GB/T 11351-89 Castings Weight Tolerances
GB/T 11351-89 specifies the weight tolerances to be used in weight inspection of the castings. Standard test pieces are provided for the determination of casting weight for comparison. This standard applies to all kinds of castings whose surface area is greater than 300cm². Special castings shall be in accordance with the specific provisions in the contract.
The standard defines the following terms: normal weight casting, total weight of the casting, normal weight, total weight tolerance, excess weight and deduction in weight. The total weight of a casting can be obtained by summarizing the weights of all its parts. The normal weight tolerance of a casting includes the variation of the gross weight and the weight of the parts. The variations of normal weight tolerance are classified into four levels: A, B, C and D, in order of the increasing of weight tolerance. The excess weight or deduction in weight shall be either not less than 5% of the normal weight or not less than 10kg, if the former is smaller than 10kg.
This standards also provides test pieces of various shapes and sizes and specification formulae for use in checking the weight of a casting. The test piece shall be made of the same material and as close as possible to the shape of the casting for which the weight is to be determined. The total weight of a test piece and its parts shall be within the normal weight tolerance. The weight of a test piece shall not exceed 10kg. The test pieces of the same kind shall have the same total weight.
It is necessary to check the weight of a casting correctly and correctly judge the excess weight or deductions in weight of the casting in accordance with the provisions of this standard in order to ensure the accuracy, safety and reliability of the casting and its parts. Wrong inspections or wrong judgments may lead to technical problems or accidents, so special attention needs to be paid.
简谐GB/T 11351-89规定重量检验铸件应使用的重量公差。标准试样被提供用于确定铸件重量供比较。本标准适用于表面积大于300cm²的各类铸件。特殊铸件应按照合同具体规定执行。
本标准定义了以下名词：正常重量铸件、铸件总重量、正常重量、总重量公差、超重和减重。铸件总重量可以通过总和其所有部件的重量而获得。铸件的正常重量公差包括毛重及所有部件的重量的变化。正常重量公差的变化被分为四级：A、B、C和D，平均重量公差按照增加的次序排列。超重或减重不得小于正常重量的5％或小于10公斤，如果前者小于10公斤。
本标准还提供各种形状和尺寸的试样和检查铸件重量的规范公式。试样应用同样的材料，并尽可能接近于要检测的铸件形状。试样的总重量及其所有部件的重量必须在正常重量公差范围内。试样重量不得超过10公斤。同一种试样的总重量应相等。
正确检查铸件重量并按照本标准的规定正确判断铸件的超重或减重，是保证铸件及其零件的准确性、安全性及可靠性的必要条件；错误的检验或判断可能引起技术问题或事故，因此需要特别注意。
