Kwabena Agyapong-Kodua

Modelling dynamic value streams in support of process design and evaluation

To remain competitive, most manufacturing enterprises (MEs) need cost-effective and responsive business processes with capability to realise multiple value streams specified by changes in customer needs. Models of MEs can play a critical role in enabling enhanced enterprise process and systems design and change based on analysis of their performance, and ongoing management and control of their operation. Typical models of MEs can provide reusable computational representations of organisational structures, processes, information, resources and related value flows in an enterprise. This paper presents a dynamic modelling approach to value stream mapping which enhances current best practice when reasoning about changing process and resource systems requirements. Here, coherent use of enterprise and simulation modelling techniques were deployed to develop value streams of a case study enterprise which is a make-to-order furniture manufacturing SME. The paper explains how models created during the modelling stages were validated and reused as a basis for informed SME decision making in relation to product realisation strategies and related organisation design and change decisions and actions.

Towards the derivation of an integrated process cost-modelling technique for complex manufacturing systems

Cost modelling is used to support business decisions, especially, when the objective is to remain competitive on price and be able to realise outputs at low cost. Many researchers and industrialists have proposed and experimented with different cost-modelling techniques with a view to influencing design and production decisions at an early stage of the development process. This has led to cost-modelling methods which have been broadly classified in this paper as qualitative and quantitative. The paper identifies current best practice cost-modelling techniques and their performance in complex and dynamic manufacturing environments. The review served as a platform to support the recommendation for an integrated cost-modelling methodology. The integrated methodology is based on the strengths of cost engineering, enterprise modelling, system dynamics and discrete event simulation modelling techniques. The method can help in the redesign and re-engineering of products and processes for better cost and value indications; support investment decision analysis; help determine appropriate business and manufacturing paradigms; influence ‘make, buy or outsourcing’ decisions and serve as a key process improvement tool.

Systems approach to modelling cost and value dynamics in manufacturing enterprises

Operations and activities in manufacturing enterprises (MEs) are undergoing frequent changes as a result of external and internal factors which actively impact on the structures, processes and work patterns of most MEs. These changes induce complexities and dynamics in the survival of most MEs. As a result of the changes, cost and value generation are also affected. To remain competitive, MEs have to continuously and flexibly adjust through the redesign and organisation of their processes and resource elements with the aim to improve key performance indicators including cost and values. This is however not simple to achieve because of the inherent and ongoing dynamics experienced by MEs. This paper shows how system dynamics modelling techniques, in the form of causal loop and iThink simulation, can be coherently used to capture salient factors which induce dynamics in MEs. The integrated modelling technique was further used to show how dynamic impacts of MEs on cost and value generation can be conveniently modelled and analysed to support decision making related to competitiveness and profitability of a case study furniture manufacturing company.

Review of semantic modelling technologies in support of virtual factory design

Comprehensive data models and standardised terminologies are required across tools and their developers to rapidly design and prototype digitised virtual factories. Also, various types of software are required to be integrated for cost-effective modelling exercises. To meet this requirement, semantic modelling technologies involving ontologies have featured prominently in many manufacturing applications. This paper considers, extensively, the current semantic requirements for digitised virtual factory design and prototyping and compares them with the capabilities of existing semantic technologies. As a result, a review of methodologies, tools and languages for creating ontologies has been reported. The review concludes with the next generation requirements for methodologies, tools and languages for creating ontologies suitable for the virtual factory design process, and further explains ongoing work associated with the creation of ontologies and reasoning mechanisms through the integrated use of ObjectLogic, OntoStudio and OntoBroker.

Development of a Multi-Product Cost and Value Stream Modelling Methodology

In support of the life-cycle engineering of manufacturing enterprises (MEs), there is a need to provide reusable computational representations of organisational structures, processes, information, resources, and related cost and value flows. Current best process mapping techniques do not suitably capture key time-based attributes of ME systems, particularly with respect to the dynamics associated with multi-product work flows through shared resource systems. However, multiple work-flow dynamics will likely impact significantly on cost and value generation, and if this kind of dynamics cannot be effectively modelled, the use of process mapping will be limited as a basis for decision-making. Therefore, this paper presents an integrated multi-product dynamic cost and value stream modelling methodology with the embedded capability of capturing aspects of dynamics associated with multiple product realisations in MEs. The first part of the research presented in this paper shows the application of an enhanced and integrated use of process mapping and enterprise modelling techniques in a case study involving a POP manufacturing company in the UK. When compared with the use of current lean-based value-stream-mapping techniques, case study results obtained when using the first part of the modelling method have led to improved solutions to problems of: analysing and estimating cost and values; and improving the design and operation of multi-product realising systems.

An integrated product–process design methodology for cost-effective product realisation

Methods related to Design for X are known to have contributed positively to product designs, resource selection and realisation of products. Despite these achievements, frequent design errors which can be attributed to the lack of integration of design and manufacturing concepts exist. Departmentalisation, skill concentration and protection of institutional interests contribute largely to the non-full integration of design and manufacturing methods. This article adopts a process-engineering approach which supports the development and integration of product and process models for design concept analysis. The methodology described in this article is part of a broad-based design methodology with a potential to improve design and manufacturing integration and offers solutions for effective and timely reconfiguration of manufacturing systems in view of meeting market demands.

Fundamentals of a co-design methodology for improving the performance of machine tools based on semantic representation

Design methods applied at the concept development stage of a design process help the derivation of alternative design solutions so that, based on product requirements and design specifications, selected design options can be evaluated. How this is achieved is important because design decisions contribute largely to the cost and manufacturability of products. The main scenario of the European machine tool (MT) industry is a small- or medium-sized enterprise designing and producing small series of dedicated MTs competing on a global market and working in close collaboration with suppliers and machine end users. In this scenario, MT manufacturers need close collaboration with their component suppliers and end users to develop effective design solutions. The article identifies some aspects of ‘collaborative design methods’ that have been applied successfully in the aerospace and automotive industries and recommends a ‘knowledge-centred’ approach with the potential to capture, transfer and share knowledge at the different life phases of the MT, but currently applied mainly at the conceptual design stage. The proposed methodology relies on a flexible knowledge-based ‘co-design environment’. The methodology will enhance knowledge capitalisation, allow early virtual assessment of design decisions and reduce re-design cycles.

Towards the derivation of an integrated design and manufacturing methodology

Design methods support the derivation of alternative design solutions, and based on product requirements, it provides a platform for the evaluation and selection of appropriate solutions. Because of the driving needs of design and manufacturing industries and also the quest to remain competitive, several design methodologies aimed at addressing aspects of industrial requirements have emerged. This study identifies current best practice design methodologies and their performance when compared with current trends in design and manufacturing. Based on the review, the strengths and weaknesses of current methods are highlighted and used as the platform to support the recommendation for an integrated design and manufacturing methodology. The integrated design and manufacturing methodology rest on the strengths of product design, cost engineering, enterprise and process simulation modelling techniques. This method can help in the (re)design and (re)engineering of products and processes for better cost indications; help determine appropriate manufacturing paradigms; perform virtual experiments to understand implication of production volume changes on designs and flexibility needs in production systems.

Resource selection ontologies in support of a recipe-based factory design methodology

Factory (re) design involves the appropriate utilisation of product, process and resource knowledge in the determination of suitable configurations of physical factory facilities which have the potential to meet industrial and organisational requirements. Different independent semantic modelling standards exist for products, processes and resources but to automate and facilitate the selection of factory resources, there is the need to semantically integrate resource capabilities with product and process requirements. This paper defines a ‘recipe-based’ approach to design factories and it is based on the assumption that capabilities and competences of reusable components (or building blocks) of factory resources can be semantically modelled and matched with product–process requirements. This approach will enable Factory Designers and Engineers to decide on relevant resource systems within finite, valuable and defined sets of requirements.

The Integrated Use of Enterprise and System Dynamics Modelling Techniques in Support of Business Decisions

Enterprise modelling techniques support business process (re)engineering by capturing existing processes and based on perceived outputs, support the design of future process models capable of meeting enterprise requirements. System dynamics modelling tools on the other hand are used extensively for policy analysis and modelling aspects of dynamics which impact on businesses. In this paper, the use of enterprise and system dynamics modelling techniques has been integrated to facilitate qualitative and quantitative reasoning about the structures and behaviours of processes and resource systems used by a Manufacturing Enterprise during the production of composite bearings. The case study testing reported has led to the specification of a new modelling methodology for analysing and managing dynamics and complexities in production systems. This methodology is based on a systematic transformation process, which synergises the use of a selection of public domain enterprise modelling, causal loop and continuous simulation modelling techniques. The success of the modelling process defined relies on the creation of useful CIMOSA process models which are then converted to causal loops. The causal loop models are then structured and translated to equivalent dynamic simulation models using the proprietary continuous simulation modelling tool iThink.