PRODUCTIVE METHOD AND SYSTEM TO CONTROL DIMENSIONAL UNCERTAINTIES AT FINAL ASSEMBLY STATES IN SHIP PRODUCTION.

Strict dimensional control of interim products through the different assembly stages is vitally important profitable ship production (1). Studies made in Finland show that a 30% reduction in labour costs is possible in hull construction (2). This reduction can be gained by eliminating unnecessary fitting and reworking using tight accuracy control methods. Although accuracy control of the prefabrication stages is important because it forms the basis for the hull production, the dimensional control of the block assembling stages is essential if major improvements in Fig.1 explains the situation. The figures for the diagram were collected from measurement experiments carried out at major Western shipyards during the years 1989-91. Usually the accuracy level of the production is reasonable at the first stages, but the inaccuracies increase rapidly and most unlinearly as a function of the complexity of the interim products. This means that the assembling methods have a strong influence on the dimensional uncertainties of the interim products (blocks) at the final assembly stages. At the same time the labour costs in these final stages are very high. Thus notable productivity improvements can be gained by implementing progressive assembling methods and dimensional control systems at these final productivity are to be achieved. assembly stages.