Center for Advanced Manufacturing and Lean Systems
Permanent URI for this communityhttps://hdl.handle.net/20.500.12588/879
The Center for Advanced Manufacturing and Lean Systems was established in 2007 at the University of Texas at San Antonio (UTSA) to provide the greater San Antonio and south Texas area industries, public and private agencies with a one-stop, unique source of expertise in flexible and lean technologies and systems, state-of-the-art technology applications with the following two thrust areas:
Advanced Manufacturing Systems: effective and efficient integration and synthesis of automation technologies, human resources, and decision-making models for design, planning, scheduling, and control of production of goods and delivery of services.
Lean Enterprise Systems: systematic elimination of waste (anything that does not add value) across the enterprise by using various lean and six-sigma tools and methodologies to continuously improve value creating processes in manufacturing and service sectors.
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Browsing Center for Advanced Manufacturing and Lean Systems by Subject "Assembly-line methods"
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Item A constructive cooperative coevolutionary algorithm applied to press line optimisation(DEStech Publications, Inc., 2014) Glorieux, Emile; Svensson, Bo; Danielsson, Fredrik; Lennartson, BengtSimulation-based optimisation often considers computationally expensive problems. Successfully optimising such large scale and complex problems within a practical timeframe is a challenging task. Optimisation techniques to fulfil this need to be developed. A technique to address this involves decomposing the considered problem into smaller subproblems. These subproblems are then optimised separately. In this paper, an efficient algorithm for simulation-based optimisation is proposed. The proposed algorithm extends the cooperative coevolutionary algorithm, which optimises subproblems separately. To optimise the subproblems, the proposed algorithm enables using a deterministic algorithm, next to stochastic genetic algorithms, getting the flexibility of using either type. It also includes a constructive heuristic that creates good initial feasible solutions to reduce the number of fitness calculations. The extension enables solving complex, computationally expensive problems efficiently. The proposed algorithm has been applied on automated sheet metal press lines from the automotive industry. This is a highly complex optimisation problem due to its non-linearity and high dimensionality. The optimisation problem is to find control parameters that maximises the line's production rate. These control parameters determine velocities, time constants, and cam values for critical interactions between components. A simulation model is used for the fitness calculation during the optimisation. The results show that the proposed algorithm manages to solve the press line optimisation problem efficiently. This is a step forward in press line optimisation since this is to the authors' knowledge the first time a press line has been optimised efficiently in this way.Item Application of lean manufacturing concepts and value stream mapping to a company that manufactures engineering to order road transportation products(DEStech Publications, Inc., 2014) Breitenbach, Fernanda A.; Ferreira, Joao C. E.In the current economic scenario, it is an increasing trend companies seeking to adapt their production systems to meet the new market demands, and at the same time to increase efficiency in their processes. Among the various methodologies available, lean manufacturing stands out as a valuable approach to have an efficient supply chain. Lean manufacturing seeks to eliminate waste, and to optimize the company resources. This paper describes the implementation of lean manufacturing concepts in a company that manufactures custom (ETO - Engineering to Order) products for road transportation (e.g. tow truck). Value Stream Mapping (VSM) was applied to one of the products of the company, which has a high variety of parts, materials, and assembly processes. VSM corresponds to a visual representation of the flow of materials and information for a product family, helping: (a) analyze the value stream in the current state, (b) identify the main sources of waste, (c) propose improvements to the current state, (d) add value to the customer. The results obtained were as follows: 75% reduction in storage time of raw materials, 49% reduction in the manufacturing lead time, 80% reduction in transport time of materials and products, 94% reduction in setup time of the assembly area, 75% reduction in waiting time, 50% reduction in positioning time of parts and subassemblies, and 20% reduction in processing time. This shows the potential application of lean concepts in ETO manufacturing environments, and the procedure proposed in this paper can be used as a reference by other similar companies.Item Applying theory of constraints to moving assembly lines(DEStech Publications, Inc., 2014) Sims, Trumone; Wan, HungDaThe first step in the Theory of Constraints (TOC) methodology is to identify the constraint. Several methods have been recommended in literature, such as looking for a backup of inventory (i.e., the operation that the inventory is waiting for is the constraint), or using linear programming or other analytical models. Yet, these methods may not be useful in a matured lean environment, which may have moving assembly lines where constraints are not obvious. This paper proposes two new methods for this purpose. The first method, Flow Constraint Analysis, takes a holistic view and evaluates whether the customer's demand is being satisfied. This evaluation is made by comparing the takt times and the cycle times of resources in the manufacturing system in order to identify the constraint(s). The second method, Effective Utilization Analysis, can be employed to pinpoint the location of the system constraint to a specific process or station. The actual production throughput is compared against the ideal capacity of the system to locate the bottleneck. This method is based on the relationship between WIP, bottleneck rate and lead time for a constant work in process (CONWIP) system. A case study of both methods applied to an actual production facility is presented.Item Considering assembly requirement specifications in product development: Identification and approach(DEStech Publications, Inc., 2014) Asadi, Narges; Schedin, Joel; Fundin, Anders; Jackson, MatsDue to the major advantages such as reduced time to market and improved quality at lowered cost, the principles of design for assembly capabilities and concurrent engineering are of great significance when developing new products. However, identifying assembly requirement specifications and considering them in New Product Development (NPD) in a timely manner, while securing efficiency and robustness of assembly processes, still remains a challenging task. In presenting a case study of an NPD project in a manufacturing company, this article focuses on the process of capturing and incorporating the requirements related to the assembly system during the early phases of NPD. Further, the results of the research study indicate the different assembly requirements in the case company and pinpoint the challenges in practices involved in handling them. The assembly requirements identified in this research reflect some of the challenges encountered in handling the requirements, through the investigated requirement practice. Based on the results, the issues of when and how to consider the assembly requirements are highlighted in the conclusions and suggestions for future research are made.Item Evaluating the role of product design and process time variability in determining a configuration of disassembly stations(DEStech Publications, Inc., 2014) Steeneck, Daniel W.; Flittner, Jonathan G.; Sarin, Subhash ChanderThe depletion of natural resources has necessitated a better management of resources. One of the methods in this regard has been the reuse of materials and parts from products at the end of their life cycles, which requires a suitable configuration of disassembly systems for an effective operation. In this paper, we compare performances of two types of system configurations: standalone tear-down-stations and disassembly lines. These system configurations are tested for the disassembly of class 8 trucks to recover parts, which are then remanufactured or refurbished for reuse. A key feature of this product, and that of a used product in general that is disassembled, is the uncertainty of the processing time of a disassembly step. This uncertainty can lead to difficulties in proper line balancing, bottlenecks, inefficient use of resources, and generally, reduced throughput. In order to overcome these limitations, in this paper, we investigate the above disassembly facility configurations, and determine how their performances are affected by variability in operation times.