System modelling for economic raw material selection

A system simulation method for economic raw material selection is presented, based on a realistic example. The total cost considered in raw materials selection is deemed to include the basic raw material cost, the extra manufacturing cost due to the selection of the particular raw material, and the final product quality cost. These costs are systematically simulated for three typical areas of interest: for the purchasing operation, for the manufacturing process and for the final product quality acceptance by the customer.     

A genetic algorithm and queuing theory based methodology for facilities layout problem

Facilities layout, being a significant contributor to manufacturing performance, has been studied many times over the past few decades. Existing studies are mainly based on material handling cost and have neglected several critical variations inherent in a manufacturing system. The static nature of available models has reduced the quality of the estimates of performance and led to not achieving an optimal layout. Using a queuing network model, an established tool to quantify the variations of a system and operational performance factors including work-in-process (WIP) and utilisation, can significantly help decision makers in solving a facilities layout problem. The queuing model utilised in this paper is our extension to the existing models through incorporating concurrently several operational features: availability of raw material, alternate routing of parts, effectiveness of a maintenance facility, quality of products, availability of processing tools and material handling equipment. On the other hand, a queuing model is not an optimisation tool in itself. A genetic algorithm, an effective search process for exploring a large search space, has been selected and implemented to solve the layout problem modelled with queuing theory. This combination provides a unique opportunity to consider the stochastic variations while achieving a good layout. A layout problem with unequal area facilities is considered in this paper. A good layout solution is the one which minimises the following four parameters: WIP cost, material handling cost, deviation cost, and relocation cost. Observations from experimental analysis are also reported in this paper. Our proposed methodology demonstrates that it has a potential to integrate several related decision-making problems in a unified framework.     

Minimising schedule cost via simulation optimisation: an application in pipe manufacturing

We present a method to minimise the cost of batch schedules for a pipe manufacturing facility. The method determines the sequence of production and start date of the batch considering raw material and finished goods holding cost, late delivery cost, and changeover. Our approach is designed to interface to the company's manufacturing execution system, and uses a simplified model of the production line for speed of execution. We demonstrate that methodology results in significant cost savings when compared to existing schedules.     

Operations planning in a supply chain system with fixed-interval deliveries of finished goods to multiple customers

Raw material ordering policy and the manufacturing batch size for fixed-interval deliveries of finished goods to multiple customers play a significant role in economically managing the supply chain logistics. This paper develops an ordering policy for raw materials and determines an economic batch size for a product at a manufacturing center which supplies finished products to multiple customers, with a fixed-quantity at a fixed time-interval to each of the customers. In this model, an optimal multi-ordering policy for procurement of raw materials for a single manufacturing system is developed to minimize the total cost incurred due to raw materials and finished goods inventories. The carried over inventory of finished goods from the previous cycle is used as initial finished goods inventory, resulting in shifting the production schedule ahead for the next cycle. A closed-form solution to the problem is obtained for the minimal total cost. The algorithm is demonstrated for multiple customer systems.     

板材加工余料管理及成本研究

板材加工余料再利用及其成本研究是制造业成本控制中的一个重要问题，为了能更准确核算产品成本，提出将制造成本中的原材料成本的定义改进为实际消耗的和耗损的不可再生产利用的原材料价值，使用移动平均法对余料库存中的同种余料消除不同批次进入库存而产生的价格差异．通过从余料管理获得效益以及管理成本的支出的分析，可以得到一个余料再利用的价值平衡点．     

Application of knowledge-based artificial immune system (KBAIS) for computer aided process planning in CIM context

In the present era, several manufacturing philosophies like lean manufacturing, total quality management (TQM), etc., have the goal of providing a quality product at reduced cost. In this research paper the process planning problem of a CIM system has been discussed where minimisation of cost of the finished product is considered as the main objective. For determining the cost of the finished product, scrap cost, forgotten by most of the previous researchers, has been considered along with other costs like raw material cost, processing cost, etc. In the present environment of concurrent engineering, optimisation of process planning is an NP-hard problem. To solve this complex problem a noble search algorithm, known as knowledge-based artificial immune system (KBAIS) has been proposed. The nobility of the proposed algorithm is that the inherent capability of AIS has been gleaned and incorporated with the property of the knowledge base. In this problem, the power of knowledge has been used for three stages in the algorithm: initialisation, selection and hyper-mutation. To demonstrate the efficacy of the proposed KBAIS, a bench mark problem has been considered. Intensive computational experiments have also been performed on randomly generated datasets to reveal the supremacy of the proposed algorithm over other existing heuristics.     

Process alternative generation from product geometric design data

A fundamental element in operating a competitive manufacturing system is the ability to control material, cost, and other production resources required to transform the raw material to a finished product. To successfully control cost, it is essential that a reliable assessment of the tasks required to manufacture the product be made. This involves identifying the operations and the machine tools required. In this research, a method of decomposing polyhedral components to generate all possible ways to process the part is presented. The technique takes as input the geometric design data of the product, analyzes and interprets the design to identify the volume of material to be machined out from the raw material block to obtain the finished product. The volume of material to be removed are characterized to generate various approach directions from which the material can be machined out. The alternate tool approach directions are used to construct an AND/OR graph that captures the process alternatives. Using this graphical representation, a model is proposed for selecting the best process plan based on some user defined criterion. The developed procedure can be integrated into a CAD/CAM system to provide the required linkage between design and manufacturing and thus, automate a critical link in manufacturing.     

Optimization of the LCD optical film cutting problem

The manufacturing of liquid crystal display (LCD) plays an important role in electronics manufacturing industries, such as televisions, smart phones, pads, laptops, monitors and electronic appliances. Due to the fact that the cost of LCD’s film materials may reach 60–70% of the production cost, appropriate cutting schemes can lead to better raw material utilisation and thus enhance manufacturers’ profitability. Accordingly, the determination of the optimal production plan for cutting different-sized LCD optimal films with the designed cutting angles to fulfil the customers’ orders is a critical issue for the LCD industry. In the past, few studies integrated the different cutting allocation strategies into a synthetic decision. This study proposes a mathematical programming model for the two-stage cutting problem for LCD optical films to determine the optimal cutting allocation strategy with consideration of the costs of raw materials, processing and disposal during the manufacturing process. For large-scale problems in which the runtime for obtaining the optimal solution may grow exponentially as the problem size increases, a heuristic algorithm is also provided to obtain the approximate solution within a reasonable time. Finally, the results of the practical case shows that, compared with the existing fixed-angle cutting method, the proposed approach reduces the total cost by 6.2% due to the better material utilisation. In addition, the processing cost is also reduced due to a decrease in the required materials.     

Selective laser melting raw material commoditization: impact on comparative competitiveness of additive manufacturing

The paper analyses the impact of cheaper metal powder supplies on the comparative competitiveness of additive manufacturing (AM). By utilising two case studies, we compare the economic impact of an innovative titanium extraction method on Selective Laser Melting (SLM) and conventional methods of machining and casting. A switch-over analysis identifies the production quantities above which conventional manufacturing is more cost competitive than additive manufacturing. This analysis is performed for current raw material as well as cheaper raw material supply. The results illustrate the improved comparative competitiveness of SLM as the titanium supply is commoditised and more readily available in powder form. The responsiveness of the supply chain is improved as the switch-over point between SLM and conventional methods increases. Moreover, as the raw material supply chain for titanium is transformed through the use of this novel extraction method, the manufacturing supply chain is simplified.     

Cumulative manufacturing capabilities: an extended model and new empirical evidence

There has been intense debate in the manufacturing strategy literature on the way in which firms work on different manufacturing capabilities, with two opposing approaches considered – the trade-off model and the sand cone model. Analysis of these models has essentially been based on study of the links amongst four classic manufacturing capabilities (quality, delivery, flexibility, and cost efficiency) and has obviated the need to consider environmental protection as an important manufacturing capability. This study analyses the theoretical arguments and the prior empirical evidence on the two models, and proposes and tests an extended sand cone model which includes the environmental protection objective alongside the four traditional ones. The research uses structural equation modelling and data from a sample of 274 manufacturers to contribute additional empirical evidence on the existence of cumulative effects amongst manufacturing capabilities. It is observed that the predominant strategic model in these firms is one of multiple, non-incompatible capabilities with cumulative effects according to the following sequence: quality, delivery, flexibility, environmental protection, and cost efficiency.     

Manufacturing lot-sizing,procurement and delivery schedules over a finite planning horizon

In this study, an integrated manufacturing system for technology-related companies whose products are experiencing continuous price decrease during the life cycle is studied for optimal procurement, production and delivery schedules over a finite planning horizon. The model considers the inventory cost both at manufacturing and at delivery from supplier. Since the price is continuously decreasing, a manufacturing firm delivers the finished goods in small quantities frequently. Frequent deliveries in small lots are effective to reduce the total cost of the supply chain. The key for high-tech industries is to reduce the inventory holding time since the component prices are continuously decreasing, and this can only be achieved by implementing an efficient supply chain. Therefore, the main purpose of this paper is to develop an integrated inventory model for high-tech industries in JIT environment under continuous price decrease over finite planning horizon while effectively and successfully accomplishing supply chain integration so that the total cost of the system is minimal. An efficient algorithm is developed to determine the optimal or near-optimal lot sizes for raw material procurement, and manufacturing batch under a finite planning horizon. Finally, the solution technique developed for the model is illustrated with numerical examples.     

Design of cellular manufacturing system with quasi-dynamic dual resource using multi-objective GA

A new concept is presented in this paper of quasi-dynamic cell formation for the design of a cellular manufacturing system, based on analysing the fact that static and dynamic cell formation could not reflect the real situation of a modern cellular manufacturing system. Further, workforce resources are integrated into quasi-dynamic cell formation and thus a quasi-dynamic dual-resource cell-formation problem is proposed. For solving this problem, this paper first establishes a non-linear mixed integer programming model, where inter-cell and intra-cell material cost, machine relocation cost, worker operation time, loss in batch quality and worker salary are to be minimised. Then, a multi-objective GA is developed to solve this model. Finally, a real life case study is conducted to validate the proposed model and algorithm. The actual operation results show that the case enterprise significantly decreases its material handling cost and workforce number and obviously increases its product quality after carrying out the obtained scheme.     

A machine learning approach to optimise the usage of recycled material in a remanufacturing environment

Remanufacturing has acquired importance in recent years because of the increasing environmental concerns of manufacturing processes that deplete the Earth's resources. Some examples of remanufactured products are automobile parts, furniture, photocopiers, and computer printers. In a remanufacturing setup, raw materials are drawn from two sources: (i) ‘cores’, which are obtained from recycled products, and (ii) ‘non-recycled’ or unused materials, which are produced from minerals freshly mined from the earth. An important decision for the manager is to select material optimally from these two sources. Using cores has environmental benefits, and because they are cheap, they reduce manufacturing costs. However, their use generally increases the production time, because of the additional pre-processing usually needed, which can negatively impact service levels. When the supply of finished products is running low, to satisfy service levels, it makes sense to use unused material. This research focuses on identifying an optimal strategy of switching between the two sources of material. A reinforcement learning algorithm is used to solve the switching problem. The switching algorithm produced encouraging results, showing up to 65% cost improvements over a policy that uses only unused materials.     

Fuzzy quality feature monitoring model

In this paper we study the modern techniques and also present a fuzzy quality monitoring model that can be used at various stages in a production operation (the raw material input stage, between production stages). The product quality may be of several types (i.e. sensory, physical, time orientation) that sometimes may not be sensed, measured, or calculated precisely due to uncertain situations. Therefore, the γ -level fuzzy Bayesian model for quality monitoring of a manufacturing process is proposed. In order to apply the Bayesian concept, the fuzzy quality characteristics are assumed as fuzzy random variables. Using the fuzzy quality characteristics, the newly developed model calculates the risk of operation for the manufacturing process, which results in determining the out-of-control process. A numerical example is also presented to demonstrate the application of the model.     

精制盐代替原盐生产煤矿许用铵梯炸药

文中以精制盐加工工艺理论为指导，进行了精制盐代原盐，取消原盐焙烧制造煤矿许用铵梯炸药的尝试。精制盐替代原盐具有降低材料成本，概治环境污染，简化工艺过程，提高炸药组分初检合格率等优点。     

An optimal batch size for an imperfect production system with quality assurance and rework

We consider a manufacturing system which receives raw material from a supplier, processes it, and delivers it to the customer periodically. The system considered is imperfect and produces defectives at a constant rate. The finished product can only be delivered if the whole lot is quality-certified. Hence, defectives have to be reworked, and the whole lot quality-checked within the cycle. Three different scenarios are considered, viz. (a) a single lot of raw material for multiple lot of finished product and delivery of the product in multiple instalments, (b) a single lot of raw material for a multiple lot of finished product and delivery of the product in a single instalment, and (c) lot-for-lot and delivery of finished product in single instalment. A total cost equation is developed for each model, and the optimal ordering quantities are evaluated. The results found are encouraging and quite simple to use for practical purposes.     

非粮质生物能源供应链优化设计研究

开发和利用生物能源可以在一定程度上缓解我国面临的能源紧张的局面。为了实现对生物能源的精益开发,有必要研究生物能源供应链的优化设计问题。在考虑原材料产量约束、精炼厂生产能力约束和需求满足约束的基础上,建立了以追求生物能源供应链总成本最小化为目标的整数规划模型,通过CPLEX软件进行求解,最终决策精炼厂的选址、精炼厂的规模设计及其年产量,并确定原材料产地、精炼厂和需求地三者之间的供应关系和配送量。以辽宁省的数据为实际算例,验证了模型的有效性。在总成本中,精炼厂的生产成本比重最大,约为总成本的59%,而运输成本最小约为8%。在此基础之上进行了灵敏性分析,讨论了该模型在价格和需求发生变化时的不同表现。     

精密锻造技术的研究进展与发展趋势

热精密锻造技术不仅能赋予零件近净复杂形状和尺寸,而且能使零件宏观性能在坯料性能基础上得到提高,是少无废料产生、绿色、节约型的高效高性能制造技术。综述了热精密锻造技术的应用现状,介绍了热模锻造、等温锻造、基于数值模拟的预制坯优化设计和精密锻造全过程工艺优化设计的国内外研究现状,最后对热精密锻造技术发展方向进行了展望。     

Simultaneous tolerance synthesis for manufacturing and quality

Tolerance allocation affects product design, manufacturing, and quality. No existing technique has been found by the authors that takes product design, manufacturing, and quality into account simultaneously. This paper introduces a new concurrent engineering method for tolerance allocation. A nonlinear optimization model was constructed to implement the method. The model minimizes the combination of quality loss and manufacturing cost simultaneously in a single objective function by setting both process tolerances and design tolerances simultaneously. The purpose of the model is to balance manufacturing cost and quality loss to achieve near-optimal design and process tolerances simultaneously for minimum combined manufacturing cost and quality loss over the life of the product. Compared to other models, this model shows significant improvements. Electronic Publication