Evaluation of superalloy heavy-duty grinding based on multivariate tests

The quality and economy of grinding depend on proper selection of grinding conditions for the materials to be ground. In order to evaluate the effect of heavy-duty grinding, a new performance index, which includes specific material removal rate, size accuracy, and grinding forces, was proposed. Robust design of experiment, including orthogonal arrays, the signal-to-noise ratio (SNR) method, and analysis of variance (ANOVA) for multivariate data, was employed to estimate the effect of uniform experimental design and to optimize grinding parameters. Empirical models of grinding force were investigated for finite element analysis of new fixture design. These empirical models, based on robust design of experiments and multiple regression methodology, have been confirmed through further verification experiments. Correlation coefficients from 0.87 to 0.96 were achieved

Feature validation in a feature-based design system

The Loughborough University of Technology Feature-Based Design System (LUTFBDS) allows detail design to be carried out in a computer aided design (CAD) environment by the addition of form features to stock material or part-machined components. An iconic user interface assists in the description parts in terms of a set of primitive features such as holes, pockets and slots or higher level compound features such as patterns of holes and counterbored holes. This feature representation is generated in parallel with the geometric data structure of the underlying boundary representation solid modeller. The feature representation is useful for a range of downstream manufacturing activities, but our research focusses on the integration of CAD with process planning. LUT-FBDS functions allows the designer or manufacturing engineer to progressively construct the final geometry of a part, and facilities are provided for the designer to modify parameters which relate to feature dimensions, location, orientation and relationships with other features. These changes may result in changes to the feature representation and hence there is a need for feature validation to ensure the integrity of the model

Component grouping for cell formation using resource elements

The work reported in this paper recognises that the traditional close association between components and a fixed route utilising a set of machine tools can no longer be relied upon as an appropriate basis for deciding component similarity and partitioning components into families in modern manufacturing applications. A new methodology for describing the capabilities of machine tools and machining facilities using generic capability units termed 'resource elements' is reported. REs are used to capture the processing requirements of components, assessing their similarity and a fuzzy grouping procedure is used for simultaneously grouping components and machine tools for cellular manufacturing applications. The reported results show that the use of resource elements leads to component groups that are more compact with better matching between processing requirements of components and the capabilities of the machine tools selected for their processing compared with the conventional machine-based approach

Component grouping for GT applications - a fuzzy clustering approach with validity measure

The variety of the currently available component grouping methodologies and algorithms provide a good theoretical basis for implementing GT principles in cellular manufacturing environments. However, the practical application of the grouping approaches can be further enhanced through extensions to the widely used grouping algorithms and the development of criteria for partitioning components into an 'optimum' number of groups. Extensions to the fuzzy clustering algorithm and a definition of a new validity measure are proposed in this paper. These are aimed at improving the practical applicability of the fuzzy clustering approach for family formation in cellular manufacturing environments. Component partitioning is based upon assessing the compactness of components within a group and overlapping between the component groups. The developed grouping methodology is experimentally demonstrated using an industrial case study and several well known component grouping examples from the published literature

Process capability models for equipment selection

Due to the increased complexity of modern manufacturing facilities and the increased demands for product variability and system flexibility there is a need for coherent formal representation of the basic knowledge domains supporting manufacturing applications such as equipment selection. The paper presents integrated framework for equipment selection based upon describing process capability at generic, machine tool and manufacturing system levels. The decision making process is designed as a sequence of steps for transforming component design information into processing requirements which are mapped into specific physical machines organised as a processing system

Geometric elements for tolerance definition in feature-based product models

Product modelling is an essential part of all computerised design and manufacturing activities. A precise mathematical model of the geometry of products is important, but must be supplemented with technological information such as the material, mechanical properties, functional specifications and tolerances. Modern CAD systems can model and manipulate components with complex geometry. However, technological information is represented as text symbols on the computer screen or drawing, and subsequent application programs are frequently unable to use this information effectively. This paper discusses this problem, and establishes the geometric elements required for the representation or dimensions and tolerances in a feature-based product modelling environment

A method for representation of component geometry using discrete pin for reconfigurable moulds

Moulding plays a paramount role in our daily life. Traditional moulding is often dedicated and expensive. As the current market trend moves from mass production towards small batch and large variation production, the demand for a mould that can reconfigure itself for different components is greater than ever. The reconfiguration of mould is often realized through discrete pins. Previous research in that field had focused on the hardware of pin actuation in order to move pins up or down to represent different components and lock the pins at certain positions. Little research has been conducted into support software development that enables rapid reconfiguration of discrete pins to represent component geometry.This paper addresses a new method of software development for the reconfigurable mould utilising discrete pins. The overall aim of the method is to provide an interface for generic discrete pin tooling in order to enable quick reconfiguration of the mould to represent component geometry. The software is composed of three parts: part discretization, pin matrix construction and adjustment and pin matrix verification

A survey of virtual prototyping techniques for mechanical product development

Repeated, efficient, and extensive use of prototypes is a vital activity that can make the difference between successful and unsuccessful entry of new products into the competitive world market. In this respect, physical prototyping can prove to be very lengthy and expensive, especially if modifications resulting from design reviews involve tool redesign. The availability and affordability of advanced computer technology has paved the way for increasing utilization of prototypes that are digital and created in computer-based environments, i.e. they are virtual as opposed to being physical. The technology for using virtual prototypes was pioneered and adopted initially by large automotive and aerospace industries. Small-to-medium enterprises (SMEs) in the manufacturing industry also need to take virtual prototyping (VP) technology more seriously in order to exploit the benefits. VP is becoming very advanced and may eventually dominate the product development process. However, physical prototypes will still be required for the near future, albeit less frequently. This paper presents a general survey of the available VP techniques and highlights some of the most important developments and research issues while providing sources for further reference. The purpose of the paper is to provide potential SME users with a broad picture of the field of VP and to identify issues and information relevant to the deployment and implementation of VP technology

RP-LC and HPTLC Methods for the Determination of Olmesartan Medoxomil and Hydrochlorothiazide in Combined Tablet Dosage Forms

Two new, rapid, precise, accurate and specific chromatographic methods were described for the simultaneous determination of olmesartan medoxomil and hydrochlorothiazide in combined tablet dosage forms. The first method was based on reversed phase liquid chromatography using an Eurosphere 100 RP C18 column (250 × 4.6 mm ID, 5 μm). The mobile phase was methanol–0.05% o-phosphoric acid (60:40 v/v) at a flow rate of 1.0 mL min−1. Commercially available tablets and laboratory mixtures containing both drugs were assayed and detected using a UV detector at 270 nm. The second method involved silica gel 60 F254 high performance thin layer chromatography and densitometric detection at 254 nm using acetonitrile–ethyl acetate–glacial acid (7:3:0.4 v/v/v) as the mobile phase. Calibration curves ranged between 200–600 and 125–375 ng spot−1 for olmesartan and hydrochlorothiazide, respectively