Training Within Industry Programs (Job Instruction, Job Method, Job Relation).
TWI represents the roots and foundations of Lean Manufacturing.
During WWII, TWI (Training Within Industry) developed in the United States training programs to improve proximity Manager skills, because of the blatant lack of qualified workforce.
TWI formalized training manuals which were prepared starting with the fall of France during WWII, on June 22, 1940. TWI invented a new approach to training (based on the works by Allen) and to the use of the workforce in the industry. These manuals would then be reprised and enhanced by TOYOTA during the 60s. It is the keystone of continuous improvement.