Tweco M-42 RPT - Manual (Page 5)

January 23, 2004 5 Manual 0-2856
1. Remove the shield cup, tip, gas distributor, and elec-
trode from the torch. Disconnect the torch leads from
the power supply to isolate the torch from power sup-
ply circuits.
2. Using an ohmmeter (set to 10K or higher), check for
continuity between the positive and negative torch
fittings. Infinite resistance (no continuity) should be
found. If continuity is found there is a problem in the
Torch or Torch Leads.
Common Operating Faults
The following lists the more common cutting faults and
the possible causes:
1. Insufficient Penetration
a. Cutting speed too fast
b. Torch tilted too much
c. Metal too thick
d. Worn torch parts
e. Cutting current too low
f. Non - Genuine Thermal Dynamics Parts
2. Main Arc Extinguishes
a. Cutting speed too slow
b. Torch standoff too high from workpiece
c. Cutting current too high
d. Work cable disconnected
e. Worn torch parts
f. Non - Genuine Thermal Dynamics Parts
3. Excessive Dross Formation
a. Cutting speed too slow
b. Torch standoff too high from workpiece
c. Worn torch parts
d. Improper cutting current
e. Non - Genuine Thermal Dynamics Parts
4. Short Torch Parts Life
a. Oil or moisture in air source
b. Exceeding system capability (material too thick)
c. Excessive pilot arc time
d. Air flow too low (incorrect pressure)
e. Improperly assembled torch
f. Non - Genuine Thermal Dynamics Parts
Inspection and Replacement of
Consumable Torch Parts
WARNINGS
Disconnect primary power to the system before
disassembling the torch or torch leads.
DO NOT touch any internal torch parts while the
AC indicator light of the Power Supply is ON.
Remove the consumable torch parts as follows:
NOTE
The tip and gas distributor are held in place by the
shield cup. Position the torch with the shield cup
facing upward to prevent these parts from falling
out when the cup is removed.
1. Unscrew and remove the shield cup from the torch.
NOTE
Slag built up on the shield cup that cannot be re-
moved may effect the performance of the system.
2. Inspect the cup for damage. Wipe it clean or replace
if damaged.
Torch Head Assembly
(70˚ Hand Torch Shown)
Shield Cup
Gas
Distributor
Tip
Electrode
A-03025
3. Remove the tip. Check for excessive wear (indicated
by an elongated or oversized orifice). Clean or re-
place the tip if necessary.
Good Tip Worn Tip
A-00323