Application of Fuzzy Logic Control Strategy for Temperature Control in Friction Stir Welding

Friction Stir welding is a solid state joining process that utilizes a rotating non-consumable tool to plastically deform and forge together parent metals. Welding can be controlled either by using Force, Temperature and Traverse or Seam Control methods. The presence of numerous parameters and conditional variations in FSW production environment can adversely affect weld quality making extensive automation processes impossible till date. The weld quality of FSW is closely related to the stability of the welding temperature. For such a non-linear complex process conventional control theory is not an appropriate choice. A fuzzy logic controller with a specially chosen triangular membership function has been suggested as an effective alternative approach. The aim of the present work includes dynamic modeling of a friction stir welding process and the use of a suitable Fuzzy tuned Control Strategy for temperature control. The Temperature at stir zone is measured using a K type Thermocouple. It has a sensitivity of 41μV/°C and also a wide variety of probes are available within its −200° C to +1250 °C range. The thermocouple is used by drilling a hole in the shank of the tool and letting it pass through it. The spindle speed is used as an appropriate variable to control temperature variations. The dynamic modeling and simulations were performed using Matlab whereas the variable values were derived during friction stir welding of aluminum.