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 product
3、ion 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 languag
4、e 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 othe
5、r 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 D-1 of th
6、e 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 Engineering7ApplicationThe ap
7、plication 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 data will
8、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 changes,especiall
9、y 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 Standardshttp:/ Appli
10、cationhttp:/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 Engineering125 Step Process
11、1 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 step involves making
12、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 Engineering15Master Control PlanWhat is
13、 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,die approach,etc.Who attends the
14、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 methods use;Past evidence,past experience,
15、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 Master Control Plan(MCP)Process meeting,Body E
16、ngineering 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 perpendicular planesThe reference frame exists in
17、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 for purposes of relating its geometry to the Datu
18、m 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 Engineering23Primary Datum PlaneWhen Datum Target Areas
19、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,effectively removes 3 degrees of freedom,i.e.1 Linear and
20、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 the part,and gauge/fixture more robust,cost effective
21、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 four way locator.GD&T for Body Engineering28Secondary Datum F
22、eatureControlled 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,and the design side of the component is the local origin of
23、 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 of freedom constrained.GD&T for Body Engineering31Tertiary Datum
24、 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 system,the orientation of the slot(length)should point to the axis o
25、f 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 geometric control of POSITION and nominated as the Tertiary Datum Feature.GD
26、&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 Engineering36Common Terms and DefinitionsReference Pocket GuidePage 2GD&T
27、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 feature of size contains the maximum amount of material within the stated
28、 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 within the stated limits of size.The Lightest partMaximum Hole Diameter
29、(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 for Regardless of Feature Size.If a material modifier is not used then Rega
30、rdless 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 verify,and rarely reflects the relevant feature function,and therefore should
31、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 MMC or LMC material condition and the geometric tolerance for that condition.
32、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 mating part.GD&T for Body Engineering42Virtual Condition(Shaft)Virtual conditio
33、n(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)=MMC-Tolerance zone value=9.0GD&T for Body Engineering44Geometric ControlsReference Pocket Guid
34、ePage 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,where applicable,are combined in a feature control frame to express a geometric tolerance.GD&T for Body Engi
35、neering46GeometricCharacteristicSymbolMaterial Condition SymbolWhere applicableMAB0.5MC MToleranceTolerance ZoneShape where applicableDatum Reference LettersGD&T for Body Engineering47Geometric ControlsEach feature of the component must be controlled for SIZE,FORM,ORIENTATION and LOCATION.In the Ame
36、rican National Standard there are fourteen geometric controls.Body Engineering use just three;1PERPENDICULARITY2POSITION3PROFILEGD&T for Body Engineering48PERPENDICULARITYReference Pocket GuidePage 29GD&T for Body Engineering49PERPENDICULARITYThe main Application for PERPENDICULARITY within Body Eng
37、ineering 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 datum feature.Any other use of this control for other features would be an additional requirement,because PERPE
38、NDICULARITY does notimply any location GD&T for Body Engineering50LMCThe Cylindrical Tolerance Zone diameter is dependant on the actual feature sizeBAPERPENDICULARITYMA019.0+0.1 0A cylindrical tolerance zone perpendicular to a datum plane within which the axis of a feature must lie.GD&T for Body Eng
39、ineering51POSITIONReference Pocket GuidePage 33GD&T for Body Engineering52POSITION Definition Position Tolerance Zones Zero at MMC Concept Boundary Concept Composite Tolerance Zones Projected Tolerance ZoneGD&T for Body Engineering53The term to describe the perfect(theoretical exact)location of indi
40、vidual 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.POSITIONGD&T for Body Engineering54VerificationAs with all Features of Size;First to be verified is that the top and bottom
41、 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 verified.GD&T does not dictate the method of verification.The decision on the gauging technique employed is the responsibility o
42、f 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 Zone,a diameter sign must precede the tolerance value,followed by the material Modifier MMC unless Regardless of Feature
43、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 Engineering57Positional Tolerance Zone 2(Non Cylindrical)A zone within which the centre,axis,of centre plane of a feature of size is
44、 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.To specify a total width Tolerance Zone,No diameter symbol precedes the tolerance value.M0.5GD&T for Body Engineering58BOUNDARYRe
45、ference 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 Engineering60As no Diameter symbol precedes the positional tolerance,a non cylindrical zone is inferred.BOUNDARYBOUNDARYBOUNDARYWhat
46、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 Tolerance 4.0 Wide Boundary4BOUNDARY1.0 MBOUNDARY5.0+1.0 0Virtual Condition12.0 MMC Width of Hole-2.0 Positional Tolerance10.0 Wide B
47、oundary102.0 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 when the part is positioned within the Datum Reference FrameThe POSITION control+BOUNDARY controls both Location and Orientation12.0 +2.
48、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 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
49、 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 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
50、Body Engineering65BOUNDARY The BOUNDARY note only applies to non cylindrical features.The POSITION control+BOUNDARY controls both Location and OrientationIn this case the word BOUNDARY must be added below the FCF and the material Modifier MMC specified after the POSITION tolerance value.No diameter
