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Inventory and Flow Time in the US Manufacturing Industry



Douglas Thomas, Anand M. Kandaswamy


Advancements in the efficient use of inputs, such as land and labor, have been a key driver of per capita income growth throughout history. One method for identifying potential efficiency improvements is lean manufacturing or lean production, a set of tools to assist in the identification and elimination of waste. Lean classifies waste into seven categories: overproduction, transportation, rework/defects, over-processing, motion, inventory, and waiting. Utilizing economic data, one can track the inventory and transportation time along with the flow time (i.e., the amount of time a unit spends in process), which reveals some of the categories of waste. This report identifies and reviews data on manufacturing inventory and flow time along with data on inter-industry interactions. It then develops a method for tracking the flow time of US manufactured products. This method is illustrated for automotive and aircraft manufacturing.
Technical Note (NIST TN) - 1890
Report Number


manufacturing, input output, automotive manufacturing, aircraft manufacturing, flow time


Thomas, D. and Kandaswamy, A. (2015), Inventory and Flow Time in the US Manufacturing Industry, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed April 19, 2024)
Created December 14, 2015, Updated June 24, 2021