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Synthesis of tolerancing by functional group
Journul ofhhmjbcturing
Systems
Vol. 21lNo. 6 2002
2000-2002 abstract and keyword index Assembly Specification by Gauge with Internal Mobilities (GZM)-A Specification Semantics Deduced from Tolerance Synthesis, Jean-Yves Dantan, Alex Balm, v2 1,
Journal of Manufacturing Systems Volume 21, Number 4,2002
n3,2002, ~~218-235 Currently, standards such as IS0 110 1 are used for the geometrical specification of mechanical parts. However, these standards are not sufficient to express exact functional requirements, even for assembly. The objective of this paper is to determine what to express exactly for assembly, that is, create the necessary specification semantics. A tolerance synthesis model is developed based on variational geometry. The model takes into account not only manufacturing deviations and gaps, but also the assembly process and nature of contacts between parts. Specification semantics is deduced from this tolerance synthesis. This semantics is based on virtual gauges, which are composed of an interface with the part and the structure. The main contribution of the virtual gauge is the concept of internal mobilities allowing displacements between different entities of the gauge. This gauge takes also in account the nature of the contact between parts. Keywords: Geometrical Product Specification, Assembly, Gauge, Tolerance Synthesis, Contact
Manufacturing System Modeling jbr Productivity Improvement, Samuel H. Huang, John P. Dismukes, J. Shi,
Qi Su, Ge Wang, Mousalam A. Razzak, D. Eugene Robinson, ~21, n4, 2002, ~~249-259 Competition and the drive for profits are forcing companies to implement various productivity improvement efforts. Implementation of total productive maintenance (TPM) techniques has led to significant productivity improvements for individual equipment, particularly in the semiconductor industry. The productivity improvements achieved at the equipment level are significant but insufficient because what a company really needs is a highly efficient system/factory. This is especially true in the discrete manufacturing industry. In this paper, an approach, based on overall equipment effectiveness (OEE), is developed to model the productivity of a manufacturing system in terms of overall throughput effectiveness (OTE). Sensitivity analysis and theory of constraints are used to help identify productivity improvement opportunities. A real-world case study is presented to illustrate the applicability of the approach. Keywords: Manufacturing System, Productivity, Modeling, Overall Equipment Effectiveness
Production Systems?, J.P.M. Schmitz, D.A. van Beek, J.E. Rooda, ~21, n3,2002, ~~236-246 In the literature, several cases are reported of models of discrete nonstochastic production systems that show irregular, apparently chaotic behavior. In this paper, a number of these cases are analyzed and the irregular behavior is attributed to: (1) chaotic behavior in hybrid models, (2) chaotic behavior in discreteevent models that use a chaotic map, or (3) periodic behavior with a period longer than the observation window. The irregular behavior of a discrete-event model of a two-machine production system is analyzed by means of nonlinear time-series analysis and sensitivity analysis. This case reveals the possibilities and limitations of the application of chaos theory to discrete-event models of production systems. Also, a new method for determining the sensitivity of discrete-event models to truly small changes is introduced. Realistic, non-artificial discrete-event models of discrete production systems that show chaotic behavior were not found in this study. Kejlwords: Chaos, Production Systems, DiscreteEvent Models, Simulation, Time-Series Analysis, Sensitivity Analysis Chaos in Discrete
Synthesis
of Tolerancing by Functional
Group, Jean Marc
Linares, Cedric Anthierens, Jean Michel Sprauel, ~21, n4, 2002, ~~260-275 This paper presents a systematic tolerancing method based on a new modeling concept called Functional Group. The tolerancing method is composed of two types of tolerancing: (1) “internal tolerancing” limits assembly errors due to the overabundance of contact points between two surface groups and (2) “external tolerancing” places one surface group next to the other. First, several tolerancing methods are presented from the literature. The small displacement screw (SDS) method is also described because it represents a very important investigation tool. Then the concept of the functional group is proposed for the tolerancing of mechanical systems. Finally, this new systematic method is implemented with an actual example in which functional tolerancing is easily carried out. Keywords: Functional Tolerancing, Tolerancing Modeling, Tolerancing Analysis, Vectorial Tolerancing, Mechanical Design
488
Systems
Vol. 21lNo. 6 2002
2000-2002 abstract and keyword index Assembly Specification by Gauge with Internal Mobilities (GZM)-A Specification Semantics Deduced from Tolerance Synthesis, Jean-Yves Dantan, Alex Balm, v2 1,
Journal of Manufacturing Systems Volume 21, Number 4,2002
n3,2002, ~~218-235 Currently, standards such as IS0 110 1 are used for the geometrical specification of mechanical parts. However, these standards are not sufficient to express exact functional requirements, even for assembly. The objective of this paper is to determine what to express exactly for assembly, that is, create the necessary specification semantics. A tolerance synthesis model is developed based on variational geometry. The model takes into account not only manufacturing deviations and gaps, but also the assembly process and nature of contacts between parts. Specification semantics is deduced from this tolerance synthesis. This semantics is based on virtual gauges, which are composed of an interface with the part and the structure. The main contribution of the virtual gauge is the concept of internal mobilities allowing displacements between different entities of the gauge. This gauge takes also in account the nature of the contact between parts. Keywords: Geometrical Product Specification, Assembly, Gauge, Tolerance Synthesis, Contact
Manufacturing System Modeling jbr Productivity Improvement, Samuel H. Huang, John P. Dismukes, J. Shi,
Qi Su, Ge Wang, Mousalam A. Razzak, D. Eugene Robinson, ~21, n4, 2002, ~~249-259 Competition and the drive for profits are forcing companies to implement various productivity improvement efforts. Implementation of total productive maintenance (TPM) techniques has led to significant productivity improvements for individual equipment, particularly in the semiconductor industry. The productivity improvements achieved at the equipment level are significant but insufficient because what a company really needs is a highly efficient system/factory. This is especially true in the discrete manufacturing industry. In this paper, an approach, based on overall equipment effectiveness (OEE), is developed to model the productivity of a manufacturing system in terms of overall throughput effectiveness (OTE). Sensitivity analysis and theory of constraints are used to help identify productivity improvement opportunities. A real-world case study is presented to illustrate the applicability of the approach. Keywords: Manufacturing System, Productivity, Modeling, Overall Equipment Effectiveness
Production Systems?, J.P.M. Schmitz, D.A. van Beek, J.E. Rooda, ~21, n3,2002, ~~236-246 In the literature, several cases are reported of models of discrete nonstochastic production systems that show irregular, apparently chaotic behavior. In this paper, a number of these cases are analyzed and the irregular behavior is attributed to: (1) chaotic behavior in hybrid models, (2) chaotic behavior in discreteevent models that use a chaotic map, or (3) periodic behavior with a period longer than the observation window. The irregular behavior of a discrete-event model of a two-machine production system is analyzed by means of nonlinear time-series analysis and sensitivity analysis. This case reveals the possibilities and limitations of the application of chaos theory to discrete-event models of production systems. Also, a new method for determining the sensitivity of discrete-event models to truly small changes is introduced. Realistic, non-artificial discrete-event models of discrete production systems that show chaotic behavior were not found in this study. Kejlwords: Chaos, Production Systems, DiscreteEvent Models, Simulation, Time-Series Analysis, Sensitivity Analysis Chaos in Discrete
Synthesis
of Tolerancing by Functional
Group, Jean Marc
Linares, Cedric Anthierens, Jean Michel Sprauel, ~21, n4, 2002, ~~260-275 This paper presents a systematic tolerancing method based on a new modeling concept called Functional Group. The tolerancing method is composed of two types of tolerancing: (1) “internal tolerancing” limits assembly errors due to the overabundance of contact points between two surface groups and (2) “external tolerancing” places one surface group next to the other. First, several tolerancing methods are presented from the literature. The small displacement screw (SDS) method is also described because it represents a very important investigation tool. Then the concept of the functional group is proposed for the tolerancing of mechanical systems. Finally, this new systematic method is implemented with an actual example in which functional tolerancing is easily carried out. Keywords: Functional Tolerancing, Tolerancing Modeling, Tolerancing Analysis, Vectorial Tolerancing, Mechanical Design
488