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1.7.2 Bend Radius bend radius: the inside radius of a formed part. 1.7.3 Bend Tangent Line bend tangent line: the line at which the flat surface of a part becomes tangent to the radius of the bend (see Fig. 2). 1.7.4 Brake Process brake process: a method of forming in which the punch is brought down on a flat pattern that is laid on the die, bending the sheet metal up and around the surface of the punch. 1.7.5 Center Line of Bend (CLB) center line ofbend (CLB): a line half the distance between the bend tangents that indicates the straight line of con- tact where the brake press bar will strike the flat pattern to form the bend (see Fig. 3). 1.7.6 Common Reference common reference: a reference line provided for use as a guide in coordinating the alignment of an item across multiple views or drawing sheets. 1.7.7 Comparator Drawing comparator drawing: a drawing defining a 2D true profile, used for overlay validation viewing of items with a comparator checking machine. 1.7.8 Contour Definition Drawing contour definition drawing: a drawing containing the mathematical, numeric, or graphic definition required to locate and define a contoured surface, also known as loft drawing. 1.7.9 Dimensional Accuracy Points dimensional accuracy points: a set of points located in a rectangular pattern to establish a means of measuring horizontally, vertically, or diagonally across the drawing to validate dimensional accuracy. 1.7.10 Flange flange: the portion of the item being bent. 1.7.11 Form Block Line (FBL) form blockline(FBL): the line representingthe intersection of the projected surfaces of the tool used for forming (see Fig. 4). 1.7.12 Grid Lines grid lines: a pattern of perpendicular lines drawn to a precise scale across the face of the drawing to validate dimensional accuracy.
1.7.13 Hydro Process hydro process: a method of forming in which the sheet metal is formed down over a die or form block by pres- sure applied through a rubber block affixed to the press ram. 1.7.14 Inside Mold Line (IML) inside mold line (IML): the line representing the intersec- tion of the projected inside surfaces of a formed item (see Fig. 2). 1.7.15 Joggle joggle: anoffsetdisplacementofmaterial fromits original plane or contour. Joggles are used to provide structural continuity between two adjacent surfaces. 1.7.16 Outside Mold Line (OML) outside mold line (OML): the line representing the pro- jected outside surfaces of a formed item (see Fig. 2). 1.7.17 Principal Plane principal plane: the flat surface of the item that flanges are developed from. 1.7.18 Printed Circuit Drawing printed circuit drawing: a drawing defining the circuitry pattern that is etched, deposited, screened, or bonded to a base material. 1.7.19 Registration Mark registration mark: a stylized pattern (symbol) that is used as a reference point for registration (IPC-T-50). 1.7.20 Reproduction reproduction: a copy that duplicates the original. Repro- ductions may be either reproducible or non- reproducible, depending on the media (MIL-PRF-5480). 1.7.21 Template template: a tool that is a dimensionally stable full size reproduction ofan undimensioned drawing that defines the profile of an item. 1.7.22 Tolerant Gage tolerant gage: accepts most part features that are within tolerance, rejects most part features not within tolerance, accepts a small percentage ofborderline out-of-tolerance features, and rejects a small percentage of borderline within-tolerance features (ASME Y14.43). 1.7.23 True Geometry Views true geometry views: views that show the actual shape description, and when it is a section view it shows the actual shape cut by the cutting plane (ASME Y14.3).
1.7.25 Validation validation: the process used by the producer of the tem- plate to check template accuracy. 1.7.26 Verification verification: the process used by the user of the template to check template accuracy. 1.7.27 Wire Harness Drawing wire harness drawing: a drawing defining the configura- tion and item identification of a wire harness assembly. 2 UNDIMENSIONED DRAWING An undimensioned drawing graphically defines the item in true geometry view(s). Dimensions may be included to establish a defined nominal value with a tolerance that is a refinement from the tolerance applied to the undimensioned features. Items that are symmetri- cal shall be completely delineated. Features are pre- sented full size, although some drawing types may be produced to a larger or smaller scale to provide appro- priate details which will be returned to actual size for production use. A method(s) to validate the accuracy of the drawing or verify the accuracy of the template shall be provided. Drawings may be prepared by manual or electronic means. 3 APPLICATIONS Undimensioned drawings are used for a variety of applications where the generation of templates is used to produce the items depicted. Undimensioned draw- ings are suitable for, but not limited to the following applications: (a) parts whose presentations involve a series of con- tours, and templates for tooling usage, e.g., compound curvature fairings (see Fig. 5) (b) parts requiring art layout for fabrication such as printed circuit boards (see Fig. 6) NOTE: Requirementsforthepreparationofprinted circuitboards are provided in IPC 2221. (c) wire harnesses (see Fig. 7)

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