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驾驶与精益 Driving and Lean

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A new optional course, International Purchasing, is launched at my alma mater, of which the professor is a man of influence in the field of purchasing in south China. He unites theory and practice and serves as the director of MBA business school. Although it is held every Saturday night for three hours, people come to attend the course in big class. Since an alumnus can have free access to this course, every Saturday I will drive to cover a round trip of 160 km between Dongguan and Guangzhou regardless of fatigue. Covering a single distance of 80 km at a speed of 100 km/h, it is reasonable that I arrive at my Alma Mater within one hour. But the actual amount of time often goes to two hours. Why such a low efficiency?


Time is only wasted in waiting before traffic lights, dragging, pausing and detouring. Waiting before traffic lights is an easy case to understand: It is typical of the nation to have a lot of traffic lights. The grounds on which the number or the shifting period of traffic lights is determined being unknown, people may wait for 30s somewhere but 3 minutes some other. Chances are large that you go through continual red lights once greeted by a first one, and vise versa. Dragging is necessary when an emergency occurs, be it poor eyesight at night, a traffic jam or a car breakdown ahead the road, caution for jaywalking pedestrians, uneven roads, driving uphill, etc. Pausing is the extreme case to dragging. It happens when the road ahead is blocked temperately, or the driver needs to go to the toilet or have a rest due to fatigue. Detouring includes two situations: taking a wrong way or a shortcut. Whereas taking a wrong way is an unintentional mistake, taking a shortcut is a purposeful choice to exchanging the distance for the time.

其实仔细看看是不是很像工厂生产线的运作,工厂不也存在这些类型的浪费吗? 高速路上是没有红灯的,只有在上高速和下高速后,这些等待如同项目初期不稳定期间,也像批量生产后生产计划排好后等待其他产品先生产,因为毕竟产能是有限的,如同马路的宽度是固定的一样。在每天的上班初期和临近下班时刻也都会出现产量偏低的情况,有人临时离岗被顶班也会出现这种情况,要是产线某道工序出现异常,物料里混杂有不良品需要挑选使用,亦会导致效率下降出现。产线停顿则可能是有计划性的中间休息或者产线人机料法环出现大问题直接造成没办法继续生产。而返工如果走错路,条条大路痛罗马,最后修理后成为正果但是时间已经浪费掉了。

The driving case is the same with the operation of production lines in factories where also exist such kinds of waste. People will not encounter traffic lights on the freeway, which are only set outside the freeway ramps. Similarly, waiting is common in a project when things remain unsettled at their beginning stage, or when products are arranged in line to be manufactured sequentially since the capacity, as is the same with a road having a fixed width, has its limitation. Low production also happens at the beginning and ending hours of a day’s work, when a worker is relieved and another takes over, when unexpected errors occurs in the process of production, or when selection of materials out of defective ones is required. A pause in production line may arise due to scheduled intervals for rest, or problems that undermine the item of man, machine, material, method and environment. Reworking is similar to detouring, in which case a product may be fixed but the time will be definitely wasted.


Having read A Quick Qay of Lean Production recently, a professional novel written by Feng Wenliang, I have had some deeper understanding of the above issues. There are some points of view that are worth learning in the book.

1.河槽容纳的流量=淤泥等原因占据的流量 + 河槽的实际流量。而清淤只需要清理一些重点河段,就可以保持整条河道的畅通。

1. Gross river flow=space taken by sludge + net river flow. Dredging can be undertaken only at some major river segments in order to keep the whole river course smooth.


2. A labor force structure in workshops can be categorized into excessive workforce, short workforce or new comers. Disordered human resource information gives rise to many problems. A solution is to allocate personnel in several deployment lines which are variable in number and determined by the actual demand of product lines. All the spare workforce is enrolled in personnel deployment lines, ready to be employed by a product line. A deployment line also helps to train new workers.


3. The two most important working positions on a production line are the first position and the dynamic bottleneck position. Whereas the first position decides the capability, the dynamic bottleneck one, where work in process accumulate the most, decides digestion, fluency and the possibility to achieve the maximum capability


4. A good factory management calls for wiping out the root of problem first and then finding ways for reinforcement and optimization. The root of problem lies in how to achieve fast improvement, and ways for reinforcement and optimization includes various methods such as 5S, standardization and equipment maintenance. They are steps of importance although they may not bring out much direct economic benefits.


5. Stock is the root of all evil.


A road is like a river. Whereas a river calls for dredging in order to keep smooth, a road requires repairing. Sludge in a river is also similar to obstacles and mud on a road. Do you have the impression that a road remains uneven after repaired, with many holes uncovered? I remember that several years ago piles of gravels will be stacked up on a road from time to time for road paving or repairing. It is obvious that a car will not be able to drive at a high speed on such a road. In a neighbor country—India, there being no fences for a freeway which cattle and sheep can cross freely, speed is nothing but out of the question.

在国内的每条高速公路乃至普通公路上,往往都有多条车道可供驾驶,每条车道的限速可能不太一样,有的限80,有的限100,通常国内的最高速限到120KM/H,跑的快的走快车道,拉了货跑不起来的走慢车道,当然还可以再快慢车道间相互切换 – 这样就具有灵活性了。几年前一些大城市开始流行建设公交专用车道 – 公交快车道,甚至现在更加细化了,货车只能走那几条车道,那几条车道只能在限定时间段供校车行驶。

Freeways and even common roads at home provide different lanes for drivers to choose, each one varying in speed range. For example, whereas one lane may have the maximum speed of 80km/h, another may be 100km/h, and the highest speed at home is usually 120km/h. Cars that drive fast go on the fast lane, and lorries that carry full goods drive slow so they go on the slow lane. Sometimes you can swift between different lanes, which gives rise to flexibility. Several years ago, the bus lane—bus rapid transit, became popular in many big cities. Now things become more specific: lorries have exclusive access to some lanes, while some other are can only be occupied by school buses during a certain time.


Imagine that a sports car running on a normal road. Is it able to run fast? The answer is no. Unless it runs ahead of all the other cars for good, with not a single car in front of it being the obstacle. The logic also applies to the situation of a single car running on the circuit. Also imagine that each car occupying a station; isn’t it true that the speed of the first car sets the upper speed limit of cars running on the lane (when there are no other lanes for shifting)? Apart from that, once an emergency occurs somewhere on the road (dynamic bottleneck), traffic police shall be on the scene immediately; otherwise there will be a traffic jam (WIP).


It is necessary that the road be equipped with normative landmarks, clear road signs, HD cameras, beautiful shelter forest for noise and wide lanes, but the first concern shall be how to solve traffic jams, a logic which happens to coincide with the way the factory tries to solve its current problems.


What I can do to ease my dreariness in each week’s long marching is no more than improve my driving and reinforce my patience. What can employees do, then, in terms of factory management? The core lies in the recognition by the factory management of the “key minority”—the major points for improvement, the parts in the chain that add actual value and the places where the “sludge” lies. It would be better if the supplier management combines the knowledge and practice of quality and other aspects. Otherwise, he shall assist the factory to find ways for fast effects through quality management approach. We should know that the popularity of Lean Six Sigma lies in the integration of the concept of Lean and that of Six Sigma, the latter of which has to do with quality.




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