What's the reason?
1. The failure of the contact tip itself
(1) The wear of the contact tip:
The wear of the contact tip is in fact the wear of the contact tip outlet due to the continuous friction under the rising temperature caused by wire feeding. In robot welding, it often leads to calibration errors and affects production efficiency. The means to reduce possibility of contact tip failure include lowering the temperature of the contact tip, adjusting the alloy composition of the contact tip, and adjusting the structure of the contact tip. The material of the contact tip include brass, red copper, chrome-zirconium copper and other materials, among which brass is the worst, red copper is slightly better, and chrome-zirconium copper is the best in durability.Sometimes, ceramic components are added to the contact tip to increase wear resistance and improve durability.
(2) The processing accuracy of the contact tip is terrible.
Due to the bad accuracy of the processing equipment or other problems, the smoothness and concentricity of the inner hole of the contact tip are not good enough.
2. Straightness and surface finish of welding wires
(1) Welding wires are often packaged in spools or drums, and may have burrs or ribs, so it may affect the contact between the welding wire and the contact tip. When welding, the contact tip should provide the minimum friction under the premise of stable conduction. The service life of the contact tip through which the dirty welding wires passes may be only one-third of that of the clean wires;
(2) Testing of hardness of welding wires: feed the wires like usual and see where the wire bending happens, if the bending happens at about 50cm to the contact tip, it means that the hardness of the wires are proper, bending within 50cm means the welding wire is too soft, bending beyond 50cm to the contact tip means the wires are too hard. Either too soft or too hard wires will bring extra wear of the contact tips and shorten their service life.
(3) In the end, the bending of wire hose will make the wires bend too, and then bring extra wear of the contact tips.
3. Unstable arc causes arc flashback
Bad arc ignition, unstable welding arc and not smooth wire feeding will result in frequent changes in the conductive point between the welding wire and the contact tip, in this situation, the service life is only half of that when the conductive point is stable;
4. Wire feeding speed or amount of deposition
Relatively speaking, a contact tip with a smaller diameter has a shorter service life. At same current of 300A, the deposition amount per unit time of 1.2mm and 1.6mm welding wires are basically the same. But the length of the 1.2mm welding wire welded is twice that of 1.6mm wires, that is, the wear amount of the 1.2mm contact tip is almost twice that of the 1.6mm contact tip at the same time at the same current.
How to prevent?
1. Purchase chrome-zirconium-copper contact tips with guaranteed processing accuracy, such as Fox Alloy contact tips whose quality has been long proven in the markets.2. The welding wires must be straightened in the wire feeding machine before welding.
3. The contact tip must be tightened with pliers. Twisting the contact tip by hand is not enough, as it will lead to unstable arc, and the contact tip is more easily worn.
4. Always clean the surface of the sleeve and the contact tip, and use anti-splash silicone oil.
5.Usually use smaller voltage ( voltage should be 14+0.04* welding current). The higher the voltage is, and more wear of contact tips there will be.
6. Clean the wire hose frequently.
7. The quality of welding wire is also a decisive factor, try to use welding wires with proper hardness. Fox Alloy welding wires are manufactured to the highest industrial quality standards, the hardness and smoothness of each spool of wires can be guaranteed.Fox Alloy welding wires can ensure longer contact tip service life.
8. The surface of the workpiece should be as clean as possible and oil & rust should be removed before welding.