1、GD&T for BodyGD&T for Body Engineering2Course content Introduction to GD&T 5 Step ProcessGD&T for Body Engineering3Introduction What is GD&T How it affects Ford Motor CompanyGD&T for Body Engineering4What is GD&TGeometric Dimensioning and Tolerancing is a technical data base through which our Produc
2、t Design and Manufacturing Organisations can talk to one another via Product Data, whether on paper or the computer graphics screenIt is the engineering product definition standard that geometrically describes design intent and provides the documentation base for the design of the quality and produc
3、tion system.It is a technique of communication between Product Engineering and Manufacturing Engineering that promotes a uniform interpretation of the requirements for making a component.GD&T for Body Engineering5What is GD&TGDT provides the dimensions of the component and the tolerances in a langua
4、ge that eliminates confusing and inconsistent notes, datum lines, and location point identifications, and replaces them with standard symbols that refer to a universal code. This code describes the dimensions and tolerances of the component with reference to the relationships of the features to each
5、 other and their functional interfaces with mating parts, assemblies, etc.GD&T for Body Engineering6AuthorisationIn 1990 Ford World-wide adopted the American National Standard for Dimensioning and Tolerancing, currently the ASME Y14.5M 1994. The authorisation for the above is documented in Standard
6、D-1 of the Ford Engineering CAD and Drafting Standards and is referenced on all our released data.This information can be accessed via Ford intranet;http:/ above document also contains an electronic copy of the ASME Y14.5M 1994 Dimensioning and Tolerancing Standard.GD&T for Body Engineering7Applicat
7、ionThe application of GDT is initially the responsibility of the relevant Component Engineer, however teamwork is the key to the correct application through the component Core Team.This provides the opportunity for all disciplines to contribute their part of the total design package. It ensures part
8、 data will satisfy design intent as well as manufacturing and inspection requirements based on function, machine capability and available technology. GD&T for Body Engineering8ApplicationIt provides the opportunity for proper Datum selection and has the potential to significantly reduce product chan
9、ges, especially those changes following final product release. The Core Team should consist at a minimum of representatives from Product Engineering, Design Engineering, Manufacturing Engineering, and Quality Engineering.GD&T for Body Engineering9More informationFord Engineering CAD and Drafting Sta
10、ndardshttp:/ Applicationhttp:/GD&T for Body Engineering10How GD&T Relates to FordThe correct application has the potential to; Influence Fit and Finish Reduce Reworks Increase Reliability Affects Assembly Process Reduce costGD&T for Body Engineering11The 5 Step Process1 2 3 4 5GD&T for Body Engineer
11、ing125 Step Process1 Utilise the new Design Concept2 Establishment of the Datum Reference Frame3 Establish GD&T Controls4 Establish Tolerances5 Final Approval of GD&T on Cad DataGD&T for Body Engineering13Step 1Utilise new design conceptGD&T for Body Engineering14Utilise new design conceptThe 1st st
12、ep involves making decisions at the basic design stage that will ultimately effect the design, manufacture and verification of the final component.This can only be successfully achieved by the relevant PD representative attending the Master Control Plan (MCP) Meetings. GD&T for Body Engineering15Mas
13、ter Control PlanWhat is the purpose of the MCP meeting in relation to PDTo establish a common understanding for the verification process of the major panels, e.g. Bodyside, Hood, Deck Lid, Door, Roof, Underbody, etc.To obtain agreement at an early stage of the design for the datum reference frame, d
14、ie approach, etc.Who attends the MeetingPD and Manufacturing, i.e. Body Engineering, DCD, Stamping, Body and Assembly.GD&T for Body Engineering16Master Control PlanWhen should the Meeting take place. Initial design concept stage, knowing the components parameters such as size and function Current me
15、thods use;Past evidence, past experience, can sometimes hinder rather than assist the new design conceptResult of meetingMay be documented in CAD, or paper formGD&T for Body Engineering17Step 2Establish Datum Reference FrameGD&T for Body Engineering18Establish Datum Reference FrameAs part of the Mas
16、ter Control Plan (MCP) Process meeting, Body Engineering and Manufacturing agreed to the definition of the Datum Features and their location.PD have Ownership of the Datum Features.GD&T for Body Engineering19Datum Reference Frame (Reference Pocket Guide, Page 8)Consists of a set of three mutually pe
17、rpendicular planesThe reference frame exists in theory only and is not on the partSufficient datum features are used to position the part in relation to the Datum Reference Frame.GD&T for Body Engineering20Datum FeaturesAn actual feature of the part used to stage/position the part in the equipment f
18、or purposes of relating its geometry to the Datum Reference Frame.GD&T for Body Engineering21Primary Datum PlaneAchieved by establishing a minimum of three Points to define a plane GD&T for Body Engineering22Primary Datum PlanePrimary Datum Plane should be Parallel to Die PlaneGD&T for Body Engineer
19、ing23Primary Datum PlaneWhen Datum Target Areas defining Primary Datum Plane are not on one single planar surface, they must be controlled one to another using the PROFILE of a SURFACE geometric control.GD&T for Body Engineering24Supporting a panel only on the designated Datum Target Areas, effectiv
20、ely removes 3 degrees of freedom, i.e. 1 Linear and 2 Rotational.GD&T for Body Engineering25Datum Target AreasDatum Target Areas should wherever possible be planar and parallel to the die plane.Primary Datum PlaneGD&T for Body Engineering26Datum Target AreasDedicated Datum Target Areas makes both th
21、e part, and gauge/fixture more robust, cost effective and Improves repeatabilityGD&T for Body Engineering27Secondary Datum FeatureGenerally a Datum Feature of Size is used , i.e. Single circular Hole, positioned on a surface that is parallel to the Primary datum Plane, and is ultimately used as a fo
22、ur way locator.GD&T for Body Engineering28Secondary Datum FeatureControlled relative to the Primary Datum Plane using the Geometric control PERPENDICULARITY.GD&T for Body Engineering29Secondary Datum FeatureThe intersection of the derived axis of the feature perpendicular to the Primary Datum Plane,
23、 and the design side of the component is the local origin of all basic dimensions; 0,0,0GD&T for Body Engineering30Supporting a panel on the designated Datum Target Areas, and using the four way locator removes another 2 Linear degrees of freedom, resulting in all 3 Linear, and 2 Rotational degrees
24、of freedom constrained.GD&T for Body Engineering31Tertiary Datum FeatureGenerally the width of a Slotted Feature of Size is used as a two way locator.GD&T for Body Engineering32Tertiary Datum FeatureTo eliminate tolerance of Datum Shift on one of the theoretical axis of the cartesian coordinate syst
25、em, the orientation of the slot (length) should point to the axis of the Secondary Datum Feature.GD&T for Body Engineering33Tertiary Datum FeatureThe slotted features width must be positioned on a surface with the slot width axis parallel to the primary datum plane, and controlled using the geometri
26、c control of POSITION and nominated as the Tertiary Datum Feature.GD&T for Body Engineering34Supporting a panel on the designated Datum Target Areas, using the four way, and two way locators removes all six degrees of freedom.GD&T for Body Engineering35Step 3Establish GD&T ControlsGD&T for Body Engi
27、neering36Common Terms and DefinitionsReference Pocket GuidePage 2GD&T for Body Engineering37Material Conditions MMCMaximum Material Condition LMC Least Material Condition RFS Regardless of Feature Size Virtual ConditionGD&T for Body Engineering38Maximum Material ConditionThe condition in which a fea
28、ture of size contains the maximum amount of material within the stated limits of size.The Heaviest PartMinimum Hole Diameter (10.0)Maximum Shaft Diameter (11.0)M10.0+1.0 0GD&T for Body Engineering39Least Material ConditionThe condition in which a feature of size contains the least amount of material
29、 within the stated limits of size.The Lightest partMaximum Hole Diameter (11.0)Minimum Shaft Diameter (10.0)To date no application in the Feature Control Frame for this symbol has been identified in Body Engineering.L10.0+1.0 0GD&T for Body Engineering40Regardless of Feature SizeThere is no symbol f
30、or Regardless of Feature Size. If a material modifier is not used then Regardless of Feature Size is assumed. The term used to indicate that a geometric tolerance or datum reference applies at any increment of size of the feature within its size toleranceRegardless of Feature Size is expensive to ve
31、rify, and rarely reflects the relevant feature function, and therefore should not be used in a Body application without the agreement of the entire core team.10.0+1.0 01.0GD&T for Body Engineering41Virtual Condition A constant Boundary generated by the collective effects of a size features specified
32、 MMC or LMC material condition and the geometric tolerance for that condition. The VIRTUAL CONDITION of features of mating parts must be matched, guaranteeing component features at their worst case for assembly will always assemble.The Virtual condition envelope is the worst condition offered to the
33、 mating part.GD&T for Body Engineering42Virtual Condition (Shaft)Virtual condition (Shaft) = MMC + Tolerance zone value= 12.0MMCLMCM1.010.0+1.0- 0=10.0=11.0Virtual ConditionGD&T for Body Engineering43Virtual Condition (Hole)MMCLMCM1.010.0+1.0- 0= 11.0= 10.0Virtual ConditionVirtual condition (Hole) =
34、 MMC - Tolerance zone value= 9.0GD&T for Body Engineering44Geometric ControlsReference Pocket GuidePage 1GD&T for Body Engineering45Feature Control Frame (Reference Pocket Guide, page 3)MAB0.5MC MGeometric characteristic symbols, the tolerance value, Material Modifiers, and Datums of Reference, wher
35、e applicable, are combined in a feature control frame to express a geometric tolerance.GD&T for Body Engineering46GeometricCharacteristicSymbolMaterial Condition SymbolWhere applicableMAB0.5MC MToleranceTolerance ZoneShape where applicableDatum Reference LettersGD&T for Body Engineering47Geometric C
36、ontrolsEach feature of the component must be controlled for SIZE, FORM, ORIENTATION and LOCATION.In the American National Standard there are fourteen geometric controls.Body Engineering use just three;1PERPENDICULARITY2POSITION3PROFILEGD&T for Body Engineering48PERPENDICULARITYReference Pocket Guide
37、Page 29GD&T for Body Engineering49PERPENDICULARITYThe main Application for PERPENDICULARITY within Body Engineering is to control a single Secondary Datum Feature of size (a hole) to be perpendicular to the Primary Datum Plane.Generally used only once within each component to define the secondary da
38、tum feature.Any other use of this control for other features would be an additional requirement, because PERPENDICULARITY does notimply any location GD&T for Body Engineering50LMCThe Cylindrical Tolerance Zone diameter is dependant on the actual feature sizeBAPERPENDICULARITYMA019.0+0.1 0A cylindric
39、al tolerance zone perpendicular to a datum plane within which the axis of a feature must lie.GD&T for Body Engineering51POSITIONReference Pocket GuidePage 33GD&T for Body Engineering52POSITION Definition Position Tolerance Zones Zero at MMC Concept Boundary Concept Composite Tolerance Zones Projecte
40、d Tolerance ZoneGD&T for Body Engineering53The term to describe the perfect (theoretical exact) location of individual features in relationship with a datum reference or other feature(s). In general the POSITION control is used to locate uniform features of size, e.g. holes, shafts, slots etc.POSITI
41、ONGD&T for Body Engineering54VerificationAs with all Features of Size;First to be verified is that the top and bottom limits of size have not been violated (Taylors Principle). A full form check at the MMC and a two pointed instrument check at the LMC.Secondly the features “Position” must be verifie
42、d.GD&T does not dictate the method of verification. The decision on the gauging technique employed is the responsibility of the core team.GD&T for Body Engineering55Position Tolerance ZonesGD&T for Body Engineering56Positional Tolerance Zone 1(Cylindrical)20.0+1.0 0To specify a Cylindrical Tolerance
43、 Zone, a diameter sign must precede the tolerance value, followed by the material Modifier MMC unless Regardless of Feature Size is intended.M0.5A cylindrical zone within which the centre axis of a feature of size is permitted to vary from its true (theoretically exact) position.GD&T for Body Engine
44、ering57Positional Tolerance Zone 2(Non Cylindrical)A zone within which the centre, axis, of centre plane of a feature of size is permitted to vary from its true (theoretically exact) position.20.0+2.0 0The tolerance value is followed by the material Modifier MMC unless Regardless of size is intended
45、.To specify a total width Tolerance Zone, No diameter symbol precedes the tolerance value.M0.5GD&T for Body Engineering58BOUNDARYReference Pocket GuidePage 37GD&T for Body Engineering59BOUNDARYIn Body Engineering controlling the centre plane of a slotted feature is rarely a priority.GD&T for Body En
46、gineering60As no Diameter symbol precedes the positional tolerance, a non cylindrical zone is inferred.BOUNDARYBOUNDARYBOUNDARYWhat we are interested in is controlling the BOUNDARY of the feature.12.0 +2.0 02.0 M1.0 M5.0+1.0 0GD&T for Body Engineering61BOUNDARY 5.0 MMC Width of Hole-1.0 Positional T
47、olerance 4.0 Wide Boundary4BOUNDARY1.0 MBOUNDARY5.0+1.0 0Virtual Condition12.0 MMC Width of Hole- 2.0 Positional Tolerance10.0 Wide Boundary102.0 M12.0 +2.0 0GD&T for Body Engineering62BOUNDARYNo portion of the slot surfaces are permitted to lie within the area described by the Virtual Condition whe
48、n the part is positioned within the Datum Reference FrameThe POSITION control + BOUNDARY controls both Location and Orientation12.0 +2.0 02.0 MBOUNDARY1.0 MBOUNDARY5.0+1.0 0GD&T for Body Engineering63BOUNDARY12.0 +2.0 02.0 MBOUNDARY2.0 MBOUNDARY5.0+1.0 0If the same Positional Tolerance value applies
49、 to both the Length and Width limits of size, then the Feature Control Frame is separated from the Limits of Size, and points directly to the slotted feature.GD&T for Body Engineering64BOUNDARY12.0 +2.0 02.0 MBOUNDARY5.0+1.0 0If the same Positional Tolerance value applies to both the Length and Widt
50、h limits of size, then the Feature Control Frame is separated from the Limits of Size, and points directly to the slotted feature.GD&T for Body Engineering65BOUNDARY The BOUNDARY note only applies to non cylindrical features. The POSITION control + BOUNDARY controls both Location and OrientationIn t
