Oladele Owodunni

A method for engineering design change analysis using system modelling and knowledge management techniques

Engineering design change management is very important to the success of engineering product development. It has been recognised that the earlier change issues are addressed, the greater product lifecycle costs can be saved. However, in practice, most engineering changes happen in the manufacturing phase, the later phase of product development. Change issues happening in the design phase, especially between the functional and the structural domains, have been a research focus in recent years, and thus there is significant research work that has been carried out to resolve early engineering change issues from different perspectives. This article presents a novel methodology that has been developed to help designers trace, analyse and evaluate engineering changes occurring in the product design phase. A modelling method is employed to enhance the traceability of potential design changes occurred between the functional and structural domains of design. Based on functional and physical models, a matrix-based method is developed to analyse change propagations between components and help find out design conflicts arising from design changes. A knowledge-based method has been proposed to resolve design conflicts by reusing previous design change knowledge. An industrial example about changes of a wind turbine cooling system has been used to help understand the methodology and prove its usefulness.

Voronoi diagram-based tool path compensations for removing uncut material in 2-D pocket machining

This paper solves the problem of uncut areas, which can arise when 21/2D pockets are machined with radial widths of cut greater than half the cutter diameter. Using the Voronoi diagram approach, three types of uncut areas are defined i.e., corner, centre and neck uncut regions. The corner uncut area is further subdivided into five different types, the centre uncut area into four and the neck uncut area into two. Techniques for detecting each type as well as algorithms for generating the tool paths for removing them are developed based on a singularity-free Voronoi diagram approach. These efficient and robust algorithms ensure that no uncut material is left behind even for complex-shaped pockets containing islands. The proposed algorithms even permit the radial width of cut to be increased to its limiting value of tool diameter. Three examples are included to illustrate the procedures for detection and removal of the different types of uncut areas.

Evaluation of existing and new feature recognition algorithms: Part 1: Theory and implementation

Abstract This is the first of two papers evaluating the performance of general-purpose feature detection techniques for geometric models. In this paper, six different methods are described to identify sets of faces that bound depression and protrusion faces. Each algorithm has been implemented and tested on eight components from the National Design Repository. The algorithms studied include previously published general-purpose feature detection algorithms such as the single-face inner-loop and concavity techniques. Others are improvements to existing algorithms such as extensions of the two-dimensional convex hull method to handle curved faces as well as protrusions. Lastly, new algorithms based on the three-dimensional convex hull, minimum concave, visible and multiple-face inner-loop face sets are described. These algorithms provide a basis for the comparative analysis that is the subject of the second paper.

Voronoi-diagram-based linking of contour-parallel tool paths for two-and-a-half-dimensional closed-pocket machining

Abstract Contour-parallel tool paths for machining milling features are formed by linking the offsets. Determination of links between offsets and the sequence in which the offsets should be traversed is a major problem. Results of efforts to link tool paths from academic researchers and developers of commercial computer-aided manufacturing (CAM) systems have shortcomings which include the fact that the linking strategies (a) are not based on clear geometric principles, (b) are not optimal, (c) do not consider technological factors such as the amount of slotting, overmilling, mode of cutting, and (d) are either not gouge-free or use tool retractions to avoid gouging. To overcome these shortcomings, this paper presents a linking algorithm which employs segments on the Voronoi diagram as links. The technological factors, hitherto ignored in previous research are considered and their optimality is ensured by employing guidelines which were mostly developed through observations of tool paths generated from a general test bed. Multiple solutions obtained after pruning out unfeasible solutions can be evaluated by users using geometrical (total tool path length) and technological (amount of overmilling, slotting, etc.) considerations or a combination of the criteria. The implementation of the algorithm is tested by generating tool paths for two two-and-a-half-dimensional (2½D) milled features. When compared with those obtained from some commercial CAM systems, they are shorter by 5 to 31 per cent.

Extendible Classification of Design and Manufacturing Features

Abstract This paper discusses three different issues in feature classification. It proposes a complete taxonomy to cater for prismatic and rotational features which can be positive or negative. It also suggests a feature definition that makes it feasible for the feature library to be extendible without additional programming effort. A unique code is given to each feature so as to avoid redundancy and ensure consistency of labelling the feature faces. This labelling is achieved by a novel formalisation method based on a newly found graph-theoretical property of a B-rep model. Results for one of the several components investigated are included.

A Framework for Improving the Sharing of Manufacturing Knowledge through Micro-Blogging

The purpose of this paper is to report on an industrial investigation, conducted within a leading power generation manufacturer, to better understand the organisational processes and challenges present in relation to the management and sharing of knowledge during product manufacturing. Findings reveal that the organisation is failing to fully benefit from web 2.0 technologies and particularly micro-blogging. Details of the investigation results are presented and a conceptual framework is proposed to demonstrate how organisations may enhance the sharing of explicit manufacturing knowledge using micro-blogging tools.

Systematic development and evaluation of composite methods for recognition of three-dimensional subtractive features

Abstract This paper describes a systematic procedure for developing composite feature detection systems from six methods for detecting three-dimensional depression features. The six methods, proposed by the authors in earlier papers, correspond to all the possible ways of grouping faces together from the simplest to the most complex grouping. All the possible ways of combining the six feature detection methods are considered and arranged in a tree structure. The possible composites are reduced to 20, using a tree pruning technique based on the criteria that the features detected should be the same (i.e. consistent), irrespective of the ordering of the faces in the B-rep model and that all faces of the component should be detected (i.e. complete coverage). A test bed for these 20 composites has been developed, implemented, and tested using carefully selected components from the public domain. The performance of these 20 composites is evaluated on the basis of suitability of the features as input to a machining application with minimal or no additional geometric reasoning, thus enabling the most promising composites to be identified.

Development and evaluation of a low-cost computer controlled Reconfigurable Rapid tool

AbstractThis paper describes the development of a low-cost rapid tool that is easily re-configurable by a single computer-controlled actuator or conventional CNC machine. The bed-of-pins concept used in popular pin-art toys and by other researchers is enhanced with a novel approach of positioning and clamping the pins in a simple, low-cost and time-saving manner which is scalable to large size products. Different tool path strategies for positioning the pins by using a CNC machine are proposed and evaluated to obtain an optimal strategy. The position of the pins, and the NC code, is automatically derived from the 3D CAD model of the part. The concept has been tested on parts made from carbon fibre and thermoplastic moulding, and sheet metalforming. The scalability of the concept to large size objects is also demonstrated.

A Methodology for Engineering Design Change Management Using Modelling and Problem Solving Techniques

The importance of design change management in engineering product development has been widely reported. However, most research focuses on the engineering change in the manufacturing phase, the later phase of product development. In this paper, a reference model for design change management has been proposed. A modelling method is employed to enhance the traceability of changes occurring between the functional model and the structural model. A matrix based method has been developed to capture change propagations at the structural level and the parametric level of product design. A structural method of change propagation analysis and change impact evaluation has been developed. Finally, conclusions are drawn and scope for further work of this research is indicated.

An investigation into the management of design for manufacturing knowledge in an aerospace company

Design engineers are under constant pressure to improve product design for better manufacturability and product performance. However, design issues and areas for improvements are normally identified in the aerospace industry during the production phase of a products’ lifecycle where design engineers have begun working on other projects under tight schedules for delivery. This investigation focuses on the issues and limitations for managing the production line manufacturing knowledge that can benefit design engineers to implement design for manufacturing strategies at a large aerospace systems manufacturer in the UK. A framework is proposed to describe the current system in order to improve the management of manufacturing knowledge for the design engineers. A prototype solution is proposed to apply in the industry to improve the implementation of design for manufacturability in the engineering function.