Which of the following is NOT one of the three main principles of lean?

The focus of lean principles is primarily to maximize value for customers by minimizing waste and optimizing processes. Among the three main principles of lean, the elimination of waste is paramount, as it seeks to reduce any activities that do not add value. Taking time out of processes emphasizes streamlining and enhancing efficiency by reducing delays and unnecessary steps. Creating better flow advocates for smooth transitions and clear pathways in processes, allowing for increased productivity and faster response times.

Increasing inventory levels, however, contradicts the foundational goals of lean. Higher inventory can lead to increased waste, as it often represents overproduction, higher carrying costs, and potential obsolescence. Lean seeks to reduce inventory to the minimum required to meet demand, thus fostering a leaner and more responsive production system. Therefore, this option is not aligned with the principles of lean methodology.