Ring projections can be a round radius faced annular ring on one face of the part. Frequently the ring is a “V” shaped ring on the face of the part. Be it a ring or individual projections the process is the same. The projection design concentrates the force and heat on the part and heat will generate there when current is applied. The connection on the top of a water heater is an example we are all familiar with. This annular projection prevents the connection from leaking water during use.
TYPICAL RING PROJECTIONS
To develop the process to make this type of weld, some starting information is helpful. There is not much available. THE WELDING INSTITUTE in the UK “TWI” does have some basic data available.
They offered some information on general design considerations. Most importantly they offered estimated values of force, time and current.
Electrode Force 18-24 kg per mm of projection length (circumference)
Weld Time 7 – 10 cycles
Welding Current 470-630 amp per mm of projection length
This information can be used for estimating the weld schedule conditions. Using these values some heating will occur. Always start at modest values and be careful until initial results have been evaluated.
These values do not state what material is being welded. Adjustments will be required to account for this. That is why there is a range. At the start of testing expect to use the full range and maybe more.
Reference: The Welding Institute, TWI – Recommendations For Resistance Welding Annular Projections