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問題一覧
1
When installing electrical powered welding machines, the installation must comply with:
applicable local electrical codes
2
Badly discolored cable lugs indicate that the connection has:
overheated during use
3
Continuous high frequency current may be required with GTAW when:
you are using alternating current
4
What current type produces good penetration and oxide removal when using GTAW on aluminum?
ac with continuous high frequency current
5
Using direct current reverse polarity with GTAW:
requires the use of larger electrodes
6
With the machine running, what is most likely to be the problem when you are unable to start an arc?
The work lead is not attached or they lead to work connection is faulty
7
Why must metal components be grounded when high frequency current is used?
high frequency current radiation must be controlled to prevent radio and television interference
8
High frequency current leakage can be prevented by:
keeping the welding cables as short and straight as possible
9
What can happen if the torch body or handle becomes cracked?
a possible shock hazard from the high frequency current can occur.
10
Water pressure on a GTaw torch should NOT exceed:
The manufacturer's recommendations
11
The end of the gas nozzle must be kept clean and uniform in order to avoid:
uneven gas coverage
12
Metal particle sticking to the inside of the ceramic nozzle May:
cause gas turbulence and possible atmospheric contamination
13
Why must collets be kept clean?
keeping collets clean ensures that the best electrical contact can be obtained between the electrode and the collet to reduce heating of the electrode and the torch body
14
A GTAW electrode that discolours when the arc is broken is an indication that:
the electrode has atmospheric contamination
15
What are symptoms of creep on a shielding gas regulator?
creep is identified when the working pressure gauge shows an increase pressure after the cylinder is opened while adjustment screw is disengaged
16
If you strike an arc and immediately experience atmospheric contamination, what part of the equipment may not be properly adjusted?
the flow meter
17
What may occur if the gas hose fittings are not tightly secured?
atmospheric air can be drawn in to the shielding gas or a loss of shielding can contaminate the weld and/or the electrode
18
What is the likely cause of porosity in a GTAW weld?
inadequate gas shielding
19
Excessive shielding gas flow may result in:
contamination of the weld puddle
20
What shielding gas is the best choice to aid in oxide removal on aluminum?
Argon
21
Contaminated shielding gas generally causes:
porosity
22
Why is argon hydrogen shielding NOT recommended for carbon steels?
hydrogen becomes dissolved in carbon steals and causes hydrogen embrittlement that may lead to cracking
23
GTAW troubleshooting can be grouped into one of which three categories? a) b) c)
process mechanical electrical
24
One reason for a crack in the weld is?
The wrong combination of filler to base metal
25
One reason for crater cracks occurring at the end of the weld is:
improper manipulation of the torch
26
What is the purpose of tailing out prior to breaking the arc?
to reduce the size of the weld puddle to prevent crater cracking
27
Incomplete penetration could be caused by:
Arc length that is too long
28
What is a likely cause of lack of fusion?
Arc length that is too long
29
Root pass suckback is the result of:
improper position of filler metal addition.
30
Tungsten inclusions in The weld zone are most often caused by:
exceeding the current limit of the electrode
31
A reason for undercut in GTAW weld is:
welding current that is set too high