库存管理

4.2JIT案例分析JIT的基本原理根据需方的指令，将需方所需的品种按桌订的数量在所需的时间送到指定的地点。

不少送，也不多送；不迟送，也不早送。

送的货品个个都保证质量。

也就是在适当的时间，把适当的物品以适当的数量，送到适当的地点。

它体现了以下要点：1．品种合适，拒绝不合适的品种规格；2．数量合适，不少，也不多；3．时间合适，不迟，也不早；4．地点合适；5．质量合适，百分之百合格。

它体现了以下优越性：1．可以实现线边零库存；2．可以实现最大的节约；3．最大限度地消除废品损失JIT 的目标JIT的中心思想即是消除一切无效劳动和浪费。

为此，JIT寻求达到以下目标：1.零废品。

传统的生产管理中，一般企业只提出可允许的不合格品的百分数和可接受的质量水平。

它们的基本假设是：不合格品达到一定数量是不可避免的。

而JIT的目标是消除各种引起不合格品的因素，在加工过程在中，每一工序都力求达到最好水平。

2.零库存。

传统的生产系统中，在制品库存和产成品库存被视为资产，代表系统中已累积的增值。

在期末时，期末库存与期初库存之差，代表这一周期增值的部分，用以指示该部门效益的提高。

当由不确定的供应者供应原材料和外购件时，原材料和外购件的库存可视为缓冲器，即是作为供应商不按期供货或顾客订货量增加时的缓冲。

而JIT则认为，任何库存都是浪费。

库存是生产系统设计不合理、生产过程不协调、生产操作不规范的产物，必须予以消除。

3、准结（订货）时间最少。

准结时间长短与批量选择相联系。

如果准结时间接近于零，就意味着批量生产的优越性不复存在。

我们知道，确定经济批量的目的是使库存总费用最小，而库存总费用是由仓库保管费与准结（订货）费所决定，批量大意味着库存量高，仓库保管费高；而批量小则库存量低，仓库保管费也低。

但批量小必然增多准结次数，在一般情况下，准结费用也随之增加。

如果准结时间趋于零，则准结成本也趋于零，就有可能采用极小批量。

JIT 的特点与作用JIT管理哲理具有普遍意义，既可适用于任何类型的制造业，也可应用于服务业中的各种组织。

JIT能够以有效和可靠的方式消除生产经营过程中的浪费，改善质量，提高用户需求的满足水平。

JIT的核心是消除一切无效劳动和浪费。

在市场竞争环境下，获取更多利润的唯一途径即是降低成本，而当今降低成本的关键就在于杜绝浪费。

JIT认为，凡是对产品不起增值作用或不增加产品附加值但却增加成本的劳动，都是属于浪费的无效劳动。

例如，多余的库存，多余的搬运和操作，造成返修品、次品和废品的作业，停工待料，没有销路的超产等。

JIT非常重视人的因素，强调全员授权参与管理。

JIT把企业员工看成是主动创新的思考者，认为最了解管理中存在的问题的是企业的一线员工，因而应当首先由他们提出解决问题的办法。

为此，一般是由上级提出目标、处理问题的原则，提供信息和培训，并对员工进行授权，各级员工在自己的权限内处理工作范围中的问题。

JIT重视员工多种技能的培训，工人必须是多面手，能在不同的设备上操作与维护，因而减少因人员缺勤造成的停工，同时增加工人对职业的荣誉感。

在 JIT的实施过程中，要成立合理化小组和质量控制小组，提倡合理化建议，将体力劳动与脑力劳动相互结合起来。

JIT追求尽善尽美，不懈进取，遇到问题，就一定要找出问题发生的根源，并运用工业工程和其他的方法，将问题彻底解决，使之不再发生。

JIT认为，不懈进取与一个组织的整体效果的提高有着密切的关系，必须为组织的每一个员工所接受，以有效地、连续地改进其生产操作和用户服务。

JIT着重对物流的控制。

采用成组单元、U形机床布置；改进工装设计，压缩准备时间，减小批量；组织平准化生产，采用拉式作业，保持各生产单元之间的物流平衡。

JIT强调全面质量管理，认为仅靠检验只能发现缺陷，而不能防止和消除缺陷，即使事后补救业已造成浪费。

因此，必须建立质量保证体系，从根源上保证产品质量。

同时，坚持预防性设备维护制度，一旦出现设备故障，就全线停车，群策群力查明事故根源，一次性彻底解决问题。

JIT追求最优的质量成本比。

JIT致力于开发旨在实现零缺陷的制造流程，表面上看起来，这似乎是个不切现实的目标。

但是，从长远的角度看，由于消除了一些冗余的功能，就可使企业大大降低成本费用，实现最优的质量成本比4.2.JIT case analysisThe basic principle of JITAccording to the instruction, place the desired varieties according to the number of table ordered within the required time to the designated. Many send, do not send; no later sent, also didn't send. Send goods all quality assurance. It is at the appropriate time, the appropriate items in the right quantities, to the right place.It embodies the following points:1.Suitable varieties, specifications are not suitable to;2.The right amount, not too little, not too much;3 .The right time, not too late, also not too early;4.Suitable location;5.Suitable girder, 100% qualifiedIt embodies the following advantages:1.It iscan achieve line side inventory;2 .It is can achieve the greatest savings;3.Maximally eliminate spoilageThe goal of JITThe central idea of JIT is to remove all of the invalid labor and waste. Therefore, JIT seeks to achieve the following goals:1.Zero waste. The traditional production management, general business only the unqualified product percentage and acceptable quality level allowed. The basic assumption of them is: the unqualified products reach a certain number is inevitable. JIT's goal is to eliminate the factors causing the unqualified products, in the process, each process will strive to reach the best level.2.Zero inventory. The traditional production system, WIP and finished goods inventory are seen as assets, has accumulated representativesystem of value. At the end of the semester, the final inventory and inventory at the beginning of the period of difference, on behalf of the cycle of value-added part, used to indicate the Department benefit. When the uncertainty of the provider of raw materials and purchased parts, inventory of raw materials and purchased parts can be regarded as a buffer, which is not as the supplier delivery schedule or customer order quantity increases buffer. But JIT thinks, any inventory is waste. Inventory is a product of the production system design is not reasonable, the production process is not harmonious, production of non-standard operation, must be eliminated.3, The quasi node (order) the least time. Quasi node length of time associated with batch selection. If the quasi node time is close to zero, means that the advantages of mass production ceased to exist. We know, determine the economic lot size is designed to make the total stock cost, and the total cost of inventory is composed of the storage fee and quasi node (order) determine the fees, large batch means high inventories, the storage fee is high; and small batch, low inventory levels, the storage fee is low. But the small batch production is bound to increase the number of quasi nodes, in general, quasi node cost increases. If the quasi node time tends to zero, then the quasi node cost tends to zero, it is possible to adopt the minimum mass.The characteristics and function of JITThe general significance of JIT manufacturing management philosophy, can be applied to any type of organization, can also be applied in the service industry. JIT can be an effective and reliable way to eliminate the production process of waste, improve quality, improve the user demand satisfaction.The core of JIT is to eliminate all invalid labor and waste. In the environment of market competition, the only way to obtain more profits is to reduce the cost, and the cost is the key to eliminate waste. JIT believes that, whatever the product has no value or not to increase the added value of the products but the increased cost of labor, are invalid labor belongs to waste. For example, excess inventory, handling and operation of excess, causing rework and scrap, defective operation, downtime to be expected, no sales of over production.JIT attaches great importance to the human factor, emphasizing the full authority to participate in the management of. JIT enterprise employees as active creative thinkers, thinks that the understanding of the problems existing in the management of enterprise employees, so should they propose a solution to the problem. Therefore, the general is a higher target, dealing with issues of principle, to provide information and training, and the staff is authorized, employees at all levels of processing in the scope of work problems in their jurisdiction. JIT attention to staff a variety of skills training, workers must be versatile, capable of operating at different equipment and maintenance, thus reducing downtime caused by staff absenteeism, and increase the sense of honor of the occupation of workers. During the implementation of JIT, to set up a reasonable group and quality control group, advocating rational suggestions, the physical labor and mental labor combined.JIT pursuit of reach the acme of perfection, tireless and enterprising, encounter problems, we must find out the root of the problem, andthe use of industrial engineering and other methods, to thoroughly solve the problem, so that no longer occur. JIT thinks, is closely related to the overall effect of tireless and enterprising and an organization's raise, must be acceptable to each organization's employees, in order to effectively, continuously improve its production operation and customer service.JIT focuses on logistics control. The group units, U shaped machine layout; improve tooling design, compression preparation time, reduce the volume; organizational level production, using pull operation, keep the logistics balance among the various production units.JIT emphasizes the total quality management, that finding defects inspection alone only, and can prevent and eliminate defects, even if the remedy has been wasted. Therefore, must establish a quality assurance system, to ensure the quality of products from the source. At the same time, adhere to preventive maintenance system, once the equipment failure, all parking, work and pull together to identify root causes, one-time completely solve the problem.Cost of quality JIT the pursuit of optimal ratio. JIT is committed to the development of the manufacturing process to achieve zero defect, on the surface, this seems to be an unrealistic goal. However, from the long-term perspective, due to the elimination of some redundantfunctions, you can enable enterprises to significantly reduce the cost, to achieve optimal quality cost ratio。