The internal stress in the material is either not fully removed or there is no annealing process performed to eliminate it. The CNC cutting depth has been set too deep. There is no coolant being used to dissipate the heat generated from cutting. The cutting process is irregular and uneven, resulting in more cuts on one side than the other. Vibration is occurring in weak clamps that are unable to hold the workpiece securely. Overly tight clamping causes the deform.