Choice of Cost-Estimation Functions Based on Statistical Quality Criteria and Technical Coherence

This paper studies the problem of choosing cost estimation functions by mixing statistical regression criteria and technical coherence. The parametric cost estimation method which looks for functional relationship between cost driver variables and the product cost is particularly well adapted to early economic evaluation during the design phase; it is simple to implement, efficient, and reactive enough to provide a powerful guideline for the designer. These cost estimation relationships (CER) are generally computed using linear or nonlinear regression algorithms. However, the problem is to identify and to choose the best CER among several candidate formulae which have been developed. In many cases, the statistical regression quality and estimation criteria are not sufficient. It is also necessary to consider the technical coherence of the CER as defined by the experts in the application domain. Therefore, an additional problem is to make these different points of view consistent. In this paper, the authors adopt a weighted multicriteria decision approach. The characteristics of the different quality criteria are described, then three practical selection methods are presented. All these methods measure the general quality of CERs, taking into account both technical and statistical points of view. The methods are based on a measure of quality using a weighted sum of normalised criteria, a weighted ranking method, and an original use of a similarity measure in the criteria space. These methods are then tested and compared using a real case.     

Manufacturing Cost Modeling for Product Design

The process of product design is driven toward achieving design specifications while meeting cost targets. Designers typically have models and tools to aid in functional and performance analysis of the design but few tools and little quantitative information to aid in cost analysis. Estimates of the cost of manufacture often are made through a cost multiplier based on material cost. Manufacturing supplies guidelines to aid in design, but these guidelines often lack the detail needed to make sound design decisions.A need was identified for a quantitative way for modeling manufacturing costs at Motorola. After benchmarking cost modeling efforts around the company, an activity-based costing method was developed to model manufacturing cycle time and cost. Models for 12 key manufacturing steps were developed. The factory operating costs are broken down by time, and cost is allocated to each product according to the processing it requires. The process models were combined into a system-level model, capturing subtle yet realistic operational detail.The framework was implemented in a software program to aid designers in calculating manufacturing costs from limited design information. Since the information tool provides an estimate of manufacturing costs at the design prototype stage, the development engineer can identify and eliminate expensive components and reduce the need for costly manufacturing processing. Using this methodology to make quantitative trade-offs between material and manufacturing costs, significant savings in overall product costs are achieved.     

Design for pressure die casting—A DFM example

The designer makes many maufacturing decisions that influence the production cost and the quality of the product. It is therefore important to ensure that the designer has a good foundation for these decisions. When talking DFM, it is important to realise that there are large differences between companies in how product design and production are carried out. The objective of the present research is to investigate and to improve the communication flow between design and production for a selected area: pressure die casting. This area is characterised by many subcontracting producers, and design and production are therefore often placed at different geographic locations. This makes an efficient communication flow even more important and it also makes the communication interface more visible. This paper discusses how manufacturing considerations are made in different design situations and how information supporting tools should be formed accordingly. Results from an investigation of DFM in a number of pressure diecasting companies and companies that design products for pressure die casting are presented. The investigation focuses on the type, the detailing level and the accessibility of the part information passing from design to production and on the manufacturing guidelines and suggestions coming from production to design.     

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。     

聚类分析算法在产品成本模型分析中的应用研究

在总结已有研究成果的基础上 ,本文介绍了聚类分析方法的基本理论 ,结合城市客车开发实例 ,研究了产品成本模型的结构以及各个子系统的成本之间以及成本项目之间的相关性问题 ,并明确了产品成本的主流因素。本文的研究对于新产品开发过程中的成本分析提供了有效的手段。     

基于成本聚类的产品设计早期阶段成本估算模型

针对产品适应性设计或变型设计早期阶段难以进行精确成本估算的特点,提出大样本条件下基于"成本聚类"的成本估算模型.通过计算参考样本和待估算产品的欧氏距离考察二者的相似度,以欧氏距离集为初始数据分别构造差异矩阵、距离矩阵和相似矩阵,实现对样本的成本聚类分析过程,最终筛选出与待估算产品最相关的样本集合,得到待估算产品成本可能落入的区间.以液压盘式制动器的制动盘零件为实例,验证方法的有效性.试验结果表明,该模型能够有效区分估算样本的相对优劣.     

基于TRIZ理论的产品可持续设计研究

可持续设计是可持续发展思想和循环经济理论在产品设计领域内的反映,是一种全新的设计理念。总结了可持续设计的概念和特点,并对可持续设计的实施策略和TRIZ理论的诸多工具在可持续设计方面的应用进行了探讨。     

A novel approach to the geometric feasibility analysis for fast assembly tool reasoning

A product assembly or disassembly is completed by means of proper tools. The selection of feasible tools is an important process in planning a complete assembly or disassembly sequence. A key tooling consideration in assembly or disassembly planning is to reason the available space for a tool application during the assembly or disassembly of a product. Currently, assembly tool reasoning about space mainly depends on simulation-based or user-interactive approaches because of its computational complexity. These approaches are inappropriate in dealing with various what-if scenarios regarding assembly or disassembly planning in a rapid product development. They also depend on users’ expertise or experience in assembly or disassembly. This paper presents a novel approach to the geometric feasibility analysis for fast assembly tool reasoning. Techniques described in this paper are advantageous not only in the aid of generating a complete assembly or disassembly plan but also in the efficient support of such systems as computer-aided assembly planning (CAAP), design for manufacturing (DFM), design for assembly (DFA), design for disassembly (DFD), and computer-aided tool selection (CATS).     

面向产品概念设计的设计工具选择与应用

本文分析了产品概念设计的特点与重要性,指出合理的选择设计工具对于提高产品开发的效率与质量至关重要。介绍了面向方案创新的CAI设计软件Pro／Innovator与支持三维建模与设计验证的CAD设计软件Solid Works,并通过一工程实例说明两种设计工具的使用很好的支持了产品概念设计过程。     

An Intelligent Knowledge-Based System for Product Cost Modelling

An intelligent knowledge-based system for product cost modellingis presented in this paper. The developed system has the capability of selecting a material, as well as machining processes and parameters based on a set of design and production parameters; and of estimating the product cost throughout the entire product development cycle including assembly cost. The proposed system is applied without the need for detailed design information, so that it can be used at an early design stage, and, consequently, redesign cost and longer lead time can be avoided. Hybrid knowledge representation techniques, such as production rules, frame and object oriented are employed to represent manufacturing knowledge. Fuzzy logic-based knowledge representation is applied to deal with uncertainty in the knowledge of cost model to generate reliable cost estimation. This paper deals with cost modelling of both a machining component and an injection moulding component, which is a process that gives high production rates, excellent quality and accuracy of products, and low manufacturing cost. Based on the analysis of the moulded product life cycle, a computer-based cost model was developed which integrated the relationship between cost factors, product development activities, and product geometry. The estimated cost included the costs of material, mould and processing. The system has been validated through a case study.     

论实现产品创新的四个纬度

指出制造业的竞争就是产品设计的竞争,而产品创新设计是一个系统工程,还从四个纬度对如何实现产品创新进行了简要分析,并指出企业在任何一个纬度实现突破都可以带来真正的产品创新.     

A Priori Assessment of Customer Costs in Designing the Life Cycle of Complex Products

The basic stages in the life cycle of a batch of complex engineering products are considered: design, production, operation, and disposal. A priori cost assessment for each stage is discussed. The cost aggregation in the consideration of multiple stages is analyzed. Requirements on the assessment are formulated. Methodological and implementation aspects of the assessment tools are outlined. The conclusion is that it is expedient to predict the costs on the basis of mathematical models of the product batch in an operational environment. The integration of multiple cost estimates is addressed.     

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。     

Functional tolerance theory in incremental growth design

The evolutionary tolerance design strategy and its characteristics are studied on the basis of automation technology in the product structure design. To guarantee a successful transformation from the functional requirement to geometry constraints between parts, and finally to dimension constraints, a functional tolerance design theory in the process of product growth design is put forward. A mathematical model with a correlated sensitivity function between cost and the tolerance is created, in which the design cost, the manufacturing cost, the usage cost, and the depreciation cost of the product are regarded as control constraints of the tolerance allocation. Considering these costs, a multifactor-cost function to express quality loss of the product is applied into the model. In the mathematical model, the minimum cost is used as the objective function; a reasonable process capability index, the assembly function, and assembly quality are taken as the constraints; and depreciation cost in the objective function is expressed as the discount rate—terminology in economics. Thus, allocation of the dimension tolerance as the function and cost over the whole lifetime of the product is realized. Finally, a design example is used to demonstrate the successful application of the proposed functional tolerance theory in the incremental growth design of the product. __________ Translated from Chinese Journal of Mechanical Engineering, 2006, 42(10): 73–79 [译自: 机械工程学报]     

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.     

Direct value added and economic weight factors in economic analysis of CIM

Throughout manufacturing history, management has searched for tools to help it set product prices accurately. Traditionally, manufacturing managers have analysed efficiency by cost makeup with the basic elements: materials, labour, overheads. Overhead costs are allocated to units of production based on a theorical correlation with labour costs. With automation, direct labour has come to be only 1 to 20% of the total manufactured costs of products. The CIM infrastructure must incorporate a wide range of management facilities. It is now time to focus on an integrative approach which embraces design, planning, process and product costing. With the direct value approach we describe a concept which gives pertinent information to adapt strategy speedily for a better profitability. In addition an economic weighting coefficient for the analysis of job contribution in the creation of added value, it is possible to control product pricing. In this way, economic information can be an element of the product and process database and thus build up an operational decision support system by means of sharing common information.     

面向成本建模的产品设计全过程信息表达

结合产品设计中全过程成本建模的特点提出了潜信息模型的新概念 ,建立了基于细胞学的潜信息模型构造框架。利用潜信息模型能够表达不全信息或迟到信息的优点 ,探讨了面向设计各阶段的潜信息模型演变算法 ,实现设计全过程信息的动态演变和表达 ,在支持产品设计全过程的成本建模中得到成功应用 ,提高了成本建模的效率及其平台的通用性。     

A manufacturability advisor for spun and rollformed sheet metal components

In today’s manufacturing scenario, accounting for manufacturability considerations at the product design stage is not an option but a necessity. When CAD/CAM tools are used to reduce design lead times, accounting for manufacturing process related considerations implicitly is often difficult. Availability of manufacturability advisor systems that analyze part geometry and other product related information for ease of manufacturing could be a solution to this problem. The purpose of a manufacturability assessment is to give feedback to the designer in order to make the product/process more effective. Present research is concerned with the development of an automated manufacturability advisor for sheet metal components. Unlike most of the work done in the past that concentrated on bending and other forming processes, present work deals with sheet metal components manufactured by two different processes, namely “spinning” and “rollforming”. Effectiveness of the proposed manufacturability advisor is demonstrated by taking the number of industrial parts as examples.     

工业设计应用计算机辅助系统的探讨

尝试将工业设计流程分为产品定位分析、产品概念及方案设计、模型制作、市场推广等4个阶段。浅析了这4个阶段计算机辅助技术的应用状况，重点对三维计算机辅助概念设计、数控加工及快速成型技术辅助模型制作等技术进行了探讨。文章力图结合现代制造企业的实际情况，实践证明利用现代计算机辅助技术，可以将工业设计的整个流程进行有机结合，从而形成一个快速、准确、高效的设计系统。     

轴一套类零件配合尺寸公差最优设计的研究

公差设计的优劣不仅直接影响产品零件装配精度的实现,而且对产品制造成本亦将产生重大影响。文章对轴－套类零件制造（加工与装配） 成本的各因素进行了分析,提出了达到装配精度要求的最优装配方法的判定准则,建立了生产成本最低的轴－套类零件最优公差设计的数学模型,并用实例验证了该模型在实际中的正确性与有效性。