Tolerance Analysis
A Comprehensive System for Computer-Aided Tolerance Analysis of 2-D...
http://adcats.et.byu.edu/Publication/97-4/cirp_2_7_97a.html
7.0 ASSEMBLY TOLERANCE SPECIFICATIONS
An engineering design must perform properly in spite of dimensional variation. To achieve this, engineering design requirements must be expressed as assembly tolerance limits. The designer must assign limits to the gaps, clearances and overall dimensions of an assembly which are critical to performance. Assembly tolerance limits are applied to the statistical distribution of the assembly variations predicted by tolerance analysis to estimate the number of assemblies which will be within the specifications. Designers need to control more than just gaps and clearances in assemblies. Orientation and position of features may also be important to performance. To be a comprehensive design tool, a tolerance analysis system must provide a set of assembly tolerance specifications which covers a wide range of common design requirements. A system of assembly tolerance specifications patterned after ANSI Y14.5 has been proposed [Carr 93]. Those ANSI Y14.5 feature controls which require a datum appear to be useful as assembly controls. However, there is a distinct difference between component tolerance and assembly tolerance specifications, as seen in Fig. 9. In the component tolerance specification shown, the parallelism tolerance zone is defined as parallel to datum A, a reference surface on the same part. By contrast, the assembly parallelism tolerance defines a tolerance zone on one part in the assembly which is parallel to a datum on another part. In order to distinguish an assembly tolerance specification from a component specification, new symbols have been proposed. The feature control block and the assembly datum have been enclosed in double boxes.
Fig. 9 Comparison of component and assembly tolerance specifications.
8.0 MODELING PROCEDURES AND RULES
The ability to model a system is a
http://adcats.et.byu.edu/Publication/97-4/cirp_2_7_97a.html
7.0 ASSEMBLY TOLERANCE SPECIFICATIONS
An engineering design must perform properly in spite of dimensional variation. To achieve this, engineering design requirements must be expressed as assembly tolerance limits. The designer must assign limits to the gaps, clearances and overall dimensions of an assembly which are critical to performance. Assembly tolerance limits are applied to the statistical distribution of the assembly variations predicted by tolerance analysis to estimate the number of assemblies which will be within the specifications. Designers need to control more than just gaps and clearances in assemblies. Orientation and position of features may also be important to performance. To be a comprehensive design tool, a tolerance analysis system must provide a set of assembly tolerance specifications which covers a wide range of common design requirements. A system of assembly tolerance specifications patterned after ANSI Y14.5 has been proposed [Carr 93]. Those ANSI Y14.5 feature controls which require a datum appear to be useful as assembly controls. However, there is a distinct difference between component tolerance and assembly tolerance specifications, as seen in Fig. 9. In the component tolerance specification shown, the parallelism tolerance zone is defined as parallel to datum A, a reference surface on the same part. By contrast, the assembly parallelism tolerance defines a tolerance zone on one part in the assembly which is parallel to a datum on another part. In order to distinguish an assembly tolerance specification from a component specification, new symbols have been proposed. The feature control block and the assembly datum have been enclosed in double boxes.
Fig. 9 Comparison of component and assembly tolerance specifications.
8.0 MODELING PROCEDURES AND RULES
The ability to model a system is a