六西格玛在提高高压锅炉管涡流探伤合格率中的应用

Application of Six Sigma for Improving Qualification Rate of Eddy Current Testing to High Pressure Boiler Tubes

通过运用六西格玛(6 Sigma)方法,采用对数回归、卡方检验和工艺验证等方法找到影响高压锅炉管涡流探伤合格率的关键因子,包括穿孔顶头寿命、磷化冲水、酸洗温度、时间和浓度、轧机信号和吹灰等,从而制定相应的改进方案。通过六西格玛项目实施,高压锅炉管的涡流探伤合格率由改进前的93.21%上升至改进后的95.71%,六西格玛水平由改进前的-1.44提高至改进后的0.66,从而节约了制造成本,提高了企业的经济效益。

Adopting the Six Sigma process and using related methods like logistic regression, chi-square test and process certification, etc., the key factors effeeting qualification rate of the eddy current testing to high pressure boiler tubes are identified, including piercing plug service life, phosphating flush, acid solution temperature and concentration, and bathing time, and rolling mill signal and dust purging etc. Accordingly, modification plan is determined. Thanks to implementation of the Six Sigma management process, the said qualification rate has enhanced from the original 93.21% to 95.71%, while the Six Sigma level is lifted from the original -1.44 to 0.66, resulting in enhancement of both operation cost-effectiveness and economic profit of the company as well.