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.
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that occurs in real life (e.g., people get sick or go on strike, trucks or shipments get delayed, machines malfunction, quality issues require scrap or rework, and customers do not always, if ever, order according to forecasts). In other words, MRP is a static model of a stochastic reality. Manufacturing requirements change all the time, according to customer orders, available parts, and so on; thus, MRP attempts to apply a high degree of precision to something that is inherently imprecise. However,