Craftsman 113.201892 Spécifications télécharger pdf (Page 25)

bent and edges fused together by melting down the excess

metal to form a bead (fig. 6). No filler rods are required.

The carbon-arc torch is ideally suited for brazing and

soldering small tubing.

Cast and mat_eable iron can be brazed with excellent

results. A bronze filler rod and common brazing flux are

used. Rust, paint or grease must be cleaned from the area

to be brazed. If it is a butt joint, such as a crack in a casting,

grind or chip out a beveled groove as for arc welding.

Apply the heat from the arc flame gradually by passing

it over the metat surrounding the ioint, When the casting

has become warm, concentrate the arc fiame at the ioint.

The important thing to remember when brazing cast iron

is never to heat the edges of the joint to the melting point.

The temperature of the work shoufd not exceed the melting

point of the filler rod. The carbons are held as close to the

work as possible without causing the meta_ to bubble. Hold

the filler rod in the left hand and heat the end of it slightly

by passing it through the arc flame. Then dip the heated

end in brazing flux. Raise the torch slightly and deposit

some of the flux at the part of the joint being heated. When

the surface of the heated metal takes on a shiny or wet

appearance, the filler rod can be applied.

Do not put the rod directly in _he flame, but hold it on the

work and let the heat of the edge of the flame and the work

melt the rod. Deposit only enough metal to fi!l the part of"

the joint that has been coated with flux. As the metal is

being deposited, move the torch along the joint slowly,

applying flux to the rod and joint as required.

Copper and copper-base alloys such as bronze and brass

may also be brazed, but as their melting temperatures are

so close to the melting point of the filler rod, the process

in many cases becomes one of welding rather than brazing.

A bronze filler rod and common brazing flux are used.

Most non-ferrous metals can be welded by manipulating

the torch and filler rod in the same manner as for brazing,

with the exception that the edges of the ioint are heated to

the melting point before depositing the filler metal. If the

work is a copper alloy, use common brazing flux. If it is an

....... ii ill i i .......... iiii

Figure 6

Figure 7

aluminum alloy, use aluminum flux. The filler rod should

be of the same analysis as the work. tf regular welding

rod is not available, strips of the parent metal may be used.

A back-up strip shoutd be used when weldlr_g thin material.

Small diameter carbons and low amperage setting are

used for soldering, The torch is held sothe work is just within

the visible edge of the flame. Apply the soldering flux and

play the flame over the work until it is just hot enough to

melt the solder. If the joint is to be sweat-soldered, tin the

surfaces to be ioined, then press them together and reheat,

adding more solder at the edges of the ioint.

One of the most practical uses of the arc torch is heating

metal for bending, forging, etc. Set the torch for a wide,

enveloping-type flame and apply the heat to the bottom of

the work (fig. 7). Since a red heat isnat visible through the

dark welding glass, the helmet must be raised periodically

so the work can be inspected to avoid overheating. To pro_

tact the eyes from the rays of the arc, hold the torch to

one side and above your head. The carbon-arc torch is

not recommended for welding mild-steel. However, it may

be used for brazing mild-steel if the metaf is too thin for

regular metallic-arc welding.

CUTTING

and other miscellaneous operations

CUTTING WITH THE ELECTRIC ARC

Arc cuffing is simply the continuation of a "'burn through"

such as you probably experienced when practicing with

light sheet-metal welding. When this action is accelerated

by using extremely high currents, it becomes an efficient

method of cutting metals. Although the edges of the cut

surfaces are not as smooth as when cut with a saw or

oxyacetylene torch, there are many cases where such pre-

cision is not required, Ordinary mild-steel welding rods

may be used. The current will vary with the type and thick-

ness of the material, In general, high currents i_crease the

speed of cutting but also increase the rod burn-off rate and

width of the cut.

START

CUT

HERE

Figure T

.v,..-MOLTEN IA_AL

STEEL

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