JB/T 53336-1999

Manufacturers of powder metallurgy (iron-based) valve guides use this standard to internally control and grade product quality. Quality inspection departments rely on it to classify products into qualified, first-class, and superior grades, guiding enterprise upgrades and product excellence. It also provides a basis for pricing high-quality products, thereby promoting overall industry quality improvement.

该标准主要用于粉末冶金（铁基）气门导管的生产企业进行内部质量控制和等级评定。质量检验部门依据本标准对产品进行合格品、一等品和优等品的分级，以指导企业升级和产品创优。同时，该标准为产品优质优价提供了依据，有助于提升行业整体质量水平。

This standard specifies the quality grading requirements for powder metallurgy (iron-based) valve guides, classifying products into three grades: qualified, first-class, and superior. It details indicators for key items (e.g., radial crushing strength, density difference), major items (e.g., metallographic structure, apparent hardness, dimensional accuracy), and general items (e.g., length tolerance, surface roughness), along with corresponding test methods and quality assessment procedures. The standard is used for quality evaluation, enterprise upgrading, and product excellence, providing a basis for high-quality pricing.

本标准规定了粉末冶金（铁基）气门导管的产品质量分等要求，将产品分为合格品、一等品和优等品三个等级。标准详细列出了关键项目（如径向压溃强度、密度差）、主要项目（如金相组织、表观硬度、尺寸精度）和一般项目（如长度公差、表面粗糙度）的指标，并规定了相应的试验方法和质量评定程序。该标准适用于质量考核、企业升级和产品创优，为优质优价提供依据。