Adjusting MRP for dynamic differentiation of identical items for process customisation

In the make-to-order (MTO) environment, different customer orders often require similar products that share identical basic features but require different customisation processes. To achieve efficiency, these products are often manufactured in a group at the initial stages. A significant issue then emerges as to how to differentiate identical items at the intermediate stages so that they can be dispatched to different kinds of work centres for process customisation. This article adjusts the current material requirements planning (MRP) approach for the MTO mode. A yield-allocating approach is then proposed for adjusting the material demand plans according to real-time process quality information. An approach for dynamically differentiating identical customised items at intermediate stages is then presented. How to implement the proposed methodology in a computer-based environment is also briefly introduced. A case study demonstrates that the proposed methodology can fulfil the dynamical differentiation task and can result in more reasonable differentiation decisions than the traditional MRP approach.     

The impact of manufacturing and supply chain improvement initiatives: A survey comparing make-to-order and make-to-stock firms

Manufacturing firms aim at improving both internal and external processes to improve the competitive advantage. Such initiatives include lean practices as well as supplier rationalization and integration. In this paper, we analyze these improvement initiatives and their impact on business performance. In particular, we explore potential differences between make-to-order (MTO) and make-to-stock (MTS) firms. We use data from 216 Australian manufacturing firms. We find a clear difference of improvement focus between MTO and MTS firms. MTO firms exhibit a significant impact of supplier integration on business performance, but not for lean practices and supplier rationalization. The situation is completely reversed for MTS firms, since they have significant effects for internal lean practices and supplier rationalization, but not for logistics integration with supplier. The results show that the distinction between MTO and MTS firms is important when analyzing manufacturing and supply chain improvement initiatives.     

REDUTEX: a hybrid push–pull production system approach for reliable delivery time in knitting SMEs

The textile sector is composed of small and medium enterprises (SMEs) worldwide. Nowadays there is a shortage of technological knowledge in SMEs. Lead time is a critical indicator in any productive company organisation. The aim of this research was to provide an approach, called REDUTEX, based on theoretical concepts of lean and synchronous manufacturing in order to help to understand the behaviour of SMEs and to improve the manufacturing process by reducing the customer lead times. The integration of these philosophies is the basis of REDUTEX; a hybrid push–pull production system approach to knitting SMEs. With this approach, it is possible to obtain a process reliability when the restrictive resource capacity (RRC) is identified, optimised and protected. By synchronising all activities to the rhythm of RRC, through a continuous flow, it is possible to obtain high-impact results through a dual automated system and product quality, through a visual control. REDUTEX uses a push system from the RRC to the location of the supermarket, where accumulated inventory may be distributed in the internal assembly department and external family workshops, making a pull system. Subsequent re-assembly processes use a push system until the end of the product. The stages of REDUTEX are explicitly described and applied to real data, so that the staff of SMEs can easily understand the behaviour of the process and implement it. One of the advantages of REDUTEX is that it does not need highly trained staff. The research methodology was conducted as a case of study in twelve SMEs and validated and implemented in three textile companies of the southern area of the state of Guanajuato in Mexico, obtaining reliable delivery times and very promising results.     

An adaptive approach to shop loading

This paper extends previous approaches to loading job shops by simultaneously considering work in progress, inventory levels as well as work load smoothing. The approach is based on a heuristic and is relatively simple in application to a practical manufacturing system. A further enhancement is proposed using a computer search routine to home in on desirable performance. The search routine sets the values of coefficients in the heuristic and so gives a loading procedure that adapts to a particular manufacturing system. The overall results indicate that the approaches proposed give substantial benefits over previous methods.     

Pull system performance measures: a review of approaches for system design and control

Abstract

Research into the effect of three factors on four major system performance measures for pull system design and control are reviewed. The three factors are: (1) qualitative or quantitative nature of the approach, (2) traditional production control or pull system approach, and (3) systems/integrative characteristics of the approach for the performance measures. The four performance measures are: (I) throughput, (2) quality, (3) material Dow, and (4) flexibility. Articles were evaluated in terms of the performance measures and factors with several articles discussed in depth, Journals and other sources were chosen to be searched based on the source having published refereed articles related to pull system performance evaluation. Articles on quantitative pull systems are not well represented in the literature. Traditional approach methods     

A practical approach to achieving Agility–a theory of constraints perspective

This article documents an action research (AR) project aimed at identifying the practical steps needed to become an agile manufacturer through a combination of the theory of constraints (TOC) and resource- based view (RBV) approaches in a small to medium enterprise (SME) in the Australian manufacturing sector. To date, lean production has been highlighted as a possible catalyst for creating an agile manufacturer, despite the evidence suggesting that lean manufacturing lacks the responsiveness and adaptability to effectively handle a rapidly changing market place and only works well in a stable environment. A more flexible system of production is required to fully encompass the agile characteristics needed to attain a competitive advantage. This research provides empirical evidence that the TOC perspective can be used as a practical approach for becoming an agile manufacturer. The study provides a workable approach for small firms to achieve ‘Agility’ in practice.     

Development and validation of a lean supply chain management measurement instrument

It is widely argued that to be competitive, a company not only needs to focus on internal aspects but on the entire supply chain. Lean supply chain management has become a means of enhancing competitiveness by improving efficiency and increasing flexibility at all stages of the supply chain. This research develops and validates a lean supply chain management measurement instrument. A two-phase approach is used for scale development and refinement. In the first phase, a literature review is conducted to identify definitions of lean supply chain management and agile supply chain management and their corresponding measurement items. In the second phase, the lean supply chain management measurement instrument is validated using survey data based on scales developed in the first phase by 59 scholars with experience in lean management and/or supply chain management. The results provide a structured and comprehensive measure of lean supply chain management indicating that there are two differentiated dimensions in the measurement instrument: one related to the operational aspects of lean supply chain strategy implementation and the second related to lean supply chain planning.     

Implementing lean sigma framework in an Indian automotive valves manufacturing organisation: a case study

The manufacturing organisations have been witnessing a key transition to lean manufacturing paradigm so as to eliminate waste. Concurrently, six sigma methodology has been widely used for reducing the defects. In order to attain the combined benefits of these two approaches, the amalgamated lean sigma framework has originated. Lean sigma framework proves drawbacks, such as lack of systematic and scientific management and feeble lean anchorage. In order to overcome these deficiencies, this article contributes a refined lean sigma framework, and its effectiveness has been test implemented in an Indian automotive valves manufacturing organisation. The implementation benefits are described in this article.     

Employee referrals: A study of ‘close ties’ and career benefits in China

This study examines the relationship between employee referrals and employees’ job tenure through the lens of social capital theory. It does so by considering the tie strength (closeness of guanxi) between referrers and referred employees in the Chinese context. In particular, we examine the mediating effect of career benefits. We theorize that close guanxi has a significant and positive impact on the job tenure of referred employees, and that career benefits (such as having a managerial role) mediate the close guanxi effect on job tenure. This highlights the critical need to recognize the tie strength as between referrers and referred employees. The support for our hypotheses comes from the use of personnel records of 4030 employees over 13 years in one large privately-owned manufacturer in China. Our study has theoretical and practical implications for the relational approach to tackling voluntary turnover in the workplace.     

基于系统柔性的MTS-MTO混合生产决策

研究生产商采用MTS、MTO混合作业的方式为不同客户提供产品和服务的策略。计划利用一组可灵活控制的动态设备处理那些不同需求的MTS和MTO生产业务,为此,我们开发了一个多服务台的排队模型,利用拟生灭过程和相位型分布得到了MTS、MTO排队系统平衡条件和稳态概率矩阵几何解。通过求解分块矩阵方程组,给出了系统队列长度、平均等待队长、顾客服务水平等绩效测度指标。建立了系统运作成本最优化的数学模型,采用搜索算法,确定了关键参数的边界值,找到了混合系统运作的最优策略。数值模拟和系统绩效比较分析结果显示：（1）动态切换策略能够更快速的帮助MTS恢复目标库存量,控制系统缺货风险,降低库存持有成本;（2）找到了满足顾客服务水平的最少的设备配置数量和库存成本最低的生产切换时间,且动态系统的平均队列长度低于静态系统;（3）混合运作策略减少了约2/3的静态系统平均队列长度,企业在队列长度减小的窗口期内可以接受更多订单和缩短MTO订单交货时间。     

Search based job scheduling and sequencing with setup times

The problem of sequencing jobs on a machine in a job shop has been approached by a number of researchers and practitioners. One of the most popular methods is to apply a priority rule to the queue at each machine. The authors have previously published details of an approach which sets the priority of a job as a linear combination of the operation times and due date for that job. The coefficients in the linear combination are set by a simulation and search procedure so as to give good performance based on the performance measure specified. This paper extends this approach to include setup time factors. This extended approach is then applied to data from an actual manufacturing system. The extended approach is shown to improve the performance of the manufacturing system in relation to existing techniques.     

Learning and Bayesian updating in long cycle made-to-order (MTO) production

We model production planning for made-to-order (MTO) manufacturing by choosing production rate to minimize expected discounted cost incurred up to a promised delivery date. Products that are MTO are often unique and customized. The associated learning curve slope and other production parameters cannot be precisely estimated before production starts. In this paper, a dynamic and adaptive approach to estimate the effects of learning and to optimize next period production is developed. This approach offers a closed-loop solution through stochastic dynamic programming. Monthly production data are used to update the joint probability distributions of production parameters via Bayesian methods. Our approach is illustrated using historical earned-value data from the Black Hawk Helicopter Program. Managerial insights are obtained and discussed.     

Lampshade Game for lean manufacturing

The purpose of this article is to introduce a new simulation game named the ‘Lampshade Game’ that can be helpful in educating students and industry professionals on lean manufacturing principles. The Lampshade Game is an active learning tool that is capable of demonstrating the advantages and disadvantages of some of the key principles of lean manufacturing (such as quality focus, pull system, flexible manufacturing and visual organisation) in comparison to craft and mass manufacturing by manually simulating the production of lampshades for each of the process types. The game enables the comparison of these three manufacturing methods using different operational and financial metrics such as inventory levels, manufacturing cycle time, customer fill rate, production yield and cost and profit. This article describes the game, its objectives, and shares experiences from several classroom implementations including an analysis of pre- and post-surveys.     

The impact of lean practices on operational performance – an empirical investigation of Indian process industries

In deciding to adopt lean manufacturing, it is imperative to investigate where and how lean practices are most needed to influence manufacturing and business performance. Such an investigation becomes indispensable when lean thinking is to be considered in a production arrangement different to the conventional, repetitive, high-volume, stable-demand and discrete-manufacturing environment. This study provides explanations of how performance is improved through the adoption of lean practices in process industries. This is a relatively under-researched area compared to the performance effects associated with the introduction and implementation of lean principles in traditional, discrete manufacturing. Based on a survey of Indian process industries, this study attempts to develop an empirical relationship between lean practices and performance improvement through the use of multivariate statistical analysis. The findings have led to the conclusion that lean practices are positively associated with timely deliveries, productivity, first-pass yield, elimination of waste, reduction in inventory, reduction in costs, reduction in defects and improved demand management. However, within a process-industry context, lean practices related to pull production were found to have a marginal impact on performance improvement. A detailed discussion of the findings along with their theoretical and managerial implications is provided in the paper.     

Experimental push/pull production planning and control system

We introduce an experimental push/ pull production planning and control software system which is designed as an alternative to a MRP-II system for mass manufacturing enterprises in China. It has the following distinguishing features: (1) putting the philosophy of JIT into the master production scheduling of MRP-II via the earliness/ tardiness production planning method; (2) controlling material input by push and processing/ assembly by pull; and (3) adjusting the parameters of the production line by the‘ suggestion for improvement of production line’ module. Simulation results have shown that the proposed system can achieve better planning and control performance than existing systems.     

The sensitivity of job mix and load capacity bottlenecks on inventory and due date performance in a manufacturing system

Based on a benchmark job-lot manufacturing system a simulation study was carried out to compare the performance of just-in-time (JIT) shop control system Kanban with conventional job-shop control procedures. The shop control policies were tested under a good manufacturing environment and the effects of job mix and load capacity bottlenecks on various shop control policies were tested. From the simulation results, it is inferred that there are shop control procedures that perform better than the Kanban in a job shop. It has been observed that even with adequate capacity, bottleneck areas surface due to fluctuations in the shop load. Kanban is not appropriate in such a situation because capacity bottlenecks can significantly reduce the ell'ectiveness of a pull system. The disparateness in the processing requirements for jobs can seriously undermine the performance of the shop. This is the type of shop environment where the shop control procedures will be most effective. Although Kanban came out best when the load capacity bottlenecks and the disparateness of the job mix were removed, the selected shop control variable combinations closely approximated the Kanban result. Although many features of JIT can be implemented in any system, companies trying to adopt JIT should remember that Kanban requires a rigid system intolerant of any deviation.     

Public sector managers: the decision to leave or remain in a job

The public sector faces a grave problem as far as managerial retention as the result of the increasing number of retirements and of voluntary resignations. Despite the vital interest in managerial turnover in the public sector, research is scarce. This study, which increases our understanding of why public sector managers leave their positions, takes a qualitative and narrative research approach in examining voluntary turnover. Interviews were conducted with operations managers (in education, social care, and technical activities) at three Swedish municipalities. We identify a multitude of environment push and pull factors with a focus on administrative support, supervisory support and illegitimate tasks. The narratives of managerial turnover reveal the complexity of the decision to leave or remain in a job, containing a mixture of push and pull factors, negative feelings, unmet expectations and extraordinary events. Three possible HRD actions to decrease undesirable managerial turnover are identified: re-work organizational structures; re-model job characteristics; and re-examine managerial turnover decisions as a long and complex process. Our hope is that the findings are used for ultimately create healthy organizations.     

Evaluation of scheduling strategies for a dynamic job shop in a tool-shared,flexible manufacturing environment

A two-phase approach is used to examine the impact of job scheduling rules and tool selection policies for a dynamic job shop system in a tool-shared, flexible manufacturing environment. The first phase develops a generalized simulation model and analyses 'simple' job scheduling rules and tool selection policies under various operating scenarios. The results from this investigation are then used to develop and analyse various bi-criteria rules in the second phase of this study. The results show that the scheduling rules have the most significant impact on system performance, particularly at high shop load levels. Tool selection policies affect some of the performance measures, most notably, proportion of tardy jobs, to a lesser degree. Higher machine utilizations can be obtained at higher tool duplication levels but at the expense of increased tooling costs and lower tool utilization. The results also show that using different processing time distributions may have a significant impact on shop performance.     

Benefits of adopting lean production on green performance of SMEs: a case study

Abstract

Small- and medium-sized enterprises (SMEs) are widely recommended to strive, not only for their performance in operational side, but they need to integrate the environmental dimension. To do that, the literature widely indicates a positive impact of lean practices on green performance. However, very few studies have been carried out in SMEs context. In this view, this paper aims at providing through a practical case study of lean implementation in a real-life small manufacturing company, the information to confirm this synergy between lean and green performance. To achieve this aim, a proposed framework of lean and green integration has been implemented in a SME producing different types of pumps. The results achieved shows that there is a strong correlation between operational metrics improvement and green metrics improvement. Moreover, the benefits of lean practices such as 5S, Kanban, SMED, AM, cellular manufacturing and quality control on green performance are widely demonstrated. Future work could study other processes and explore other case-specific supporting tools and techniques.     

Reference model for implementing an MRP system in a highly diverse component and seasonal lean production environment

Companies are currently choosing to integrate logics and systems to achieve better solutions. These combinations also include companies striving to join the logic of material requirement planning (MRP) system with the systems of lean production. The purpose of this article was to design an MRP as part of the implementation of an enterprise resource planning (ERP) in a company that produces agricultural implements, which has used the lean production system since 1998. This proposal is based on the innovation theory, theory networks, lean production systems, ERP systems and the hybrid production systems, which use both components and MRP systems, as concepts of lean production systems. The analytical approach of innovation networks enables verification of the links and relationships among the companies and departments of the same corporation. The analysis begins with the MRP implementation project carried out in a Brazilian metallurgical company and follows through the operationalisation of the MRP project, until its production stabilisation. The main point is that the MRP system should help the company's operations with regard to its effective agility to respond in time to demand fluctuations, facilitating the creation process and controlling the branch offices in other countries that use components produced in the matrix, hence ensuring more accurate estimates of stockpiles. Consequently, it presents the enterprise knowledge development organisational modelling methodology in order to represent further models (goals, actors and resources, business rules, business process and concepts) that should be included in this MRP implementation process for the new configuration of the production system.