Downloaded from https://www.everyspec.com APPENDIX C MIL-STD-31000A Data exchange: Faces may not trim properly. Automated self-healing may insert undesirable tiny or narrow faces. Finite element analysis: Mesh algorithms may fail or produce excessive numbers of elements. Numerically controlled manufacturing: Tool-path-generating software may fail. Tool paths may gouge the work piece. Recommended correction: Rebuild the affected areas with common boundary curves C.7.6.2. Non-tangent faces (G-SH-NT). Definition: Adjacent faces are not tangent (G 1 discontinuity). Effects of condition on CAD data quality: Non-tangent faces are not necessarily indicative of poor data quality.
In some cases, such as square corners, chamfered, and beveled edges, non-tangent conditions are intended. When curves are intended to be tangent, but aren’t, then G1 discontinuity is indicative or poor quality. Non-tangent conditions are usually visible to the unaided eye and can be felt by finger tips on physical models. Design or drafting: A quality defect only when tangency is intended. Data exchange: No harmful effects on data exchange. Finite-element analysis: No harmful effects on mesh generation or model solution. Numerically controlled manufacturing: Sharp edges should generally be avoided in manufacturing.
However, when making machine parts, removal of sharp edges may be covered by a general note or specification. When tangency is intended between surfaces, non-tangent surfaces produce noticeable defects in finished products. Recommended correction: Adjust one or both faces to eliminate the unwanted condition. C.7.6.3. Non-smooth faces (G-SH-NS). Definition: Radius of curvature changes at the common boundary of two faces (G 2 discontinuity). 115