制动盘产品认证中灰铸铁盘体抗拉强度判定依据分析

Analysis of Tensile Strength of Grey Cast Iron Disc Body in Brake Disc Product Certification

针对认证机构在产品认证活动过程中,采用经验公式或估算方法评价产品符合性的适用性问题,以制动盘灰铸铁盘体为例,分析用单铸试棒抗拉强度参考值折算本体预期抗拉强度(最小值),作为灰铸铁盘体本体抗拉强度的适用性,得出灰铸铁盘体抗拉强度不能按折算值判定的结论。指出经验公式适用性分析的2个关键点,一是确定经验公式在相关认证中采用的标准或标准性技术文件中是否有直接规定;二是认证机构应对检验检测机构的资质进行必要的核实,确定支撑经验公式的相关认证用标准或标准性文技术件是否在检验检测机构获得批准的资质范围内。

Certification bodies implement empirical formula or estimation method to evaluate the applicability of the product conformity in the process of product certification activities.Taking the grey cast iron disc body of brake disc as an example,the expected tensile strength(minimum value)of the body converted by reference value of single cast test bar is analyzed as the applicability of it,and a conclusion is drawn that the tensile strength of the disc body cannot be determined according to the converted value.It points out two key points of applicability analysis of empirical formula.One is to determine whether empirical formula is directly stipulated in relevant certification standards or normative documents.The other,the certification body verifies the qualification of the inspection and testing institution,it shall determine whether the relevant certification standards or normative documents supporting the empirical formula are within the approved qualification scope of the inspection and testing institution.