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This paper describes a method called the Nexus method used for evaluating tolerance stack problems with position, circular runout, total runout and concentricity tolerances. The method constructs a graphical representation of features termed the Nexus cell. The cell contains all the geometric information of the feature in numerical values. After each feature is represented by a Nexus cell, the cells are linked up to form the Nexus model for the part. Once the model is completed, it can be used to evaluate GDT problems associated with the part. The method is capable of arriving at accurate results when dealing with several special cases of position tolerances. Applications of the proposed method have been illustrated and possible uses of such a method were discussed. [ABSTRACT FROM AUTHOR]

The process of assigning tolerances in product design, more often than not, will affect the functionality and cost of the product. An unnecessarily tight tolerance leads to higher cost while an excessively loose tolerance may lead to malfunctioning of the product. Traditionally, this important phase of tolerance allocation is done intuitively to satisfy design constraints based on the skills and experience of the designers. In most cases, the result is not optimum and modification of the allocated tolerances is required. After the tolerances are allocated, the next step is to ensure that the assembly can be manufactured with the resources available. This can usually be verified by performing tolerance charting for the assembly. However, if the result shows that the blueprint (B/P) tolerances specified are too tight, the entire process of tolerance allocation and tolerance charting has to be repeated. This paper presents an efficient method of integrating the process of allocating optimum B/P tolerances in product design with the process of tolerance charting in process planning. This method ensures that the assembly is manufactured with optimum working dimensions and tolerances and yet satisfies all the assembly requirements. Two models are constructed. One based on process sequence and another based on the relationship between each component. Using the models coupled with unique algorithms, sets of linear equations are formulated based on the design constraints and assembly requirements. With another set of equations derived in terms of the process capabilities, the optimum B/P tolerances, working dimensions and tolerances can be determined by solving the equations. [ABSTRACT FROM AUTHOR]

The tolerance chart is a graphical method for representing the manufacturing dimensions of a workpiece or assembly, at all stages of its manufacture. It is used to control tolerance stack up when the machining of a component involves inter-dependent tolerance chains. The build of the tolerance model is a complicated procedure. This paper aims at presenting a simple and systematic approach the generic capsule approach, to the process of tolerance stack analysis. The model is constructed, representing the given and the unknown dimensions. The proposed method uses, as the name implies, a generic capsule, which takes into account all the related aspects of the axis and surface type of tolerance stacks. Links are then established using the model, which help formulate the stack path of interest, into a linear equation. The equation is used to complete the tolerance stack analysis module. This will be explained using a variety of geometric dimensioning and tolerancing examples, as we progress. In addition, it is generic and hence simple to practice. [ABSTRACT FROM AUTHOR]

This paper introduces an alternative method to conventional tolerance analysis of an assembly of parts/components. It presents a simple yet powerful approach whereby tolerance stacks are modelled and analysed very quickly and effortlessly. Two examples are used to illustrate how the model is built and used for analysing tolerance stacks. Several other examples are tested out with the model developed and attached to show how simple and effective it is to use. [ABSTRACT FROM AUTHOR]

The objective of this research work is to develop a tool collision detection system for turning operations. Spatial representation technique is used for object representations of cutting tool, workpiece, workholding device and machining envelope to detect intersection or interference between solids. The algorithm, developed using Turbo C++, is able to detect various types of collisions and to modify the machining envelope to avoid collision. The algorithm is also able to determine the cutting tool efficiency based on the machining envelope. The effectiveness of the method has been illustrated with an example. [ABSTRACT FROM AUTHOR]

This paper introduces a simple and direct method to derive process links between feature planes. Consequently, the relationship between process and blue-print dimensions can be expressed as an array of linear equations and inequalities. By applying appropriate constraints to these models, the desired working dimensions and tolerances can be solved using LINDO, a linear programming optimization software. An example is also included to illustrate the method. [ABSTRACT FROM AUTHOR]

This paper presents software to assist the tool designer of modular fixturing assembly. The software comprises a knowledge-based Adviser, a fixturing component assembly program and a CAD system. The Adviser assists the tool designers in selecting components from a modular fixturing system (MFS). The fixturing component assembly program will then position and assemble the modular fixturing components. The final assembly is then displayed in the CAD system. An example is also included to demonstrate the working principle of the software. [ABSTRACT FROM AUTHOR]

A modification of phase-shifting interferometry is proposed for microsurface profiling of flat surfaces under vibrating conditions. With this technique the required phase shift, achieved by quarter-wave plates and polarizers, is free of errors associated with motion. A nearly common optical-path configuration is achieved, and the effect of environment is reduced. The effect of environment on the optical system is also studied. Moreover, the measurement of phase is instantaneous, which increases the versatility of this technique to measure vibrating objects. Experiments were carried out on a smooth mirror surface excited with high-frequency vibrations, and the technique was found to be immune to vibrations of both high and low frequency. OCIS codes: 120.4570, 120.5050.