By Mike Sammons
Recently there’s been a migration to transfer the features and benefits of heavier industrial machines into light industrial welders—and offer them at affordable prices. This movement meets the diverse needs of welding professionals and first-time welders, however advanced performance doesn’t matter until a machine is set up correctly. Here are some tips to set up MIG welders with integrated wire feeders, as well as a look at some of their newest capabilities.
1. Installing a MIG gun and feed rolls
For positive wire feeding performance, feed rolls must match the wire diameter and type. To flip or install a new feed roll, release the pressure roller arm and remove the feed roll retention knob. Use a smooth-groove drive roll for solid wire and a V-knurled roll for flux cored wire. For aluminum, use a spool gun for better feeding performance of this soft wire.
2. Setting the feed roller tension
Proper tension on the feed rolls is essential for consistent welding performance—you want to add just enough tension to prevent the wire from slipping. To check tension, hold the gun nozzle 1/8 of an inch from a non-conductive surface. Pull the trigger, and the feed rollers should start to slip. Now hold the gun two inches from the surface. The wire should feed out and bend—this indicates proper tension. If the wire stutters because the feed rolls slip, add tension in half turn increments.
3. Setting wire brake tension
After installing the wire spool and before welding, you need to set the wire brake tension. To do this, turn the nut clockwise to apply more tension and counter-clockwise to release tension. The brake is correctly adjusted when the spool stops within one-half to two inches after releasing the trigger. The wire should be slack without becoming dislodged from the spool. If the wire spool stops immediately after releasing the trigger, there’s too much tension on the spool.
4. Choosing and installing consumables
To ensure proper arc performance, you must use the correct contact tip size that corresponds to the wire diameter used. Before installing the contact tip, note that the gun liner is present at the end of the conductor tube. Now slip the tip over the welding wire, seat it into the conductor tube or gas diffuser and screw on the shielding gas nozzle. Non-threaded tips, such as Tweco VELOCITY2 consumables, extend consumable life and improve performance.
5. Choosing the correct gas
To MIG weld steel with the short circuit transfer mode, a mixed gas blend of 75% argon and 25% CO2 works best in most applications, as it creates the least amount of spatter, the best bead appearance, and helps prevent burn-through on thinner materials. You can also use 100% CO2 for deeper penetration on thicker sections. It costs less but produces more spatter and a rougher-looking bead.
To spray transfer weld, use a mixed gas with a higher argon content, such as 90/10. To MIG weld stainless steel, most welders use a “tri-mix” gas blend with helium, argon and CO2. And finally, to MIG weld aluminum and silicon bronze, welders use 100% argon.
6. Installing a regulator and setting gas flow
Stand on the opposite side of the cylinder, point the valve opening in a safe direction and crack the cylinder valve to clear any dust and close it quickly. Install the regulator by threading the large nut onto the cylinder and use a wrench to tighten the nut (always use a wrench to tighten metal-to-metal connections).
For welding with typical wire diameters, set the gas flow rate to approximately 20 to 25 cubic feet per hour. If you notice porosity, or for welding in mildly breezy conditions, increase flow rates to 30 CFH. Do not increase flow rates beyond 30 CFH because excessive rates create turbulence that can pull in outside air and contaminate the weld.
7. Manual MIG or Synergic MIG?
In manual mode, you fine tune the arc by adjusting voltage and wire feed speed (tips on that shortly). Synergic MIG offers one knob control and takes the guesswork out of fine tuning the arc. It makes the machine easy to set up and even easier to adjust. Use the digitally-driven menu to select the wire type, wire diameter and gas combination. With that information entered, you can weld thicker or thinner metal just by increasing or decreasing wire feed speed; the machine will adjust other parameters automatically. A “trim voltage” control (which controls voltage in manual mode) enables you to adjust the weld bead profile, typically to create a flatter bead with better wet-out at the toes of the weld.
8. More Functions
Digital controls and advanced displays on machines such as ESAB’s Rogue EM 190 PRO provide access to such functions as:
• Trigger selection mode to select between four trigger modes: 2T (standard operation), 4T (trigger latch), spot weld and stitch weld.
• Memory functions to store and recall favorite job parameters.
• The ability to set and adjust gas pre-flow time, creep start or run-in speed, burnback time and gas post-flow time.
• Other items include lists of wear and spare part numbers, recommended filler metals, general maintenance practices and even the owner’s manual.
• Arc Dynamics
9. Understanding Arc Dynamics
Arc Dynamics allows you to adjust the intensity of the welding arc on a scale, such as from -9 to +9. A lower setting makes the arc softer with less weld spatter and has better wetting action of the weld puddle. Higher arc control settings give a more driving arc which can increase weld penetration.
10. Fine tuning your MIG arc
To fine tune your MIG arc, start by using an amperage that matches the wire diameter, shielding gas and material thickness. Voltage controls the height and width of weld bead, as well as the wire melt-off rate.
A finely tuned MIG arc has a “sizzling bacon” sound that signifies a proper balance of wire feed speed and voltage. A harsh sound with a lot of pops usually means that the wire is melting faster than it is coming out of the gun. To solve the problem, decrease voltage or increase wire feed speed. If the wire stubs into the base metal, there is not enough voltage to melt the wire. Solve this by increasing voltage or reducing wire feed speed. SMT
Mike Sammons is the global product manager with ESAB Light Industrial Products.
