As stated in another article “How Do I Dress a Resistance Welding Electrode”, the best way is to remove the electrode and remachine it in the tool room where it can be done accurately. For projection welding this may be the only option if the electrode has elaborate machined surfaces or dimensions. If the projection face is merely a flat face which many are other option are possible.
There are no specific tools that I would recommend for dressing.
Manually a block of wood with emery paper on one or both sides as needed. Close the electrodes with lite pressure and rotate the emery paper till the desired flatness is achieved. This could also be a two sided fine flat file followed by fine emery paper.
Hand held pneumatic dressers are available with standard flat faced cutters up to ¾” diameter.
Two sided fine file
If dressing time is an issue, another set of electrodes is the answer.
At time to dress (shift or break time) switch out your electrodes for a new or recently dresses set and continue running. Then dress the used set off line and put them back in que for the next electrode dress/change. This can be repeated till worn out. Many facilities find this useful in reducing their projection welding electrode cost.
Automatic the local welding supply distributor can put you in contact with a supplier that can deliver a tailor made automated system that could rotate into position when desired to do the dressing. It certainly would cost more than that block of wood but could be automated to dress every “X” operations as you determine. Automated systems are used every day for robotic systems with standard spot weld electrodes. It will boil down to cost vs benefit.
Reference: Article – “HOW DO I DRESS A RESISTANCE WELDING ELECTRODE?”
AWS Standard – J1.2:2016 “Guide to Installation and Maintenance of Resistance Welding Machines”