【正文】 s study the function of the inspection.To assure the quality, inspection plays important part when defectives are inevitable.Inspection is not a test, but it should have three factors. decide the criterion of judgment appropriately clearly. evaluate the quality by testing. pare the test results to the criterion, and to judge whether acceptance or rejection.We sometimes have problems with lack of definite criterion.The results and data of the inspection should be utilized for improvement of original processes. There are two types of inspection, total inspection and sampling inspection. The former is usually for the outgoing inspection, and the latter is mainly for the ining inspection of the parts.Total inspection⊙In the case where the quality of each product should be assured.⊙Large number of defects is included.⊙The cost of inspection is cheap enough to inspect all the products.Sampling inspection⊙In order to reduce the cost of inspection, estimate the quality level from partial sample, and judge if they might bring bigger risk to the next process or not.46Maintenance of tools, machines and measuring instruments.We are utilizing many kinds of tools, machines, and measuring instruments in our workshop.Today, machines are widely operated automatically by electronic devices.Bu。44Let39。s consider about Quality Control,Do you know what is Quality Control?Do you understand which points are more difficult to carry out Quality Control?Are you carrying out Quality Control successfully?39。s make the operation standard easy to understand with necessary drawing, and keep it in certain place for easy reference.43Enough training of the job is necessary.Do you know how to solder?Do you understand when and how poor soldering happens?Can you solder perfectly without any defectives?39。s standardize operation of the job. (Operation standard)To produce the products with minimum dispersion, each process of operation and procedure should be kept same as constant as possible, no matter when and who39。s study relationship between Product Quality and your job.Each process of operation is responsible for final product Quality.For example, even a small operation like picking up the parts could cause defective products, because of rusting mg by grease of finger, or deformation when it is pinched. Before producing defective products, let39。t1 and if we stratify the data from various points of view, we will be able to find out the most effective causes.Important points are,(1) Stratification is based on causeandeffect diagram.(2) Stratify the data from various points of view.(3) After the stratification, check the difference of dispersion.37Analysis of the data. Part 2. (Scatter diagram, Control chart)(1) Scatter diagram,To know the relationship between cause and effect, (for example, relationship between torque of air driver and air pressure,) it is convenient to draw a scatterDiagram, plotting data of the cause on the horizontal axe, data of the effect on the vertical axe. We can see the relationship clearly, and it is helpful to solve the problem.(2) Control chart,Dispersion includes types of causes. One is inevitable cause, (like dispersion caused by ordinary machine.) and another is unusual cause. (Like dispersion caused by different quality of the material.)We have to control the latter, and find the variation of these causes by control chart. Let39。s start analyzing the cause of dispersion from this Histogram.36 Analysis of the data. part 1. (Stratification)Any products that we produce have dispersion in performance, or dimensions. Our theme is to minimize this dispersion, and we have to know the cause of dispersion, but final data itself usually tells nothing about causes.One of the practical ways to find out causes is stratification. When the diameter of the shaft of certain machine has excess dispersion, and if they are made by two machines, we have to stratify the data corresponding to each machine.Then, we can find difference between machine 4 and B, and if adjustment of machine A is incorrect, we can easily adjust it.This is one example of 39。 actual situation of our workshop, or quality level of products, and we can use this to find out actual causes.33 Priority policy for maximum effectiveness. (Pareto diagram)We find many kinds of problems around. It is almost impossible to attack all these problems by limited time and person and cost.In order to get maximum effectiveness, we have to know which problems are the major ones, and attack them with strong priority policy.For this purpose, Pareto diagram is fully helpful. This diagram is such arranged that bigger item es left. Pareto principle says, 80% of problems e from only 20% of major items.So, for example, in order to attack 2 or 3 major items only, it is important to set up strong priority policy, neglecting all other items.34 Let39。s observe the fact, and collect the data.In our daily activities there are many cases where we talk and discuss without confirming the fact. Moreover, sometimes it happens that something to be believed as the tact is found that it was not the fact but an opinion of somebody.In such a way, we cannot proceed quality control scientifically and it is difficult to improve quality of products or quality control system.First, we have to watch and observe the workshop and actual defective products by our own eyes.When we get an information of trouble, immediate visit to the workshop is necessary.This action is called, Onthespot confirmation.The scientific approach begins by data and numbers.Let39。s better not to hesitate to change the plan in order to achieve the objective without foil.26 Checking the result and revaluationAt the beginning of the process, everybody starts with full enthusiasm, but in the course of time, it sometimes happens that the enthusiasm fade away, and no