PUSH/PULL SUPPLY CHAIN MODELS

　　推动价值链模型

　　A push model of the supply chain relies on manufacturers producing according to historical demand patterns and pushing products out to distributors and customers. Inventory is held at various points as a buffer against unexpected demand or production delays. By contrast, in a pull model demand stimulates production and delivery. Essentially, just-in-time inventory control is a pull model as ordering and production are triggered by customers’ orders. No orders are raised nor production started until there is downstream demand.

　　供应链的推动模型依赖于制造商根据历史需求模式来生产，然后将产品推向经销商和客户。存货是在不同的时点可以作为一个缓冲区来满足未预计的需求或者生产延误。与此相反，在推动模式下，需求刺激生产和运输。从本质上讲，无库存制度是一个推动模式，因为生产是因为已有的客户需求或客户订单。没有订单，就不会开始生产，直到下游有需求为止。

　　Of course, pure push or pull models exist only in theory: demand for a product will never cause a supply chain to start mining iron ore and producing steel. Nor will a push model guarantee that products made will be bought. At some point, in every supply chain, demand push will meet demand pull, and inventory will accumulate there. Note that large geographical distances between suppliers and customers, or processes that take time (such as growing crops) make pull systems more difficult to organise.

　　当然，纯粹的推动模型只存在于理论中：对产品的需求不会导致延迟开采铁矿石和钢铁生产。推动模型也不能保证产品会被买走。在某些时候，在每一个供应链，需求推动会满足需求拉动并且库存会积累。如果供应商和客户之间有大的地理距离或者过程需要较长时间(如种植农作物)，那么推动模型将更难组织。

　　However, inventory can be minimised and customer service improved if all parties in the supply chain can be better synchronised and have the ability to react quickly. For example, a traditional model of replenishing inventory in supermarkets would rely on each supermarket issuing an order to suppliers, probably by electronic data interchange (EDI), once inventory falls below reorder level. However, orders then arrive ‘out-of-the-blue’ at suppliers, who either have to have sufficient production capacity or who have to hold inventories to respond quickly. A better way is to give suppliers access to supermarkets’ inventory records through an extranet so that inventory levels and rates of change can be monitored. Supplies can be dispatched even without having to wait for an order. In this way, suppliers will be much better able to anticipate demand and produce accordingly. Better synchronisation and lower inventory levels have been achieved.

　　然而，如果价值链中所有各方同步并且必须迅速作出反应，那么库存可以最小化并且客户服务将会改善。例如，一个传统的模型就是补充超市的库存，这个依赖于每个超市的电子数据，一旦存货达到再订购水平，其就会给供应商发布订单。然而，意外的订单使得供应商既没有足够的生产能力也没有足够的存货来应对。一个更好的方法让供应商通过外部网络进入超市的库存系统，使得库存水平和变化率可以进行监控。供应商可以在没有订单的情况下直接派送。这样一来，供应商将能够更好地预测需求然后相应的生产。更好的同步和更低的库存水平便可以实现。

　　Information technology is of great assistance in moving towards a pull model as it influences the downstream supply chain through the 6I’s of e-business:

　　l Intelligence – for example, internet sites can track user activity and from that analyse which products are growing or falling in popularity. Information can be fed directly into a data warehouse for subsequent analysis and data mining.

　　l Interactivity – internet customers can customise their purchases. For example, some computer companies build to order allowing different combinations of hardware and software to be chosen.

　　l Integration – following on from interactivity, once an order has been placed, the pull process can begin by scheduling component ordering, production and despatch.

　　l Individualisation – for example, relevant offers can be made to each customer. If someone has bought a particular printer, then subsequently offers can be made to sell ink or toner cartridges.