Bilingual Specifications and the Version the Factory Actually Reads
Chinese line operators execute off simplified internal shop routing cards rather than signed Western drawings, making direct process sheet audits mandatory.
GB/T 1804 Standards
Meaning
Technical requirements for general tolerances on linear and angular dimensions apply to parts without individual tolerance indications. The gb/t 1804 standards establish four classes of accuracy ranging from fine to very coarse. These rules govern the acceptable deviation for machined components used in various industrial applications.
Dimensional Accuracy
Production plants use these defaults to simplify drawings while maintaining control over non-critical features. When a designer invokes the gb/t 1804 standards, they avoid the need to label every single edge or hole. This practice reduces the clutter on a technical document and focuses the attention of the inspector on the critical dimensions.
Tolerance Class
Selection of a specific grade depends on the capability of the machinery and the requirements of the final assembly. Most domestic factories target the medium class for standard industrial components. The gb/t 1804 standards provide a reference for both the manufacturer and the quality inspector.
Every class has a specific table that defines the permissible deviation for a range of nominal sizes. This prevents disputes between the purchasing office and the supplier regarding the precision of non-functional surfaces.
Inspection Boundary
Verification of these tolerances occurs during the final audit of the finished batch. If a part falls outside the range defined by the gb/t 1804 standards, it is rejected despite the absence of an explicit drawing note. This system reduces the likelihood of assembly interference.