Then again, some people question whether computer systems are even needed for achieving lean manufacturing. After all, some lean tools entail merely physical processes and best practices on the shop floor, where transactional enterprise systems have little to offer. Also, given that computers were not widely available when lean manufacturing and kanbans first emerged, many enterprises have stuck with manually-driven lean methods. For such methods, an evolutionary step forward entails the use of custom spreadsheets and reports to support lean functions such as kanban management and heijunka calculations (see Lean and World Class Manufacturing and the Information Technology Dilemma—The Loss of Corporate Consciousness). It is interesting to note, however, that even in such cases, material requirements planning (MRP) systems still can be used to hold core master data on items and bills of material (BOM), though these records have to be tweaked with an eye toward lead time-oriented information.
As usual, the truth might be somewhere in a middle—lean manufacturing and IT are not in opposition, and all good lean systems have both physical systems in the plant and near real time IT backbones that centralize data, especially if there is an automatic data entry and capture function. In fact, some people say that the whole point of the lean philosophy is to simplify the physical processes so that one does not need to manage overly complex data systems, though it is still necessary to manage the relevant data at the points where corrections are needed. To that end, many IT systems are designed to bring from the field only the data that management or decision-makers can do something about.
The reality is that most companies operate in a hybrid, mixed-mode environment where flow or lean and traditional batch or push manufacturing models coexist within the same facility, and where production and demand requirements can change throughout the different stages of a product’s life cycle. Manufacturers can produce both high-volume goods with steady demand and low-volume goods with fluctuating demand, and their product mix may include engineer-to-order (ETO), make-to-order (MTO), and make-to-stock (MTS) items.