Tolerance elements: an alternative approach for cost optimum tolerance transfer

Dimitrellou, Sotiria Ch.; Diplaris, S. C.; Sfantsikopoulos, M. M.

doi:10.1080/09544820701874039

Cited by 16 publications

(7 citation statements)

References 19 publications

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“…Process sequences and elementary functions should be easier to collect and maintain at a manufacturing company. With a similar objective, the method proposed in [49][50][51] associates a cost-tolerance function with a five-digit code (tolerance elements) that takes into account the shape and size of the part. Cost data are retrieved from a process database, where a company could assess the relative difficulty in satisfying given tolerances when machining different types of part features.…”

Section: Methods For Parameter Selectionmentioning

confidence: 99%

“…Yet it remains simple enough to get analytical solutions to the allocation problem: as reported in [1], statistical allocation by Lagrange multipliers results in optimal tolerances Ti proportional to the powers 1/(ki+2) of products kibi; more applications of the same method with different assumptions are reported in [6,45,46]. Other applications use different methods such as sequential quadratic programming [47][48][49][50][51], genetic algorithms [52][53][54], particle swarm optimization [55][56][57], migration algorithms [58], artificial bee colony [59], and Monte Carlo [60]. The function has also proved useful for dealing with complex mechanisms and assemblies [61][62][63] and with special formulations of the allocation problem, which include geometric tolerances [64], mean-shift stackup [65], optimization based on process capability [66], and the optimal partitioning of components for selective assembly [67,68].…”

Section: Reciprocal Powermentioning

confidence: 99%

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Selection of parameters in cost-tolerance functions: review and approach

Armillotta

2020

Int J Adv Manuf Technol

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The paper deals with the cost-tolerance functions used in minimum-cost tolerance allocation on mechanical assemblies. The consistency of the cost-tolerance functions associated with different dimensions of a tolerance chain is a necessary condition for a correct optimization of tolerance values. This requires a careful selection of function parameters, in order to take into account all the variables influencing the cost, and thus to compare the costs of the different dimensions in a common scale. The cost-tolerance functions proposed in the literature are reviewed, revealing that the parameters are often selected without explicit reference to empirical data or objective rules. The development of procedures for parameter selection has been addressed in several studies, which are also reviewed along with the needed cost data published in textbooks and reports. Finally, an original approach is proposed to build cost-tolerance functions for combined processes, for which fewer results or methods are available. The parameters of a reciprocal power function, chosen for the favorable balance between accuracy and ease of use, are expressed through an empirical relationship with some design variables; these include the nominal dimensions, and the type and size of the part features involved in the allocation problem. An application example shows that the proposed procedure results in optimal tolerance values consistent with common design criteria.

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Section: Methods For Parameter Selectionmentioning

confidence: 99%

Section: Reciprocal Powermentioning

confidence: 99%

Selection of parameters in cost-tolerance functions: review and approach

Armillotta

2020

Int J Adv Manuf Technol

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“…These studies show that common cost evaluation and cost assigning procedures are not as applicable as required. 54 The continuous effort to increase part interchangeability, evaluate and reduce cost has prompted research in the area of tolerance allocation.…”

Section: Accuracy Design Methods Of Machine Toolmentioning

confidence: 99%

Geometric accuracy allocation for multi-axis CNC machine tools based on sensitivity analysis and reliability theory

Cheng

Zhang

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part C:

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Machining accuracy of a machine tool is influenced by geometric errors produced by each part and component. Different errors have varying influence on the machining accuracy of a tool. The aim of this study is to optimize errors to get a desired performance for a numerical control machine tool. Applying multi-body system theory, a volumetric error model was constructed to track and compensate effects of errors during operation of the machine, and to relate the functional specifications on volumetric accuracy to the permissible errors on the joints and links of the machine. Error sensitivity analysis was used to identify the influence of different errors (especially the errors which have large influences) on volumetric error. Based on First Order and Second Moment theory, an error allocation approach was developed to optimize allocation of manufacturing and assembly tolerances along with specifying the operating conditions to determine the optimal level of these errors so that the cost of controlling them and the cost of failure to meet the specifications is minimized. The approach developed was implemented in software and an example of the geometric errors budgeting for a five-axis machine was discussed. It is identified that the different optimal standard deviations reflect the cost-weighted influences of the respective parameters in the equations of the functional requirements. This study suggests that it is possible to determine the coupling relationships between these errors and optimize the allowable error budgeting between these sources.

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“…The costtolerance experimental data were used to set the training sets to establish a cost-tolerance network. Dimitrellou et al [19] introduced a new concept 'tolerance element' as a machining process-related geometric entity with attributes associated with the accuracy cost, and presented a method for cost optimum conversion of functional tolerances into machining tolerances transferred to one or more datum reference frames. Singh et al [20,21] presented the reviews of research on the manufacturing cost models in tolerance design.…”

Section: Manufacturing Cost Functionsmentioning

confidence: 99%

Development of a function oriented computer aided tolerancing (FOCAT) system

Peng

2011

Proceedings of the Institution of Mechanical Engineers, Part B:

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Functional tolerancing of a mechanical part depends on the assembly and manufacturing function. This paper presents an approach for functional tolerance design and optimization. Functional surfaces are classified according to ISO specification. Dimensional and geometric tolerance types are specified based on design rules. Well-constrained analysis is presented to avoid over- and under- constrained tolerance design. A tolerance values optimization model is established with manufacturing cost functions and assembly stackup constraints. A computer-aided tolerancing (CAT) system is developed to provide designer with an effective tool for ensuring the functional tolerancing of the entire assembly. The system is applied to perform a tolerance design for a three-dimensional (3D) assembly .

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Tolerance elements: an alternative approach for cost optimum tolerance transfer

Cited by 16 publications

References 19 publications

Selection of parameters in cost-tolerance functions: review and approach

Selection of parameters in cost-tolerance functions: review and approach

Geometric accuracy allocation for multi-axis CNC machine tools based on sensitivity analysis and reliability theory

Development of a function oriented computer aided tolerancing (FOCAT) system

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