Method for providing real-time monitoring of contact tip performance

1. A method for tracking welding contact tip deterioration in real time, the method including the steps of:

establishing a reference that relates welding parameters during welding production to contact tip life;

choosing a representative weld from among the welds that are performed on a single part;

monitoring welding parameters of a contact tip during use only while performing the same representative weld on each successive part;

comparing the monitored welding parameters to the reference;

providing real-time feedback to an operator; and

predicting contact tip failure from the comparison.

2. The method of claim 1 , further including the step of:

providing a warning when welding parameters deviate unacceptably from the reference.

3. The method of claim 1 , further including the step of:

scheduling a contact tip change when welding parameters deviate unacceptably from the reference.

4. The method of claim 1 , wherein monitoring welding parameters of a contact tip during use includes:

measuring one of welding current and welding voltage in real time.

5. The method of claim 1 , wherein providing real-time feedback to an operator includes:

displaying a control chart including average welding current plotted as a function of part count.

6. The method of claim 5 , wherein the step of displaying a control chart further includes the steps of:

forming four horizontal lines, the horizontal lines corresponding to a welding current value of an upper control limit, a welding current value of a lower control limit, a welding current value of an upper tolerance limit, and a welding current value of a lower tolerance limit;

defining a warning region between the upper control limit and the upper tolerance limit, and between the lower control limit and the lower tolerance limit; and

defining a critical region beyond the upper tolerance limit and beyond the lower tolerance limit.

7. The method of claim 6 , wherein the upper tolerance limit is set at 115% of a command welding current and the lower tolerance limit is set at 85% of the command welding current.

8. The method of claim 6 , wherein the upper and lower control limits are set manually.

9. The method of claim 6 , further including the step of:

issuing a warning signal if the monitored welding parameters fall into the warning region.

10. The method of claim 6 , further including the step of:

replacing the contact tip if the monitored welding parameters fall into the critical region.

11. The method of claim 5 , wherein the step of displaying a control chart further includes the steps of:

setting a lower control limit at a welding current value that is less than a command welding current value, and setting a lower tolerance limit at a welding current value that is less than the lower control limit;

defining a warning region between the lower control limit and the lower tolerance limit;

defining a critical region that is below the lower tolerance limit;

displaying the values of the average welding current that are outside the warning region and critical region in a green color, displaying the values of the average welding current that are in the warning region in a yellow color, and displaying the values of the average welding current that are in the critical region in a red color.

12. The method of claim 5 , wherein the step of displaying a control chart further includes the steps of:

forming a solid white vertical line for an average welding current value that is within upper and lower control limits;

forming a dashed black-and-white vertical line for an average welding current value that is out of the lower control limit but within a lower tolerance limit; and

forming a solid black vertical line for an average welding current value that is below the lower tolerance limit.