Using value stream mapping to improve forging processes

Abstract

Value stream mapping is a technique that uses icons to map the flow of product through a manufacturing system. These icons are aided by summary statistics to further detail the specific manufacturing system. The value stream mapping process usually consists of defining the current state of the system and then, using the principles of lean manufacturing, mapping an improved future system state. Although this is the popular technique, variants and refinements of it exist. This work examines the various techniques of value stream mapping and the methods used to evaluate value stream maps to improve manufacturing systems. The past and current research into value stream mapping and the methods to analyze these maps are compared and contrasted. A set of core analysis questions is developed that summarize the various value stream mapping methodologies. The application of these questions to an enhanced value stream map is developed as a tool, hybrid value stream mapping. Hybrid value stream mapping is then used to analyze the current state value stream map of a manufacturing process, the forging of automotive ring gears. The answers to the core analysis questions enabled the identification of weaknesses in the manufacture of ring gears and suggested system-wide problems. To further clarify and suggest means to rectify these weaknesses, methods beyond the scope of value stream mapping were utilized. By using systems based on standard inventory theory, economic production quantities, techniques to improve information visibility, and methods to enhance production equipment savings of over $4.7 million net present value were discovered for the ring gear production process.