JJ104 Workshop Technology Chapter8 Brazing

7/21/2019 JJ104 Workshop Technology Chapter8 Brazing

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Oxy-Acetylene; Welding, Brazing, Cutting and Heating

Lesson: Oxy-Acetylene Brazing

Standard B7.5 - Know basic repair skills using a variety of techniques, such as braing or hard surfacing



Brazing• Is classified by the

American Welding

Society (AWS) as a

liquid – solid pase

!onding process"

#" Liquid- Filler metal ismelted (Brass Rod).

$" %olid- Base metals are

not melted (heated only).

&" 'ase- The temperatureat hich bonding ta!es

place beteen the solid

base metal and li"uidfiller metal

(" Bonding- To secure orhold together.



Brazing• A form of elding characteri#ed by the use

of base metal temperatures abo$e %&&degrees but belo the melting point of the

base metal.• Bra#ing Temperature' ccurs around )(*+

degrees

• ost metals can be *oined by bra#ing butthe proper filler rod and flu+ must be used.

• Flu+ is re"uired to prepare the metals for *oining and the filler rod bonds the base

metals together.• ,A-TI/ All bra#ing processes should be

preformed in a ell'$entilated area. To+icfumes may be generated by the bra#ing

process.



Adantages o Brazing

#" Lo. /e0perature' since the base metal does not

ha$e to melt0 a lo temperature heat source can

be used.

$" 1ay !e per0anently or te0porarily 2oined'

since the base metal is not damaged0 parts may be

disassembled at a later time by simply reapplying

heat.



Adantages o Brazing Cont"

&" 3issi0ilar 0etals can !e

2oined- bra#ing can *oin

dissimilar metals0 such as copper

to steel0 aluminum to brass0 and

cast iron to stainless steel.

(" 1etals o arious tic4ness can

!e 2oined- $ery thin metal can

be *oined to thic! metal ithout burning0 arping0 and

o$erheating them.



Adantages o Brazing Cont"

5" 6asy realign0ent-

parts can easily be

realigned0 throughreheating the *oint and

repositioning the part.



7L896% <OL<63 B=A>?

/ree 0a2or unctions1. To remo$e any o+ides that form as

a result of heating the metal.

2. To promote etting.

3. Aid in capillary action.

•. Wetting is te peno0enon .ere!y a

liquid iller 0etal or lux spreads and

aderes in a tin, continuous layer on a

solid !ase 0etal"

•. Capillary action is te orce tat pulls iller

0etal @!rass troug te 2oint"



'reparing te 1etals to !e Brazed

• All paint0 rust0 grease0dirt must be remo$ed

from the surface area prior to beginning to bra#e.

• The successful bra#ing

operation depends onclose *oint tolerances0meaning no ma*orgaps.



Brazing %eet 1etal

• The folloing bra#ing

techni"ues can be

utili#ed in all bra#ingapplications. This

e+ample uses strips of

14 gauge sheet steel in

the Flat T position.



Brazing %eet 1etal

1. Select the proper

elding no##le0 brass

rod si#e and flu+.

2. Follo safety and

operating procedures for

setting up cylinders and

regulators.

•. Acetylene 5 6 psi

•. +ygen 5 6 7 8 psi.



Brazing %eet 1etal Cont.

3. btain a neutral to

slightly o+idi#ing

flame on torch.4. 9reheat metal only to

a dull red color. If

the base metal is

heated to a highertemperature a porous

deposit ill result.



Brazing %eet 1etal Cont"

6. Touch flu+ed rod to

heated portion and

allo some flu+ tomelt and react ith

the base metal.

•. The melted flu+

reacts to chemicallyclean the base metal.




:. elt off small amounts

of flu+ed rod and if it

flos freely and ;tins<

(adheres to the heated

base metal)0 the correct

temperature has been

reached. aintain this

temperature bycontinually mo$ing the

flame o$er the metal.




%. ,ontinue to dip rod

into the molten

puddle and addsufficient amount of

brass to the base

metal to build up the

bead.




8. ,ontinue to tin and

build a bead until the

desired section has been co$ered.

=. With a chipping

hammer0 remo$e the

flu+ co$ering (slag)on the bead.



Brazing %eet 1etal

JJ104 Workshop Technology Chapter8 Brazing

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