An algorithm for the automatic generation of an assembly process for modular fixture parts

In metal mold production systems, rapid, high-quality, and low-cost production technologies are needed. In these systems, assembly tasks to make fixtures to immobilize the mold are required. The mold must be firmly fixed in order to resist the force generated by NC machine tools. In this article, we discuss the automatic generation of an assembly process for modular fixture parts in the systems. The assembly drawing of the parts can be obtained from STEP/AP203, which is a text file of CAD/CAF data. In these data, the shape and configuration of all assembled fixtures are included. The shape of each fixture is constructed with planar, cylindrical, and conical surfaces. From the data, the number of surfaces in contact with other surfaces is derived for each part, and valid contacts are judged for their degree of importance. A tree of contacts among all fixtures is derived. In the numerical examples, the assembly process is automatically generated by our proposed method. It is shown that a suitable assembly process is obtained.     

Optimization algorithm for PCB assembly of modular mounters

We propose an optimization method to maximize the productivity of PCB assembly of modular mounters. The modular mounter is a series of compact SMD placement modules each having assembly heads and feeder lanes. The throughput of the mounter is maximized by balancing the assembly time of each module. We identify the problem as an integer programming problem, and divide the problem into a feeder arrangement problem and a mount sequence problem by decoupling the path into forward arcs and backward arcs. Integer-programming based algorithms such as the branch-andbound algorithm and transportation algorithm are applied to solve the formulated problems. Simulation results are presented to verify the usefulness of the proposed method.     

Designing parallel assembly lines

In this paper, alternative assembly line design strategies for a single product are discussed. The problem occurs when the production volume is substantially high and there are more operators needed than the number of assembly operations. The objective is to determine the number of assembly lines with minimum total manpower. It is allowed to have multiple assembly lines with identical configuration. A 3-phase methodology is proposed; 1) assembly line balancing, 2) determining parallel stations, 3) determining parallel lines. Later, the proposed procedure is illustrated with a numerical example.     

Knowledge acquisition for decision support systems on an electronic assembly line

Increasing global competition has made many manufacturing companies recognize that competitive manufacturing in terms of low cost and high quality is crucial for success. Real-time process control and production optimization are, however, extremely challenging areas because manufacturing processes are getting ever more complex and involve many different parameters. This is a major problem when building decision support systems especially in electronics manufacturing. Although problem-solving is a knowledge intensive activity undertaken by people on the production floor, it is quite common to have large databases and run blindly feature extraction and data mining methods. Performance of these methods could, however, be drastically increased when combined with knowledge or expertise of the process.This paper describes how defect-related knowledge on an electronic assembly line can be integrated in the decision making process at an operational and organizational level. It focuses in particular on the efficient acquisition of shallow knowledge concerning everyday human interventions on the production lines, as well as on the factory-wide sharing of the resulting information for an improved defect management. Software with dedicated interfaces has been developed using a knowledge representation that supports portability and flexibility of the system. Semi-automatic knowledge acquisition from the production floor and generation of comprehensive reports for the quality department resulted in an improvement of the usability, usage, and usefulness of the decision support system.     

Ergonomic planned supply in an automotive assembly line

The objective of this research is to identify the benefits of ergonomic improvements in workstations and in planned parts supply in an automotive assembly line. Another aim is to verify to what extent it is possible to create competitive advantages in the manufacturing area with reduction in vehicle assembly time by using technological investments in ergonomics with benefits to the worker and to the company. The Methods Time Measurement (MTM) methodology is chosen to measure the process time differences. To ensure a reliable comparison, a company in Brazil that has two different types of assembly line installations in the same plant was observed, and both assembly lines were under the same influences in terms of human resources, wages, food, and educational level of the staff. In this article, the first assembly line is called “new” and was built 6 years ago, with high investments in ergonomic solutions, in the supply system, and in the process. The other is called “traditional” and was built 23 years ago with few investments in the area. © 2010 Wiley Periodicals, Inc.     

Designing a mixed-model assembly line to minimize the costs of idle and utility times

A mixed-model assembly line with either closed or open stations is considered in this research. The problem is to minimize the total cost of the utility time and idle time incurred due to different line parameters (launch interval, station length, starting point of work, upstream walk, locus of the operator’s movement, etc.) and operation sequences of the mixed models. Two models for both closed-station and open-station systems are developed to determine line parameters optimally. The models are tested with a three-station mixed-model line in which the station type is assumed either closed or open. This research shows that a set of line parameters are available for which the total cost of utility and idle times is minimal. Results indicate that the minimum total cost of utility and idle times in an open-station system is less than that in a closed-station system for a given line length. Other results pertinent to the line design are also demonstrated.     

Lane selection in an AGV-based asynchronous parallel assembly line

Automated Guided Vehicles (AGVs) have the flexibility to meet the material handling requirements of asynchronous assembly lines. Furthermore, AGVs can select from among alternative paths in accordance with a prescribed lane selection rule, thereby facilitating the use of parallel server workstations.

In this paper, motivated by our work in the automotive industry, several new lane selection rules are proposed. One of these, First Available Server/First Available Buffer/Balanced Work Content (FAS/FAB/BWC), is compared to two existing rules: Alternating Server, and First Available Server/First Available Buffer/Expected Completion Time (FAS/FAB/EC). Three performance measures — job throughput, workload balance among servers, and alteration of input job sequence — are employed. A SIMAN simulation model of a small, asynchronous parallel assembly line is used to study the impact on system performance of both the lane selection rule and the number of parallel servers. Interaction between these two factors is studied through ANOVA. A number of interesting findings are reported for results of the lane selection rules with respect to the three performance measures. Their interpretation is used to motivate further research.     

Optimal distribution of technological operations on an assembly line

A mathematical formulation is proposed for optimal assignment of technological operations to assembly line stations. The properties of feasible and optimal solutions are investigated. Algorithms for the solution of the relevant problems are given.Translated from Kibernetika, No. 4, pp. 45–54, July–August, 1990.     

A scheme for mechanical assembly design and assembly line layout conceptualization

A scheme in this paper makes possible to analyze a complex assembly design at an early design stage and generate assembly sequences efficiently. The designer's knowledge is used to obtain the preference module set. The modulability of the set is tested and used to generate assembly sequences hierarchically. Sequences generated by this scheme reflect the designers' preference for modules and facilitates to figure out an assembly line layout from an assembly design. The applicability of the scheme is verified in an example.     

Distributed Bayesian diagnosis for modular assembly systems—A case study

The growing interest in modular and distributed approaches for the design and control of intelligent manufacturing systems gives rise to new challenges. One of the major challenges that have not yet been well addressed is monitoring and diagnosis in distributed manufacturing systems. In this paper we propose the use of a multi-agent Bayesian framework known as Multiply Sectioned Bayesian Networks (MSBNs) as the basis for multi-agent distributed diagnosis in modular assembly systems. We use a close-to-industry case study to demonstrate how MSBNs can be used to build component-based Bayesian sub-models, how to verify the resultant models, and how to compile the multi-agent models into runtime structures to allow consistent multi-agent belief update and inference.     

Multi-criteria decision making for assembly line balancing

Assembly line balancing often has significant impact on performance of manufacturing systems, and is usually a multiple-objective problem. Neither an algorithmic nor a procedural assembly line balancing methodology is usually effective in solving these problems. This article proposes a data envelopment analysis (DEA) approach to solve an assembly line balancing problem. A computer-aided assembly line balancing tool as Flexible Line Balancing software is used to generate a considerable number of solutions alternatives as well as to generate quantitative decision-making unit outputs. The quantitative performance measures were considered in this article. Then DEA was used to solve the multiple-objective assembly line balancing problem. An illustrative example shows the effectiveness of the proposed methodology.     

Designing low-complexity electrical consumer products for ecological use

This study examined the environmental impact of low-complexity electrical consumer products during their use in a domestic context. In the experimental scenario, 48 users were asked to use a kettle under different conditions. On-product information (OPI), task instruction, and kettle design were employed as independent variables in a mixed multi-factorial design to examine their effects on different parameters of ecological performance (e.g., water and electricity consumption). Measures of user variables (environmental concern, knowledge, domestic habits, environmental control beliefs) were also taken to examine their relationship with performance parameters. The results revealed main effects of ecological task instruction, OPI and (partly) kettle design on ecological user behaviour. Habits, environmental concern and control beliefs were found to be related to performance parameters whereas knowledge was not. The implications of the results for product design are discussed against the background of a strong prevalence of habits and low ecological user motivation.     

Bacterial Foraging Optimization Algorithm for assembly line balancing

Assembly line balancing is the problem of assigning tasks to workstations by optimizing a performance measure while satisfying precedence relations between tasks and cycle time restrictions. Many exact, heuristic and metaheuristic approaches have been proposed for solving simple straight and U-shaped assembly line balancing problems. In this study, a relatively new optimization algorithm, Bacterial Foraging Optimization Algorithm (BFOA), based heuristic approach is proposed for solving simple straight and U-shaped assembly line balancing problems. The performance of the proposed algorithm is evaluated using a well-known data set taken from the literature in which the number of tasks varies between 7 and 111, and results are also compared with both an ant-colony-optimization-based heuristic approach and a genetic-algorithm-based heuristic approach. The proposed algorithm provided optimal solutions for 123 out of 128 (96.1 %) test problems in seconds and is proven to be promising.     

Dynamic analysis of an automobile assembly line considering starving and blocking

Dynamic analysis considering starving and blocking of machines in networks of closed loops has a great importance in most automobile assembly lines. In this work, an actual automobile assembly line is modelled as a network of closed loops of machines and intermediate buffers formed by conveyors. As a consequence of it, machines can work in both, stationary or transitory regimes. The influence of the working regimes of the machines or the proportion of four-door cars between the doors’ disassembly and assembly stations on the starving and blocking transmission from the main assembly line has been analyzed. These factors have not been considered yet by the existing literature and they have a great significance in the performance of this kind of manufacturing systems.     

Web-based modular interface geometries with constraints in assembly models

The use of a modular technique in modeling for assembly can improve design efficiency and reduce the cost of product development. This paper presents an approach to an assembly model that was built using modular interface geometries. This paper proposes a novel, hybrid modular design strategy instead of the traditional, top-down design process. The curve-joint method is used as a simplified process for converting a 3D solid model to a skeleton model with interface geometries in modeling for assembly. This research builds assembly interface geometries with their constraints in the assembly model instead of using information about individual assembly parts for the product. These interface geometries are easy to share, and they deliver the design requirements properly. They also ensure that minimal efforts will be required in the design change process. By implementing this method, the constraints of the features in modular assembly parts can be transferred to interface geometries. Designers can easily add, replace, and delete design parts in the modular product. Module interaction for application programmed interface (MIAPI) is developed using HTML and JavaScript. The module structure of products can be verified via the web-based Internet in VRML format. These simplified assembly models that have fewer constraints allow design project managers to simulate the functioning of the product in the modularized design before the prototype is built. By using the assembly models, customers can easily choose various modules to assemble the exact products they are seeking via the Internet process. A desk lamp model is used as the example for implementation to validate the feasibility of this research.     

Designing a quasi-spherical module for a huge modular robot to create programmable matter

There are many ways to implement programmable matter. One is to build it as a huge modular self-reconfigurable robot composed of a large set of spherical micro-robots, like in the Claytronics project. These micro-robots must be able to stick to each other and move around each other. However, the shape of these micro-robots has not been studied yet and remains a difficult problem as there are numerous constraints to respect. In this article, we propose a quasi-spherical structure for these micro-robots, which answers all the constraints for building programmable matter, helping the realization of an interactive computer-aided design framework. We study different scenarios, validate the ability to move and propose methods for manufacturing these micro-robots.