Simple subcontracting rules for make-to-order shops with limited subcontractor capacity: an assessment by simulation

Companies that produce a high variety of customised products often suffer from large fluctuations in demand. Subcontracting can be an important means of overcoming resulting capacity shortages during high demand periods. A set of effective subcontracting rules, for determining which jobs to subcontract and which to produce internally, has recently been presented in the literature for this type of company. But evaluations of these rules have assumed subcontractor capacity is infinite. This study examines the impact of limited subcontractor capacity on the performance of the three best-performing subcontracting rules for make-to-order companies using a simulation model of an assembly job shop. Limiting subcontractor capacity inhibits the ability of a subcontracting rule to protect the internal shop from surges in demand, which negatively affects performance. However, significant performance differences between the rules evaluated are maintained, which underlines the importance of choosing the right subcontracting rule. Further analysis reveals that a limit on the work that can be subcontracted leads to less work being subcontracted more often, which requires adequate response by management. Meanwhile, the assumption of infinite capacity results in sporadically subcontracting a large amount of work. The results have important implications for future research and practice.     

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.     

有限分布信息条件下MTO再制造系统提前期优化

在只知道零部件再制造时间有限分布信息（即一阶矩、二阶矩）条件下,基于MTO再制造策略研究由再制件和采购件组成的再制品的提前期问题,该问题被描述为一个矩问题。以最小化库存持有成本和缺货成本为目标建立min-max优化模型,在具有相同一阶矩、二阶矩的分布集合中寻找使最坏分布下的目标函数值最小的最优再制造提前期。最后通过算例进行了验证,求解结果与传统假设再制造时间服从正态分布、均匀分布得到的结果吻合较好,但本文的方法更符合生产实际,能保证在具有同样一阶矩和二阶矩的所有分布情况下的解的鲁棒性,对企业制定再制造计划、采购计划等具有现实的指导意义。     

Information architecture for effective Workload Control: an insight from a successful implementation

The implementation of Workload Control (WLC), a Production Planning and Control concept uniquely designed for Make-To-Order companies, has been a constant challenge. Scholars argued that WLC is largely developed through simulations of well-defined environments while much more complex circumstances (e.g. information availability) have emerged in field research. A recent trend of WLC research is to improve the practical applicability of the concept, where empirical evidence is essential. However, success in WLC implementation remains impeded. The availability of data has been a significant area that frustrates the implementation process. While there is a tendency to simplify data requirements in recent WLC theory development, it is important to understand and maintain the information that is essential for the concept to be effective. For the first time in the field, this paper details the information architecture for WLC. Key informational entities of relevance to the input/output control functions in WLC as well as performance measurement are discussed based on evidence from a successful implementation. The paper not only sheds light for practitioners on how to construct an information system that facilitates successful WLC implementation but also has implications for future development of WLC mechanisms coping with information uncertainties in practice.     

信息不对称对闭环供应链MTO和MTS模式的影响研究

在MTO(按订单生产)和MTS(按库存生产)两种模式下,比对了信息不对称和信息共享下产品定价、废旧品回收率和零售商利润的区别,研究结果显示:(1) 产品定价、废旧品回收率和零售商利润不受生产模式改变的影响;(2) 在某些条件下,信息共享下产品的批发价、零售价、和废旧品回收率均高于信息不对称时的相应值,进行信息共享会增加闭环供应链的总体利润,但零售商有可能通过信息共享丧失信息优势,从而使得其利润受损。因此为了促使零售商参与信息共享,信息共享参与方应投资建立安全的通信系统,以保证共享信息不被泄露。另外本文通过引入纳什讨价还价模型建立了一个公平的利润划拨机制,该机制使得最后的利润划分只取决于各参与方的议价能力,与各参与方对通信系统投资大小无关。     

绿色供应链中不对称需求预测下的信息共享研究

研究了由一个制造商和一个零售商组成的绿色供应链和他们的需求预测信息共享问题。考虑了两种方案：订货型生产方案和库存型生产方案，两种方案下分别考虑了无信息共享和信息共享两种情况。分析了预测信息对两种方案下制造商利润、零售商利润和信息共享价值的影响，同时研究了绿色成本系数对信息共享的影响。研究表明，两种方案中制造商始终能从信息共享中获利，而零售商只有在制造商绿色成本系数较低时才会自愿共享预测信息。当绿色成本系数较高时，制造商可以通过一个讨价还价合同，促进零售商进行信息共享。当绿色成本系数很高时，供应链成员之间不存在信息共享。此外，库存型生产方案中信息共享带来的总收益增量要高于订货型生产方案，因此，库存型生产方案中参与者信息共享的可能性要高于订货型生产方案。     

顾客可能取消订单的MTO企业订单定价策略

研究了顾客下订单后可能取消订单的按订单生产型企业的定价策略。顾客到达后向企业询问订单报价,如果价格合适,顾客将下订单,否则选择离开。引入了顾客接受概率模型,以最大化订单期望利润为目标,得出了订单最优定价和最大期望利润。通过分析最优定价和最大期望利润对于各参数的敏感性得出:最优定价是系统积压订单数的增函数,是订单取消概率和取消订单赔偿比例的减函数;而最大期望利润是系统积压订单数的减函数,是取消订单赔偿比例的增函数。通过数值分析发现,在顾客确实可能取消订单的背景下,如果决策者在对订单进行定价时不考虑这一可能性,将会减小企业获得的最大期望利润。