SCIENCE AND TECHNOLOGY ENGLIAH FOR MECHANICAL ENGINEERING Machining accuracy is expressed quantitatively by the magnitude of machining error. Machining error is defined as the difference between the parameters of a machined part and that of a perfect (absolutely accurate) part specified in the part drawing. The machining error varies from part to part even in the same batch of production. Although machining errors al ways exist in machining processes, a part can be considered acceptable, provided the magnitude of machining errors do not 公差 exceed the tolerance limits. The tolerance represents the maximum allowable machining error. The required machining accuracy of a part is specified by the designer, while the machining accuracy requirements of the part in each machining stage are determined in accordance with the needs and accuracy of the process by the process plannerSCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING Machining accuracy is expressed quantitatively by the magnitude of machining error. Machining error is defined as the difference between the parameters of a machined part and that of a perfect (absolutely accurate) part specified in the part drawing. The machining error varies from part to part even in the same batch of production. Although machining errors always exist in machining processes, a part can be considered acceptable, provided the magnitude of machining errors do not exceed the tolerance limits. The tolerance represents the maximum allowable machining error. The required machining accuracy of a part is specified by the designer, while the machining accuracy requirements of the part in each machining stage are determined in accordance with the needs and accuracy of the process by the process planner. 公 差