THE IMPLEMENTATION OF A SYSTEMATIC METHOD FOR IDENTIFYING THE ROOT CAUSES OF MANUFACTURING NEGATIVE PROCESS YIELD IN A NORTH AMERICAN FASTENER MANUFACTURING FACILITY

Abstract

Negative process yield is an unexplained expense that does have a significant impact on profits. As like most other manufacturing processes, there are multiple processing operations that a finished good can be exposed to during the course of the entire process. Negative process yield can occur during these known operations but without accurate reporting and data collection, it becomes a moot point. In order to investigate this unexplainable phenomena properly, understanding of what could possibly cause this from occurring must be achieved. In the case of the North American fastener manufacturing plant, missing pieces that are not accounted for through the normal scrap reporting process are often referred to as “negative process yield”. Loss of material from the various processes has been identified as a problem for the North American fastener manufacturing plant. The set of tools that assist in the identification and steady elimination of waste also referred to as lean principles and techniques must be used during the study. This study will examine and analyze the data collected and associated with the loss of unexplained production pieces throughout the production process and what the financial implications or effects have on margins or profits. The Taguchi Design of Experiment (DOE) method is to be used for the experiment. Roy stated that the main focus of the application of DOE is to improve quality. The definition of quality varies widely depending on the applications, but it must be defined before any experimental technique can be produced with meaningful results. Taguchi offers a generalized definition for quality of performance. He regards performance as the major component of product or process quality. A reduced variation results in a reduction in scrap, less rejection of product, and fewer warranty returns, consequently reducing costs, and improving profits and improving customer satisfaction. The result of the study indicated that the form tool was the most significant factor and the levels or grades of material used for those tools could have an effect on the machining process. There was also an indication that the drilling operation needed to be focused on and that the grade of material used, either carbide or high speed steel, be seriously considered based on the application and desired speeds and feeds of the drill depending on the substrate material of the fastener.