This research has examined the cost estimating and cost modeling research literature and identified the benefits and limitations of existing practices. Particular emphasis has been placed on the methods available for developing cost models at the early stages of product and process development where data from which to develop models is scarce. Shortfalls in existing practices have been identified as well as potential methods of resolving these limitations. Of these methods Virtual Manufacturing appears to offer the greatest potential for resolving issues with lack of data availability by enabling such data to be generated. Detailed trials have, therefore, been undertaken to examine the effectiveness of Virtual Manufacturing in terms of its ability to generate valid data in the quantities required to ensure accurate cost models can be developed. In addition, the research has involved the use of Data Mining techniques to identify the cost estimating relationship's within the data output from the Virtual Manufacturing trials. Here the aim has been to investigate the potential use of Data Mining techniques to fully automate the data analysis stage of the cost model development process.

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The intellectual arrangement of parts in an assembly is a difficult task. Modern CAD environments contain tools which allow CAD part models to be brought together and problems such as clashes to be discovered. Clashes occur when components in an assembly unintentionally violate others. If clashes are not identified and designed out before manufacture, the physical parts will not assemble together without rework. This work introduces a novel approach for eliminating clashes by identifying which parameters defining the part features in a CAD assembly need to change, and by how much, to eliminate the clashes. Consideration is given to the fact that it is sometimes preferable to modify some components in an assembly rather than others, and that some components in an assembly cannot be modified as the designer does not have control over their shape. One of the interesting insights offered by this work is that certain aspects of design intent related to component interfaces in an assembly can be enforced by identifying the faces between the different components, and understanding the effect of parameters which define the model has on them. The work presented in this thesis determines which parameters should be related to one another and, more importantly, how parametric sensitivities are used to: (a) identify parametric relationships between different parameters in the CAD assembly, and (b) constrain the assembly using the identified relationships to define the design intent of the assembly. The developed processes advances the state-of-the-art CAD systems by explicitly determining the relationships between the parameters and eliminating clashes in CAD models. A well-captured design intent for assembly models will enable the designer to design out manufacturing and assembly difficulties at an early product development stage. The approaches have been tested on a number of example models in this thesis.

End milling is a widely used cutting process involved in different types of finishing profile machining, where the geometry is complex, the tolerances are small and the cost of the operations is high. Despite tremendous developments in CAM software, cutting tool technology and machine tool technology, end-milling results still depend to a large extent on the knowledge inherent within manufacturing staff. The work presented in this thesis is a CAD/CAM-related strategy that promotes high efficiency machining by taking into consideration the process geometry, the cutting forces, and surface accuracy requirements of a particular part. The study is focused on cutting process geometry identification, milling operation modelling and machining parameters optimisation. A hybrid model of the end-milling process has been developed, which incorporates several models, based on different approaches in order to reflect the specifics of the complex milling process. This research has developed an optimisation strategy, which is a tool for defining optimum cutting conditions. The cutting tool deviation reflects the action of the cutting forces and is the dominant parameter in the machining error equation, consequently it takes the major role in the optimisation process. A mechanistic-force model and two-stage cantilever model of the cutting tool are the basis of the end-milling simulation. The optimisation strategy generates variable feed rate which is constrained by the machining errors, tolerances and surface roughness requirements. The presented machining error synthesis converts the general optimisation approach to the particular machining process, taking into consideration the geometrical error of a specific machine tool, the accuracy of the cutting tool and the CAM tool path tolerance. This research enhances the identification of cutting-force coefficients by developing a new methodology based on the experimentally obtained cutting-tool deviation. The new methodology provides the simulation process with instantaneous cutting-force coefficients, which are independent of the cutting operation geometry. It can be applied to any end-milling configuration if the workpiece material and cutting tool are the same. The experimental results verify the theoretical findings and confirm that the proposed optimisation approach creates a more efficient operation-planning environment. The optimised tool paths achieve the required surface accuracy and surface roughness, and performed the cutting operations at shorter machining times, compared with the same operations cut with constant cutting conditions. The experimental programme also includes a comparison between up- and down-milling.

The early stages of the product design process are defined as those when initial product concepts are conceived in accordance with a design brief. High numbers of ideas will be generated as designers iteratively develop concepts towards more refined design solutions. The early stages of the design process are rich with trial and error providing the optimum time for making major design decisions with minimal risk. Prototypes play a critical role in designers’ ability to explore and evaluate concepts against the user's requirements and needs during this time. The role of prototypes is emphasised to an even greater degree when adopting user centric design methodologies. The term computer-embedded device is used to describe a type of product which features embedded processing power. Examples of this type of device include hospital monitoring equipment, satellite navigation devices, microwave ovens, washing machines, car park ticket machines and mobile phones to name just a few examples. Such devices typically feature bespoke hardware with custom user interfaces. These devices are inherently complex to design due to reliance upon a multitude of disciplines including industrial design, software engineers, electronics engineers and human computer interaction experts. The need for such a multi disciplinary team presents a major challenge for industrial designers when attempting to prototype this type of product. A number of attempts have been made to alleviate the prototyping challenges faced by designers associated with these products. Some of this work has resulted in the development of so called prototyping toolkits which aim to abstract some of the electronics and programming knowledge required to create interactive prototypes. However, previously there has been little research which focused on exploring the interactive prototyping needs of designers during the very early stages of the design process. This thesis explores the needs of designers involved in the development of computer-embedded devices during the early stages of the design process, in relation to interactive prototyping. The research includes the development of an experimental prototyping toolkit. The toolkit's development was informed through the findings of a critical literature review which identified suggestions relating to early stage interactive prototyping requirements. The toolkit provided a means of directly exploring to what extent the requirements previously suggested met with the actual needs of designers working at this stage of the design process by creating an intervention in existing design processes. The research trialled the toolkit with six carefully selected industrial collaborators. These collaborations ranged in profile and market from an independent User Centric Design consultant through to a Global Mobile Phone Corporation. This research has found that it is possible to produce tangible interactive prototypes during the early stages of the design process within a timescale of one to two hours. The research has also concluded that the barriers towards interactive prototyping during the early stages extend beyond being solely attributed to a lack of suitable prototyping tools. The research identified major limitations in the existing prototyping tools available to designers, as well as a lack of integration between the industrial design and the interaction design associated with the design of computer-embedded devices. This lack of integration poses a major barrier towards the successful design of computer-embedded devices.

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