S. Carmo-Silva

Distributed Design of Product Oriented Manufacturing Systems

Manufacturing leanness and agility are requirements of today’s manufacturing systems. Leanness call for a best fit of the manufacturing systems to products, therefore requiring product oriented manufacturing systems (POMS). Manufacturing agility can be achieved through easy systems reconfiguration to fit changing manufacturing requirements, which may mean dynamically configuring POMS. For this a suitable design system is required. Due to complexity of this design, and to the need for using suitable design methods, which may not be available locally, distributed sources of design services can be used. This paper presents and describes a prototype of a Distributed Design system for POMS based on a POMS design methodology and distributed suppliers of design services.

Linking production paradigms and organizational approaches to production systems

Publisher Summary Manufacturing system design and operation is critical to achieve strategic company objectives. This must aim fitting manufacturing systems capabilities to the different demand market environments, taking into consideration, the different approaches and strategies that should be used. This chapter illustrates a framework for characterizing production system conceptual models and linking them to both production paradigms and organizational approaches to production, such as lean and agile manufacturing. The conceptual models identified are useful for aiding to implement organizational approaches and fit manufacturing systems to manufacturing requirements determined by different product demand patterns. An interrelation between production conceptual models, organizational approaches to production, and production paradigms is illustrated.

Aligning workload control theory and practice: lot splitting and operation overlapping issues

This paper addresses the problem of lot splitting in the context of workload control (WLC). Past studies on WLC assumed that jobs released to the shop floor proceed through the different stages of processing without being split. However, in practice, large jobs are often split into smaller transfer sublots so that they can move more quickly and independently through the production process and allow operations overlapping relating to the same job. This paper assesses the performance of different lot splitting policies for job release and dispatching strategies under lot splitting. A new dispatching rule was designed to specifically take advantage of lot splitting and operations overlapping in the context of WLC. Discrete-event simulation is used to assess system performance in relation to the ability to provide shorter delivery times and on time deliveries. Results highlight the importance of releasing the sublots of the same job together and demonstrate that combining an effective lot splitting policy with an appropriate dispatching rule can enhance the performance of production systems.

Scheduling in product oriented manufacturing systems

Scheduling is one of the most important decisions in production control systems. This paper explores different approaches for scheduling two stage jobs in two configurations of product oriented manufacturing systems, namely an hybrid flow shop (HFS) and a parallel machine flow shop (PMFS). An industrial case is analyzed from the automotive components industry. The HFS problem resolution is compared with PMFS one in terms of makespan and other performance measures. The results allow concluding that the HFS performs considerably better than the PMFS.

An Architecture for a Web Service Based Product Configuration Information System

Competition in the today’s global economy is intensifying the use of the new paradigm of mass customization. Such a paradigm is characterized by the need to deal with a very large variety of products determined by a substantial increase in customer specific product requirements. Implementing this paradigm requires agility and effectiveness in the customer-producer interaction and also in the order-production-delivery cycle. Web-based product configurators can provide an opportunity for improved interaction between producer and customer, and for a more formal, agile and effective process of both product and customer orders specification. In this paper, we propose architecture and describe the functionalities of a web based system for interactive product and customer order configuration. The proposed system can be also of value for supporting product data management and the production and delivery functions.

Generic POLCA: An Assessment of the Pool Sequencing Decision for Job Release

We present a simulation study for assessing the impact of pool sequencing rules for job release in a make-to-order general flow shop under the Generic POLCA order release and materials flow control system. Four pool sequencing rules are tested when the workload released to the shop floor is measured: (1) in jobs; and (2) in processing time units. Performance results based on both, the ability to deliver jobs on time and to provide short delivery times, show that a capacity slack rule based on the corrected aggregate workload perform best.

Improving materials flow through autonomous production control

Abstract Autonomous Production Control (APC) aims at improving production systems performance through fast and flexible reaction to changes in dynamic environments. In this paper, a new APC method for job routing decision-making is proposed and its performance compared with that of two other APC methods, namely the Queue Length Estimator and the Pheromones, and with two conventional control strategies – a centralized and a random decision-making strategy. A discrete-event simulation model of a flexible flow shop operating under make-to-order was used to evaluate performance. Results show that the new method outperforms those with which it was compared, under high system workload and high variability of orders’ arrival and operation times. The study gives a contribution for better understanding of the performance behavior of APC methods, having important implications for industrial practice and for future research on autonomous production control.

Bottleneck-Oriented Order Release: An Assessment by Simulation

Bottleneck-oriented order release has been advocated as an effective and simplified strategy for production control. Due to product mix changes and jobs processing time variety, the emergence of short term shifting bottlenecks is typical in low-volume and high-variety manufacturing. But is bottleneck-oriented order release effective in this production environment? In this paper, we report a simulation study carried out to evaluate the performance of two bottleneck-oriented strategies: Fixed Bottleneck Control (FBC) and Dynamic Bottleneck control (DBC). The performance of these strategies is compared with the performance of Workload Control (WLC) under three levels of bottleneck criticality in terms of the overload imposed to the system bottleneck relatively to the non-bottlenecks. Results show that the WLC clearly outperforms both, FBC and DBC. Moreover, the DBC showed to perform better than the FBC only when the level of bottleneck criticality is low, i.e. when the workload is balanced across work centres.

Load-Based Generic Polca: Performance Assessement Using Simulation

POLCA (i.e. Paired-cell Overlapping Loops of Cards with Authorization) is a card-based decision support system for production control, developed to support the adoption of Quick Response Manufacturing. Two variants of POLCA have been proposed in the literature to improve POLCA performance: Load Based POLCA and Generic POLCA. In this paper, we combine these two variants into a single production control system and analyse its performance for different backlog-sequencing rules. The results of a simulation study carried out for a make-to-order flow shop, support the strategy of combining these two POLCA variants and show that capacity-slack backlog sequencing based on corrected aggregate load have the potential for improving performance.

Materials Flow Control in Hybrid Make-to-Stock/Make-to-Order Manufacturing

Today’s company competiveness is favoured by product customisation and fast delivery. A strategy to meet this challenge is to manufacture standard items to stock for product customisation. This configures a hybrid environment of make-to-stock and make-to-order. To explore the advantages of this requires good understanding of production control. Thus, we study production under hybrid MTS-MTO, organising the system in two stages. The 1st manufactures items to inventory, which are then customised in the 2nd. We analyse how the percentage of tardy orders is affected by the inventory of items required to achieve a given fill rate. The impact of two mechanisms for releasing orders to both stages is also analysed. Results of a simulation study indicate that most of the reduction on the percentage of tardy orders is achieved by a moderate increase in the stock level of semi-finished products. Moreover the percentage of tardy orders decreases if suitable controlled release of orders is exerted.