B. Mathematical Knowledge
The size of parts is an important basis for manufacturing
and examining. Annotating sizes on part drawing should satisfy
design requirements, and be convenient for processing and
measuring. Size selection has a great impact upon the part
performance. The parameter used in current parametric
modeling is different from the date sets of engineering part size.
Generally speaking the engineering size cannot drive the
product model for the reason that the modeling parameter is
determined by the convenience of the product modeling
interactional definition while the engineering size and tolerance
is defined according to product functions and control
requirement of manufacturing accuracy. In a certain sense the
product model defined based on engineering size makes users
knows what only, but not how. Therefore it is necessary to sort
out the mathematical knowledge which comes from the
engineering size.