Lean manufacturing is a methodology used to reduce inefficiencies within the manufacturing process. Lean isn’t a single process and consists of a number of tools and methods that help optimize the production line. Various tools within lean focus in on the seven wastes and this is the case with Just in Time supply which focus’s on wastes associated with inventory.
Without effective control inventory can severely impact operational costs. Inventory waste can usually be identified where inventory is held in excess of what is immediately required from the manufacturing process. Away from the production line inventory may be stored in a variety of locations from storage warehouses, transit locations and forward holding stores in advance of being delivered to the production line. Just in time supply aims to optimize both the amount and locations of inventory within the manufacturing environment.
The origins of Just in time supply
Just in time has it’s origins in the automotive industry and was used by Henry Ford as part of early automotive manufacturing techniques. This technique was then adapted and utilized within other automotive environments such as Toyota. In deed Toyota view JIT as one of the “two pillars of the Toyota production system.
JIT should not be seen as a panacea more as just a part of an overall toolset and as other manufacturing efficiencies are obtained the variable of material supply can be further optimized to suit requirement.
Toyota implemented JIT by reviewing its manufacturing plans and processes which included optimization strategies such as designing its production process to take into account commonality of tooling and parts requirements. Through minimizing parts holdings Toyota implemented signalling systems to provide demand for replacement materials.
Without Just in time methods stock levels are often controlled by procurement and financial organizations and therefore differing decisions to manufacturing requirements can be made – for example price discount on large volumes of stock are often leveraged or batch sizes are supplier rather than procurement led which can lead to more stock being held than is directly needed.