The contact tip is a very important component of the welding gun and choosing the right contact tip for your welding applications and understanding how to maintain it so that it delivers the best performance is extremely important for producing a high-quality weld. Typically, the contact tip is the most frequently replaced component in the welding torch and also the most misunderstood part.
The function of the contact tip is to guide the wire and transfer current from the conductor tube to the workpiece via the filler wire. It also plays a very critical role in wire targeting and transfer of current. The size of the contact tip determines the size of wire to use and the amount of filler material which is distributed during the welding process. Using too big or too small a contact tip can cause problems like overheating, micro-arcing, wire jamming and friction, that causes wire burn-back.
When the contact tip of the torch starts to wear, the hole of the tip gets elongates and it loses electrical conductivity. This affects the ability of the gun in transferring current to the welding wire. The TCP (tool centre point) also starts fluctuating as the wire moves inside the oversized tip. All this results in lower penetration, poor starting of the arc and reduced quality of the weld.
Solving Common Contact Tip Problems
Once you have chosen the appropriate contact tip depending on your welding application, here are a few steps to follow to ensure that you’re getting the most out of your gun’s contact tip.
Allow the Torch to Cool
Before you change the contact tip, make sure that the torch has cooled down. It can be very difficult and dangerous to try and change the contact tip while the torch is hot. A hot torch can cause the contact tip to get cross-threaded, which can ruin the tip, as well as the torch’s neck.
Use the Correct Torch Tip Size
Ensure that the tip you use is of correct size, as using a larger tip can cause problems in current transfer resulting in micro-arcing and a hotter tip that can cause wire burn back. Using a tip that is undersized increases the friction and causes the wire to get jammed in the tip or feed unsteadily, which can also result in wire burn back.
Tighten the Tip Properly
If the contact tip is not tightened correctly, it can cause micro-arcing, poor current transfer and overheating. When this occurs, it can cause poor arc starts, erratic wire feeding and burn back of the wire into the contact tip.
Check the Contact Tip Appearance
If the contact tip turns blue or purple in colour, it means that the connection is poor, the torch’s amperage rating or duty cycle has been exceeded, or the consumables are too big for the torch. In severe cases, the exterior of the contact tip gets covered in scales.
Selecting the right contact tip is extremely important for the welding application and also understanding how to keep the tip functioning at its best and maintaining it is as important as choosing the other parameters and components required in order to produce a high-quality weld.