The National Shipbuilding Research Program. Process Analysis Via Accuracy Control

Effective shipbuilders accomplish in-house, only work which by nature and volume can be performed in accordance with the concept of Group Technology (GT). Parts, subassemblies and assemblies, i.e., interim products, needed for an end product, are classified by the problems inherent in their manufacture. Thus, regardless of differences in designs and quantities required, interim products are manufactured on dedicated production lines, i.e., process flows. A main flow, such as for producing a hull block, is supported by coordinated subordinate flows such as one for producing sub-blocks. With such dependencies, a control system is required to monitor accuracy in order to avoid delays and rework, particularly when blocks are joined together in a building dock during hull erection. However, accuracy control (A/C) having a statistical basis does considerably more. A/C involves the regulation of accuracy as a management technique for constandy improving productivity of an entire manufacturing system. A/C is the scientific means which the world s leading shipbuilders employ for constantly identifying and prioritizing the problems which must be addressed to obtain the greatest rates of productivity improvement. The statistical basis makes clear the relationship between cause and effect. As Dr. W. Edwards Deming teaches, the obligation to improve the system never ceases. Statistics is the branch of mathematics dealing with collection, analysis, interpretation and presentation of masses of numerical data. The methods of statistics are methods of applied mathematics. Shipbuilding engineers who manage A/C programs must at least understand college-level elementary statistics.