Ford_福特GDT形位公差培訓(xùn)材料ppt課件

1、GD&T for BodyCourse contentIntroduction to GD&T5 Step ProcessIntroductionWhat is GD&THow it affects Ford Motor CompanyWhat is GD&TGeometric Dimensioning and Tolerancing is a technical data base through which our Product Design and Manufacturing Organisations can talk to one another via Product Data,

2、 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 production system.It is a technique of communication between Product Engineering and Man

3、ufacturing Engineering that promotes a uniform interpretation of the requirements for making a component.What is GD&TGDT provides the dimensions of the component and the tolerances in a language that eliminates confusing and inconsistent notes, datum lines, and location point identifications, and re

4、places 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 other and their functional interfaces with mating parts, assemblies, etc.AuthorisationIn 1990 Ford World-wi

5、de 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 the Ford Engineering CAD and Drafting Standards and is referenced on all our released data.This information can be accessed via

6、 Ford intranet;www-wise.ford/non-regulatory.htmlThe above document also contains an electronic copy of the ASME Y14.5M 1994 Dimensioning and Tolerancing Standard.ApplicationThe application of GDT is initially the responsibility of the relevant Component Engineer, however teamwork is the key to the c

7、orrect 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 satisfy design intent as well as manufacturing and inspection requirements based on function, machine capability and av

8、ailable technology. ApplicationIt provides the opportunity for proper Datum selection and has the potential to significantly reduce product changes, especially those changes following final product release. The Core Team should consist at a minimum of representatives from Product Engineering, Design

9、 Engineering, Manufacturing Engineering, and Quality Engineering.More informationFord Engineering CAD and Drafting Standardswww-wise.ford/non-regulatory.htmlGDT Applicationcadmethods.fordHow GD&T Relates to FordThe correct application has the potential to;Influence Fit and FinishReduce ReworksIncrea

10、se ReliabilityAffects Assembly ProcessReduce costThe 5 Step Process123455 Step Process1Utilise the new Design Concept2Establishment of the Datum Reference Frame3Establish GD&T Controls4Establish Tolerances5Final Approval of GD&T on Cad DataStep 1Utilise new design conceptUtilise new design conceptTh

11、e 1st step 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. Master Control PlanWha

12、t 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, die approach, etc.Wh

13、o attends the MeetingPD and Manufacturing, i.e. Body Engineering, DCD, Stamping, Body and Assembly.Master 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, can

14、sometimes hinder rather than assist the new design conceptResult of meetingMay be documented in CAD, or paper formStep 2Establish Datum Reference FrameEstablish Datum Reference FrameAs part of the Master Control Plan (MCP) Process meeting, Body Engineering and Manufacturing agreed to the definition

15、of the Datum Features and their location.PD have Ownership of the Datum Features.Datum Reference Frame (Reference Pocket Guide, Page 8)Consists of a set of three mutually perpendicular planesThe reference frame exists in theory only and is not on the partSufficient datum features are used to positio

16、n the part in relation to the Datum Reference Frame.Datum FeaturesAn actual feature of the part used to stage/position the part in the equipment for purposes of relating its geometry to the Datum Reference Frame.Primary Datum PlaneAchieved by establishing a minimum of three Points to define a plane

17、Primary Datum PlanePrimary Datum Plane should be Parallel to Die PlanePrimary 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.Supporting a panel only on the d

18、esignated Datum Target Areas, effectively removes 3 degrees of freedom, i.e. 1 Linear and 2 Rotational.Datum Target AreasDatum Target Areas should wherever possible be planar and parallel to the die plane.Primary Datum PlaneDatum Target AreasDedicated Datum Target Areas makes both the part, and gaug

19、e/fixture more robust, cost effective and Improves repeatabilitySecondary 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.Secondary Datum FeatureContr

20、olled relative to the Primary Datum Plane using the Geometric control PERPENDICULARITY.Secondary 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 all basic dimensions; 0,0,0Supportin

21、g 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.Tertiary Datum FeatureGenerally the width of a Slotted Feature of Size is used as a two way locator.T

22、ertiary 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 of the Secondary Datum Feature.Tertiary Datum FeatureThe slotted features width must be positioned on a surface

23、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.Supporting a panel on the designated Datum Target Areas, using the four way, and two way locators removes all six degrees of freedom.Step 3

24、Establish GD&T ControlsCommon Terms and DefinitionsReference Pocket GuidePage 2Material ConditionsMMCMaximum Material ConditionLMC Least Material ConditionRFS Regardless of Feature SizeVirtual ConditionMaximum Material ConditionThe condition in which a feature of size contains the maximum amount of

25、material within the stated limits of size.The Heaviest PartMinimum Hole Diameter (10.0)Maximum Shaft Diameter (11.0)M10.0+1.0 0Least 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 Diamete

26、r (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 0Regardless of Feature SizeThere is no symbol for Regardless of Feature Size. If a material modifier is not used then Regardless of Feature Size

27、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 not be used in a Bod

28、y application without the agreement of the entire core team.10.0+1.0 01.0Virtual 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. The VIRTUAL CONDITION of features of mating pa

29、rts 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.Virtual Condition (Shaft)Virtual condition (Shaft) = MMC + Tolerance zone value= 12.0MMCLMCM1.010.0+1.0- 0=10.0=

30、11.0Virtual ConditionVirtual Condition (Hole)MMCLMCM1.010.0+1.0- 0= 11.0= 10.0Virtual ConditionVirtual condition (Hole) = MMC - Tolerance zone value= 9.0Geometric ControlsReference Pocket GuidePage 1Feature Control Frame (Reference Pocket Guide, page 3)MAB0.5MCMGeometric characteristic symbols, the

31、tolerance value, Material Modifiers, and Datums of Reference, where applicable, are combined in a feature control frame to express a geometric tolerance.GeometricCharacteristicSymbolMaterial Condition SymbolWhere applicableMAB0.5MCMToleranceTolerance ZoneShape where applicableDatum Reference Letters

32、Geometric ControlsEach 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;1PERPENDICULARITY2POSITION3PROFILEPERPENDICULARITYReference Pocket GuidePage 29PERPENDIC

33、ULARITYThe 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 datum feature.Any other use of this control f

34、or other features would be an additional requirement, because PERPENDICULARITY does notimply any location LMCThe 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

35、 of a feature must lie.POSITIONReference Pocket GuidePage 33POSITIONDefinitionPosition Tolerance ZonesZero at MMC Concept Boundary ConceptComposite Tolerance ZonesProjected Tolerance ZoneThe term to describe the perfect (theoretical exact) location of individual features in relationship with a datum

36、 reference or other feature(s). In general the POSITION control is used to locate uniform features of size, e.g. holes, shafts, slots etc.POSITIONVerificationAs 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

37、 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 of the core team.Position Tolerance ZonesPositional Tolerance Z

38、one 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 Size is intended.M0.5A cylindrical zone within which the centre axis of a feature of size is permitted to vary fro

39、m its true (theoretically exact) position.Positional 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 un

40、less Regardless of size is intended.To specify a total width Tolerance Zone, No diameter symbol precedes the tolerance value.M0.5BOUNDARYReference Pocket GuidePage 37BOUNDARYIn Body Engineering controlling the centre plane of a slotted feature is rarely a priority.As no Diameter symbol precedes the

41、positional tolerance, a non cylindrical zone is inferred.BOUNDARYBOUNDARYBOUNDARYWhat we are interested in is controlling the BOUNDARY of the feature.12.0 +2.0 02.0M1.0M5.0+1.0 0BOUNDARY 5.0 MMC Width of Hole-1.0 Positional Tolerance 4.0 Wide Boundary4BOUNDARY1.0MBOUNDARY5.0+1.0 0Virtual Condition12

42、.0 MMC Width of Hole- 2.0 Positional Tolerance10.0 Wide Boundary102.0M12.0 +2.0 0BOUNDARYNo 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 L

43、ocation and Orientation12.0 +2.0 02.0MBOUNDARY1.0MBOUNDARY5.0+1.0 0BOUNDARY12.0 +2.0 02.0MBOUNDARY2.0MBOUNDARY5.0+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

44、to the slotted feature.BOUNDARY12.0 +2.0 02.0MBOUNDARY5.0+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.BOUNDARY The BOUNDARY note only a

45、pplies 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 symbol precedes the tolerance value in the Featu

46、re Control FrameThe positional tolerance specified for the length may differ from that specified for the width.To SummariseZero at MMC conceptReference Pocket GuidePage 44Zero at MMC conceptThe Zero at MMC concept applies only to features whos sole function is CLEARANCEM10.0L11.51.02.59.010.310.510.

47、89.09.09.09.0Actual Mating EnvelopeTolerance Zone (Dia)Virtual Condition10.0+1.5 0What is the smallest diameter hole permissible?Question?10AnswerExample of current specificationM1.0AMMBCExample of current specificationYesAnswerQuestion?If a feature of the part was measured, and t

48、he hole was found to be Dia 9.6, would this part be reject? M10.0L11.51.02.59.010.310.89.09.09.09.09.0Actual Mating EnvelopeTolerance Zone (Dia)Virtual Condition10.0+1.5 0M1.0AMMBCExample of current specificationBut, would the rejected part be functional? Question?AnswerTo make t

49、he part acceptable we would need to change the data specification.10.0+1.5 0If the part meets the functional gauge requirements, we know the part is functional.The part has been rejected because of feature size alone.Therefore it must have been manufactured to a tighter specification than that state

50、d on the data.M1.0AMMBCExample of current specificationWhat needs to change? Question?The specification for the hole needs to change, by adopting the “Zero at MMC conceptAnswerM10.0L11.51.02.59.010.310.89.09.09.09.09.0Actual Mating EnvelopeTolerance Zone (Dia)Virtual Condition10.

51、0+1.5 0M1.0AMMBCZero at MMC concept+2.5 09.0Example:To comply with the “Zero at MMC concept for clearance holes;The Specified value of the Feature of Size is modified to equal the Virtual Condition, i.e. (MMC-Positional Tolerance).The geometric tolerance value is incorporated into the features limit

52、s of size10.0+1.5 0M1.0AMMBCA zero tolerance is specified in the Feature Control Frame, and the material modifier MMC MUST follow the zero tolerance value.M 0AMMBCM9.00Zero at MMC concept10.0L11.51.02.59.09.010.39.09.010.89.09.0Actual Mating EnvelopeTolerance Zo

53、ne (Dia)Virtual Condition9.09.09.09.0The Zero at MMC concept gives Manufacturing the FULL range of tolerance available, and since the MMC size is now equal to the VIRTUAL CONDITION, no separate MMC feature size verification is required. (Taylors Principle)The LMC feature size must still be functiona

54、lly derived and verified9.0+2.5 0M 0ABCThe specified Feature of Size is not the target size for manufacturing.Zero at MMC conceptThe tolerance available is dependant on the Feature of SizeM9.00The nearer the actual punch size is to the LMC, the larger the Tolerance of Position10.0L

55、11.51.02.59.09.010.39.09.010.89.09.0Actual Mating EnvelopeTolerance Zone (Dia)Virtual Condition9.09.09.09.0M 09.0+2.5 0VIRTUAL CONDITION & MMCLMC FEATURE SIZEStandard Punch SizeM 0 9.0+2.5 0Punch diameter will be LMC minus 0.1mm rounded up or downM9.0010.0L11.51

56、.02.59.09.010.39.09.010.89.09.0Actual Mating EnvelopeTolerance Zone (Dia)Virtual Condition9.09.09.09.015.2715.1715.212.7612.6612.711.511.411.4LMC-0.1mmExamplePunch Dia.Composite Positional TolerancesReference Pocket GuidePage 45Composite Positional Tolerances(For groups of holes)

57、MA2.020.0+0.3 0M0.5MBMCA3 x FIX HOLESThe upper segment is referred to as the “Pattern Locating Tolerance Zone Framework (PLTZF)The lower segment is referred to as the “Feature Relating Tolerance Zone Framework (FRTZF)Composite Positional TolerancesActual HoleFeature Relating tolerance ZoneMA2.0M0.5M

58、BMCAPattern Locating Tolerance ZoneComposite Positional TolerancesMA2.0M0.5MBMCAComposite Positional TolerancesMA2.0M0.5MBMCAThe control requires that each actual feature axis must lie within the specified tolerance zones of both the upper and lower segments simultaneouslyComposite Positional Tolera

59、ncesMA2.0M0.5MBMCAThe control requires that each actual feature axis must lie within the specified tolerance zones of both the upper and lower segments simultaneously25.025.0Composite Positional TolerancesIts application is supported by the entire core team.The control reflects the part feature manu

60、facturing process.It will be verified in full down stream.The added-on cost to the verification process is justified by the required feature function.Before specifying this control verify that;Projected Tolerance ZoneReference Pocket GuidePage 43Projected Tolerance ZoneThe projected tolerance zone p