Ghader Emami - Master Of Laws, Mayor In Region 4 Of Tabiz Municipality, Tabriz, Iran
Karim Feyzi Laleh - MA Student Of International Relations, Senior Manager In Region 4 Of Tabriz Municipality, Tabriz, Iran
Farzaneh Radfar - Msc System Management And Productivity, Expert In Region 4 Of Tabriz Municipality, Tabriz, Iran

Control chart has been widely used to determine whether the state of machining process is stable or not, and pattern recognition technology is often used to automatically judge the changing modes of control chart. The widely used control chart techniques are XR and X –S . These are called traditional variable control charts. A traditional variable control chart, consists of three lines namely CL, UCL and LCL. These limits represent that the process is either in-control or out-of-control . For many problems, control limits could uncertainty. In this situation, fuzzy set theory is a useful tool to handle this uncertainty. Fuzzy control limits provide a more accurate and flexible evaluation. In this paper, the fuzzy α−cut,

Fuzzy numbers; statistical process control; XR control chart; α−cut; α-level fuzzy midrange