Cost model development using virtual manufacturing and data mining: part II—comparison of data mining algorithms

Cost models of manufacturing processes are an important tool enabling enterprises to make reasonable predictions and forecasts in relation to the production costs for existing and new products. Accurate and robust cost models can help to provide significant competitive advantage for manufacturing organisations. Advanced computational methods such as virtual manufacturing and data mining have been identified as potentially powerful techniques for generating cost models that bypass the problems associated with traditional cost modelling processes. Part I, of this two-part paper, described the development of a cost model development methodology that makes use of virtual manufacturing models and data mining techniques and used case study data to validate this methodology. A critical part of this methodology is the selection and use of effective data analysis techniques that can identify accurate and robust cost estimating relationships. Part II now examines in detail the effectiveness of alternative data mining algorithms in terms of their ability to develop relationships that are (1) representative of the real causal relationships that exist and (2) able to provide a high level of estimating accuracy. More specifically, it focuses on the data generated by virtual manufacturing models and how the size and complexity of the generated data sets impact the accuracy of the cost estimating relationships.     

A methodology for creating initial state table values for adaptive control of computer integrated cells

The concept of using state tables to define real time control alternatives for an automated manufacturing system has been previously documented; however, the methodology for obtaining values for the control vectors associated with these tables has not been well defined. The procedure presented in this paper utilises several data analysis tools to create, modify, cluster, merge, and recognise control data which is appropriate to a specific control situation. Experiments with a computer-controlled, manufacturing cell, which emphasises material handling, will be utilised throughout to explain the methodology. Experimental results are discussed. Research reported in this paper has been partially supported by NSF Grant CDR 8500022.     

面向大批量定制的产品成本估算方法研究

研究了大批量定制生产的特点和产品定制层次，并对不同的产品定制层次提出了不同的成本估算方法，建立了面向大批量定制的产品成本估算模型，针对设计定制中需要重新设计的零部件，进行了类似零件成本，制造成本和装配成本的估算，利用该方法可以为定制产品提供快速，合理、科学的报价依据。     

面向成本的设计中的成本构成及其估算框架的研究

认为面向成本的设计（DFC）是指在满足用户不前提下,对尽可能降低成本的的产品设计提供技术支持。在分析DFC中成本构成及其估算方法的基础上,提出了综合运用多种估算方法并与成本管理工作相结合的DFC的成本估算策略。运用人工智能技术建立DFC的成本估算框架。框架采用多级多阶段结构并综合运用多种成本估算方法对产品全生命周期成本进行估算。     

A cost-tolerance analytical approach for design and manufacturing

Tolerance assignment in mechanical engineering product design and manufacturing is critical both for product quality and performance as well as for its manufacturing cost. Simple design rules, industry available comparative experimental data, tables, charts, and personal expertise are currently used for cost optimum tolerancing. Such a methodology is not very practical, requires considerable time and effort and is not always suitable for a CAD/CAM environment. To face these limitations, a new model for the manufacturing cost-tolerance function has been developed and is presented in the paper. It may well be used for direct-tolerance optimisation applications and it is shown that it produces results that are in satisfactory agreement with existing cost-tolerance data. Its use is further analysed and demonstrated in solving linear manufacturing tolerance transfer problems.     

Problématique de la conception d'un siège ferroviaire en matériaux composites

Technical and economical constraints of composite material train seats design. The aim of this work is to design a frame of metro seat in composite materials and to establish a design methodology, in order to reduce the weight of structure and the manufacturing cost, respecting the specifications that impose technical and economical constraints. A global analysis was done on all parameters related to the design of the structure: sizing, assembly, manufacturing process and choice of composite materials to use. The retained solution permits reducing the manufacturing cost with regard to the metallic seat, by reducing the number of components to assembly.     

Object-oriented methods for manufacturing information systems

Object-oriented programming (OOP) is now widely used in application software development. OOP has advantages connected with handling complexity, reusability, extendability, modularity and data abstraction, enabling it to handle modern programming requirements more effectively than conventional programming methods. Successful advanced manufacturing systems demand increasing complexity, flexibility and integration between computer applications. An object-oriented approach is particularly promising for the design and development of manufacturing information systems. This paper outlines the concepts of object-oriented methods, and describes an object-oriented application development methodology for manufacturing information systems. A CASE (Computer-Aided Software Engineering) tool is used for system modelling and for direct source-code generation. A case study describing the development of a quality management information system is presented, which was implemented using a C++ development environment. Although the research described here is concerned with quality management information systems, the proposed design methodology is applicable to other areas of manufacturing, and conclusions are drawn concerning the uses of OOP in manufacturing information systems generally.     

Assessing the structural complexity of manufacturing systems configurations

Modern manufacturing systems are increasingly required to be flexible and adaptable to changing market demands, which adds to their structural and operational complexity. One of the major challenges at the early design stages is to select a manufacturing system configuration that both satisfies the production functional requirements and is easy to operate and manage. A new metric for assessing the structural complexity of manufacturing system configurations is presented in this paper. The proposed complexity metric incorporates the quantity of information using an entropy approach. It accounts for the complexity inherent in the various modules in the manufacturing system through the use of an index derived from a newly developed manufacturing systems classification code. The code captures the effect of various component types and technologies used in a manufacturing system on the system’s structural complexity. The presented metric would be helpful in selecting the least complex manufacturing system configuration that meets the requirements. An engine cylinder head production system is used to illustrate the application of the proposed methodology in comparing feasible but different manufacturing system configurations capable of producing the cylinder head based on their structurally inherent complexity.     

Cost drivers-based method for machining and assembly cost estimations in mould manufacturing

Dies and moulds represent an essential element in manufacturing process and significantly influence the fabrication time and cost of the products. Moreover, the market continuously asks the die manufacturers for products that have better characteristics in terms of finishing, complexity or flexibility within a reduction of the time to market and cost, so as to follow the rapid changes in the product design. Therefore, in order to give to the customer the best cost-performance solution, companies require accurate and reliable tools for die manufacturing cost estimation both for commercial purposes and for comparisons amongst different design solutions. In this context, the paper proposes a method for manufacturing cost estimation based on the definition of cost drivers. The method was implemented using a database coming from a company specialized in the production of dies for sheet forming and rubber injection and it allowed to estimate a cost estimation relationship (CER) function that is able to correlate the cost drivers with the manufacturing cost of machining and assembly phases. In particular, the method allowed to overcome the limitations related to the available data as the company's own storage criterion, unbalancing and high and non-uniform scattering that do not allow use of the variance analysis technique.     

Developing an integrated framework for feature-based early manufacturing cost estimation

The major objective of concurrent engineering is to consider the related downstream manufacturing during the design stage. Estimating manufacturing cost during the early design stage is one area that has been given little attention by researchers. However, if the product manufacturing cost can be estimated during the design stage, designers can modify a design to achieve proper performance as well as a reasonable cost at an early stage of the product development process.Basically, manufacturing cost is determined by shape complexity, product precision and tooling process. That is, if these data can be obtained and considered during the design stage, estimating manufacturing cost during the early product development stage will become a feasible task.In this research, a framework for estimating the manufacturing cost in terms of a feature-based approach is proposed. This system tends to estimate the manufacturing cost of a design according to the shapes and precision of its features. The objective of this research is to provide a tool to assist a designer, who has little knowledge about the manufacturing process, to estimate the fabrication cost of a design during its conceptual stage, in order to reduce unnecessary costs in the downstream process.     

An integrated framework for die and mold cost estimation using design features and tooling parameters

Tooling is an essential element of near net shape manufacturing processes such as injection molding and die casting, where it may account for over 25% of the total product cost and development time, especially when order quantity is small. Development of rapid and low cost tooling, combined with a scientific approach to mold cost estimation and control, has therefore become essential. This paper presents an integrated methodology for die and mold cost estimation, based on the concept of cost drivers and cost modifiers. Cost drivers include the geometric features of cavity and core, handled by analytical cost estimation approach to estimate the basic mold cost. Cost modifiers include tooling parameters such as parting line, presence of side core(s), surface texture, ejector mechanism and die material, contributing to the total mold cost. The methodology has been implemented and tested using 13 industrial examples. The average deviation was 0.40%. The model is flexible and can be easily implemented for estimating the cost of a variety of molds and dies by customizing the cost modifiers using quality function deployment approach, which is also described in this paper.     

A cost-tolerance model for process sequence optimisation

This paper concerns the modelling of cost-tolerance data for various manufacturing processes and the optimisation of process sequences based on minimum production cost. A natural spline model representing the cost-tolerance relationship is introduced. A methodology to optimise the process sequences is developed using an expert system approach. An example to illustrate the methodology and the optimisation model is presented     

DESIGN OF RECONFIGURABLE MANUFACTURING SYSTEMS WITH STRONGLY COUPLED NATURE

Today's manufacturing environment forces manufacturing companies to make as many product variations as possible at affordable costs within a short time. Mass customisation is one of most important technologies for companies to achieve their objectives. Efforts to mass customisation should be made on two aspects: ① To modularize products and make them as less differences as possible; ② To design manufacturing resources and make them provide as many processes variations as possible. This paper reports our recent work on aspect ②, i.e. how to design a reconfigurable manufacturing system (RMS) so that it can be competent to accomplish various processes optimally; Reconfigurable robot system (RRS) is taken as an example. RMS design involves architecture design and configuration design, and configuration design is further divided in design analysis and design synthesis. Axiomatic design theory (ADT) is applied to architecture design, the features and issues of RRS configuration design are discussed, automatic modelling method is developed for design analysis, and concurrent design methodology is presented for design synthesis.     

制造业中产品全生命周期成本的研究概况综述

对全生命周期成本(LCC)的内涵、构成和估算方法进行了详细的介绍,并综述了国内外LCC分析在产品设计、价值工程、设备管理等方面的应用及其研究现状,并针对我国的实际情况,指出除了军事方面进行深入研究和应用LCC方法外,更应该加强对民用产品方面的应用,并提出在我国亟待开展的全生命周期成本问题研究重点和途径有：LCC标准的制定、面向成本的设计方法和价值工程、LCC数据收集等。     

Improving automation standards via semantic modelling: Application to ISA88

Standardization is essential for automation. Extensibility, scalability, and reusability are important features for automation software that rely in the efficient modelling of the addressed systems. The work presented here is from the ongoing development of a methodology for semi-automatic ontology construction methodology from technical documents. The main aim of this work is to systematically check the consistency of technical documents and support the improvement of technical document consistency. The formalization of conceptual models and the subsequent writing of technical standards are simultaneously analyzed, and guidelines proposed for application to future technical standards. Three paradigms are discussed for the development of domain ontologies from technical documents, starting from the current state of the art, continuing with the intermediate method presented and used in this paper, and ending with the suggested paradigm for the future. The ISA88 Standard is taken as a representative case study. Linguistic techniques from the semi-automatic ontology construction methodology is applied to the ISA88 Standard and different modelling and standardization aspects that are worth sharing with the automation community is addressed. This study discusses different paradigms for developing and sharing conceptual models for the subsequent development of automation software, along with presenting the systematic consistency checking method.     

并行工程环境的面向成本设计

在分析产品成本相关领域研究的基础上 ,提出了并行工程环境的面向成本的设计 (Designforcost,DFC)的概念、方法与体系结构。研究了在设计阶段进行产品成本估算的方法 ,提出了基于特征的零件制造成本估算方法     

Simultaneous process mean and process tolerance determination with asymmetrical loss function

Process design involves process mean and process tolerance determination. Process mean determination is finding the best settings for product quality, without affecting manufacturing cost. However, process tolerance determination is a manufacturing process selection which generally affects manufacturing cost and product quality. In this study, asymmetric quality loss is considered in measuring product quality, and tolerance cost is adopted in representing manufacturing cost. To reflect the combined effect of process mean and process tolerance completely, failure cost is added to the category of manufacturing cost. Then, based on the sum of these three costs, a simultaneous optimization of process mean and process tolerance is determined for process planning in the early stages of development.     

基于多重相关特征质量损失函数的公差优化设计

在重点推导了具有多重相关特征产品的质量损失与尺寸公差的函数关系的基础上,提出了多重相关特征产品的公差优化设计方法,建立了基于制造成本一质量损失的公差优化设计的综合模型,建立该模型的目的是寻求制造成本和质量损失之间的平衡,实现旨在提高产品质量和降低成本的公差优化设计。应用实例验证了所提出方法的有效性。     

Simultaneous optimal selection of design and manufacturing tolerances with different stack-up conditions using scatter search

The allocation of design and manufacturing tolerances directly influences the manufacturing cost and functionality of a product. Traditionally, it is carried out in two phases; CAD and CAPP, in a sequential manner. This approach has the drawbacks of more lead-time and sub-optimality. The present work reports on a procedure to simultaneously allocate both design and manufacturing tolerances based on minimum total manufacturing cost. The optimization model for tolerance design is a non-linear multivariable problem. Since such a problem may have a noisy surface, there is a need to apply an efficient global optimization technique. In the present work, scatter search, one of the recently emerged optimization techniques in the area of metaheuristics, is applied successfully to determine the optimal tolerances at the minimum manufacturing cost. An example is taken from the literature to explain the proposed methodology. The results exhibit the effectiveness of the proposed algorithm over other methods.     

Reduction of product platform complexity by vectorial Euclidean algorithm

In traditional machine, equipment and devices design, technical solutions are practically independent, thus increasing designs cost and complexity. Overcoming this situation has been tackled just using designer’s experience. In this work, a product platform complexity reduction is presented based on a matrix representation of technical solutions versus product properties. This matrix represents the product platform. From this matrix, the Euclidean distances among technical solutions are obtained. Thus, the vectorial distances among technical solutions are identified in a new matrix of order of the number of technical solutions identified. This new matrix can be reorganized in groups with a hierarchical structure, in such a way that modular design of products is now more tractable. As a result of this procedure, the minimum vector distances are found thus being possible to identify the best technical solutions for the design problem raised. Application of these concepts is shown with two examples.