Total Quality Control. JIT goes with it a stronger emphasis on quality control. A defective part brings production to a grinding halt. Poor quality simply cannot be tolerated in a stockless manufacturing environment. In other words, JIT cannot be implemented without a commitment to total quality control (TQC). TQC is essentially an endless quest for perfect quality. This approach to quality is opposed to the traditional belief, called acceptable quality level (AQL). AQL allows defects to occur provided they are within a predetermined level.