Combination of Lean value-oriented conception and facility layout design for even more significant efficiency improvement and cost reduction

Global market competition and fluctuating customers’ demands require manufacturing enterprises to focus on cost reduction and efficiency improvement to increase competitiveness and sustainability. The purpose of the research was the elaboration of the methodology and procedure of a new combined efficiency improvement method which basically applies Lean methods and also uses the facility layout design (FLD) method simultaneously, integrating the different advantages of these methods, which is even more efficient that applying each of the methods individually. The main significant added-value of the study is the elaboration of a new combined method, which results in even more significant improvement of efficiency and several KPIs, furthermore, cost reduction, which is confirmed by a real case study for the improvement of a manufacturing plant. In the case study, the application of 13 Lean methods and the FLD method (which aims at the minimisation of material workflow, travel distance of materials, material handling cost and space used for assembly) led to the improvement of 10 quantitative and 5 qualitative indicators: productivity; cycle-time; number of workstations and operators; WIP (work-in-process) inventories; space used for assembly; material workflow; travel distance of materials; material handling cost; labour cost; component supply; products’ quality; transparency; standardisation; workplace ergonomics.     

Quality improvement methods for hexahedral element meshes adaptively generated using grid‐based algorithm

The quality of finite element meshes is one of the key factors that affects the accuracy and reliability of numerical simulation results of many science and engineering problems. In order to solve the problem wherein the surface elements of the mesh generated by the grid‐based method have poor quality, this paper studied mesh quality improvement methods, including node position smoothing and topological optimization. A curvature‐based Laplacian scheme was used for smoothing of nodes on the C‐edges, which combined the normal component with the tangential component of the Laplacian operator at the curved boundary. A projection‐based Laplacian algorithm for smoothing the remaining boundary nodes was established. The deviation of the newly smoothed node from the practical surface of the solid model was solved. A node‐ and area‐weighted combination method was proposed for smoothing of interior nodes. Five element‐inserting modes, three element‐collapsing modes and three mixed modes for topological optimization were newly established. The rules for harmonious application and conformity problem of each mode, especially the mixed mode, were provided. Finally, several examples were given to demonstrate the practicability and validity of the mesh quality improvement methods presented in this paper. Copyright © 2011 John Wiley & Sons, Ltd.     

Concurrent optimal allocation of design and process tolerances for mechanical assemblies with interrelated dimension chains

Concurrent tolerance allocation has been the focus of extensive research, yet very few researchers have considered how to concurrently allocate design and process tolerances for mechanical assemblies with interrelated dimension chains. To address this question, this paper presents a new tolerance allocation method that applies the concept of concurrent engineering. The proposed method allocates the required functional assembly tolerances to the design and process tolerances by formulating the tolerance allocation problem into a comprehensive model and solving the model using a non-linear programming software package. A multivariate quality loss function of interrelated critical dimensions is first derived, each component design tolerance is formulated as the function of its related process tolerances according to the given process planning, both manufacturing cost and quality loss are further expressed as functions of process tolerances. And then, the objective function of the model, which is to minimize the sum of manufacturing cost and expected quality loss, is established and the constraints are formulated based on the assembly requirements and process constraints. The purpose of the model is to balance manufacturing cost and quality loss so that concurrent optimal allocation of design and process tolerances is realized and quality improvement and product cost reduction is achieved. The proposed method is tested on a practical example.     

Financial incentives for ambulatory care performance improvement.

BACKGROUND: Measuring and improving the quality of care while curtailing costs are essential objectives in capitated care. As patient care moves from the hospital to outpatient settings, quality management resources must be shifted to ambulatory care process improvement. The Quality Improvement and Efficiency Financial Incentives Program at Stanford University Medical Center was adopted to increase quality improvement efforts and contain costs. THE INCENTIVE PROGRAM: Each department's budget for care of capitated patients was reduced by 5% from the previous year. Return of a reserve fund (10% of payments for specialty care) required completion of substantive quality improvement projects and containing costs. Successful departments were also eligible for bonus funds. Implementation strategies included endorsement by clinical leaders, physician education, use of administrative data to identify project topics and support measurement of quality and cost variables, project templates and time lines, and the availability of clinical quality managers with special expertise in clinical process improvement. RESULTS: Eight of 13 clinical departments developed and implemented 19 ambulatory quality improvement projects to varying degrees. Success in the program was roughly correlated with the potential impact of the incentive on revenues and the status of the lead person selected by the department to spearhead their efforts. Only 5 departments achieved their cost containment goals. DISCUSSION: Financial incentives are one method of encouraging physicians to use clinical process improvement methods. Endorsement by clinical leaders and selection of realistic beginning projects enhance chances for success. The capitated population has attributes that make it an attractive focus for initial quality improvement efforts.     

Optimal process control for multiple dependent subprocesses

A renewal theory approach is proposed to derive the cost model for multiple dependent subprocesses. The optimal individual Y control chart and multiple cause-selecting control chart are thus constructed to monitor the overall product quality and specific product quality contributed by the multiple dependent subprocesses. They can be used to maintain the process with minimum cost and effectively distinguish which component of the subprocesses is out of control. The optimal design parameters of the proposed control charts can be determined by minimizing the cost model using a simple grid search method. An example is given to illustrate the application of the optimal individual Y control chart and multiple cause-selecting control chart. © 1998 John Wiley & Sons, Ltd.     

基于价值工程的民用飞机维修目标成本分配

基于价值工程相关理论,利用模糊综合评价方法确定民用飞机各系统或部件的功能评价值,进而确定民用飞机各系统的成本系数,进行目标成本分配。文章寻求民用飞机维修目标成本分配的新思路,对现实工作具有指导和借鉴意义。     

集成化质量管理系统的设计开发

通过对我国制造业所面临的主要质量改进问题的分析,以笔者开发的集成化质量管理系统为基础,阐述了面向制造业的集成化计算机辅助质量管理系统的设计开发方法。所开发的系统实现了质量管理工具和方法的集成应用,为制造业持续质量改进提供了一个基础管理平台。     

价值工程在某军用包装袋中的应用

目的 基于价值理论研究,以提高某军用包装袋价值的有效途径。方法 应用价值工程程序,首先对某军用包装袋的功能进行定量分析,然后计算出各零部件的成本及成本系数,再对零部件成本和功能匹配情况进行分析,找出价值系数不合适的零部件,最后对不合适的零部件提出建议,为该产品的改进提供方向。结果 运用价值功能理论分析发现,由于军用包装袋的可靠性要求,若提高功能其成本必然会提高,故仅能通过功能不变、降低成本的方法来提高价值。结论 通过对军用包装袋进行价值分析,可得出提高包装袋价值是降低成本的唯一途径,为军用包装的成本控制提供了新思路。     

Integrated predictive maintenance strategy for manufacturing systems by combining quality control and mission reliability analysis

Predictive maintenance (PdM) is an effective means to eliminate potential failures, ensure stable equipment operation and improve the mission reliability of manufacturing systems and the quality of products, which is the premise of intelligent manufacturing. Therefore, an integrated PdM strategy considering product quality level and mission reliability state is proposed regarding the intelligent manufacturing philosophy of ‘prediction and manufacturing’. First, the key process variables are identified and integrated into the evaluation of the equipment degradation state. Second, the quality deviation index is defined to describe the quality of the product quantitatively according to the co-effect of manufacturing system component reliability and product quality in the quality–reliability chain. Third, to achieve changeable production task demands, mission reliability is defined to characterise the equipment production states comprehensively. The optimal integrated PdM strategy, which combines quality control and mission reliability analysis, is obtained by minimising the total cost. Finally, a case study on decision-making with the integrated PdM strategy for a cylinder head manufacturing system is presented to validate the effectiveness of the proposed method. The final results shows that proposed method achieves approximately 26.02 and 20.54% cost improvement over periodic preventive maintenance and conventional condition-based maintenance respectively.     

基于共振稀疏分解和松鼠优化算法的滚动轴承故障诊断

共振稀疏分解方法在滚动轴承故障诊断方面得到广泛应用,分解参数的选取对故障分离效果起决定性影响.为保证参数选择的准确性,提出基于松鼠算法的自适应共振稀疏分解多参数优化方法.以信号低共振分量峭度最大作为目标,使用松鼠算法同时优化共振稀疏分解的品质因子与权重系数;利用最优品质因子和权重系数对滚动轴承振动信号进行共振稀疏分解,...     

A cost-based method for comparing alternative refrigerants applied to R-22 systems: Remplacement du R22: méthode de comparaison des frigorigènes candidats

This paper describes the development and application of a general purpose method for comparing alternative refrigerants. The method utilizes a single performance index based upon minimum cost for a simplified system operating with a given cooling capacity and efficiency. The cost-based method is an improvement over other methods for evaluating refrigerants in that it more appropriately considers the influence of both thermodynamic and transport properties on refrigerant choice and it allows consideration of additional costs associated with some replacements (e.g. safety features for flammable refrigerants). A computer model based upon this method was used to evaluate the performance of several leading R-22 replacement candidates for window air conditioners. Primarily, the cost differences between alternative refrigerants are associated with the heat exchangers and the refrigerant/oil requirements. The cost differences associated with different compressor displacement requirements were found to have a minor influence on overall cost differences. For the optimized systems, all of the alternatives had system costs that were within about 4% of those for R-22. Further, the differences between most of the alternative refrigerants were smaller than the uncertainties in the analysis.     

基于仿真的制冷产品质量预测与优化

产品质量的预测与优化是产品设计的关键。提出了基于仿真的制冷产品质量预测与优化方法,将现实中存在的不确定因素和设计参数的波动以概率分布的形式输入制冷系统仿真模型,并结合随机模型方法实现了在设计阶段对产品质量进行预测。同时提出了一种获取产品质量损失函数的新方法,即采用中心复合试验设计与蒙特卡洛模拟结合,获得设计能力指数随部件容差变化的响应面模型,将该模型作为约束条件,以成本最低为目标,对部件容差进行优化后显著提高了产品的质量与经济性。     

Flexible parts feeding for flexible assembly

A key obstacle to the economic application of flexible automation is parts feeding. Traditionally, dedicated devices such as vibratory bowl feeders have performed parts feeding. Such devices have a high cost, and are dedicated to a single component geometry and, consequently, the number of dedicated feeders required for a planned variety of products is equal to the number of distinct part types. This results in a high capital cost that can only be justified in a dedicated mass production environment, where there are long production runs and few product changes. Dedicated feeding methods are also usually too inflexible for robotic assembly systems where there is a wide range of component types in small batches being produced at lower rates. Flexible feeders capable of feeding many different part types are now commercially available but they are invariably large and costly. This paper describes a compact, low cost belt feeder prototype based on Pherson et al.'s (1983) concept but, which is capable of feeding complex geometries using modern sensor technology for part recognition, a standard non-active orientation blade, and a novel method for handling cylindrical parts.     

基于动态可靠度和经济优化相结合的服役桥梁维修加固风险决策

服役桥梁的维修加固需要综合考虑安全和经济的问题,基于服役桥梁的动态可靠度,以后续服役期内收益期望值最大或损失期望值最小为目标函数,对服役桥梁的维修加固决策进行了探讨,利用实际检测数据修正抗力模型,对一座服役期为35年的钢筋混凝土梁桥动态可靠度进行了计算,同时,比较分析了汽车荷载等级的提高和采用不同维护加固措施对后续服役期内动态可靠度的影响。该方法结合工程实际,把失效损失与失效风险相结合,对桥梁结构的维修加固决策有一定的指导作用。     

Optimal investment and lot-sizing policies for improved productivity and quality

Productivity and quality are an integrated component of the operational strategy of any firm. An increase in productivity implicitly assumes an improvement in quality. The concept of dynamic process quality control and smaller lot-size production have been employed to eliminate defective items, to reduce the cycle time of a product and to improve quality and productivity. We present a mathematical model to establish the relationship between various parameters of productivity and quality. In addition, the proposed model is used to determine the optimal levels of productivity and quality parameters such as batch sizes, and investment in set-up and process control operations. The basic criterion considered for optimizing the level of such parameters is the minimization of total system cost. The proposed model relates productivity and quality to set-up reduction, queueing of batches, batch sizes, and drift rate reduction. We conclude with an example problem to illustrate the behaviour and application of the model.     

A risk-adjusted exponentially weighted moving average control chart for detection of the scale parameter in surgical quality monitoring

Risk-adjusted control charts have been widely used in monitoring surgical quality in detecting risks of surgical performance. Most of the previous approaches focus on shifts in the location parameter as well as the existence of the scale parameter, which cannot get the full measure of the scale parameter under different levels. Ignoring the magnitude of the scale parameter, the monitoring methods cannot detect different variations of surgical mortality that is measured by scale parameter and required to reflect surgical quality improvement. The method of detecting variations in surgical quality is of interest in surgical quality improvement. This paper uses a new weighted h-likelihood method to obtain a weighted score test for the surgical risks from the logistic model. Then an exponentially weighted moving average chart can be constructed to monitor the changes in the variance of risks, which could be of interest in practical surgical monitoring programs. Simulation results indicate that the proposed approach performs more efficiently than existing methods under various magnitudes of shifts in scale parameters on top of different pre-set threshold stability. In addition, the application of the proposed method to real surgical data from the Surgical Outcome Monitoring and Improvement Program in Hong Kong shows the improvement and deterioration in a hospital's outcomes.     

工程和设计中人因工程学方法的适应性分析

目的 通过构建一个多维的人因工程学方法适应性分析模型,为人因工程领域研究人员在繁多的人因工程学方法中确定合适的方法解决工程和设计问题提供思路与指导.方法 调研人因工程学方法,构建了一个包含十一个大类76种人因工程学方法的方法集,然后从研究对象、信效度、资源成本以及时间成本四个维度对人因工程学方法的遴选过程展开分析,探讨了适应性分析模型各维度在应用过程中不同分析顺序、不同等级设定级别等对适应性分析的影响,通过案例探讨了该适应性分析方法在实际工作中的应用.结论 人因工程学方法适应性分析方法可以针对目标分析场景有效地筛选出合适的人因工程学研究方法,本方法具有简约直观的特点,在应用中不需要大量的计算,可以为人因工程学方法适应性分析提供方法筛选的思路.     

Robust tolerance design by computer experiment

Tolerance design affects the quality and cost of a product cycle time. Most of the literature on tolerance design problems has focused on developing exact methods to minimize manufacturing cost or quality loss. The inherent assumption in this approach is that the assembly function is known before a tolerance design problem is analysed. With the current development in CAD (Computer-Aided Design) software, design engineers can proceed with the tolerance design problems, without knowing assembly functions in advance. In this study, the Monte Carlo simulation is employed using VSA-3D/Pro software to obtain experimental data. Then the design of experiments (DOE) approach is adopted for data analysis in order to select critical components for cost reduction and quality improvement. Implementing the discussed computer experiments, a tolerance design analysis which improves quality and reduces cost can be performed for any complex assembly via computer during the early stage of design.     

Aspects of TBC service experience in aero engines

The frame conditions to apply advanced materials technologies in aero engines are envisaged from view point of an aircraft operator and performer of allocated maintenance repair and overhaul activities. Main targets are the reliable operation of the parts, the steady ecological improvement during operation and the reduction on overall cost per flight hour based on increased knowledge. The application of Thermal Barrier Coatings (TBCs) may contribute to reach these goals. They may – for example – add to optimised operation by reducing fuel consumption and by protecting important engine parts. The principles of a long term engine parts operation and repair philosophy are outlined to clarify the property requirements for reliable engine operation. Typical TBC‐protected components within actually operated civil aero engines are described. Silicate deposition on a HTP Blade and erosive attack of TBC is introduced exemplarily. A repair sequence to counteract surface degradation is introduced.     

Process quality improvement and setup reduction in dynamic lot-sizing

Previous work on setup reduction to dynamic lot-sizing with process improvement is extended. In this dynamic lot-sizing model, a new calculation of lot size is made at every setup, but the decision to invest jointly in setup reduction and process improvement is made at the initial setup. In the analysis, it is assumed that setup reduction and process quality are functions of capital expenditure. Such setup cost reductions and process quality improvements can arise from investing in new technology. A procedure is developed to find the optimal lot size, total cost, and required investments, and the solution is illustrated using declining exponential functions and power functions to model both setup cost reduction and process quality improvement. The implications of the analysis and the tradeoffs involved are discussed and illustrated numerically and graphically.