MinarcMig Parts FAQs
Straight answers to the questions people ask most when buying spare parts for a compact MIG welding machine and its torch.
Which parts of a compact MIG machine's torch wear out first?
The consumables at the front of the torch wear first: the contact tip, the gas nozzle and the gas diffuser. Behind them, the liner that guides the wire along the cable also wears and can clog with dirt and copper dust.
A worn contact tip causes an unstable arc, a clogged liner causes poor wire feed, and a spatter-filled nozzle upsets the gas shield. Replacing these in good time protects weld quality and helps avoid damage to the torch.
How do I know when to change the contact tip?
Change it when the arc becomes unstable or erratic, when the hole in the tip has worn out of round, or when the tip is burned or deformed. As the hole enlarges, electrical contact with the wire becomes inconsistent, which shows up as an unsteady arc.
If the wire has burned back and fused to the tip, replace the tip rather than reuse it, and look for the cause, such as a wrong-size tip, a restricted liner or a poor earth connection. There is no fixed interval, because it depends on the wire, the current and how long you weld.
Does the contact tip size matter?
Yes. The hole must match the diameter of the wire you are using, with only a very small clearance so the wire can slide freely while still making good electrical contact. An oversized hole lets the wire move about, causes arcing inside the tip and is a common cause of burnback, so a bigger tip is not a cure for feeding problems.
For aluminium wire, use tips made for that wire. Check the wire size on the spool and the size marked on the tip when you order.
Why does the liner have to be cut to the right length?
The liner must reach the correct point at both ends of the torch. If it is trimmed too long or too short, the wire can snag or be unsupported, which causes serious feeding problems.
The correct amount of liner to leave protruding or to trim back is given in the maker's instructions for your torch, and many makers supply a gauge or marks to help. Follow those, and do not guess the length.