Every welding machine has the same core controls, and every welding instructor says the same thing: the machine does not make the weld, the parameters do. Understanding what each setting physically does lets you fix a bad weld on the first pass instead of the third. This guide explains the six parameters that control every arc weld.

VOLTAGE

Voltage controls the arc length. Higher voltage stretches the arc longer and widens and flattens the bead; lower voltage shortens the arc and produces a narrower, steeper bead. Voltage is the parameter that shapes the weld and affects how well it wets out at the toes.

  • Too high — a wide, flat, spattery bead with poor profile control.
  • Too low — a tall, narrow, convex bead with risk of lack of fusion.
  • For MIG, voltage sets the arc characteristic; for TIG and stick it is mostly determined by the process and electrode.

CURRENT (AMPERAGE)

Current is the heat input. More amperage means more heat, deeper penetration, and a bigger puddle. Less amperage means a colder, shallower weld. Every electrode and wire has a rated amperage range, and the amperage guide covers matching current to electrode size.

  • Amperage too low — lack of fusion, poor penetration, cold lap.
  • Amperage too high — burn-through on thin metal, undercut, excessive distortion.
  • On aluminum and stainless, current choice also drives the heat that controls warping.

TRAVEL SPEED

Travel speed is how fast the arc moves along the joint. It controls how much weld metal is deposited per inch and how long the base metal stays molten.

  • Too fast — a thin, peaked bead with poor penetration and undercut.
  • Too slow — a wide, overheated puddle, excess reinforcement, and burn-through.
  • The correct speed leaves a bead about 1.5–2 times the electrode diameter, with a flat to slightly convex profile.

CTWD (CONTACT TIP TO WORK DISTANCE)

For wire-fed processes, the stick-out — the distance from the contact tip to the work — changes the electrical resistance of the wire and therefore the heat. A longer stick-out adds resistance and heats the wire more; a shorter one gives a hotter, more penetrating arc.

  • Typical MIG/FCAW stick-out: 10–19 mm, kept consistent by resting the nozzle on the work.
  • Too long — spatter, unstable arc, porosity, low penetration.
  • Too short — the nozzle heats up and blocks gas flow, and the tip can contact the puddle.

TORCH ANGLE

The angle of the torch or electrode relative to the joint directs the arc force and the puddle. Drag angle (pushing) points heat backward and gives a flatter, smoother bead; push angle is used for deposition; and vertical and overhead work changes the angle again.

  • Work angle (left-right) must split the joint: 45° on a fillet weld.
  • Travel angle for MIG: 10–15° drag for steel, 10–15° push for aluminum.
  • Wrong angles cause undercut on one toe, lack of fusion on the other, or slag rolling ahead of the puddle.

WIRE FEED SPEED

On wire-fed machines, wire feed speed is what actually sets the amperage: the machine feeds more wire, draws more current, and melts it into a larger puddle. It is the deposition control — more wire per minute, more metal per minute.

  • Wire feed and voltage must be balanced: voltage too high for the feed speed gives spatter and a flat bead.
  • Feed speed too low — small, erratic beads and burnback into the tip.
  • Feed speed too high — a roping, convex bead and overheating the wire.
Pro Tip

Change one parameter at a time. If you move voltage and wire feed and travel speed together, you will never know which one caused the result — or which one fixed it.

HOW TO DIAL IN A NEW JOINT

Every new job is a small experiment. A reliable sequence:

  • Start with the procedure range for your process and material — from the MIG parameter charts or the process guide.
  • Run a practice bead on scrap of the same thickness.
  • Check penetration, bead shape, and toes against what the joint needs.
  • Adjust one parameter, test again, and compare.
  • Write down what worked — a job that takes ten minutes to dial in saves ten hours in rework.
Watch Out

Do not chase parameters to fix a fit-up problem. If the joint is gapped or mismatched, no amperage in the world will save it — fix the fit-up first.

THE BOTTOM LINE

Voltage shapes the bead, current delivers the heat, travel speed controls the deposit, stick-out and angle direct the arc, and wire feed sets the deposition rate. Learn what each one does, change them one at a time, and you can set up any joint in a few practice beads instead of a pile of grinders.