Setup Optimization in High-Mix Surface Mount PCB Assembly

Siirretty Doriast

Algorithmic Solutions for Combinatorial Problems in Resource Management of Manufacturing Environments

This thesis studies the use of heuristic algorithms in a number of combinatorial problems that occur in various resource constrained environments. Such problems occur, for example, in manufacturing, where a restricted number of resources (tools, machines, feeder slots) are needed to perform some operations. Many of these problems turn out to be computationally intractable, and heuristic algorithms are used to provide efficient, yet sub-optimal solutions. The main goal of the present study is to build upon existing methods to create new heuristics that provide improved solutions for some of these problems. All of these problems occur in practice, and one of the motivations of our study was the request for improvements from industrial sources. We approach three different resource constrained problems. The first is the tool switching and loading problem, and occurs especially in the assembly of printed circuit boards. This problem has to be solved when an efficient, yet small primary storage is used to access resources (tools) from a less efficient (but unlimited) secondary storage area. We study various forms of the problem and provide improved heuristics for its solution. Second, the nozzle assignment problem is concerned with selecting a suitable set of vacuum nozzles for the arms of a robotic assembly machine. It turns out that this is a specialized formulation of the MINMAX resource allocation formulation of the apportionment problem and it can be solved efficiently and optimally. We construct an exact algorithm specialized for the nozzle selection and provide a proof of its optimality. Third, the problem of feeder assignment and component tape construction occurs when electronic components are inserted and certain component types cause tape movement delays that can significantly impact the efficiency of printed circuit board assembly. Here, careful selection of component slots in the feeder improves the tape movement speed. We provide a formal proof that this problem is of the same complexity as the turnpike problem (a well studied geometric optimization problem), and provide a heuristic algorithm for this problem.Siirretty Doriast

Historical reconstruction of polychlorinated biphenyl (PCB) exposures for workers in a capacitor manufacturing plant

We developed a semiquantitative job exposure matrix (JEM) for workers exposed to polychlorinated biphenyls (PCBs) at a capacitor manufacturing plant from 1946 to 1977. In a recently updated mortality study, mortality of prostate and stomach cancer increased with increasing levels of cumulative exposure estimated with this JEM (trend p values = 0.003 and 0.04, respectively). Capacitor manufacturing began with winding bales of foil and paper film, which were placed in a metal capacitor box (pre-assembly), and placed in a vacuum chamber for flood-filling (impregnation) with dielectric fluid (PCBs). Capacitors dripping with PCB residues were then transported to sealing stations where ports were soldered shut before degreasing, leak testing, and painting. Using a systematic approach, all 509 unique jobs identified in the work histories were rated by predetermined process- and plant-specific exposure determinants; then categorized based on the jobs' similarities (combination of exposure determinants) into 35 job exposure categories. The job exposure categories were ranked followed by a qualitative PCB exposure rating (baseline, low, medium, and high) for inhalation and dermal intensity. Category differences in other chemical exposures (solvents, etc.) prevented further combining of categories. The mean of all available PCB concentrations (1975 and 1977) for jobs within each intensity rating was regarded as a representative value for that intensity level. Inhalation (in microgram per cubic milligram) and dermal (unitless) exposures were regarded as equally important. Intensity was frequency adjusted for jobs with continuous or intermittent PCB exposures. Era-modifying factors were applied to the earlier time periods (1946-1974) because exposures were considered to have been greater than in later eras (1975-1977). Such interpolations, extrapolations, and modifying factors may introduce non-differential misclassification; however, we do believe our rigorous method minimized misclassification, as shown by the significant exposure-response trends in the epidemiologic analysis

A Multi-Exchange Neighborhood Search Heuristic for an Integrated Clustering and Machine Setup Model for PCB Manufacturing

In the manufacture of printed circuit boards, electronic components are attached to a blank board by one or more pick-and-place machines. Frequent machine setups, though time consuming, can reduce overall processing time. We consider the Integrated Clustering and Machine Setup (ICMS) model, which incorporates this tradeoff between processing time and setup time and seeks to minimize the sum of the two. Solving this model to optimality is intractable for very large-scale instances. We show that ICMS is NP-hard and consequently propose and test a heuristic based on multi-exchange neighborhood search structures. Initial numerical results are very encouraging. Keywords: Printed circuit board assembly, feeder slot assignment, product clustering, integer programming, computational complexity, heuristics

Optimization of product assignment to assembly lines

Dissertação de mestrado em Industrial engineering and ManagementThe work presented in this dissertation was developed in an industrial context integrated in the production control and management department of the Bosch Car Multimedia Portugal S.A – Braga automatic insertion. The problem addressed in this dissertation was finding the best distribution of product families to assign in different lines according to the physical and technical constraints of the assembly lines. In the approach of the problem, it was used tools and techniques of the Operational Research discipline through mathematical modeling, in order to analyze complex situation and obtain more efficient solutions to help in the decision-making process. Based on production data, production needs forecasts and assembly line physical availability, models with different sets of constraints and objective functions were created to present solutions that best fit the question and the specific problem of the present production context. Through specific software that suited the problem, the previously created models were solved, and the solutions were analyzed and evaluated to suit the company’s current needs and for possible and feasible implementation of the solutions.O trabalho apresentado nesta dissertação foi desenvolvido em contexto industrial integrado no departamento de planeamento e controlo de produção da área de inserção automática da Bosch Car Multimédia Portugal S.A - Braga. O problema abordado nesta dissertação foi encontrar a melhor distribuição de famílias de produtos a alocar nas diferentes linhas de produção de acordo com as suas restrições físicas e técnicas. Na abordagem do problema recorreu-se a técnicas de Investigação Operacional através de modelação matemática, para analisar situações complexas e obter soluções mais eficientes. Tendo como base dados da produção, previsões de necessidades e disponibilidade física da produção, foram criados modelos com diferentes conjuntos de restrições e funções objetivo por forma a apresentar soluções que melhor se adequassem à pergunta e ao problema específico do contexto produtivo presente. Através da utilização de software, foram resolvidos os modelos criados anteriormente, sendo que as soluções foram analisadas e avaliadas para a adequação às necessidades atuais da empresa e para a sua possível e viável implementação

Environ Sci Pollut Res Int

We developed a semiquantitative job exposure matrix (JEM) for workers exposed to polychlorinated biphenyls (PCBs) at a capacitor manufacturing plant from 1946 to 1977. In a recently updated mortality study, mortality of prostate and stomach cancer increased with increasing levels of cumulative exposure estimated with this JEM (trend p values\ue2\u20ac\u2030=\ue2\u20ac\u20300.003 and 0.04, respectively). Capacitor manufacturing began with winding bales of foil and paper film, which were placed in a metal capacitor box (pre-assembly), and placed in a vacuum chamber for flood-filling (impregnation) with dielectric fluid (PCBs). Capacitors dripping with PCB residues were then transported to sealing stations where ports were soldered shut before degreasing, leak testing, and painting. Using a systematic approach, all 509 unique jobs identified in the work histories were rated by predetermined process- and plant-specific exposure determinants; then categorized based on the jobs' similarities (combination of exposure determinants) into 35 job exposure categories. The job exposure categories were ranked followed by a qualitative PCB exposure rating (baseline, low, medium, and high) for inhalation and dermal intensity. Category differences in other chemical exposures (solvents, etc.) prevented further combining of categories. The mean of all available PCB concentrations (1975 and 1977) for jobs within each intensity rating was regarded as a representative value for that intensity level. Inhalation (in microgram per cubic milligram) and dermal (unitless) exposures were regarded as equally important. Intensity was frequency adjusted for jobs with continuous or intermittent PCB exposures. Era-modifying factors were applied to the earlier time periods (1946-1974) because exposures were considered to have been greater than in later eras (1975-1977). Such interpolations, extrapolations, and modifying factors may introduce non-differential misclassification; however, we do believe our rigorous method minimized misclassification, as shown by the significant exposure-response trends in the epidemiologic analysis.DYT1/Intramural CDC HHS/United States2015-09-02T00:00:00Z23475444PMC455772

Baskı devre kartı dizgi atölyelerinde hat dengeleme

In assembling printed circuit boards (PCB), the use of numerically or computer controlled electronic component placement machines has become quite popular in the last decades. However, serious operations research problems arise through their use such as, allocation of component types to machines, board production schedule, feeder configuration and placement sequencing. In this study, the problem of allocation of component types to machines is taken up where two non-identical machines are deployed serially on a line to complete the assembly process of PCBs. For the solution of this problem three heuristic algorithms are suggested and their performances are investigated on experimental data.Son yıllarda baskı devre kartlarının (BDK) dizgisinde nümerik veya bilgisayar kontrollü elektronik dizgi makinalarının kullanımı yaygın hale gelmiştir. Ancak, bu beraberinde komponent tiplerinin makinalara atanması, kart üretim çizelgelemesi, besleyici düzeni ve dizgi sırası gibi karmaşık yöneylem araştırması problemlerini getirmiştir. Bu çalışmada, birbirinden farklı iki makinanın aynı hatta olması durumu için komponentlerin makinalara atanması problemi ele alınmıştır. Bu problemin çözümü için üç ayrı sezgisel algoritma geliştirilmiş ve performansları örnek veriler üzerinde incelenmiştir

An Optimal Algorithm for Integrating Printed Circuit Board Manufacturing Problems

Printed circuit boards appear in a wide array of products and thus their production is crucial to the contemporary electronics industry. A global approach to planning the complex and multi-stage production process is currently intractable. Nonetheless,significant improvements can be made by integrating closely related elements within the planning process. We focus here on the integration of two key problems -- product clustering and machine setup. In the product clustering problem, board types with similar component requirements are clustered together for assembly under a common configuration of the pick-and-place machine. In the machine setup problem, an optimal configuration of the pick-and-place machine is found for each of these clusters. In practice and in the literature, the product clustering and machine setup problems are typically solved sequentially. By instead solving the two problems simultaneously, we are able to find an optimal tradeoff between processing and setup times. We present the Integrated Clustering and Machine Setup model as a set partitioning problem. We describe a branch-and-price algorithm for solving this exponentially large problem. We introduce a rank-cluster-and-prune, a method for solving the imbedded pricing problems by combinatorial search, and conclude with computational results

Workload Balancing in Printed Circuit Board Assembly Shops

Son yıllarda baskı devre kartlarının (BDK) dizgisinde nümerik veya bilgisayar kontrollü elektronik dizgi makinalarının kullanımı yaygın hale gelmiştir. Ancak, bu beraberinde komponent tiplerinin makinalara atanması, kart üretim çizelgelemesi, besleyici düzeni ve dizgi sırası gibi karmaşık yöneylem araştırması problemlerini getirmiştir. Bu çalışmada, birbirinden farklı iki makinanın aynı hatta olması durumu için komponentlerin makinalara atanması problemi ele alınmıştır. Bu problemin çözümü için üç ayrı sezgisel algoritma geliştirilmiş ve performansları örnek veriler üzerinde incelenmiştir.In assembling printed circuit boards (PCB), the use of numerically or computer controlled electronic component placement machines has become quite popular in the last decades. However, serious operations research problems arise through their use such as, allocation of component types to machines, board production schedule, feeder configuration and placement sequencing. In this study, the problem of allocation of component types to machines is taken up where two non-identical machines are deployed serially on a line to complete the assembly process of PCBs. For the solution of this problem three heuristic algorithms are suggested and their performances are investigated on experimental data