Match your tip to the one of the two groups the Resistance welders Manufacturers Association has developed to classify and categorize the different tips used... In the .pdf which Jarhead 1 posted for you, there's a quick list of the groups listed and are shown as this:
"Electrode Tips
Copper is the base metal normally used for resistance spot welding tongs and tips. The purpose of the electrode tips is to conduct the welding current to the workpiece, to be the focal point of the pressure applied to the weld joint, and to conduct heat from the work surface. The tips must to maintain their integrity of shape and characteristics of thermal and electrical conductivity under working conditions. Electrode tips are made of copper alloys and other materials. The Resistance Welders Manufacturing Association (RWMA) has classified electrode tips into two groups: Group A − Copper based alloys, Group B − Refractory metal tips
The groups are further classified by number. Group A, Class I, II, III, IV, and V are made of copper alloys. Group B, Class 10, 11, 12, 13, and 14 are the refractory alloys.
Group A, Class I electrode tips are the closest in composition to pure copper. As the Class Number goes higher, the hardness and annealing temperature values increase, while the thermal and electrical conductivity decreases.
Group B compositions are sintered mixtures of copper and tungsten, etc., designed for wear resistance and compressive strength at high temperatures. Group B, Class 10 alloys have about 40 percent the conductivity of copper with conductivity decreasing as the number value increases. Group B electrode tips are not normally used for applications in which resistance spot welding machines would be employed." This is located in the same Handbook of Resistance Welding from Miller Electric that jarhead1 shared with you from his own post...
Here's another article from the AWS on resistance welding electrode caps or tips you night be interested in reading also:
http://www.aws.org/w/a/wj/2003/11/feature1/Does this sort of question sound familiar to you?
November 2013 by Donald F. Maatz Jr.
Q: "We are resistance spot welding on galvanized coated parts and experiencing what we consider to be short electrode life. We start each production run with welds that barely meet their size requirements but finish with expulsion so severe we end up destroying the electrode face. We are hesitant to change the weld schedule due to the small initial weld size and have instead focused on the current stepper, to little effect. The water flow, electrode cap size, weld force, secondary current, and weld time are all in line with RWMA guidelines. Any ideas would be appreciated."
If this is very similar to your situation, you may want to take a look and read this .pdf of Q & A:
http://www.aws.org/rwma/rwma-qa-2013-11.pdf Here are some more Q & A:
http://www.aws.org/rwma/rwma_qa.html Here's the RWMA Home page:
http://www.aws.org/rwma/index.htmlHere's some Tuffaloy links:
http://tuffaloy.com/ Here's their Catalogue:
http://tuffaloy.com/tuffaloy-catalog.html Resistance Welding Caps:
http://tuffaloy.com/resistancew/27-resistance-welding-caps.html Welding Data:
http://tuffaloy.com/resistance-welding-help-aids/welding-data.html Resistance Welding Help Aids:
http://tuffaloy.com/resistance-welding-help-aids.htmlHere's another quick link that may be helpful:
http://www.mtimicrowelding.com/electrodes.cfm Glidcop® Dispersion Strengthened Copper:
http://www.spotweldingconsultants.com/glidcop.htm Copper Tungsten / Tungsten & Molybdenum (Elkonite®):
http://www.spotweldingconsultants.com/tungsten.htmlELKONITE, ELKON AND ANVILOY MATERIAL:
http://www.nsrw.com/products/cmw/Elkonite_Elkon_Anviloy_Material_5.pdf http://www.tjsnow.com/supplies/cmw/w05f.pdfI could go on and on but I'll stop here because I'm tired and need to take a nap so, I hope this helps.
Respectfully,
Henry
