Quality Control Method Analysis For The New Developed Heating Element Of Electric Water-heater

The problems of heating element scaling and inner tank water leakage are the two main quality problems disturbing the manufacturers of electric water heater. On the basis of DOE (Design of Experiment) and FMEA (Failure Mode and Effects Analysis), this paper conducts the quality control method analysis for the new type low-scaling and low-magnesium-consumption heating element of electric water heater during research and development phase.Firstly, this paper introduced the basic theory of electric water heater, the main quality problems happening in the market and imitations of existing solutions, and then put forward a specific technical solution as a new type low-scaling and low-magnesium- consumption heating element of electric water heater.On the basis of DOE technology, this paper conducted the optimization design towards the main parameters such as heating element metal material, painting material and technical process during the research and development phase of this kind of new type heating element. After the test finished, with the analysis method of maximum variance and the consideration of actual cost and delivery timing, the best parameters combination was decided. Furthermore, on the basis of above, the technical process of new heating element was continually optimizing using orthogonal experiment method. After this test finished, the best process parameters was got by implementing the comprehensive evaluation method.Then, the new logistic process of this kind of new type heating element was analyzed with FMEA method to figure out the potential failure mode, raise the new solution for continual improvement, calculate the RPN before and after implementation of quality solution and fill up in the analysis table.Finally, on the basis of implementation of above mentioned quality control methods, certain quantity of electric water heaters assembled with new type heating element were sold to certain place together with other electric water heater assembled with old type heating element. And after one year usage, it's found that the market rejection rate of electric water heaters with new type heating element was only 2‰, while for which with old type heating element, the rate is as high as 13‰.In a conclusion, the usage of new type heating element and the implementation of relative quality control methods will obviously lengthen the expected life of electric water heaters, decrease the market rejection cost and improve customer satisfaction.