Lean manufacturing began as the Toyota Production System in the Japanese auto industry of the 1970s and 1980s. It’s main goals were to eliminate waste, reduce the need for managing large inventories, and provide optimum quality at the least cost by making quality control decisions an immediate part of the manufacturing process. Waste at all levels is monitored, examined and eliminated. Like most management systems, lean manufacturing does not come without its own set of disadvantages.
Because only a small amount of inventory is kept on hand, lean manufacturing depends heavily on suppliers that can provide products for the manufacturing process dependably and without interruption. Problems like employee strikes, transportation delays and quality errors on the part of suppliers can create manufacturing holdups that can be fatal. Vendors may be unable or unwilling to supply parts or products on a tighter schedule or in smaller amounts. These needs can burden suppliers with unprofitable costs and create tensions that ultimately affect the manufacturing process and can cause frequent changes of suppliers, or even difficulties finding suppliers who can provide on the necessary schedule at all.
Implementing lean manufacturing often means completely dismantling previous physical plant setups and systems. Training employees can be lengthy and acquiring managers experienced in lean manufacturing process can add considerably to companies payroll expenses. The purchase of machinery that increases efficiency, and the setup of smaller work cells can add to long-term debt. Small and medium-sized businesses, in particular, may find the cost of changeover to lean manufacturing processes prohibitive.
Lean manufacturing processes require a complete overhaul of manufacturing systems that may cause stress and rejection by employees who prefer old ways of doing things. Moreover, lean manufacturing requires constant employee input on quality control, which some employees may feel disinclined or unqualified to do. Older employees may prefer previous methods and can cause resistance among others in the work group. This is where good managers become crucial to the changeover to lean manufacturing. There may also be some difficulty finding managers with sufficient leadership and persuasion skills to overcome this resistance.
Because lean manufacturing processes are so dependent on supplier efficiency, any disruption in the supply chain--and therefore, on production--can be a problem that adversely affects customers. Delivery delays can cause long-lasting marketing problems that can be difficult to overcome.