The five principles of lean thinking: Value, Value Stream, Flow, Pull and Perfection Womack & Jones. (1996) .
*Value: is the value offered to a customer at a specific time and for a specific price, it depends on each customer.
*The value stream: is the set of activities from design, different stages of production to to the final product delivered to the customer. there three types of value stream:
-Value added: these activities generate value.
-Type one Muda: This Muda or waste is unavoidable.
-Type two muda: activities with no value and have to be avoided.
*The Flow: achievement of tasks along the value stream so that a product proceeds from design, different stages of production to to the final product delivered to the customer with no stoppages, scrap or backflows.
*The pull: in a pull system instructions goes from downstream to upstream means nothing is produced by the upstream supplier until the downstream customer signals a need.
*Perfection: is a total elimination of muda so that all undertaken activities along the value stream create value.