Where are the tolerances for jigs and surfaces?
The accuracy is best at 20% of the size error
Precision machining precision fixture usually needs to be higher than that of machined parts for vehicles, drilling, milling, machining center fixture on the coaxality, verticality and parallelism, position accuracy, flatness, straightness tolerances, or higher requirements, these tolerances must be combined with requirements of machining parts drawing technology also need to check form and position tolerances, meet the machining accuracy requirements that meet the quality requirements for the purpose of processing at the same time, pay attention to the processing cost, because of the higher accuracy, processing costs increase relatively, so in the design, according to the actual circumstances!Note: 1) the value of the shape tolerance usually given on the same element should be less than the location tolerance;2) when the actual elements comply with the inclusion principle, the shape tolerance should be less than the size tolerance, and the ratio is about 25%-63%.In short, in order to scientifically and reasonably label the geometric tolerance, it is necessary to systematically study the book of tolerance, coordination and technical measurement!The above point of view is for reference only, and the specific form and tolerance requirements should be determined according to the actual situation!
General hole according to the 6.7 level accuracy, shaft according to the 5.6 level accuracy, position degree Phi 0.01, specific according to the fixture requirements and so on to decide.
