MRPⅡ/ERP概述及实例分析

介绍了MRPⅡ和ERP的概念、意义、原理及实施方法，并分析了我国企业实施MRPⅡ／ERP的现状，通过两个实例说明企业应当如何成功实施MRPⅡ／ERP系统。     

制造企业MRP实施方案解析

通过对ERP（企业资源计划）系统子模块MRP（物料需求计划）的上线方案的描述,阐述在制造企业如何成功实施及后续维护MRP系统,以期为企业建立提供决策、计划、控制与经营业绩评估的全方位和系统化的管理平台。     

ERP的渊源及其在石油物探企业的适用性

<正> 一、ERP的兴起(一)从MRP到MRPⅡ要想更好地理解ERP的概念,我们在此先谈谈它的前身——MRP和MRPⅡ。上个世纪60年代,随着技术的发展,计算机已经不再只是科研单位的专用工具,而是越来越多地走进了企业,为企业提供全面的数据存储和处理服务。同时,西方国家经济在经历了二战后的疯狂增长和繁荣之后,市场竞争变得更加激烈。在当时的社会生活中占据主导地位的汽车、石油、重工业企业,开始使用大型计算机来处理企业内部管理过程中的大量数据统计和运算工作。1965年,针对当时企业出现的供应滞后、交货不及时等问题,APICS(美国生产与库存管理协会)提出了MRP(物料需求计划)的概念。通过MRP管理软件的信息集成系统,企业对生产制造过程中的"销、产、供"等实现了信息集成,使得企业在库存管理上进行     

《制造业库存控制技术与策略》系列讲座之四库存控制与仓储的关系

物流管理流程中库存控制最关键的一个控制点是库存数据的准确性。 这一点从企业实施ERP的过程就可以得到印证。企业实施ERP要成功，要有两个标志，一个是库存数据准确性要达到95％以上；另一个是MRP是可运行的，也就是说这个企业是用MRP来下达采购与生产计划，而不是手工计划，并且MRP运行结果是可靠的。[第一段]     

ERP黑洞的认识根源

从1981年沈阳第一机床厂从德国工程师协会引进了第一套MRPⅡ软件以来,MRPⅡ类软件在中国的应用与推广已经走过了近20年的风雨历程。20年来我国企业在应用MRPⅡ/ERP系统方面投资80亿元人民币,但是成功率不到10％,达到预期目标的更是廖廖无几。还有一大批企业组织开发适用于自己的管理信息系统,但几乎无一成功。时至今日,我国仍有大批企业陷入自我挖掘ERP的高科技深潭。 然而,大量的研究与实践已经充分表明,ERP在我国应用的成败并不取决于技术、资金、互联网系统、应用     

基于BPR之ERP及其财务控制

企业资源计划(Enterprise Resources Planning 简称ERP,下同)自90年代初在美国兴起以来,很快地超越了管理信息系统MIS和制造资源计划MRP而成为市场的新亮点,大批有实力的公司先后研发并实施ERP系统。据有关资料知:《财富》500强中有四分之三以上的公司已经成功地启用了ERP系统。这些企业之所以能够成功地实施ERP系统,主要是因为其体制合理、机制灵活、制度先进、环境适宜、观念超前。它们勇于从根本上革新思想、改革体制、改进规制,善于在实质上创新业务、转换机制、再造流程,敢于在本质上推动管理、突出财务、强化控制,并且从需求出发,正确地选择软件厂商,同步落实技术基础和人员培训等工作。     

浅论实施企业管理信息化应关注的几个问题——实施ERP的几点感触与建议

山西煤机制造公司是为煤炭生产企业提供运输装备的大型煤机制造企业。1998年管理信息系统的建立,成功实施了当时在西方国家广泛应用的制造资源计划（MRPⅡ）计算机管理信息系统,为企业管理上水平打下了坚实的基础。     

管理软件在企业价值链中的地位和作用探析

本文从分析企业价值链入手 ,阐明了管理软件在其中处于重要的地位 ,并起着突出的作用。管理软件是企业价值链的生命线。在此基础上 ,简介了MRP、MRPⅡ和ERP等几个流行的管理软件。     

应用MRP实施汽车生产装配控制的途径

MRP必须建立在完善的企业管理基础工作之上。基础工作不健全,则MRP无法运行。反过来,实施MRP又对企业的基础工作有较强的促进作用。应用MRP实施汽车生产装配控制可采取如下途径。1　生产控制系统模型的建立及其特点大型汽车生产企业生产控制的关键环节在于汽车生产的装配生产过     

国外企业财务软件的发展历程

国外企业财务软件的发展与现代企业管理软件ERP的发展密不可分。ERP的发展大致经历了4个阶段(如表1所示)：MRP(Material Requirement Planning，物料需求计划)阶段(也称作基本MRP阶段)，闭环式(MRP(Closed Loop MRP)阶段，MRPⅡ(Manufacturing Resource Planning，制造资源计划)阶段，ERP(Enterprise Resource Planning，企业资源计划)阶段。     

How to unlock the benefits of MRP (materiel requirements planning) II and Just-in-Time

Manufacturing companies need to use the best and most applicable parts of MRP II and JIT to run their businesses effectively. MRP II provides the methodology to plan and control the total resources of the company and focuses on the processes that add value to their customers' products. It is the cornerstone of total quality management, as it reduces the variability and costly activities in the communication and subsequent execution of the required steps from customer order to shipment. JIT focuses on simplifying the total business operation and execution of business processes. MRP II and JIT are the foundations for successful manufacturing businesses.     

Multiplant MRP

Many manufacturing firms have multiple manufacturing plants, located in geographically diverse parts of the world. This situation is becoming more common, as firms establish new plants in foreign countries to take advantage of low labor cost. In such cases, it is not unusual for the firm to retain production capability of certain key parts in a backup plant, with the necessary equipment and trained workforce in place. High volume production could be obtained relatively quickly from the backup plant in case of an emergency at the main supplying plant. In such multiplant settings, the transportation costs are significant. Throughout this paper, we use the term “multisourced parts” to describe parts produced in more than one location.Material Requirements Planning (MRP) is the component of a total manufacturing control system that is designed to manage inventory and plan orders for parts and material with dependent demand (demand derived from the demand of other items). Most of the literature on MRP systems discusses MRP methodology in a single-plant environment. Most MRP software systems in use today are single-plant systems.Currently, it is common for firms with multiple plants treated as cost centers to use an independent single-plant MRP system for each and handle the transshipment problems manually. Because of lack of coordination of production schedules between supplying and demanding plants, those firms hold more inventory and experience longer lead times than necessary to compensate for uncertainties in schedules and supply policies.The purpose of this article is to enhance single-plant MRP systems for coping with multiplant situations in which: the plants are regarded as cost centers, there exist multisourced parts, and the transportation costs are significant. The multiplant MRP system should recognize that parts are produced in different plants, make offset calculations for in-transit lead times, and consider transportation costs when establishing production requirements and shipping routes for multisourced parts. The objective is, beginning with the corporate-determined master schedule for finished products, to communicate in one planning cycle time-phased planned order release schedules and shipping/delivery schedules to each manufacturing plant producing components for the finished products.We first present a simplified framework for the multiplant MRP system, where a transportation algorithm is incorporated into the MRP logic. Then we refine this simplified framework to handle more complex aspects of a multiplant network. These complexities include the treatment of requirements that are not shipped on time and the regeneration of new MRP schedules. We also observe that the solution to the transportation problem described above is affected by the lot-sizing rules employed. In addition, we discuss several important issues and decisions that confront a firm when implementing a multiplant MRP system.     

MRP (materiel requirements planning) II education: a team-building experience

Conestoga Wood Specialties, a leader in the woodworking industry, is constantly striving for continuous improvement in manufacturing and service. Recently, the company embarked on a major MRP II education effort that served as a framework for team building. This team building concept has carried over into other aspects related to the business, such as the formalization of the sales and operations planning meeting. At Conestoga Wood, it is recognized that successful team building is necessary to achieve and maintain world-class performance.     

Integrating MRP (materiel requirements planning) into modern business

Time is the commodity of the '90s. Therefore, we all must learn how to use our manufacturing systems to shorten lead time and increase customer satisfaction. The objective of this article is to discuss practical ways people integrate the techniques of materiel requirements planning (MRP) systems with just-in-time (JIT) execution systems to increase customer satisfaction. Included are examples of new ways people use MRP systems to exemplify the process of continuous improvement--multiple items on work orders, consolidated routings, flexing capacity, and other new developments. Ways that successful companies use MRP II for planning and JIT for execution are discussed. There are many examples of how to apply theory to real life situations and a discussion of techniques that work to keep companies in the mode of continuous improvement. Also included is a look at hands-on, practical methods people use to achieve lead time reduction and simplify bills of material. Total quality management concepts can be applied to the MRP process itself. This in turn helps people improve schedule adherence, which leads to customer satisfaction.     

Resolving uncertainty in manufacturing systems

This paper examines the effectiveness of three commonly practiced methods used to resolve uncertainty in multi-stage manufacturing systems: safety stock under regenerative material requirements planning (MRP) updates, safety capacity under regenerative MRP updates, and net change MRP updates, i.e., continuous rather than regenerative (periodic) updates. The use of safety stock reflects a decision to permanently store materials and labor capacity in the form of inventory. When unexpected shortages arise between regenerative MRP updates, safety stock may be depleted but it will be replenished in subsequent periods. The second method, safety capacity, overstates the MRP capacity requirements at the individual work centers by a prescribed amount of direct labor. Safety capacity either will be allocated to unanticipated requirements which arise between MRP regenerations or will be spent as idle time. The third method, net change, offers a means of dealing with uncertainty by rescheduling instead of buffering, provided there is sufficient lead time to execute the changes in the material and capacity plans.Much of the inventory management research has addressed the use of safety stock as a buffer against uncertainty for a single product and manufacturing stage. However, there has been no work which evaluates the performance of safety stock relative to other resolution methods such as safety capacity or more frequent planning revisions. In this paper, a simulation model of a multi-stage (fabrication and assembly) process is used to characterize the behavior of the three resolution methods when errors are present in the demand and time standard estimates. Four end products are completed at an assembly center and altogether, the end products require the fabrication of twelve component parts in a job shop which contains eight work centers. In addition to the examination of the three methods under different sources and levels of uncertainty, different levels of bill of material commonality, MRP planned lead times, MRP lot sizes, equipment set-up times and priority dispatching rules are considered in the experimental design.The simulation results indicate that the choice among methods depends upon the source of uncertainty, and costs related to regular time employment, employment changes, equipment set ups and materials investment. For example, the choice between safety stock and safety capacity represents a compromise between materials investment and regular time employment costs. The net change method is not designed to deal effectively with time standard errors, although its use may be preferred over the two buffering alternatives when errors are present in the demand forecasts and when the costs of employment changes and equipment set ups are low. The simulation results also indicate that regardless of the method used, efforts to improve forecasts of demands or processing times may be justified by corresponding improvements in manufacturing performance.     

探析如何提高MRP系统中主生产计划的有效性

从需求和计划编制两个方面分析提高主生产计划有效性的方法。MRP是计划主导型的生产计划和控制系统,主生产计划作为MRP系统的关键模块,决定着企业的采购、生产、库存、交付等。MRP系统是由需求驱动的,通过分析,提出综合运用聚焦预测法采提高需求的准确性。主生产计划的准确性和稳定性,则通过在编制过程中运用滚动计划法、定期评审、适度冻结等方法得以实现。     

Research issues for multi-level lot sizing in MRP systems

What lot size model(s) to use in a Material Requirements Planning (MRP) system is an unresolved and often debated issue. The concept of dependent demand, the complex network defined by the product structure, the dynamics of an operating MRP-based system, and the subsequent use of the planned order release schedule by other company subsystems represent a totally new environment for making and managing lot size decisions.The purpose of this paper is to identify and briefly examine ten research issues related to lot sizing in a dependent demand product structure. These ten issues expand the solution space for lot sizing in an MRP-based system compared to a reorder point based system. Areas for further research are suggested.     

Read my lips--no more late deliveries

Over 70,000 materiel requirements planning (MRP) and manufacturing resource planning (MRP II) systems have been implemented in this country in the last 20 to 30 years. Yet the question many of the companies who own these systems are asking is, "Was it worth it?" Less than a third of the companies are answering in the affirmative. Two key differences between the satisfied and the not-so-satisfied companies are (1) support to the user community and (2) management involvement in the day-to-day use of the system. Without these two items, the improvements brought about by an MRP or MRP II system will most likely be mediocre at best.     

The cost of inflated planned lead times in MRP systems

Much of the current literature in the field of production and inventory control systems stresses the need to revise traditional forms of thinking regarding production processes, the role of inventories for work in process, and the need for reduced lead times or flow times. Group technology, manufacturing cells, and other means of incorporating repetitive manufacturing techniques into traditional job-shop settings constitute the leading edge in system development.Still, there is resistance to these dramatic changes, and traditional “business as usual” methods still predominate. This study attempts to illustrate graphically the cost justification associated with reduction in lead times which generally results from these new concepts. In most job shops today, lead times are much longer than they need to be due to inflation of lead time estimates. Actual lead times for the manufacture of fabricated and assembled products have been shown to be a direct consequence of the planning lead times used in the MRP planning process—a form of self-fulfilling prophesy.The research employs a simulation model of a factory using MRP as a planning tool in a multiproduct, multilevel production environment. Manufacturing costs constitute the dependent variable in the experiments, defined as the sum of material costs (including expedite premiums), direct labor costs (including overtime premiums), inventory carrying costs, and overhead costs. The independent variable being manipulated is the planned lead time offset used in the MRP planning process. Twenty values of planned lead time are evaluated ranging from a value that includes no slack time at all (pure assembly line) up to a value that allows 95% slack (queue) time which, unfortunately, is not uncommon in many job shops today. Stochastic variables in the model include customer demand and actual processing times—the sum of set-up and run times.The result of the study is a cost curve formed over the range of independent lead time variables that is constructed using nonlinear regression techniques. The conclusions from the resultant graph clearly indicate the cost consequences of long lead times, with exponential cost increases beyond the 80–90% queue time level. Total costs are 41% higher at the maximum lead time allowance compared to the minimum. Clearly, this study demonstrates the need for lead time reduction, either through downward adjustment of MRP planned lead times or by introducing new manufacturing concepts.     

The road to business process improvement--can you get there from here?

Historically, "improvements" within the organization have been frequently attained through automation by building and installing computer systems. Material requirements planning (MRP), manufacturing resource planning II (MRP II), just-in-time (JIT), computer aided design (CAD), computer aided manufacturing (CAM), electronic data interchange (EDI), and various other TLAs (three-letter acronyms) have been used as the methods to attain business objectives. But most companies have found that installing computer software, cleaning up their data, and providing every employee with training on how to best use the systems have not resulted in the level of business improvements needed. The software systems have simply made management around the problems easier but did little to solve the basic problems. The missing element in the efforts to improve the performance of the organization has been a shift in focus from individual department improvements to cross-organizational business process improvements. This article describes how the Electric Boat Division of General Dynamics Corporation, in conjunction with the Data Systems Division, moved its focus from one of vertical organizational processes to horizontal business processes. In other words, how we got rid of the dinosaurs.