Process for the supervision of a welding process by resistance

The invention relates to a method of monitoring a welding process by resistance of a stack of metal parts (1), wherein during the passage of a current through electrodes applied to this stack, comparing a first threshold (Cf1) increasing evolution of a parameter (Cf (t)) representative of the clamping force of these electrodes.The method of the invention further comprises a step of comparing a second threshold ( Cf2) a decreasing trend of the measured parameter (Cf (t)) for the current flow, and report an anomaly when the downward trend exceed in magnitude the second threshold (Cf2).