During the welding production process, there are many reasons why a welding robot may burn the contact tip.
Observable symptoms that indicate frequent contact tip replacement include: wear at the tip exit causing the wire to deflect, which in turn offsets the actual welding path and location of the TCP point. This can lead to welding defects such as displaced or missing welds.
Analysis of problems arising from wear of the welding robot contact tips
1. Causes of contact tip failure
The wear of the contact tip of the welding robot can be attributed to the friction caused by continuous wire feeding under the increasing temperature of the contact tip. This wear, which occurs at the contact nozzle exit, often leads to calibration errors that decrease production efficiency during the robot's welding operation.
Efforts should be made to lower the temperature of the contact tip, including considerations in the composition and structural processing of the contact tip.
Materials for the contact tip include brass, copper, and the best of them is chrome-zirconium copper. Even the inclusion of ceramic components in the contact tip can increase its abrasiveness.
In addition, the processing accuracy of the contact tip is often compromised due to the accuracy of processing equipment or other problems, resulting in less than desirable smoothness and concentricity of the inner hole of the contact tip.
2. Arc Instability Leading to Arc Blowback
Causes of this problem include poor arc initiation, unstable arc, impaired wire feed, and cleanliness of the part surface. However, these factors do not necessarily affect the performance of the contact tip itself.
Welding malfunction at this point is generally related to the characteristics of the welding power source, the quality of the welding wire, the effectiveness of wire feeding, the wire hose and the structural design of the contact tip.
When the conductive point of the welding wire inside the contact tip changes frequently, its service life becomes only half of what it is when the conductive point is stable.
3. Factors such as straightness and surface cleanliness of the welding wire
The welding wire used by welding robots is often packaged in drums or coils and may have burrs or grooves. These imperfections can potentially interfere with the contact between the wire and the contact tip.
During robotic welding, the contact tip must provide minimal friction while maintaining stable conductivity. The life of a contact tip used with dirty welding wire may be only one third of the life of a tip used with clean wire.
To evaluate the quality of the wire, we consider the degree of relief from annealing stress, which manifests itself in the straightness of the wire. Test feedback shows how the wire automatically bends 50mm in front of the welding torch tip: if it bends forward, the wire is too soft; if you bend backwards, it is very difficult.
The hard wire is more harmful to the contact tip. Furthermore, if the wire feed hose from the wire feeder to the welding gun is kinked, it can also cause the wire to bend.
4. Wire feed speed or deposition rate
Generally, the smaller the diameter of the contact tip, the shorter its service life. For a current of 300A, welding wires 1,2 and 1,6 have approximately the same fill volume (melt) per unit time.
The length of wire 1.2 is twice that of wire 1.6, which means that for the same current and time, the wear of contact tip 1.2 is almost twice that of tip 1.6.
Assuming that both contact tips 1.6 and 1.2 have wear of 0.2 mm, this 0.2 mm represents 12.5% of tip 1.6 and 16.7% of tip 1.2, therefore the 1.2 wire has a larger deviation range.
5. Open grounding devices or wires can cause high temperatures, leading to slag adhesion
How to prevent welding robots from burning the contact tip and strategies for improvement
1. Purchase contact tips made of chrome-zirconium copper from reputable brands that guarantee accuracy.
2. Ensure the straightness of the welding wire.
3. The contact tip must be tightened with pliers, it is not suitable to tighten it by hand alone. This can lead to an unstable arc and increased wear on the contact tip.
4. Keep a regular cleaning gun station and apply anti-splash silicone oil.
5. It is recommended to use a lower voltage, selecting an approximate formula of 14+0.04 current. Higher voltage leads to greater losses.
6. Regularly clean the wire feed path.
7. The quality of the welding wire is also a decisive factor.
8. Keep the surface of the part as clean as possible, minimizing oil contamination.
