The Common Methods to Determine the Parameters of Technical Standards Zhang Yue-yi China Ji Liang University

Content Introduction Classification of quality characteristic Methods to determine the technical parameters Methods to determine the specification limits Conclusion

Introduction There are always some technical parameters and specification limits in the technical standards. The technical parameters and specification limits of each characteristic are all different.

Classification of quality characteristic Quality characteristic Measurement characteristic Counting characteristic

Classification of quality characteristic Measurement characteristic the nominal the better the smaller the better the larger the better or

Methods to Determine the Parameters Parameter design Quality function deployment Reliability design

Parameter design Parameter design is the chief component of the Taguchis three stage design. The basic idea of the parameter design is to determine the optimal level of all technical parameters by using the orthogonal array and S/N ratio, including raw materials, electronic parts and components. Meanwhile, in order to minimize the quality fluctuation, we must decrease the influence of all kinds of interference by the parameter design.

Quality function deployment Quality function deployment(QFD) is the method of product design and development driven by customer, it adopts certain method to accurately transform the customer demands into the technical and process parameters.

The house of quality(HOQ)

Reliability design Reliability is the ability of the product or system to perform and maintain its functions in routine circumstances, as well as hostile or unexpected circumstances. Reliability design is to solve product reliability at the design stage.

Methods to Determine the specification limit Quality loss function Safety coefficient

Quality loss function The quality loss function of the nominal the better characteristic: The quality loss function of the smaller the better characteristic: The quality loss function of the larger the better characteristic:

Quality loss model of the nominal the better characteristic A 0

Method to determine the loss coefficient k When the product becomes out of use, that is to say, the quality characteristic value is beyond the functional limit, the loss is A 0 yuan. Thus: So, loss coefficient:

Method to determine If the product is unqualified, the rework cost of the product is A yuan, the specification limit of the quality characteristic is:

Example The target value of the output voltage of the television power circuit is 115V, the functional limit, the loss of losing functionality yuan. A Determine the loss coefficient of the loss function;

B If the rework cost of the unqualified product A=1 yuan, the specification limit of the quality characteristic can be determined. Thus, the technical parameter and specification limit of the output voltage of the television power circuit:

Quality loss model of the smaller the better characteristic

Quality loss model of the larger the better characteristic

Safety coefficient A: the loss of the unqualified product; A 0 : the loss of the product that the characteristic value is beyond the functional limit. Safety coefficient: Generally, safety coefficient.

the nominal the better The relationship between the specification limit and the functional limit 0 of the nominal the better characteristic: Then, the specification limit :

Conclusion As the customer demand is becoming higher and higher, not only for product performance, but also for security, economy, reliability, appearance quality, service, etc. The technical parameter and specification limit of every characteristic need to be determined by certain methods.

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