Lean principles are difficult to employ in complex environments, but materials requirement planning has well-known limitations. The theory of constraints, which is complementary to lean manufacturing when it comes to low volumes and complex environments, may provide an answer.
environment, however, the kanban JIT approach no longer makes sense, since the product mix by product type, routings, and process times becomes widely divergent, causing the prediction of kanban sizes to be impractical and temporary, or wandering bottlenecks to appear all over the shop floor. Indeed, where the order mix changes or not all resources are dedicated to lean flow manufacturing, then kanban sizes must continuously be reevaluated. In these situations, a theory of constraints (TOC) approach is