Lincoln Electric Pro-MIG 140 manual Process Guidelines, Making a Weld, Cleaning Tip And Nozzle

B-5 OPERATION B-5

Contact Tip

Wire Electrode

3/8"– 1/2"(10-13mm) Contact Tip to Work Distance(CTWD)

FIGURE B.6

Making A Weld

1.See “Process Guidelines” in this section for selec- tion of welding wire and shielding gas and for range of metal thicknesses that can be welded.

2.See the Application chart on the inside of the wire feed compartment door for information on setting the Pro-MIG 140 controls. Refer to Table B.1 for aluminum and stainless wire.

3.Set the Voltage (“V”) and Wire Speed (“olo’”) con- trols to the settings suggested for the welding wire and base metal thickness being used, refer to Applications chart on the inside of the wire drive compartment door.

4.Check that the polarity is correct for the welding wire being used and that the gas supply, if required, is turned on.

5.When using Innershield electrode, remove the gas nozzle and install the gasless nozzle. This will improve visibility of the arc and protect the gas dif- fuser from weld spatter. Refer to the MAINTE- NANCE section for details on nozzle replacement.

GUN CABLE

WORKPIECE

ARC

WORK CLAMP

FIGURE B.7

6.Refer to Figure B.7. Connect work clamp to metal to be welded. Work clamp must make good elec- trical contact to the workpiece. The workpiece must also be grounded as stated in “Arc Welding Safety Precautions” in the beginning of this manu- al.

7.Position gun over joint. End of wire may be lightly touching the work.

8.Place hand shield in front of face, close gun trig- ger, and begin welding. Hold the gun so the con- tact tip to work distance is about 3/8 inch (10 mm).

9.To stop welding, release the gun trigger and then pull the gun away from the work after the arc goes out.

10.When no more welding is to be done, close valve on gas cylinder (if used), momentarily operate gun trigger to release gas pressure, and turn off the Pro-MIG 140.

Cleaning Tip And Nozzle

Clean the contact tip and nozzle to avoid arc bridging between the nozzle and contact tip which can result in a shorted nozzle, poor welds and an overheated gun. Hint: Anti-stick spray or gel, available from a welding supply distributor, may reduce buildup and aid in spat- ter removal.

PROCESS GUIDELINES

The Pro-MIG 140 can be used for welding mild steel using the GMAW, single pass process which requires a supply of shielding gas or it can be used for the self- shielded, Innershield® process (FCAW).

The recommended gases and electrodes for GMAW are welding grade CO2 gas or an argon-CO2blended gas (75 to 80% argon and 25 to 20% CO2) and .025" (0.6 mm) diameter Lincoln Super Arc L-56 mild-steel welding wire, supplied on 12-1/2 lb (5.7 kg) spools.

The recommended electrode for the self-shielded process is .035” (0.9 mm) diameter Lincoln Innershield® NR-211-MP. This electrode can be used for all position welding of 20 gauge (1.0 mm) through 5/16" (8 mm) steel. Thickness of 1/4" (6 mm) and 5/16" (8 mm) require multiple passes. This wire can also be used for the welding of galvanized coated sheet metal.

Pro-MIG 140