ASME AED-1-2018 pdf – Aerospace and Advanced Engineering Drawings. Produced at the AssembLy LeveL. When a feature of size produced during assembly is designated as a datum feature, it shall be fully defined per ASME Y14.5.
5.4 Aggregate Datum
The aggregate features of the designated aggregate datum restrict one or more degrees of freedom without affecting any inherent motion within the assembly. An aggregate datum with no inherent motion shall be identified per para. 5.4.1 and specified in a feature control frame per ASME Y14.5. An aggregate datum with inherent motion shall be identified per para. 5.4.1 and specified in a feature control frame per para. 5.4.2. Where aggregate datum features are accessible, a physical datum feature simulator should be used. Where aggregate datum features are not accessible with a physical datum feature simulator, the combined effect of the assembly acts as the physical datum feature simulator.
5.4.1 Identifying an Aggregate Datum Feature. The aggregate datum feature symbol is the letters “AG” within a hexagon. See Figure 1-1. An aggregate datum feature symbol shall be associated with at least one of the features used to derive the aggregate datum. The aggregate datum feature symbol or the word “AGGREGATE” shall be placed next to the datum feature symboL. See Figure 5-4.
5.4.2 Identifying Inherent Motion of an Assembly. The inherent motion of the assembly shall be indicated by
(a) a datum reference frame symbol placed with at least one of the axes aligned with the inherent motion
(b) the appropriate degree of freedom symbol placed after the aggregate datum feature reference letter in the feature control frame
(c) an asterisk placed after the degree of freedom symbol to indicate motion direction or freedom rather than the motion constraint default per ASME Y14.5
A note may be used to clarify movement or method on how the assembly is to be restrained.
For an assembly with motion, at least one full cycle of the movement is required for verification, UOS. See Figure 5-4.
6.1 BLind HoLes
6.1.1 BLind HoLe CatLout. The blind hole symbol may be used to indicate a blind hole. See Figure 1-1.
When the blind hole symbol is used, the acceptable boundaries of the hole bottom configuration shall be as shown in Figure 6-1 for a blind hole or Figure 6-2 for a blind hole with a through hole.
6.1.2 DriLL Point Defined by CaLLout. The preferred drill point may be indicated with a modified blind hole symbol as shown in Figure 1-1. See Figure 6-3 for a 135-deg drill point callout example.
6.2 Edge Breaks
When the term “EDGE BREAK” or another edge break callout is specified, the edge break may take the form of a radius, a chamfer, or a combination of both. See Figure 6-4 for edge break examples.
If a blend is required between the flat surface permissible in the edge break tolerance zone and the adjacent surfaces to eliminate abrupt changes in material topography, the blend shall be specified. It could be a radius, a partial ellipse, or a combination of both.
Edge breaks may be produced in any manner that is not otherwise restricted by the design authority. Where an edge break is specified with only a high limit size, e.g., .030 MAX, the lower limit shall be interpreted as having no measurable size; however, burrs and sharp edges that may cause a cut-type injury are not permitted.
6.3 Radius
Radius tolerance and controlled radius tolerance ofASME Y14.5 are amended as described in paras. 6.3.1 through 6.3.4.
6.3.1 Radius ToLerance. A radius symbol, R, creates a zone defined by two arcs (the minimum and maximum radii). The part surface shall lie within this zone. Where the center of the radius is located via dimensions, the arcs are concentric. See Figure 6-5. Where the center of the radius is not located (tangent located), the arcs create a crescent- shaped tolerance zone whose “width” is set by placing both the maximum and minimum radii tangent to the adjacent surfaces. See Figure 6-6.