AC/DC welding controls

CURRENT CONTROL

This adjusts the main welding current/amperes.

GAS PRE-FLOW

Pre-flow can be set so that the argon flows before the arc starts, pushing air out of the torch before welding starts; 0.2 secs is enough.

START CURRENT

A start current can be selected lower than the set welding current. Sometimes it is a percentage; sometimes it can be amps. It just depends on the brand of machine.

UP SLOPE

This adjustment is usually 0–10 seconds. The main welding current will rise from a minimum set amperage up to the main current selected in the time selected. Turn this back to zero when learning. One less thing to think about.

DOWN SLOPE

Down slope is used when you want to cool the weld pool down slowly. This avoids crater cracks and hollow finishes. Depending on the brand, this adjustment is usually 0–10 seconds. Some machines may call this ‘crater fill’.

GAS POST-FLOW

Gas post-flow adjustment 1–20 seconds. This keeps the argon flowing after the welding has finished, which cools the tungsten electrode while it is still glowing. It stops oxidization and contamination. Some machines have automatic post-flow that is synced to the set current. Trying to save money by turning this timer down will only result in a dirty, oxidized tungsten electrode. A 2.4mm tungsten electrode at 150A will need about 10 seconds post-flow. A 3.2mm tungsten at 200A may be 12 seconds.

PULSE PEAK CURRENT ADJUSTMENT

This sets pulse amperage and is usually set higher than the base (main) current amperage. If the machine calls it ‘background current’ then the (main) current is the (top) peak and the background current is set at the lower pulse setting. This setting can be set as a percentage of the main current or an amperage setting.

PULSE FREQUENCY ADJUSTMENT

This sets how many pulses per second, 0.5–200.0Hz. A setting of one or two pulses per second is excellent for timing when dipping the TIG rod into the weld pool. But turning the pulse rate up will give you a narrower, deeper penetrating weld bead. As you turn the pulse rate up you will lose sight of the flashes at around 30 pulses per second.

PULSE RATIO

Normally the pulse will be

50/50 per cent. This is half the time at the top and half the time at the lower pulse setting. A setting such as 30/70 per cent (that’s 30 per cent of the time at the higher pulse current) is ideal for that scalloped-looking weld often seen on intercooler piping and aluminium motorbike frames.

AC BALANCE

This is your penetration or cleaning action.

Personally, I like more cleaning as it isn’t hard to achieve good penetration with welding aluminium. Setting the balance to 60 per cent negative and 40 per cent positive will make the arc wider. There will be less penetration and more cleaning action.

AC FREQUENCY ADJUSTMENT

Traditional TIG welders have a fixed frequency of 50. Advanced technology allows AC frequency adjustment from 20 to 250Hz. The higher you turn up the frequency, the more the width of arc from the tungsten decreases. This allows more control of weld pool, which you will notice will also get narrower and you can increase travel speed. The ‘AC’ noise of the arc will increase when AC frequency is turned up. This is normal. When welding dirty/ contaminated material more cleaning may need to be selected.