how often should a direct current arc welding machine be inspected
every 3 months
how do you clean a direct current arc welding machine and how often
clean dry compressed air and every 3 months
in the direct current arc welding machine the contacts of the motor starter switches and the rheostat should be cleaned and replaced if necessary when?
Every year
how often do you check the bearings on a direct current arc welding machine
twice a year
what is used to loosen scale oxides and slag off the weld
chipping hammer
what is a wire brush used for in welding
clean each weld bead before further welding
If a electrode has been in moisture then you weld with it what could happen.
Excessive splattering, lead to the formation of cracks in the welded area
What does moisture do to a electrodes
Destroys the desirable characteristics of the coating
Electrodes expose to damp there for more than 2 or 3 hours should be dried by heating in a suitable oven. How long? What temp? and what do you do when you take them out?
2 hours
500 degrees fahrenheit
place in moisture proof container
can you use a electrode if the core wire is exposed
No
What kind of weld does a DC straight polarity produce
Shallow wide weld
what kind of weld does a d c reverse polar produce
deep penetrating narrow weld
all metals fall into 2 categories what are they
Ferrous
Nonferrous
What categories does aluminum, copper,magnesium and titanium alloys fall in
Nonferrous metals
What category does metals that contain iron
Ferrous metals
What does the electrode covering do or how does it work
Shield the molten merely from the atmosphere as it is transferred across the arc and improves smoothness stability of the arc
Unused electrode stubs and splatter account for about what? Percent consumed electrode
44 percent
What is the principal force which accounts for the transfer of filler metal in flat position welding
Gravity
When not welding in a flat position you should use what kind of electrode
Smaller electrode must be used to avoid excessive loss of weld metal and slag
temperatures can get as hot as what in shielded metal arc welding
9000 degrees
What are the 3 types of free flight metal transfer in a welding arc.
Projected (spray)
Repelled (by Co2)
Gravitational (globular)
what is the force which keeps the filler metal and slag globules in contact with molten base or weld metal in the crater is known as ?