A material selection methodology and expert system for sustainable product design

Material selection is one of the main phases of product design process that has great impact on the manufacturing of sustainable products. One of the best approaches of material selection for sustainable products is life cycle engineering (LCE). But LCE is a costly and cumbersome task and it is not economic to perform this task for a large number of proposed materials in order to choose the most suitable one for a sustainable product. Instead, it is more reasonable to make a preliminary filtering on the proposed materials and obtain a shorter list of candidate materials and then perform LCE on alternatives which are obtained from preliminary filtering. Since environmental friendliness of materials is a critical sustainability issue, so it is a good criterion for preliminary filtering of alternatives. In this paper, a new methodology is proposed to support preliminary filtering of alternatives from environmental viewpoint. The methodology uses the knowledge of experts in the field of eco-design. The knowledge is translated to decision making rules and a decision tree is developed to guide the choice. In order to use the capabilities of frame-based systems, an object-oriented approach for representation of knowledge is also proposed. Moreover, a prototype hybrid expert system based on the proposed methodology called material selection expert system for sustainable product design is developed to support the task of preliminary filtering. Finally, a case study from tire manufacturing industries is presented to show the validity of the proposed system. The results show that the system can determine the appropriate candidate materials and hence improve the possibility of manufacturing of more sustainable products. Eliminating alternatives that do not have the necessary conditions for sustainable product leads to a large saving in time and cost of the LCE evaluation process     

Java-based computer-aided process planning

This investigation addresses distributed environments for computer-aided process planning (CAPP) over a network. The Java 2 Enterprise Edition (J2EE) standard using Java is applied to implement cross-platform and distributed computing architecture, thus reducing the system loading during manufacturing process planning. The product-oriented standard, standard exchange of product (STEP), model data is applied to define a robust data model that associates product, shape, and feature definitions and provides the mechanisms for data exchange, sharing, and integration with other engineering systems, such as computer-aided design (CAD) and computer-aided manufacturing (CAM). STEP AP224 is engaged to define the machining features of machined products in the proposed CAPP system. The life cycle of a product from design to sale, and especially the period of manufacturing, can be greatly shortened; the cost of manufacturing can be reduced and the quality of the product can be improved using the proposed CAPP system.     

Knowledge-based system for assignment of parts to machine cells

This paper presents a decision tool for assignment of parts to machining cells. A modelling system and associated expert modules: analyser, synthesiser and recogniser have been developed to perform the automatic and dynamic assignment of parts directly from a feature-based CAD modelling system to manufacturing cells. It is based on the knowledge acquired from design features of parts and manufacturing processes. Feature-based representation of components structure and related machining operations is presented. The proposed algorithm allows the integration of CAD and CAM. Some elements of expert systems, pattern recognition and finite-state automata are applied in this research. Symbolic strings containing the design and machining attributes of components are analysed using knowledge rules and syntactic pattern recognition techniques, then cell inference and part assignment are carried out. A case study is included to illustrate the feasibility of the above approaches. This research, provides some useful contributions for both CAD and CAM integration as well as parts assignment for cellular manufacturing.     

Concurrent optimization of machining process parameters and tolerance allocation

With the advent use of sophisticated and high-cost machines coupled with higher labor costs, concurrent optimization of machining process parameters and tolerance allocation plays a vital role in producing the parts economically. In this paper, an effort is made to concurrently optimize the manufacturing cost of piston and cylinder components by optimizing the operating parameters of the machining processes. Design of experiments (DoE) is adopted to investigate systematically the machining process parameters that influence product quality. In addition, tolerance plays a vital role in assembly of parts in manufacturing industries. For the selected piston and cylinder component, improvements efforts are made to reduce the total manufacturing cost of the components. By making use of central composite rotatable design method, a module of DoE, a mathematical model is developed for predicting the standard deviation of the tolerance achieved by grinding process. This mathematical model, which gives 93.3% accuracy, is used to calculate the quality loss cost. The intent of concurrent optimization problem is to minimize total manufacturing cost and quality loss function. Genetic algorithm is followed for optimizing the parameters. The results prove that there is a considerable reduction in manufacturing cost without violating the required tolerance, cutting force, and power.     

Cutting parameter optimization in NC milling

The continuous demand for higher productivity and product quality asks for better optimizing of the machining process. In this case, numerical controlled (NC) milling is a processing technology massively applied in the metal manufacturing industry; it has received very important interest in this century because it has a very high productivity and high work piece surface quality. The main objective of this work is to evaluate the machining time of different cycles, in 2.5?D NC milling. The prediction of the optimal values of cutting speed was analyzed to minimize both time and cost of die production. Optimum and economical values of cutting speed give, respectively, minimum production time and minimum production cost. An experimental study is carried out to validate machining time calculation models developed in this work. The cutting parameters analyzed in this study are cutting speed, feed per tooth, and the radial cutting depth.     

Shared and service-oriented CNC machining system for intelligent manufacturing process

To improve efficiency, reduce cost, ensure quality effectively, researchers on CNC machining have focused on virtual machine tool, cloud manufacturing, wireless manufacturing. However, low level of information shared among different systems is a common disadvantage. In this paper, a machining database with data evaluation module is set up to ensure integrity and update. An online monitoring system based on internet of things and multi-sensors "feel" a variety of signal features to "percept" the state in CNC machining process. A high efficiency and green machining parameters optimization system "execute" service-oriented manufacturing, intelligent manufacturing and green manufacturing. The intelligent CNC machining system is applied in production. CNC machining database effectively shares and manages process data among different systems. The prediction accuracy of online monitoring system is up to 98.8% by acquiring acceleration and noise in real time. High efficiency and green machining parameters optimization system optimizes the original processing parameters, and the calculation indicates that optimized processing parameters not only improve production efficiency, but also reduce carbon emissions. The application proves that the shared and service-oriented CNC machining system is reliable and effective. This research presents a shared and service-oriented CNC machining system for intelligent manufacturing process.     

交互式虚拟设计与同步制造技术算法与图形系统研究

产品的创意外形设计与快速试制对于更好地满足产品多品种、短开发周期、优美外形、提高市场竞争力等需求具有重要意义,而现有的CAD/CAM和快速原型制造技术在这一方面仍然存在一些不足,这里提出的交互式虚拟设计与同步试制系统利用虚拟现实技术和计算机数字雕刻技术,在交互设计、创意设计、快速试制、材料多样性等方面都有所突破。文章阐述了在设计过程中工作描述、刀具轨迹包络计算、图形布尔运算、以及高速逼真图形显示等关键技术。实际工作设计与制造实验证明所开发的系统技术可行,已经可以进行基本的产品外形设计与同步制造。     

Knowledge formalization for product–process integration applied to forging domain

Efficient and effective forging process selection for a given set of product characteristics and requirements is a multicriterion problem strongly influenced by interdependent factors like product complexity, design requirements, product quality, resource availability, and cost. These factors are formalized based on the information provided regarding the role and experiences of experts in product–process design; however, design representation is considered as a network of product and process parameters and expert’s knowledge as a set of constraints applied on the parametric network. This paper proposes an integrated product–process approach to evaluate its consistency and is useful in selecting suitable forging process and product design parameters. Computer support tool has been developed to present and to integrate the product parameters, the process characteristics, and the expert’s knowledge related to forging domain to select an appropriate forging process evaluated through a constraint propagation algorithm. This approach is validated through a case study presented at the end.     

面向工艺设计的制造过程建模

基于工艺设计对产品制造成本、质量和效率的重要影响,提出了一种基于工艺设计的制造过程建模方法,以通过对过程模型的仿真,预测、分析和优化工艺设计效果。基于对制造过程的特征分析,采用面向对象的方法,首先将制造过程定义为一组成对象,并划分为制造活动、过程控制和制造资源3类成分对象,建立了制造过程类结构模型和动态过程模型。分别定义了工序类、制造资源类和过程控制类的类结构模型,以及各类对象的方法和属性。基于这些模型开发了一种计算机辅助工艺设计系统,可快速、自动地构建工艺设计定义的制造过程模型,并对过程参数（成本、时间）、切削加工、工件物流进行计算和仿真。     

Tolerance chart balancing with a complete inspection plan taking account of manufacturing and quality costs

This paper introduces a mathematical model of tolerance chart balancing for machining process planning under complete inspection. The criteria considered in this study are based on the combined effects of manufacturing cost and quality loss, under constraints such as process capability limits, product design specifications, and product quality requirements. Manufacturing costs include the machining cost, part cost, inspection cost, reworking cost, and replacement cost. The machining cost is expressed in geometrical decreasing functions, which represent tolerances to be assigned. Process variability is expressed in quadratic loss functions, which represent the deviation between the part measurement and the target value. An example is presented to demonstrate the proposed model. A comparison made with previous methods shows that the proposed model minimizes the total cost of manufacturing activities and quality-related issues in machining process planning, particularly in the early stages. Moreover, the applications are not be limited to machining process planning but can also be used in other forms of production planning.     

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.     

A flexible process information reuse method for similar machining feature

Dynamically changing machining conditions and uncertain manufacturing resource availability are forcing manufacturing enterprises to search advanced process planning in order to increase productivity and ensure product quality. As growing quantities of the three-dimensional process models are gradually applied, reusing the embedded manufacturing information in process models with less time and lower cost attracts a lot of attention. In this paper, a new flexible method is presented to reuse the existing process information based on retrieval of the similar machining feature. First, the three-level organization model is introduced to represent the process information; the machining feature which is seen as the parent layer carries the corresponding manufacturing information. To ensure accurately that the process information are obtained, the associated mechanism between the machining feature and process information is created. Second, an eight-node representation scheme is designed to represent the similar machining feature having same variations in topology and geometry. For accelerating similar feature retrieval, the extension-attributed adjacency graph and the topological relationship of the machining feature faces are built. Finally, some aircraft structural parts are utilized in the developed prototype module to verify the effectiveness of the proposed method. This method can be used as the basis for accumulation of the process information; it can promote the development and application of the intelligent process planning.     

Minimizing manufacturing costs for thin injection molded plastic components

Minimizing the cost of manufacturing a plastic component is very important in the highly competitive plastic injection molding industry. The current approach of R&D work focuses on optimizing the dimensions of the plastic component, particularly in reducing the thickness of the component during product design, the first phase of manufacturing, in order to minimize the manufacturing cost. This approach treats the component dimensions established in the product design phase as the given input, and uses optimization techniques to reduce the manufacturing cost of mold design and molding for producing the component. In most cases, the current approach provides the correct solution for minimizing the manufacturing cost. However, when the approach is applied to a thin component, typically when miniaturizing products, it has problems finding the true minimum manufacturing cost. This paper analyses the shortcomings of the current approach for handling thin plastic components and proposes a method to overcome them. A worked example is used to illustrate the problems and compare the differences when using the current approach and the new method proposed in the paper.     

Minimizing manufacturing costs for thin injection molded plastic components

Minimizing the cost of manufacturing a plastic component is very important in the highly competitive plastic injection molding industry. The current approach of R&D work focuses on optimizing the dimensions of the plastic component, particularly in reducing the thickness of the component during product design, the first phase of manufacturing, in order to minimize the manufacturing cost. This approach treats the component dimensions established in the product design phase as the given input, and uses optimization techniques to reduce the manufacturing cost of mold design and molding for producing the component. In most cases, the current approach provides the correct solution for minimizing the manufacturing cost. However, when the approach is applied to a thin component, typically when miniaturizing products, it has problems finding the true minimum manufacturing cost. This paper analyses the shortcomings of the current approach for handling thin plastic components and proposes a method to overcome them. A worked example is used to illustrate the problems and compare the differences when using the current approach and the new method proposed in the paper.     

Knowledge management to support product development in cold roll-forming environment

Knowledge and information management has focused on how available knowledge is exploited to enhance organisational performance especially in marketing, costing, design, and manufacturing activities; however, there is limited information on how knowledge acquired during product development can be utilised to provide decision support throughout the product life cycle. Existing knowledge management systems do not seem to provide information on well-known manufacturing constraints and product attributes identified during product development. Secondly, such systems do not provide the means to identify, capture, formalise, present and utilise tacit knowledge which have a major impact on overall product development process. Consequently, knowledge and experiences gained from existing projects are sometimes poorly documented and therefore are not available for reuse in future projects. An organised transfer of knowledge from previous projects will no doubt enhance the quality, efficiency, cost, and time to market of new products and processes. The study carried out here has developed a knowledge management framework to support product development in a cold roll-forming manufacturing environment. Process modelling supported by Integrated Definition for Function Modeling methodology was applied to guide the identification of information and knowledge required to support product development and also for effective decision making in routine cold roll forming.     

Simultaneous manufacturing shape optimization for minimum cost of milling using interior point method

This paper presents an integrated manufacturing shape optimization method and explores the tradeoff between mass and machining cost with the application of the end-milling that used to machine a topological die. The aim is to make a simultaneous optimization method between product manufacturing and its topological shape to close the gap between theoretical work and practical needs. This innovative method depends on some manufacturing functional issues and shape constraints. The objective function is minimizing the total cost of process including the material and machining cost. The initial shape of the part is constructed by using B-splines and hole generation-based topological concept; the design variables are x- and y-coordinates of the control points that represent the B-splines. The cutting parameters of the milling process such as the cutting speed, the feed per flute, and the tool diameter are also optimized. The simultaneous manufacturing shape optimization problem will be achieved by interfacing between MATLAB2011a and ANSYS15 programs using interior point method (IPM) as a mathematical optimization solver. The comparison between the initial total cost and its optimal results for studied cases is presented, and the influence of the required batch size on the final shape is discussed. It is found that the reduction percentage in the cost function can receive 69% for small batch size (batch 50 pieces) and 54.18% for large batch size (batch 5000 pieces). The result from this simultaneous optimization is that the batch size of the required product influences the topological shape of the product.     

Generation and Evolutionary Learning of Cutting Conditions for Milling Operations

In metal cutting processes, cutting conditions have an influence on reducing the production cost and time and deciding the quality of a final product. This paper presents a new methodology for continual improvement of cutting conditions. It is called GELCC (generation and evolutionary learning of cutting conditions). GELCC is a key component of an operation planning system for milling operations. It performs the following three functions: 1. The modification of recommended cutting conditions obtained from a machining data handbook. 2. The incremental learning of obtained cutting conditions using fuzzy ARTMAP neural networks. 3. The substitution of better cutting conditions for those learned previously by a proposed replacement algorithm. Various simulations illustrate the performance of GELCC, and then the simulation results for a given part are provided and discussed.     

关于连接块的工艺设计及夹具设计

产品制造过程中,由于定位不准确或振动,会使得产品加工误差比较大,满足不了产品的使用要求,或者勉强满足但生产效率太低,导致生产成本增加。因此,在产品加工前必须对产品进行工艺分析及必要的夹具设计以提高工作效率,降低生产成本。     

Integrated tolerance optimisation with simulated annealing

Tolerance is one of the most important parameters in design and manufacturing. The allocation of design and machining tolerances has a significant impact on manufacturing cost and product quality. This article presents an analytical model for simultaneously allocating design and machining tolerances based on the least-manufacturing-cost criterion. In this study, tolerance allocation is formulated as a non-linear optimisation model based on the cost-tolerance relationship. A new global optimisation algorithm, simulated annealing, is employed to solve the non-linear programming problem. An example for illustrating the optimisation model and the solution procedure is provided.     

A WWW-Based Information Management System for Rapid and Integrated Mould Product Development

As efficient management of product information that covers the whole life cycle is critical to the enhancement of corporate competitiveness. This paper explores the design and development of a World Wide Web (WWW) based product development information management system for a cross-nation manufacturing corporation that is headed by a holding company in Christchurch, New Zealand. Since product data are often managed in a distributed computing environment, common object request broker architecture (CORBA) is employed to ensure the interoperability among distributed information objects. A STEP-based information framework is proposed to preserve the openness of the system. This WWW-based information management system is discussed in this paper, which includes two major components: 1. WWW-based product design and development distributed object-oriented databases and knowledge bases. 2. A WWW-based integrated system platform. Several sub-models are introduced, which include an object-oriented database structure, a WWW-based information management system, a WWW database tool, an information access tool, the incremental process-planning method, a cost-optimisation model and an integrated software platform for the integration of CAD, CAPP, CAM, and a WWW-based information management system.