In normal conditions the contact tip affect to the wire feed resistance by approx. 10…20 %.
When the contact tip gets crowded, then the wire feeding resistance may grow, so that it is impossible to feed the wire.
Reasons for crowded contact tip can be:
- Spatters, dirt etc.
- Over heating
If the contact tip´s temperature rises to 250…300 ēC, then 0,5…2,5 hours of welding with 250…300 A current may block the contact tip. When the temperature of the contact tip is 100…150 ēC, then the lifespan of the contact tip is much longer.
A crowded or blocked contact tip is the biggest reason for wire feeding problems! |