Shop Floor Level Research Articles

Multi-objective supervisory flow control based on fuzzy interval arithmetic: Application for scheduling of manufacturing systems

Complex production systems can produce more than one part type under multiple and possibly conflicting objectives. This paper considers the design of the multiple objective real-time scheduling problem of a multiple-part-type production system. Based on fuzzy control theory and fuzzy arithmetic intervals, distributed and supervised continuous-flow control architecture has been proposed. The objective is to balance the production process by adjusting the continuous production rates of the machines on the basis of the average behaviour. The supervisory control aims to maintain the overall performance within acceptable limits. In the proposed approach, the problem of a real-time scheduling of jobs is considered at the shop-floor level. In this case, the actual dispatching times are determined from the continuous production rates through a discretisation procedure. To deal with conflicts between jobs at a shared machine, a decision for the actual part to be processed is taken using some criterions which represent a measure of the job’s priority. A case study demonstrates the efficiency of the proposed control approach.

A NeuroEndocrine-Inspired Manufacturing System Using the Potential Field Concept

The manufacturing industry must have manufacturing systems that deal with the agile response to the appearance and changing conditions.As biological organisms are quite capable of adapting to environmental changes and stimulus, bio-inspired concepts have been recognized much suitable for adaptive manufacturing system control. This paper, therefore, proposes a NeuroEndocrine-Inspired Manufacturing System (NEIMS) using the potential field concept. The proposed NEIMS control architecture is inherited from neuro-control and hormone-regulation principles to agilely deal with the frequent occurrence of unexpected disturbances at the shop floor level. Hormone-regulation can impel system to be equilibrium through a potential field approach. From the cybernetics point of view, the control model of NEIMS has been described in detail. And a test bed has been set up to enable the NEIMS simulation.

Decision Making Platform Supported on ICTs: Application to the Management of Ground Handling Operations at an Airport

AbstractThe required harmonization of information and communication technologies (ICTs) with operational decision-making demands new alignment software techniques, especially at shop floor level. This alignment exists when people, systems, processes and technology are properly positioned to support company strategies; which in turn support the overall mission and goals. But the required integration is not easy as physical elements, implementation platforms and shop floor management operate as black boxes with a conspicuous lack of information sharing. In order to face this situation, this paper proposes the use in environmental alignment of concepts and technologies coming from manufacturing control. The application of an agent-based alignment supported by new “Visibility Frameworks” (as EPC Information Services) in scheduling levels is presented. A layered agent space is used in adapted platforms, where the interaction protocol between them and the decision making process, are based on sharing Markov reward parameters. This paper proposes the use of Markov parameters so as to maintain the system aligned, reflecting the company's global policy guidelines in every single decision taken in the plant, terminal or logistic centre. A software tool has been developed/deployed by which it has been possible to test these new ideas in the ground handling management of the Ciudad Real Central Airport.

STEP-NC Compliant Intelligent Process Planning Module: Architecture and Knowledge Base

STEP-NC (ISO 14649) is a new feature-based machine tool control language between CAM and CNC. In contrast with conventional G&M code (ISO 6983), it could provide richer and more machining information for CNC controller at shop floor. Therefore, it's feasible to develop an embedded micro process planning module in CNC controller. Meanwhile, some other information models such as manufacturing resources are essential for completing the intelligent process planning. The main thrust of this paper is focused on two fields: i) Proposition of a framework for STEP-NC compliant controller, ii) Development of knowledge base with OWL for the process planning in CNC controller. A novel STEP-NC compliant controller named OntoStep CNC is presented, which could accept ISO 14649 machining models and then generate optimized tool path based on knowledge base and rules at the shop floor level.

Behaviour and integration of service-oriented automation and production devices at the shop-floor

Automation and manufacturing systems are changing in the direction of cooperative ecosystems with heterogeneous entities. An important feature that should be considered is the vertical integration from the business needs down to the shop-floor where the real action takes place. This paper analyses the integration of shop-floor devices into the IT-enterprise but maintaining also a certain degree of independence in terms of behaviour. Service-oriented paradigm is used as the main backbone due its proven merits in the business levels and recently also in automation and production systems. In the provided example, high-level Petri nets (HLPN) demonstrate a set of useful features, namely the partial behaviour description and analysis and some parameters in the integration. The resulting application leads to an easy integration of autonomous devices in the IT-enterprise, taking especially in account the requirements of the shop-floor level.

“Taking on Corporate Bullies”: Cintas, Laundry Workers, and Organizing in the 1930s and Twenty-First Century

Based on interviews with workers and organizers, union and company records, legal documents, and media sources, this article compares laundry unionism in the 1930s and early 2000s at Cintas, North America’s largest industrial launderer and uniform rental provider. Employing resource mobilization theory, social movement unionism, and collective identity theory, the article argues that laundry workers were able to organize in the 1930s because of the simultaneous presence of union resources and internal activist solidarities at the shop floor level. While UNITE HERE (now Workers United) has run an innovative comprehensive campaign to organize Cintas, the absence of solidarity on the shop floor has impeded organization.

Modeling of orders in autonomously controlled logistic systems

The paper extends the Autonomous Logistics Engineering Methodology (ALEM) by a deeper understanding of immaterial logistic objects to trigger manufacturing processes. Further, a hierarchical modeling concept is introduced to split customer orders logically into partial orders, which run directly at the shop floor level. Each partial order consists of certain manufacturing steps. The amendments enable adequate modeling of autonomous manufacturing processes. The research is a further step to integrate autonomously controlled processes in logistics.

‘Safe enclaves’? American multinationals and Spanish trade unionism

By examining two case studies in Spain's automobile industry, this article analyzes the part played by the multinational corporation (MNC) in the historical transformation of Spanish trade unionism at shop-floor level. The literature on organizational change, often aimed at explaining the ability of MNCs to diffuse human resource policies and practices across borders, is used to explore MNCs’ ability to introduce organizational changes into the specific local conditions they are forced to deal with. Of the three possible types of organizational change examined (‘continuity and institutional inertia’, ‘discontinuous and revolutionary change’, and ‘hybridization’), the authors find there is a strong evidential tendency towards hybridization. The MNCs under scrutiny were able to transform some aspects of the work of trade unions at the workplace level (wages, promotion, selection), but found they had to adapt their management style to the Francoist state's labour legislation – namely, concerning professional classification and functional mobility. The authors also contend that it was the role of these companies as MNCs, not their country of origin, which opened the way to the transformation of trade union organization and labour relations at the local level in Spain, since such a transformation accelerated once French and Italian multinationals took over each one of the MNCs under examination.

Perencanaan Scheduling dan Rescheduling dengan Metode Heuristic SPT Guna Meminimumkan Mean Tardiness dan Makespan

To complete customer's demand so company must make a plan with using production schedule. Some diffrculties usually happen in shop floor level is a new job which is put in a production schedule that have arranged before. So that the old production schedule have to revised by reschedulling. The procedure that be used to schedule the real time production consist of n job m machine is algoritm of Hueristik Dispatching Rule Shorted Processing Time (SPT) method to minimize mean tardiness and makespan.

Joint consideration of production scheduling, maintenance and quality policies: a review and conceptual framework

Performance of a manufacturing system depends on its ability to simultaneously meet several requirements such as: quick response to market demand, high product quality, low manufacturing costs and timely deliveries; which in turn strongly depend on performance at the shop floor level. In the past, the shop floor level operational policies in the context of scheduling, maintenance and quality have been examined in isolation. However, it is hypothesised that these three aspects of operations planning may also have some interaction effect and hence joint consideration of various policy options pertaining to quality, maintenance and scheduling on the performance of the manufacturing system is an important area for investigation. In this paper, a review of literature addressing the joint consideration of these three aspects is presented and research gaps are highlighted. As a preliminary work, some numerical investigations are also presented to highlight the importance of joint consideration of these three aspects. Finally, a conceptual methodology is presented that can lead to further developments in this field. Some potential research areas in this context are identified.

Shipping operations quality assurance for fibreglass reinforced plastics manufacturers

This paper presents an employee-participated approach to implement a quality assurance procedure related to the shipping operations in a fibreglass reinforced plastics (FRP) manufacturer. Our research is motivated by a local FRP company where a lot of customer complaints and quality problems occurred after the product was shipped. While numerous researches have focused on manufacturing process quality control, there is a lack of research in quality assurance procedures for shipping operations. In our research, employees at both the technical and shop-floor level were involved in the development of a quality assurance programme. First we reviewed the existing shipping procedures at the FRP manufacturer. A quality audit form with input from the technical personnel was then designed to identify possible quality problems. After collecting information from the operational personnel using the audit form, we analysed the audit results and developed a set of guidelines and procedures tailored to the shipping operations. The total participation-based procedure would suit most of the small to medium fibreglass manufacturers to achieve continuous quality improvement.

A proposal for integrating production control and quality control

PurposeThe purpose of this paper is to present a practical proposal for integrating production control (PC) and quality control (QC) at the shop floor level.Design/methodology/approachThe proposed method is based on three principles which relate PC and QC at the shop floor level. The proposal is applied successfully at the world's largest pencil factory.FindingsThe results show that the proposed method contributes to improve four performance indicators related to PC and QC at the company studied: increase the average throughput in about 28.9 per cent; reduce the average value of work in process (WIP) in about 35.6 per cent, reduce the average lead time by about 45.4 per cent, and reduce the average defect rate by about 71.4 per cent.Research limitations/implicationsThe proposal (mainly because of principle III) is developed to be applied in repetitive production (RP) systems, i.e. environments characterized by low production volume and low product variety.Practical implicationsSome practical implications for industrial managers arises from this study: managers must consider the importance of integrated PC and QC functions in order to get better results concerning performance indicators such as throughput, WIP, lead time, and rejection rate; the materials flow simplification is a prerequisite for a lot of improvement initiatives at the shop floor level; the adequate choice of the production control system (PCS) is vital in order to get positive results regarding the performance indicators related to PC; the determination of the production pace (or rate) for a RP system must take account capacity restrictions and the influence of defect rate on production rate.Originality/valueThe paper is original in that it shows that the performance of the shop floor level can be improved by means of integrating PC and QC, by discussing and implementing a method which simplifies the material flow in the shop floor level, chooses the most adequate PCS and shows how the production rate influence on the rejection rate. Therefore, the paper is important for those which practice industrial management, more specifically on PC and QC functions.

Comparing the impact of different rescheduling strategies on the entropic-related complexity of manufacturing systems

The primary objective of this paper is to compare five rescheduling strategies according to their effectiveness in reducing entropic-related complexity arising from machine breakdowns in manufacturing systems. Entropic-related complexity is the expected amount of information required to describe the state of the system. Previous case studies carried out by the authors have guided computer simulations, which were carried out in Arena 5.0 in combination with MS Excel. Simulation performance is measured by: (1) entropic-related complexity measures, which quantify: (a) the complexity associated with the information content of schedules, and (b) the complexity associated with the variations between schedules; and (2) mean flow time. The results highlight two main points: (a) the importance of reducing unbalanced machine workloads by using the least utilised machine to process the jobs affected by machine breakdowns, and (b) low disruption strategies are effective at reducing entropic-related complexity; this means that applying rescheduling strategies in order to manage complexity can be beneficial up to a point, which, in low disruption strategies, is included in their threshold conditions. The contribution of this paper is two-fold. First, it extends the application of entropic-related complexity to every schedule generated through rescheduling, whereas previous work only applied it to the original schedule. Second, recommendations are proposed to schedulers for improving their rescheduling practice in the face of machine breakdowns. Those recommendations vary according to the manufacturing organisations’ product type and scheduling objectives. Further work includes: (a) preparing a detailed workbook to measure entropic-related complexity at shop-floor level; and (b) extending the analysis to other types of disturbances, such as customer changes.

Upgrading mixed ventilation systems in industrial conditioning

Mixing ventilation systems (MVS) involve injecting cold air from the upper part of the room. The resulting turbulent mixing of the cold stream with ambient air determines a cooling of the whole volume and establishes an uniform temperature level with a very low vertical temperature gradient. While this method is commonly practiced it may not be energy efficient as the entire room volume gets cooled while often only the lower room volume, occupied by personnel at the shop floor level, needs conditioning. This may be a severe drawback especially in high-ceiling buildings and when process equipment with high thermal loads are utilized. In this paper an easily retrofitted improvement solution to existing MVS, called retrofit hybrid displacement ventilation system (RHDVS) is suggested and compared with a traditional MVS taking into account technical and economic performances. The study was carried out resorting to experimental measurements on a single-diffuser pilot installation of the RHDVS in an actual industrial facility, to characterize the existing MVS and estimate the performance improvement obtainable with the proposed RHDVS. An economic analysis was finally performed to assess the retrofit economic feasibility in case it is extended to the entire plant. Respect mixing ventilation, a reduction of the air flow rate cooling requirement from 12 to 6 kJ/kg resulted in the considered application, with an average cost saving of 50,000 €/yr. A pay back time of less than 1 year followed, making the upgrade to RHDVS an interesting alternative.

An implementing framework for holonic manufacturing control with multiple robot-vision stations

The paper describes a holonic control architecture and implementing issues for agile job shop assembly with networked intelligent robots, based on the dynamic simulation of material processing and transportation. The holarchy was defined considering the PROSA reference architecture relative to which in-line vision-based quality control was added by help of feature-based descriptions of the material flow. Two solutions for production planning are proposed: a knowledge-based algorithm using production rules, and an OO resolved scheduling rate planner (RSRP) based on variable-timing simulation. Failure- and recovery-management are developed as generic scenarios embedding the CNP mechanism into production self-rescheduling. Aggregate Order Holon execution is realized by OPC-based PLC software integration and event-driven product transportation. The holonic control of multiple networked robot-vision stations also features tolerance to station computer- (IBM PC-type), station controller- (robot controller), quality control- (machine vision) and communication- (LAN) failure. Fault tolerance and high availability at shop-floor level are provided due to the multiple physical communication capabilities of the robot controllers, to their multiple-axis multitasking operating capability, and to hardware redundancy of single points of failure (SPOF). Implementing solutions and experiments are reported for a 6-station robot-vision assembly cell with twin-track closed-loop pallet transportation system and product-racking RD/WR devices. Future developments will consider manufacturing integration at enterprise level.

Supporting agile supply chains using a service-oriented shop floor

The globalized nature of current business environments led to the emergence of new networked enterprise organizational paradigms (supply chains, extended enterprises, virtual enterprises, collaborative networks, etc.) to meet changing requirements and tackle profitable but volatile opportunities overall agility is required. Eventually the shop floor will have to react and accommodate (re)adjustments in the supply chain making it an important piece in the competitiveness puzzle. So far, the research focus has been in high level aspects of supply chain management and the integration of shop floor activities in the process has been left relatively unattended. However, shop floor data is increasingly required in business tools that support decision making. In this context, failing to support agility at shop floor level can compromise the agility of the supply chain. Recent developments in networked information technologies and embedded devices allow enabling intelligence in shop floor rendering it an active and live entity that further enhances the dynamics of the supply chain. The goal of the present work, supported by an implemented test case in the assembly domain, is to demonstrate how one is able to seamless integrate the shop floor with external tools and achieve a highly reconfigurable environment that adapts to changing production requirements and disturbances using service-oriented technology.

From Flexibility to Evolvability: ways to achieve self-reconfigurability and full-autonomy

In the field of production engineering the past paradigms have focused on the concept of system flexibility; introducing both automation and computer science at shop floor level. Nevertheless their limits in approaching some fundamental areas, such as modularization and control issues, make them unsuitable for tackling the challenges in the manufacturing scenario of today. In this paper the past approaches with their underlining weaknesses have been reviewed, which leads up to the proposal of a methodology for the creation of a manufacturing system that is based on the Evolvable Paradigm. The salient points of this scheme are: the process oriented approach to modularization, the link between the development of the system and the design of the product. Fundamental requirements in pursuing these issues are to deeply study the processes in order to represent them at the hardware level, and to develop a distributed control system to handle emergent behaviour. The potential economical benefits that come from the Evolvable Paradigm include that automation can be a sustainable approach both large enterprises and for SMEs.

Challenging resistance to change from the top to the shop floor level: an exploratory study

Managerial discourse and related academic literature often portray resistance to change as an irrational phenomenon, something counterproductive, that is caused by a minority of workers affected, and which works to the detriment of a business. We suggest to re-examine the conventional wisdom with regard to the phenomenon of 'resistance to change' considered as emanating exclusively from the lower echelons of an organisation. We use an in-depth case study method, focusing on a large-scale telecommunications company in order to analyse the mechanisms through which resistance to change is manifested at all levels of the organisation. Two main types of resistance emerge from our research: tacit and explicit resistance. These phenomena appear in various forms, depending on the category of the organisational actor concerned. Our research strongly indicates the importance of middle-level managers in the implementation of strategic organisational change.

Product customisation: a case for the application of a real-time discrete event simulation for traceability in food manufacturing (SIMTrack)

The tracking and traceability of manufactured products, and in particular food products, has a large impact on product customisation and customer satisfaction. In order to enhance the philosophy of product mass customisation in the food industry, this paper proposes a flexible product tracking system that is configurable to the boundaries of any given system, thereby circumventing the difficulties that are encountered by the physical limitations of the present tracking and tracing technologies. The specific objectives are to: minimise the physical, technical and cost constraints by reducing hardware requirements as compared to conventional tracking and traceability systems; facilitate the acquisition of traceability information at the shop-floor level prior to packaging – the collected data will then be transferred to higher levels of production management systems and current business-to-business tracking systems; ensure the flexibility of the proposed software and its configurability to any given system. The information gathered from the proposed system can then be linked with customer inputs, leading to improved customer satisfaction and product quality. In order to achieve the usage of mobile sensors and detectors that are situated at critical positions on the lines and the connection to a real-time production process, simulation tools such as Arena, Witness SIMUL8, etc., are proposed. By using simulation techniques and statistically sound sample observations, it is possible to trace product ingredients in minute detail with 95% confidence.

The Freedom to Set Research Agendas — Illusion and Reality of the Research Units in the Dutch Universities

The Dutch higher education and research system has incrementally changed during the last decade. Several reforms, initiated by the government, have hinted towards influencing the basic processes within universities, such as research programming. However, it is largely unknown how these reforms have been implemented at the university shop floor level. Are the core activities of academics influenced by the reforms? Do academics still enjoy the academic freedom as they used to do? In this paper, we address the responses of four research units to changed institutional environments (two units in biotechnology and two in medieval history). Based on 33 interviews, we mapped their views on present-day research programming and problem choice in their units. The results show that the research units preserve their own research agenda to a large extent: the academic credibility process is paramount.