Accelerated Innovation Development of Laser Metrology for Steel Bridge Fabrication

This report documents the use of a laser metrology technique in the production of splice connections for steel bridge girders which was successfully performed at Hirschfeld Industries steel bridge fabrication plant in Bristol, VA. Over the course of this project, the traditional method of splice connection fabrication was studied and compared alongside a newer method involving the use of laser metrology to enable the use of pre-drilled girder splice connection holes and custom fabricated splice plates. The primary benefit of this new method is that time consuming match drilling of girder splice connections is replaced with automated drilling methods. This new technique was demonstrated on girders that were fabricated for use in a new bridge being built in Dandridge, Tennessee. In addition to documenting the technique and its implementation, this report examines various aspects of the technology used, costs and benefits, possible sources of error, and potential uses and extensions of the technique in the future. Based on the findings in this report and the implementation documented, it is clear that the laser metrology technique studied can successfully be implemented in steel bridge fabrication; furthermore, this technique has great potential to provide significant time, money, and space savings in the girder fabrication process. Funding for the research of this project was provided thru FHWA’s Accelerated Innovation Deployment (AID) grant. This program provides funding as an incentive for eligible entities to accelerate the implementation and adoption of innovation in highway transportation

Intelligent production control for time-constrained complex job shops

Im Zuge der zunehmenden Komplexität der Produktion wird der Wunsch nach einer intelligenten Steuerung der Abläufe in der Fertigung immer größer. Sogenannte Complex Job Shops bezeichnen dabei die komplexesten Produktionsumgebungen, die deshalb ein hohes Maß an Agilität in der Steuerung erfordern. Unter diesen Umgebungen sticht die besonders Halbleiterfertigung hervor, da sie alle Komplexitäten eines Complex Job-Shop vereint. Deshalb ist die operative Exzellenz der Schlüssel zum Erfolg in der Halbleiterindustrie. Diese Exzellenz hängt ganz entscheidend von einer intelligenten Produktionssteuerung ab. Ein Hauptproblem bei der Steuerung solcher Complex Job-Shops, in diesem Fall der Halbleiterfertigung, ist das Vorhandensein von Zeitbeschränkungen (sog. time-constraints), die die Transitionszeit von Produkten zwischen zwei, meist aufeinanderfolgenden, Prozessen begrenzen. Die Einhaltung dieser produktspezifischen Zeitvorgaben ist von größter Bedeutung, da Verstöße zum Verlust des betreffenden Produkts führen. Der Stand der Technik bei der Produktionssteuerung dieser Dispositionsentscheidungen, die auf die Einhaltung der Zeitvorgaben abzielen, basiert auf einer fehleranfälligen und für die Mitarbeiter belastenden manuellen Steuerung. In dieser Arbeit wird daher ein neuartiger, echtzeitdatenbasierter Ansatz zur intelligenten Steuerung der Produktionssteuerung für time-constrained Complex Job Shops vorgestellt. Unter Verwendung einer jederzeit aktuellen Replikation des realen Systems werden sowohl je ein uni-, multivariates Zeitreihenmodell als auch ein digitaler Zwilling genutzt, um Vorhersagen über die Verletzung dieser time-constraints zu erhalten. In einem zweiten Schritt wird auf der Grundlage der Erwartung von Zeitüberschreitungen die Produktionssteuerung abgeleitet und mit Echtzeitdaten anhand eines realen Halbleiterwerks implementiert. Der daraus resultierende Ansatz wird gemeinsam mit dem Stand der Technik validiert und zeigt signifikante Verbesserungen, da viele Verletzungen von time-constraints verhindert werden können. Zukünftig soll die intelligente Produktionssteuerung daher in weiteren Complex Job Shop-Umgebungen evaluiert und ausgerollt werden

E -commerce for the metal removal industry

The popularity of outsourcing fabrication introduces a problem, namely an inevitable loss of data as information is translated from design to fabrication or from one system to another. Unsatisfactory information, delivered to the outsourcing facility, and inefficient communications between design and fabrication certainly cause enormous economic losses from late product delivery or bad product quality. To overcome these data transferring problems and to improve communications between the design and fabrication sides, a design and manufacturing methodology for custom machined parts in E-Commerce is suggested and implemented in this dissertation. This methodology is based on the idea of a Clean Interface like the Mead-Conway approach for VLSI chip fabrication [MEAD81]. Essential design information for fabricating parts properly with NC (Numerical Controlled) milling machines is expressed in machining/manufacturing features, fabrication friendly terminologies, and is represented by a new language called NCML (Numerical Control Markup Language). NCML is based on XML (Extensible Markup Language)---the document-processing standard proposed by the World Wide Web Consortium (W3C). NCML is designed to include the minimum requisite information necessary for the manufacturer to produce the product. The designer defines NCML, which overcomes geographical separation between design and manufacturing, and minimizes unnecessary interactions caused from lack of information. To prove the possibility of custom machine part fabrication and E-Commerce with NCML, three software systems are implemented. These three systems are FACILE/Design, FACILE/Fabricate, and E-Mill. FACILE is a prototype CAD/CAM system developed to verify NCML feasibility as an Electronic Data Interchange (EDI) format. FACILE/Design is a system based on manufacturing features like holes, contours, and pockets. It can be used to create geometric models, verify the design, and create NCML files. The NCML file is imported by FACILE/Fabricate and turned into G-codes by applying appropriate cutting conditions. Simplified machining simulation and cost estimation tools using NCML inputs are also developed to show some examples of NCML applications that can help design and manufacturing activities. To demonstrate how NCML could be used in a web-based application, an E-Business model called E-Mill has been implemented. E-Mill is a market place for machined parts whose data is encoded in NCML. To make E-Mill a feasible E-Commerce model, two-way communication based on NCML data and the visualization of 3D geometric models in the Virtual Reality Modeling Language (VRML) are equipped with a competitive matchmaking mechanism. In this dissertation, a whole system based on NCML bridges the gap between design and manufacturing. As a part of the NCML validation process for the new system, the pros and cons of NCML design features are discussed. A system for cost estimation is calibrated and compared to real cutting results for the purpose of validation

A Simulation of composite dispatching rules, CONWIP and push lot release in semiconductor fabrication

This paper evaluates dispatching rules and order release policies in two fabs representing two wafer fabrication modes, namely, ASIC and low-mix high-volume production. Order release policies were fixed-interval (push) release, and constant work-in-process, CONWIP (pull) policy. Following rigorous fab modeling and statistical analysis, new composite dispatching rules were found to be robust for system cycle time and due-date adherence measures, in both production modes

Break, Make, Retake: Interrogating the Social and Historical Dimensions of Making as a Design Practice

Making and digital fabrication technologies are the focus of bold promises. Among the most tempting are that these activities and processes require little initial skill, knowledge, and expertise. Instead, they enable their acquisition, opening them up to everyone. Makerspaces and fab labs would blur the identities between professional and amateur, designer and engineer, maker and hacker, ushering in a broad-based de-professionalization. Prototyping and digital fabrication would unite design and manufacturing in ways that resemble and revive traditional craftwork. These activities and processes promise the reindustrialization of places where manufacturing has disappeared. These promises deploy historical categories and conditionsexpertise, design, craft production, manufacturing, post- industrial urbanismwhile claiming to transform them. This dissertation demonstrates how these proposals and narratives rely on imaginaries in which countercultural practices become mainstream by presenting a threefold argument. First, making and digital fabrication sustain supportive environments that reconfigure contemporary design practice. Second, making and digital fabrication simultaneously reshape the categories of professional, amateur, work, leisure, and expertise; but not always in the ways its proponents suggest. Third, as making and digital fabrication propagate, they reproduce traditional practices and values, negating much of their countercultural and alternative capacities. The dissertation supports these claims through a multi-sited and multinational ethnographic investigation of the historical and social effects of making and digital fabrication on design practice and the people and places enacting. The study lies at the intersection of science and technology studies, human-computer interaction, and design research. In addressing the argument throughout this scholarship, it explores three central themes: (1) the idea that making and digital fabrication lead to instant materialization of design while re-uniting design with manufacturing; (2) the amount of skill and expertise expected for participation in these practices and how these are encoded in rhetoric and in practice; and (3) the material and social infrastructures that configure making as a design practice. The dissertation demonstrates that that the perceived marginality of making, maker cultures, digital fabrication allows for its bolder promises to thrive invisibly by concealing other social issues, while the societal contributions of this technoculture say something different on the surface

Application of lean scheduling and production control in non-repetitive manufacturing systems using intelligent agent decision support

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Lean Manufacturing (LM) is widely accepted as a world-class manufacturing paradigm, its currency and superiority are manifested in numerous recent success stories. Most lean tools including Just-in-Time (JIT) were designed for repetitive serial production systems. This resulted in a substantial stream of research which dismissed a priori the suitability of LM for non-repetitive non-serial job-shops. The extension of LM into non-repetitive production systems is opposed on the basis of the sheer complexity of applying JIT pull production control in non-repetitive systems fabricating a high variety of products. However, the application of LM in job-shops is not unexplored. Studies proposing the extension of leanness into non-repetitive production systems have promoted the modification of pull control mechanisms or reconfiguration of job-shops into cellular manufacturing systems. This thesis sought to address the shortcomings of the aforementioned approaches. The contribution of this thesis to knowledge in the field of production and operations management is threefold: Firstly, a Multi-Agent System (MAS) is designed to directly apply pull production control to a good approximation of a real-life job-shop. The scale and complexity of the developed MAS prove that the application of pull production control in non-repetitive manufacturing systems is challenging, perplex and laborious. Secondly, the thesis examines three pull production control mechanisms namely, Kanban, Base Stock and Constant Work-in-Process (CONWIP) which it enhances so as to prevent system deadlocks, an issue largely unaddressed in the relevant literature. Having successfully tested the transferability of pull production control to non-repetitive manufacturing, the third contribution of this thesis is that it uses experimental and empirical data to examine the impact of pull production control on job-shop performance. The thesis identifies issues resulting from the application of pull control in job-shops which have implications for industry practice and concludes by outlining further research that can be undertaken in this direction

Links between modularization critical success factors and project performance

textThrough the exporting of a portion of site-based work to fabrication shops, modularization (MOD) can enhance efficiency in the construction industry. The industry, however, applies modularization at only a low level. To reach higher levels of modularization, the EPC industry needs new approaches. Previous studies have identified the current trends in and barriers to the industry's application of modularization. Moreover, in 2013, the Construction Industry Institute's (CII) Research Team 283 identified 21 critical success factors (CSFs) that create an optimum environment for a broader and more effective use of modularization. However, the researcher has identified a need to better understand the relative significance of MOD CSFs and their associations with project performance. Thus, the research was conducted to provide recommendations for better project performance by identifying correlations between the accomplishment of MOD CSFs and project performance and examining actual modular projects' MOD CSF accomplishment. This study identified four statistically significant positive correlations. Those are between the accomplishment of MOD CSFs and: 1) cost performance; 2) schedule performance; 3) Construction performance; and 4) Startup performance. In addition to the correlation analysis, the study also identified the CSFs that appear to contribute the most to 1) "Modular Project Success", 2) Construction success, 3) Startup success, 4) Cost performance, and 5) Schedule performance. To collect information on the actual industrial modular projects, the study surveyed industry experts. By using this study, many industrial project stakeholders from owners to fabricators, designers and EPC contractors, will be able to understand the relationships between MOD CSFs and project performance. Such an understanding should motivate them to achieve better project performance through implementing modularization CSFs.Civil, Architectural, and Environmental Engineerin