Frequent replacement of the contact tip: The appearance is that the outlet of the contact tip is worn out, causing wire feed deflection... In fact, the welding track is offset, that is, the position of the TCP point is shifted, resulting in welding defects such as welding deviation or welding leakage.
Causes of wear
1. The reason for the failure of the contact tip itself: the wear of the contact tip itself originates from the wear at the outlet of the contact tip due to the friction of the continuous wire feeding under the rising temperature of the contact tip. When the head is welding, it often leads to calibration errors. As it affects the production efficiency, it is necessary to reduce the temperature of the contact tip, including the processing of the contact tip composition and the structure of the contact tip. The material of the contact tip: brass, red copper, chromium zirconium copper and other materials, of which brass is the most inferior, red copper is slightly better, and chromium zirconium copper is the best; even ceramic components are added to the contact tip to increase wear resistance. Once again, the processing accuracy of the contact tip, due to the accuracy of the processing equipment or other problems, the finish and concentricity of the inner hole of the contact tip are not good enough.
2. Reasons for the straightening of the welding wire and the surface finish: The welding wire is often packed in a tube or coil, and has burrs or ribs, so it may affect the contact between the welding wire and the conductive tip. When welding, the conductive tip The minimum friction should be provided under the premise of stable conduction. The life of the contact tip when the wire is dirty may be only one-third of that of the clean wire; to determine the quality of the wire, the degree of annealing stress relief of the wire, the performance is how straightening is, the test is: 50mm in front of the welding gun nozzle, whether the wire is It can be bent automatically. Bending forward indicates that the welding wire is too soft. Bending backward indicates that the welding wire is too hard. The hard welding wire is the most costly to the contact tip. Secondly, whether the wire feeding hose from the wire feeder to the welding gun is bent. Cause the welding wire to bend.
3. Arc instability leads to arc burnback. One of the causes includes poor arc ignition, unstable arc, poor wire feeding, cleanliness of the surface of the workpiece, etc., but it does not necessarily affect the performance of the contact tip itself. Welding at this time The fault is roughly related to the characteristics of the welding power source, the quality of the welding wire, the wire feeding effect, the structure design of the wire feeding hose and the contact tip, etc. When the conductive point in the welding wire and the contact tip is constantly changing, its life is only half of that when the conductive point is stable;
4. Wire feeding speed or welding amount: Relatively speaking, the smaller the diameter, the shorter the service life of the contact tip. With the same current of 300A, the filling (melting) amount per unit time of 1.2mm and 1.6mm welding wires is basically the same. The length of the 1.2mm welding wire is twice that of 1.6mm, that is to say, the wear amount of the 1.2mm contact tip is almost twice that of the 1.6mm contact tip at the same current and the same time. Assuming that both the 1.6mm and 1.2mm contact tips are worn by 0.2mm, this 0.2mm is 12.5% of 1.6mm and 16.7% of 1.2mm. The 1.2mm welding wire has a larger beating range.
Improvement Measures
1. Purchasing conductive nozzles made of chromium, zirconium, copper and large-brand products with guaranteed processing accuracy.
2. Straightening of welding wire.
3. The contact tip must be tightened with pliers. Twisting by hand is not enough. The arc is unstable and the contact tip is more expensive!
4. The gun cleaning station is normal and sprayed with anti-splash silicone oil.
5. Generally, use a smaller voltage, and use the approximate formula 14+0.04* current, the voltage is high, and the loss is large.
6. The wire feeding pipe should be cleaned frequently.
7. The quality of welding wire also has a decisive factor.
8. The surface of the workpiece should be as clean as possible and less oily.
Post time: Jun-25-2021