It is likely that a standard published 3 or 4 projection weld schedule does not exist in the literature. The options are start testing from scratch or look at spot welding data for the same material that may exist.
The best way is to use a known similar weld schedule to estimate for the initial test coupons.
Simply use the data for one spot weld and multiply current and force by three or four depending upon spot spacing. Time stays the same.
FOUR PROJECTION PART
This is described in a previous article in this blog:
For complete details of proces variable and set up see:
Weld schedules are availble in the references below for some standard materials.
AWS and RWMA both publish spot welding schedules that can be used to develop a projection welding schedule. They also have published projection welding schedules for many materials.
Reference: AWS Standard C1.1 Recommended Practices for Resistance Welding
RWMA - Resistance Welding Manual 4th Edition
Tuffaloy Product Inc. Catalog
CMW Inc. Resistance Welding Products Catalog