Doug Love

Evaluation of design decisions through CIM and simulation

Argues that while engineering decisions can have a significant impact on the fortunes of a manufacturing business, the methods of evaluation currently available are limited in their ability to predict, accurately, comprehensively and reliably, the full financial effect of such decisions. Proposes the creation of a “whole business simulator” (WBS) from the elements of a computer integrated manufacturing (CIM) system and specialist simulation modules. Argues that the system would be capable of evaluating any engineering decision by generating the time‐phased financial performance of the simulated company in the form of standard accounting reports. Describes a demonstration system which has been developed to prove the viability of the concept.

Evaluating design implementation strategies using enterprise simulation

Concurrent engineering and design for manufacture and assembly strategies have become pervasive in use in a wide array of industrial settings. These strategies have generally focused on product and process design issues based on capability concerns. The strategies have been historically justified using cost savings calculations focusing on easily quantifiable costs such as raw material savings or manufacturing or assembly operations no longer required. It is argued herein that neither the focus of the strategies nor the means of justification are adequate. Product and process design strategies should include both capability and capacity concerns and justification procedures should include the financial effects that the product and process changes would have on the entire company. The authors of this paper take this more holistic view of the problem and examine an innovative new design strategy using a comprehensive enterprise simulation tool. The results indicate that both the design strategy and the simulator show promise for further industrial use.

Expanding the capabilities of manufacturing simulators through application of object-oriented principles

Abstract There are many simulation tools to evaluate decision making in the design or operation of manufacturing systems, but their ease of use and scope of application vary greatly. Deficiencies in current products are examined to consider whether they can be solved by applying object-oriented principles to the design of a data-driven simulator. These principles can permit the design of a system that can be freely extended, allowing “objects” with different authors to be reused via object class libraries. The system developed retains ease of use while removing limits on applications. Emphasis is on manufacturing engineering and dynamic evaluation requirements.

Retrieving designs from a sketch using an automated GT coding and classification system

While the retrieval of existing designs to prevent unnecessary duplication of parts is a recognised strategy in the control of design costs the available techniques to achieve this, even in product data management systems, are limited in performance or require large resources. A novel system has been developed based on a new version of an existing coding system (CAMAC) that allows automatic coding of engineering drawings and their subsequent retrieval using a drawing of the desired component as the input. The ability to find designs using a detail drawing rather than textual descriptions is a significant achievement in itself. Previous testing of the system has demonstrated this capability but if a means could be found to find parts from a simple sketch then its practical application would be much more effective. This paper describes the development and testing of such a search capability using a database of over 3000 engineering components.

The key to object-oriented simulation: separating the user and the developer

Simulation tools should be both easy to use and applicable to a wide range of problems. In practice, however, a compromise exists giving rise to a range of software from simulators to simulation languages. Object-oriented techniques have the potential to overcome this compromise; the ability to reuse and extend software could enable the development of a simulator that would be extended over time. The use of object-oriented techniques to date has mainly resulted in the development of powerful but difficult to use libraries. Ideally the skills of manufacturing engineers should be concentrated on building models of manufacturing systems whilst the skills of software developers should be concentrated on adding new functionality. This paper presents a mechanism whereby the roles of engineer and developer are clearly split to provide an easy to use simulator with a potentially very wide range of application.

Evaluating approaches to product design and sourcing decisions in multinational companies

Product design and sourcing decisions are among the most difficult and important of all decisions facing multinational manufacturing companies, yet associated decision support and evaluation systems tend to be myopic in nature. Design for manufacture and assembly techniques, for example, generally focuses on manufacturing capability and ignores capacity although both should be considered. Similarly, most modelling and evaluation tools available to examine the performance of various solution and improvement techniques have a narrower scope than desired. A unique collaboration, funded by the US National Science Foundation, between researchers in the USA and the UK currently addresses these problems. This paper describes a technique known as Design For the Existing Environment (DFEE) and an holistic evaluation system based on enterprise simulation that was used to demonstrate the business benefits of DFEE applied in a simple product development and manufacturing case study. A project that will extend these techniques to evaluate global product sourcing strategies is described along with the practical difficulties of building an enterprise simulation on the scale and detail required.

Developing an enterprise simulator to support electronic supply-chain management for B2B electronic business

The application of any e-Solution promises significant returns. In particular, using internet technologies both within enterprises and across the supply (value) chain provides real opportunity, not only for operational improvement but also for innovative strategic positioning. However, significant questions obscure potential investment; how any value will actually be created and, importantly, how this value will be shared across the value chain is not clear. This paper will describe a programme of research that is developing an enterprise simulator that will provide a more fundamental understanding of the impact of e-Solutions across operational supply chains, in terms of both standard operational and financial measures of performance. An efficient supply chain reduces total costs of operations by sharing accurate real-time information and coordinating inter-organizational business processes. This form of electronic link between organizations is known as business-to-business (B2B) e-Business. The financial measures go beyond simple cost calculations to real bottom-line performance by modelling the financial transactions that business processes generate. The paper will show how this enterprise simulator allows for a complete supply chain to be modelled in this way across four key applications: control system design, virtual enterprises, pan-supply-chain performance metrics and supporting e-Supply-chain design methodology.

Modelling the relationship between local logistics management decisions and overall supply chain performance: a research agenda

Supply chains are advocated widely as being the new units for commercial competition and developments have made the sharing of supply chain wide information increasingly common. Most organisations however still make operational decisions intended to maximise local organisational performance. With improved information sharing a holistic focus for operational decisions should now be possible. The development of a pan supply chain performance framework requires an examination of the conditions under which holistic decisions provide benefits to either the individual enterprise or the complete supply chain. This paper presents the background and supporting methodology for a study of the impact of an overall supply chain performance metric framework upon local logistics decisions and the conditions under which such a framework would improve overall supply chain performance. The methodology concludes a simulation approach using a functionally extended Gensyms e-SCOR model, together with case based triangulation, to be optimum.

Stimulating design reuse through automated coding

In designing new product the ability to retrieve drawings of existing components is important if costs are to be controlled by preventing unnecessary duplication if parts. Component coding and classification systems have been used successfully for these purposes but suffer from high operational costs and poor usability arising directly from the manual nature of the coding process itself. A new version of an existing coding system (CAMAC) has been developed to reduce costs by automatically coding engineering drawings. Usability is improved be supporting searches based on a drawing or sketch of the desired component. Test results from a database of several thousand drawings are presented.

Development of Simulation Techniques for the Design of Nagare Flow Production Systems

Simulation techniques have been used for some time to assess the dynamic behaviour of manufacturing systems. The trend towards ‘Japanese’ style production systems has presented some challenges to dynamic analysis: complex and flexible operator working patterns are difficult to model using traditional simulation techniques. The term ‘nagare’ has been used to describe production systems consisting of low technology machine tools arranged in a IT shape. Operators travel in a circular pattern moving components from machine to machine. This paper will present a manufacturing simulator that is able to model nagare production systems. Features within the simulator assist the user in developing simulation models. Typically the speed of developing simulation models confines their use to checking the final design. It will be shown that this simulator can be used to design, as well as evaluate, such production systems.