Design and manufacturing tolerances optimisation with quality loss functions

Abstract Tolerance design bridges design and manufacturing. Concurrent design of tolerances and manufacturing processes may ensure the manufacturability, reduce the manufacturing and other related costs, decrease the number of fraction nonconforming (or defective rate), and shorten the production lead time. Since process capability indices relate tolerance specifications to manufacturing process capabilities, it is quite natural to apply them to concurrent design of tolerances and processes. As process shifts often exist in a manufacturing process, using Cp does not yield a good estimation of fraction nonconforming. Index Cpk does not precisely measure process shift either, but Cpm does. Therefore, this research compares the applications of Cp, Cpk and Cpm based on a numerical example of non-linear mechanical tolerance synthesis. In addition, the Taguchi quality loss function is used together with the manufacturing cost as the objective function.

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Vibration Analysis of Rotor-Fluid Film Bearing System Using Monte Carlo Method

Volume 5: 22nd International Conference on Design Theory and Methodology; Special Conference on Mechanical Vibration and Noise ◽

10.1115/detc2010-28323 ◽

2010 ◽

Author(s):

Zhengkai Zhang ◽

Youyun Zhang ◽

Yongsheng Zhu

Keyword(s):

Monte Carlo ◽

Vibration Analysis ◽

Monte Carlo Analysis ◽

Working Environment ◽

Fluid Film ◽

Design Parameters ◽

Rotor Vibration ◽

Design And Manufacturing ◽

Manufacturing Tolerances ◽

Bearing System

The rotor-fluid film bearing systems are widely used in machinery due to their small size, low price, and capability of carrying load. However, if its design and manufacturing is inappropriate, the use of rotor-fluid film bearing system will suffers from some problem such as violent vibration. Although the checking calculation has been carried out during the design process, nominal value of design parameters is usual used to prognosis the vibration characteristics of rotor-fluid film bearing system. However, in practice, these parameters always vary within a certain range due to manufacturing tolerances and variation of working environment. In this paper, a model for simulating the performance of rotor-fluid film bearing system has been established. Monte Carlo analysis was performed to evaluate the effects of manufacturing tolerances and variation of working environment on the rotor vibration. In the end, a uncertainty analysis is carried out to demonstrate which of the factors has the greatest effect on the rotor vibration at different rotational speed.

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Research of Asymmetric Quality Loss Function with Triangular Distribution

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.655-657.2331 ◽

2013 ◽

Vol 655-657 ◽

pp. 2331-2334 ◽

Cited By ~ 2

Author(s):

Qiu Jin ◽

Shao Gang Liu

Keyword(s):

Mathematical Models ◽

Loss Function ◽

Loss Functions ◽

Optimum Process ◽

Triangular Distribution ◽

Quality Loss ◽

Quality Loss Function ◽

Process Mean ◽

Asymmetric Quality Loss

The asymmetric quality loss functions with the triangular distribution for determining the optimum process mean are studied. The condition of using the linear and quadratic asymmetric quality loss function in the model is considered. The eight mathematical models under an asymmetric quality loss function with the triangular distribution based on the analysis of the linear and quadratic asymmetric quality loss function are presented. Finally, the validity of models is verified by the examples.

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