L-TEC PCM-70 - Maintenance; Common Cutting Faults; Inspection and Cleaning; Flow Testing

too slow
too fast
correct
Fig. 5 - Effect of Cutting Speed
D.
position so that the cooling fan has time to remove the
heat from the unit. Then shut off the primary power at
the main disconnect switch.
COMMON CUTTING FAULTS
Listed below are common cutting problems followed by
probable causes of each. If problems are determined to be
caused by the PCM-70 Console, refer to the troubleshooting
section in booklet Form 14-390.
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Insufficient Penetration.
a. Cutting speed too fast.
b. Damaged cutting tip.
c. Improper gas pressure.
d. Standoff too low.
. Main Arc Extinguishes.
a. Cutting speed too slow.
. Dross Formation. (In some materials and thick-
nesses, it may be impossible to get dross-free cuts.)
a. Cutting speed too fast or too slow.
b. Improper gas pressure.
c. Faulty tip or electrode.
d. Standoff too low.
. Double Arcing. (Damaged Tip Orifice.)
. Low gas pressure.
. Damaged cutting tip.
Loose cutting tip.
. Incorrect electrode “set-back” (PT-121).
. Contact with work.
Heavy spatter.
. Very low speed on thin plate.
neven Arc.
. Incorrect electrode “set-back” (PT-121).
. Damaged cutting tip.
Electrode not straight or centered.
. Partially plugged holes on front end insert of torch.
(See PT- 121 torch booklet, F-12-794.)
. Unstable Cutting Conditions.
a. Incorrect cutting speed.
b. Loose cable or hose connections.
c. Electrode and/or cutting tip in poor condition.
d. Incorrect electrode set-back (PT-121).
. Main Arc Does Not Strike.
a. Loose connections.
b. Improper *Stand-off" between torch and work.
11
c. Torch not over the work.
d. Torch not properly adjusted.
8. Poor Consumable Life.
a. Improper gas pressure.
b. Improper electrode “set-back”.
c. Check O-ring on the front end insert of torch (see
PT-121 torch booklet, F-12-794).
Vi. MAINTENANCE
If this equipment does not operate properly, stop work
immediately and investigate the cause of the malfunction.
Maintenance work must be performed by an experienced
person, and electrical work by a trained electrician. Do not
permit untrained persons to inspect, clean, or repair this
equipment. Use only recommended replacement parts.
NOTE: For detailed maintenance, troubleshooting, and
parts information on the PCM-70 Console, see Form
14-390.
A. INSPECTION AND CLEANING
Frequent inspection and cleaning of the PCM-70 cutting
machine is recommended. Some suggestions for inspecting
and cleaning are as follows:
WARNING
Make sure the power is shut off.
1. Check heat shield on torch. It should be replaced if
damaged.
2. Check the torch electrode and cutting tip for wear on a
daily basis. Remove spatter or replace if necessary.
. Make sure cable and hoses are not damaged or kinked.
4. Make sure all plugs, fittings, and ground connections
are tight.
5. With all input power disconnected, and wearing proper
eye and face protection, blow out the inside ofthe cutting
power supply using low-pressure dry compressed air.
e
CAUTION: Water occasionally accumulates in compressed
air lines. Be sure to direct the first blast of air
away from the equipment to avoid damage.
6. Occasionally bleed water from the filter beneath the air
regulator.
B. FLOW TESTING
WARNING
Avoid fatal shock. Follow the steps below to assure safe
flow measurement.
1. Shut off input power at the main disconnect switch.
2. Lift the top lid of the PCM-70 and unplug the torch
switch cord.
3. Close the lid.