• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.13 no.1
• /
• pp.28-34
• /
• 2004

In this study, new way of evaluating manufacturing cost Is organized and applied. In real manufacturing circumstances, tolerances of parts and assemblies are closely related to the cost. Several researches have been tried to identify the relations and set models. Moreover tolerances have influences on the maintenance of the manufacturing facilities. However Past researches have not considered the processing cost for the failed products. Therefore maintenance costs are represented as stochastic expressions, which include reliability of assembly and facilities. The stochastic nature of the maintenance cost is modeled and solved using Markov chain approach. Results show that this approach gives reliable estimations with remarkable computing time reduction.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.12
• /
• pp.75-83
• /
• 2010

Every mechanical part for mass production has dimensions with tolerances in engineering drawing. Tolerance is given to guarantee assemble parts together satisfying functional requirements and dimensional constraints. Tolerance is essential factor for standardization of parts or assembly and has huge influence on manufacturing cost. It will be desirable to have tolerances as broad as possible for minimizing manufacturing cost. This paper describes tolerance analysis of u-joint assembly that is a part of automobile steering system. Within the range of tolerances of parts, accumulated effect is estimated by arithmetic calculation, probability theory and Monte carlo simulation. Each result is compared to investigate the method for increasing productivity.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2010.04a
• /
• pp.19-21
• /
• 2010

In this study, regarding to the generalization of the map, we analyze how the different tolerances influence on the performances of linear generalization operators. For the analysis, we apply the generalization operators, especially two simplification algorithms provided in the commercial GIS software, to 1:1000 digital topographic map for analyzing the aspect of the changes in positional error depending on the tolerances. And we evaluate the changes in positional error with the quantitative assessments. The results show that the analysis can be used as the criteria for determining proper tolerance in linear generalization.

• Proceedings of the Safety Management and Science Conference
• /
• 2008.04a
• /
• pp.417-428
• /
• 2008

Designers have to consider voice of customer, process capability, manufacturing standards & condition, manufacturing method, characteristics of products to decide tolerances. Especially, in case of position of hole and pin, designers have to consider process capability to decide tolerances. The traditional position tolerances used in a drawing are theoretical values which are allocated to position under the worst case assembling condition that both hole and pin are the maximum material condition(MMC). However, When the process capability is high, more exact product size can be produced under stable manufacturing condition. larger clearance of hole and pin can be allocated. In this point of view, manufacturer could increase the yield by allocating larger position tolerance than theoretical position tolerance of hole and pin considering process capability.

• Journal of the Korea Safety Management & Science
• /
• v.11 no.1
• /
• pp.75-85
• /
• 2009

Designers have to consider voice of customer, process capability, manufacturing standards & condition, manufacturing method and characteristics of products to decide tolerances. Especially, in case of position of hole and pin, designers have to consider process capability to decide tolerances. The traditional position tolerances used in a drawing are theoretical values which are allocated to position under the worst case assembling condition that both hole and pin are the maximum material condition(MMC). However, when the process capability is high, more exact product size can be produced under stable manufacturing condition. Larger clearance of hole and pin can be allocated. In this point of view, manufacturer could increase the yield by allocating larger position tolerance than theoretical position tolerance of hole and pin considering process capability.

• IE interfaces
• /
• v.16 no.spc
• /
• pp.39-44
• /
• 2003

As one of many design variables, the role of dimension tolerances is to restrict the amount of size variation in a manufactured feature while ensuring functionality. In this study, a nonlinear integer model has been modeled to allocate the optimal tolerance to each individual feature at a minimum manufacturing cost. While a normal distribution determines statistically worst tolerances with its symmetrical property in many previous tolerance allocation studies, a asymmetrical distribution is more realistic because its mean is not always coincident with a process center. A nonlinear integer model is modeled to allocate the optimal tolerance to a feature based on a beta distribution at a minimum total cost. The total cost as a function of tolerances is defined by machining cost and quality loss. After the convexity of manufacturing cost is checked by the Hessian matrix, the model is solved by the Complex Method. Finally, a numerical example is presented demonstrating successful model implementation for a nonlinear design case.

• Textile Coloration and Finishing
• /
• v.9 no.6
• /
• pp.51-57
• /
• 1997

The lightness, chroma and hue tolerances with respect to the standard colour position in the CIELAB space have been studied in detail using the various existing data sets and the set form this study. The lightness tolerance showed a clear dependency upon the metric lightness for medium to light colour, but in the case of dark colours there was a discrepancy between the data sets. Both the chroma and hue tolerances showed dependency upon both the chroma and hue-angle and not the single dependency upon the metric chroma, as assumed in the CIE94 formula. New weighting functions were derived from the above experimental evidence, and finally a new formula, LCD(Leeds Colour Difference) was proposed. The LCD formula is nearly as simple and flexible as CIE94 but smoothes the individual weighting functions, especially for lightness tolerances for light colours and chromaticity discrimination near the blue region.

• Journal of the Korean Society for Precision Engineering
• /
• v.10 no.3
• /
• pp.205-219
• /
• 1993

제품의 기하학적 칫수 공차는 생산제품의 품질관리에 매우 종요하며, 측정기기의 발달과 함께, 컴퓨터를 이용한 기하하적 공차 해석의 수요와 경향은 늘고 있는 추세이다. 본 논문에서는, ISO의 공차 정의에 기초한 공차들(진직도공차, 편평도공차, 진원도공차, 평행도공차, 직각도공차, 윤곽공차)을 해석할 수 있는 컴퓨터 모듈이 개발되었다. 특히 윤곽공차의 경우 측정프로브의 반경의 효과가 배제되는 알고리즘을 개발하였다. 개발된 컴퓨터 모듈을 실제적인 측정작업에 적용하였으며, 고종도와 고효율성을 보임을 입증하였다.

• Proceedings of the Safety Management and Science Conference
• /
• 2002.05a
• /
• pp.99-103
• /
• 2002

It is the basic requirement of product characteristics to specify geometric dimensions and tolerances during design process of parts assembly. Therefore, there are many tolerance stack analysis method to explain tolerance zone. Tolerance stack analysis is to calculate gap using tolerances which includes geometric and coordinate dimension. In this study, we compared several different stack analysis method and try to suggest more general method called the Virtual Method to analyze tolerance stack.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.14 no.24
• /
• pp.31-41
• /
• 1991

The producer's to tolerance concept (in contrast to the consumer's tolerence) fellows naturally from the notion of continuous loss function Emerging producer tolerance methodology has proceeded without benefit of carefully defined assumptions. We rectifg this omission and consider the process mean deviation. Then develope the models for which determine the tolerenes in cases of the-nominal-the-best, the-smaller-the-better and the-larger-the-better. Finally the numerical examples are Presented to illustrated these results and also the sensitivity analysis to apprehend the changes of loss tolerances varying with mean is presented.