:

• MAGNESIA

magnesia . On ignition, the chemical reactions proceed so rapidly that the contents would be lost over the edges unless the crucible were closed with a See also:

• COVER (from the Fr. convert, from couvrir, to cover, Lat. cooperire)

cover . The result of the reaction is that two layers are produced, the bottom one of pure iron, the See also:

• TOP (cf. Dan. top, Ger. Topf, also meaning pot)

top one of oxide of alumina or See also:

• CORUNDUM

corundum . If the contents are poured over the edge, the slag follows first, and is followed by the metal . But in welding the metal is poured first through the bottom upon the joint . It is practically pure wrought iron in a molten state, at 3000° C., or 5400° F . The heat is so intense that it is possible thus to See also:

• BURN, RICHARD (1709-1785)

burn a clean hole through a 1 in. wrought iron See also:

• PLATE

plate . The joints are pre-pared by abutting them, and See also:

• PROVISION (Lat. provisio)

provision is made with clamps to grip and retain them in correct positions . Often, but not always, the See also:

• PART

part to be welded is enclosed in a See also:

• MOULD

mould, into which the thermit is tapped from the crucible . The applications of thermit welding are numerous . A wide See also:

• FIELD (a word common to many West German languages, cf. Ger. Feld, Dutch veld, possibly cognate with O.E. f olde, the earth, and ultimately with root of the Gr. irAaror, broad)
• FIELD, CYRUS WEST (1819-1892)
• FIELD, DAVID DUDLEY (18o5-1894)
• FIELD, EUGENE (1850-1895)
• FIELD, FREDERICK (18o1—1885)
• FIELD, HENRY MARTYN (1822-1907)
• FIELD, JOHN (1782—1837)
• FIELD, MARSHALL (183 1906)
• FIELD, NATHAN (1587—1633)
• FIELD, STEPHEN JOHNSON (1816-1899)
• FIELD, WILLIAM VENTRIS FIELD, BARON (1813-1907)

field is that of See also:

• TRAMWAY

tramway rails, of which large See also:

• NUMBERS, BOOK OF
• NUMBERS, PARTITION OF

numbers have been successfully welded .

Steel girders have been welded, as also have broken and faulty steel and iron castings, broken shafts, broken sternposts (for which crucibles 6 ft. in height with a capacity of 7 cwt. have been constructed), and wrought iron pipes . Another application is to render steel ingots See also:

• SOUND
• SOUND, THE (Danish Oresund)

sound, by introducing thermit in a See also:

• BLOCK
• BLOCK (from the Fr. bloc, and possibly connected with an Old Ger. Block, obstruction, cf. " baulk ")
• BLOCK, MAURICE (1816–19or)

block on an iron See also:

• ROD (O.E. rodd, probably related to Norw. rudda, stick, rodda, stake)
• ROD, EDOUARD (1857-1910)

rod into the mould, which prevents or greatly lessens the amount of piping in the See also:

• HEAD (in 0. Eng. heafad; the word is common to Teutonic languages; cf. Dutch hoofd, Ger. Haupt, generally taken to be in origin connected with Lat. caput, Gr. KerbOvi7)
• HEAD, SIR EDMUND WALKER, BART
• HEAD, SIR FRANCIS BOND, BART

head, due to shrinkage and occlusion of gases . (J . G . H.) Electric Welding.—In electric welding and metal working the heat may be communicated to the metal by an electric arc, or by means of the electric resistance of the metal, as in the See also:

• THOMSON, JAMES (1822-1892)
• THOMSON, JAMES (1834-1882)
• THOMSON, JAMES (r700-1748)
• THOMSON, JOHN (1778-184o)
• THOMSON, JOSEPH (1858-1895)
• THOMSON, SIR CHARLES WYVILLE (1830-1882)
• THOMSON, THOMAS (1773-1852)
• THOMSON, WILLIAM (1819-189o)

Thomson process . Arc welding is the older Arc welding: See also:

• PROCEDURE (Fr. procedure, from Lat. procedere, to go for-ward)

procedure, and it appears to have been first made use of by de Meritens in 1881 for uniting the parts of storage-See also:

• BATTERY (Fr. batterie, from battles, to beat)

battery plates . The work-piece was placed upon a support or table, and connected with the See also:

• POSITIVE (or PORTABLE) ORGAN

positive See also:

• POLE (FAMILY)
• POLE, REGINALD (1500-1558)
• POLE, RICHARD DE LA (d. 1525)
• POLE, WILLIAM (1814—1900)

pole of a source of current capable of maintaining an electric arc . The other pole was a See also:

• CARBON (symbol C, atomic weight 12)

carbon rod directed by the hand of the operator so as first to make contact with the work-piece, and then to effect the proper separation to maintain the arc . The heat of the arc was partly communicated to the work and partly dissipated in the hot gases escaping into the surrounding See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air . The result was a See also:

• FUSION

fusion of the metallic See also:

• LEAD
• LEAD (pronounced iced)

lead of the storage-battery plate which united various parts of the plate . The process was somewhat similar to the operation of lead-burning by the See also:

• HYDROGEN [symbol H, atomic weight x-oo8 (0=16)]

hydrogen and air See also:

• BLOWPIPE

blowpipe, as used in the formation of joints in chemical tanks made of See also:

• SHEET

sheet-lead . The method of de Meritens has been modified by Bernardos and Olszewski, Slavienoff, See also:

• COFFIN (from Lat. cophinus, Gr. K64wos, a coffer, chest or basket, but never meaning " coffin " in its present sense)

Coffin and others .

In the Bernardos and Olszewski process the work is made the negative pole of a See also:

• DIRECT

direct current See also:

• CIRCUIT (Lat. circuitus, from circum, round, and ire, to go)

circuit, and an arc is See also:

• DRAWN

drawn between this and a carbon rod, to which a handle is attached for manipulating . As this rod is the positive terminal, particles of carbon may be introduced as a constituent of the metal taking part in the operation, making it hard and brittle, and causing cracks in the joint or filling; the metal may, in fact, become very hard and unworkable . The Slavienoff modification of the arc-welding process consists in the employment of a metal electrode in See also:

• PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place of the carbon rod . The metal electrode gradually melts, and furnishes fused drops of metal for the filling of vacant spaces in castings, or for forming a joint between two parts or pieces . In arc welding, with a current source at practically See also:

• CONSTANT, BENJAMIN (1845-1902)

constant potential, a choking resistance in See also:

• SERIES (a Latin word from serere, to join)

series with the heating arc is needed to secure stability in the arc current, as in electric arc See also:

• LIGHTING

lighting from constant potential lines . Little effective work can be done by the Bernardos and Olszewski method with currents much below 150 amperes in the arc, and the value in some cases ranges above 500 amperes . The potential must be such that an arc of 2 to 3 in. in length is steadily maintained . This may demand a See also:

• TOTAL

total of about 150 volts for the arc and the choking resistance together . In the Slavienoff arc the potential required will be naturally somewhat See also:

• LOWER

lower than when a carbon electrode is used, and the current strength will be, on the other hand, considerably greater, reaching, it appears, in certain cases, more than 4000 amperes . In some See also:

• RECENT

recent applications of the arc process the See also:

• POLARITY (Lat. polaris, poles, pole)

polarity of the work-piece and the arc-controlling electrode has, it is understood, been reversed, the work being made the positive pole and the movable electrode the negative . More heat See also:

• ENERGY (from the Gr. ivipyela; iv, in, ipyov, work)

energy is thus delivered to the work for a given total of electric energy expended . The arc method is essentially a fusing process, though with due usual laminated iron-transformer core, I, constituting a closed iron care it is used for heating to plasticity the edges of iron sheets to be magnetic circuit threading both See also:

• PRIMARY

primary and secondary electric welded by pressure and hammering .

It has been found applicable circuits . The terminals of the single-turn secondary serve as See also:

• CON

con-in special cases to the filling of defective spots in iron castings, by fusing into See also:

• BLOW, JOHN (1648-1708)

blow-holes or other spaces small masses of similar metal, added gradually, and melted into union with the See also:

• BODY

body of the piece by the heat of the arc . Similarly, a more or less See also:

• COMPLETE

complete union between separate pieces of iron plate ; to i in. in thickness has been effected by fusing additional metal between them . The range of operations to which the arc process is applicable is naturally some-what limited, and depends to a large extent upon the skill acquired by the operator, who necessarily See also:

• WORKS

works with his eyes well screened from the glare of the large arc . Unless the space in which the work is carried on is large, the irritating vapours which rise from the arc stream add to the difficulty . Strong See also:

• DRAUGHTS (from AS. dragan, to draw)

draughts of air which would disturb the arc must also be avoided . These factors, added to the relative slowness of the work and the uncertainty as to its result, have tended to restrict the application of arc welding in practice . Moreover, much heat-energy is dissipated in the arc See also:

• FLAME (Lat. flamma; the root flag- appears in flagrare, to burn, blaze, and Gr. d, XEryew)

flame and passes into the air, while, owing to the See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

time required for the work, the metal undergoing treatment loses much heat by See also:

• RADIATION, THEORY OF

radiation . Yet the method requires little special machinery . The current may be !! taken from existing electric lighting and power circuits of moderate potential without transformation, and may be utilized with simple appliances, consisting chiefly of heavy See also:

• WIRE (A.S. wir, a wire; cf. Swed. vire, to twist, M.H.G. wiere, a gold ornament, Lat. viriae, armlets, ultimately from the root wi, to twist, bind)

wire leads, a carbon or metal electrode with a suitable handle for its manipulation, a choking or steadying resistance, and See also:

• SCREEN (usually, but very doubtfully, connected with Lat. scrinium, a box for holding books, from scribere, to write; a connexion with Ger. Schranke, barrier, has been suggested)

screen of dark See also:

• GLASS
• GLASS (O.E. glees, cf. Ger. Glas, perhaps derived from an old Teutonic root gla-, a variant of glo-, having the general sense of shining, cf. " glare," " glow ")
• GLASS, STAINED

glass for the operator's eyes . In 1874 Werdermann proposed to use, as a sort of electric blow-See also:

• PIPE

pipe, the flame gases of an electric arc blown or deflected by an air See also:

• JET (Fr. jais, Ger. Gagat)

jet or the like—a See also:

• SUGGESTION

suggestion subsequently revived by Zerener for arc welding . The arc in this instance is deflected from the space between the usual carbon electrodes by a magnetic field .

The metal to be heated takes no part in the See also:

• CONDUCTION, ELECTRIC

conduction of current, the heat is communicated by the gases of the arc, and, to a small extent, by the radiation from the hot carbon electrodes between which the arc is formed . The process is scarcely to be called electric in any true sense . Another curious operation, resembling in some respects the arc methods, has been proposed for the heating of metal pieces before they are brought under the hammer for forging or welding . The end of a metal bar is plunged into an electrolytic See also:

• BATH
• BATH, THOMAS THYNNE
• BATH, WILLIAM

bath while connected with the negative pole of a lighting or other electric circuit having a potential of 10o to Igo volts . The positive pole is connected with a metal plate as an anode immersed in the electrolyte, or forming the See also:

• SIDE
• SIDE (mod. Eski Adalia)

side of the containing vat or tank . A See also:

• SOLUTION (from Lat. solvere, to loosen, dissolve)

solution of See also:

• SODIUM [symbol Na, from Lat. natrium; atomic weight 23.00 (0=16)]

sodium or See also:

• POTASSIUM [symbol K (from kalium), atomic weight 39.114 0=16)]

potassium carbonate is a suitable electrolyte . That part of the bar which is immersed acts as a See also:

• CATHODE

cathode of limited surface, and is at once seen to be surrounded by a luminous glow, with See also:

• GAS

gas bubbles arising from it . The immersed end of the bar rapidly heats, and may even melt under the liquid of the bath . It is probable that an arc forms between the surface of the metal and the adjacent liquid layer, the intense heat of which is in part communicated to the metal and in part lost in the solution, causing thereby a rapid heating of the bath . This singular See also:

• ACTION

action appears to have been first made known by Hoho and See also:

• LAGRANGE, JOSEPH LOUIS (1736-1813)

Lagrange . It is distinctly a See also:

• FORM (Lat. forma)

form of electric heating, having no necessary relation to such subsequent operations as welding, and is, moreover, wasteful of energy, as the heat is largely carried off in the liquid bath . The process of Elihu Thomson first brought to public See also:

• NOTICE

notice in 1886, has since that time been applied commercially on a large scale to various metal-welding operations .

The process . pressed together in See also:

• FIRM

firm contact; and a current is made to See also:

• TRAVERSE

traverse the proposed joint, bringing it to the welding temperature . The union is effected by forcing the pieces together mechanically . The characteristic feature of the process is the fact that the heat is given out in the body of the metal . The voltage does not usually exceed two or three, though it may reach four or five volts; but as the resistance of the metal pieces to be joined is See also:

• LOW, SETH (1850- )
• LOW, WILL HICOK (1853- )

low, the currents are of very large values, sometimes reaching between go,000 and See also:

• IOO

ioo,000 amperes . Even for the joining of small wires the current is rarely less than 10o amperes . Such currents cannot, of course, be carried more than a few feet without excessive loss, unless the conductors are given very large section . With alternating currents, also, the effectiveness of the work speedily diminishes, on account of the inductive drop in the leads, if they are of any considerable length . The carrying of the welding currents over a distance of several feet may, in fact, lead to serious losses . These difficulties are overcome in the Thomson we'.ding transformer, which resembles the step-down See also:

• TRANSFORMERS

transformers used in electric lighting See also:

• DISTRIBUTION (Lat. distribuere, to deal out)

distribution by alternating currents, with the exception that the secondary coil or conductor, which forms part of the welding circuit, usually consists of only one turn of See also:

• GREAT

great section, S S (fig . I) . This is often made in the form of a See also:

• COPPER (symbol Cu, atomic weight 63.1, H=1, or 63.6, O = 16)

copper casing, which surrounds or encloses the primary coil P P in whole or in part .

The primary coil is of copper wire of many turns . The secondary casing, with the primary enclosed, is provided with thenexions and supports for the welding clamps C D, which hold the work . The clamps are variously modified to suit the See also:

• SIZE

size, shape and See also:

• CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character of the metal pieces, MN, to be welded, and the proportions of the transformer itself are made proper for the conditions existing in each See also:

• CASE
• CASE, JOHN (d. 1600)

case . The potential of the primary circuit may be selected at any convenient value, provided the winding of the coil P P is adapted thereto, but usually 30o volts is employed, and the periodicity is about 6o cycles . Inasmuch as only the proposed joint and a small amount of metal on each side of it are concerned in the operation, the delivery of energy is closely localized . The See also:

• CHIEF (from Fr. chef, head, Lat. caput)

chief See also:

• ELECTRICAL
• ELECTRICAL (or ELECTROSTATIC) MACHINE

electrical resistance in the welding circuit is in the projections between the clamps, where the electric energy is delivered and appears as heat . A portion of the energy is, as usual, lost in the transformation and in the resistance of the circuits elsewhere, but, by proper proportion- See also:

• ING

ing, the loss may be kept down to a moderate percentage of the total, as in other electric work . The pieces are set firmly in the welding clamps, with the ends to he joined in See also:

• ABUTMENT

abutment and in electric contact . The projecticn of each piece from the clamp varies with the section of the pieces, their form and the nature of the metal, and the time in which a joint is to be made; but it rarely exceeds the thickness or diameter of the pieces, except with metals of high heat conductivity such as copper . When the pieces are in place the current is turned into the primary coil of the transformer, sometimes suddenly and in full force, but more often gradually . Switches and regulating devices in the primary circuit permit complete and delicate See also:

• CONTROL (Fr. contrdle, older form contre rolle, from Med. Lat. contra-rotulus, a counter roll or copy of a document used to check the original; there is no instance in English of the use of " control " in this, its literal, meaning)

control . At least one of the clamps, D (fig .

I), is movable through a limited range towards and from the other, and is thus the means of exerting pressure for forcing the softened metal into complete union . In large work the See also:

• MOTION (Lat. motio, from movere, to move)
• MOTION, LAWS OF

motion is given by a See also:

• HYDRAULIC

hydraulic See also:

• CYLINDER (Gr. KvAwSpos, from KvXivaety, to roll)

cylinder and See also:

• PISTON (through Fr. from Ital. pistone or pestone, a great pestle, from Late Lat. pistare, to pound, a frequentative form of classical Lat. pinsere)

piston, under suitable control by valves . At about the time the current is cut off, it is usual to apply increased pressure . The softened metal is upset or pressed outwards at the joint and forms a characteristic See also:

• BURR, AARON (1756-1836)

burr, which may be removed by filing or grinding, or be hammered down while the metal is still hot . Sometimes the burr is not objectionable, and is allowed to remain . Lap welds may be made, but butt welds are found to be satisfactory for most purposes . The See also:

• APPEARANCE (from Lat. apparere, to appear)

appearance of See also:

• ROUND (O. Fr. rond, Lat. rotundus, the Fr. is the source also of Du. rond; Ger., Swed., Dan. and Nor. rond)

round bars in abutment before welding is shown in fig . 2 at A; and at B they are represented as having been joined by an electric butt weld, with the slight upset or burr at the joint . Before the introduction of the Thomson process a few only of the metals, such as See also:

• PLATINUM [symbol Pt, atomic weight 145.0 (0=16)]

platinum, See also:

• GOLD
• GOLD [symbol Au, atomic weight 195.7(H = 1),197.2(0 =16)]

gold and iron, were regarded as weldable; now nearly all metals and See also:

• ALLOYS (through the Fr. aloyer, from Lat. alligare, to combine)

alloys may be readily joined . Such combinations as See also:

• TIN (Lat.- stannum, whence the chemical symbol " Sn "; atomic weight =117.6, 0=16)

tin and lead, copper and See also:

• BRASS
• BRASS (O. Eng. braes)

brass, brass and iron, iron and See also:

• NICKEL
• NICKEL (symbol Ni, atomic weight 58.68 (0=16))

nickel, brass and See also:

• GERMAN
• GERMAN, DUTCH AND SCANDINAVIAN

German See also:

• SILVER

silver, silver and copper, copper and platinum, iron and German silver, tin and See also:

• ZINC

zinc, zinc and See also:

• CADMIUM (symbol Cd, atomic weight 112.4 (0=16))

cadmium, &c., are easily made; even brittle crystalline metals like See also:

• BISMUTH

bismuth and See also:

• ANTIMONY (symbol Sb, atomic weight 120.2)

antimony may be welded, as well as different metals and alloys whose fusing or softening temperatures do not differ too widely . If the See also:

• MEETING (from " to meet," to come together, assemble, 0. Eng. metals ; cf. Du. moeten, Swed. mota, Goth. gamotjan, &c., derivatives of the Teut. word for a meeting, seen in O. Eng. Wit, moot, an assembly of the people; cf. witanagemot)

meeting ends conduct sufficiently to start the heating, it is not necessary that they should See also:

• FIT

fit closely together, nor is it necessary that they should be quite clean, the effect of the incipient heating being to confer conductivity upon the scale and oxide at the joint . Thomson metal pieces to be united are held in massive clamps and 8 In some cases the application of a flux, such as borax, enables the welding to be accomplished at a lower temperature, thus avoiding See also:

• RISK

risk of injury by excessive heating .

While the pieces are heating, the increase of temperature may raise the specific resistance of the metal so that the current required will be lessened per unit of See also:

• AREA

area, while on the other hand the growing perfection of contact during welding, by increasing the conducting area at the joint, compensates for this in that it tends to the increase of current . With some alloys like brass and German silver, which have a low temperature coefficient, this compensating effect is nearly absent . The increase of specific resistance of the metals with increase of temperature table the See also:

• WATTS, ALARIC ALEXANDER (1797-1864)
• WATTS, GEORGE FREDERICK (1817-1904)
• WATTS, ISAAC (1674-1748)

watts for a given section be multiplied by the time, the relation between the total energy required for different sections of the same metal, or for the same section of the different metals, is obtained . These products are given under the head of See also:

• WATT, JAMES (1736-1819)

watt-seconds . It will be seen that the energy increases more rapidly than the sections of the pieces-doubtless because the larger pieces take a longer time in welding, with the result of an increased loss by conduction of heat along the bars back from the joint . If the time of welding could be made the same for various sections, it is probable that the energy required would be more nearly in direct proportion to the area of section for any given metal . This relation would however, only hold approximately, as there is a greater relative loss of heat by radiation and convection into the air from the pieces of smaller section . The total energy in watt-seconds for any given section of copper will be found to be about See also:

• HALF

half as much again as that for the same section of iron, while the amounts of energy required for equal sections of brass and iron do not greatly differ .