The implementation of a fabrication cell and the optimisation of a pull system with a decision support system

Manufacturing Resource Planning (MRPH) systems are used by forty per cent of UK manufacturing companies (Little, 1990). In cases where the implementation of the system was successful the companies have experienced reductions in inventories and lead times but the results were not always as good as they were anticipated. The justification of the major capital expenditure that is required for the implementation of the MRPn system was not always achieved by the benefits gained. Meanwhile, Just in Time (JFI) manufacturing environments experience benefits in terms of rapid stock- turns, due-date compliance and quality that MRPH users could not resist. This research initially focused on the investigation of the reasons of failure of MRPH implementations in low volume high variety manufacturing environments. The main reason being that the implementation of the MRPH system was not complemented by a shop floor re-organisation. The thesis reports an investigation and some elements of implementation of a change in the manufacturing operations of a company. The manufacturing environment that was used for this investigation was Reyrolle Switchgear Ltd. The production control system used by the company is MRPn, however, the implementation of the system was not as successful as it was anticipated. In order to cope with excessive stock, management decided to introduce a pull system for controlling the production of a limited number of components. The application of the pull system was limited because of the complexity in controlling the response of the manufacturing facilities, which had a functional layout. In order to establish an effective pull system, cellular manufacturing was introduced. The methodology used was "Line Analysis" which is a sub technique of "Production Flow Analysis". The pull system was complemented by a Decision Support computer based system in order to facilitate and enhance planning and inventory control. The changes were implemented and considerable improvements were achieved. The candidate is a researcher/investigator partly promoting the changes reported, implementing methods and investigating their effect

Fault-tolerant networks-on-chip routing with coarse and fine-grained look-ahead

Fault tolerance and adaptive capabilities are challenges for modern networks-on-chip (NoC) due to the increase in physical defects in advanced manufacturing processes. Two novel adaptive routing algorithms, namely coarse and fine-grained (FG) look-ahead algorithms, are proposed in this paper to enhance 2-D mesh/torus NoC system fault-tolerant capabilities. These strategies use fault flag codes from neighboring nodes to obtain the status or conditions of real-time traffic in an NoC region, then calculate the path weights and choose the route to forward packets. This approach enables the router to minimize congestion for the adjacent connected channels and also to bypass a path with faulty channels by looking ahead at distant neighboring router paths. The novelty of the proposed routing algorithms is the weighted path selection strategies, which make near-optimal routing decisions to maintain the NoC system performance under high fault rates. Results show that the proposed routing algorithms can achieve performance improvement compared to other state of the art works under various traffic loads and high fault rates. The routing algorithm with FG look-ahead capability achieves a higher throughput compared with the coarse-grained approach under complex fault patterns. The hardware area/power overheads of both routing approaches are relatively low which does not prohibit scalability for large-scale NoC implementations

Shop-floor scheduling as a competitive advantage:A study on the relevance of cyber-physical systems in different manufacturing contexts

The aim of this paper is to analyse the relevance of cyber-physical systems (CPS) in different manufacturing contexts and to study whether CPS could provide companies with competitive advantage by carrying out a better scheduling task. This paper is developed under the umbrella of contingency theory which states that certain technologies and practices are not universally applicable or relevant in every context; thus, only certain companies will benefit from using particular technologies or practices. The conclusion of this paper, developed through deductive reasoning and supported by preliminary simulation experiments and statistical tests, is that factories with an uncertain and demanding market environment as well as a complex production process could benefit the most from implementing a CPS at shop-floor level since a cyber-physical shop-floor will provide all the capabilities needed to carry out the complex scheduling task associated with this type of context. On the other hand, an increase in scheduling performance due to a CPS implementation in factories with simple production flows and stable demand could not be substantial enough to overcome the high cost of installing a fully operational CPS

Constraint-Based Supply Chain Inventory Deployment Strategies

The development of Supply Chain Management has occurred gradually over the latter half of the last century, and in this century will continue to evolve in response to the continual changes in the business environment. As organizations exhaust opportunities for internal breakthrough improvements, they will increasingly turn toward the supply chain for an additional source of untapped improvements. Manufacturers in particular can benefit from this increased focus on the chain, but the gains realized will vary by the type of supply chain. By applying basic production control principles to the chain, and effectively using tools already common at the production line level, organizations address important supply chain considerations. Both the Theory of Constraints and the factory physics principles behind the Constant WIP concepts focus on the system constraint with the aim of controlling inventory. Each can be extrapolated to focus on a system whose boundaries span the entire supply chain

Application of Parallel Processing for Object Oriented Discrete Event Simulation of Manufacturing Systems

Industrial Engineering and Managemen