(精品)GD&TTrainingcourse

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,GD&T:Core skills,A one-day Seminar for Engineers&technical staff,GD&T Core skills Course outline,Define the benefits of GD&T,Understand Features and Features-of-size,Understand and recognise Datum features,Understand Datum precedence,Recognise GD&T,symbology,Understand and apply Rule 1(Perfect form at MMC),Read and apply Profile tolerances,Read and apply simple Tolerances of position,Understand refinement,Generalised rules of application,GD&T Advanced Skills Course outline,Review the basics,回顾基本,Complex applications,复杂应用,Gauging GD&T callouts,Understand theoretical datum,理解理论基准,Applying complex TOP and refinements,Controlling patterns of features,Applying Symmetry,Cylindricity,Roundness,Angularity&,Runout,.,Defining the benefits of GD&T(1),251,0.5,365,1.0,-A-,251,365,2.0 A,Co-ordinate,Tolerancing,Paper drawings require Basic dimensions to be given.Nowadays 3D CAD drawings define the basic dimensions GD&T supports a paperless drawing office,老的,2D,图纸要求基本的尺寸,现在,3D,的,CAD,图纸定义了,GD&T,Defining the benefits of GD&T(2),Datums,defined explicitly on the drawing(in the contract).,Drawing,Gauge#1,Gauge#2,-A-,A,3.0,GD&T,Coordinate Dimensions,Defining the benefits of GD&T(2),Taking the First example(all these are legal measurements of the dimension):,Drawing,ISIR Inspection,Audit Inspection,Goods In Inspection,Test&development,Engineering,END VIEW,Is it any wonder we have to do R&r studies?,Defining the benefits of GD&T(3),GD&T defines,Mating Conditions,not just tolerances and provides control of Size and Position,simultaneously,by controlling a features,envelope.,3.0,M,10.0,0.5,Defining the benefits of GD&T(3),Gauging Most GD&T callouts can be simply gauged using Go/No-Go gauges,A,B,C,2.0 A B C,1.0 A,10 x,This callout which relates the pins to the,datums,and also groups them can be gauged using just 2 Go/,NoGo,gauges,Position,Controls of,Position,Surface Profile,Line Profile,Angularity,Controls of,Orientation,Perpendicularity,Concentricity,Parallelism,Flatness,Controls of,Form,Straightness,Circularity,Symmetry,Cylindricity,Circular,runout,Total,runout,Introducing GD&T,Symbology,Defining Features and Features of size,10.0,0.5,Feature of Size,(,Ie,it has a size dimension),Also,Holes,Slots and Tabs,Feature,(Has no size dimension),Understanding Material conditions,Maximum Material condition is when Holes and Slots are at smallest limit(Maximum volume),and Pins and Tabs are at biggest limit(Maximum volume),Least Material condition is when Holes and Slots are at biggest limit(Least Volume),and Pins and Tabs are at smallest limit(Least Volume).,Maximum(and Least)Material Condition only apply to Features of size(Holes,pins,slots and tabs).,A Feature(A plane)doesnt have a feature size dimension,so MMC cannot apply(the area of the plane doesnt count).,MMC,LMC,10.0,0.5,From the Earlier Example:,10.5,9.5,Understanding Material conditions,Understanding Material conditions,RFS(Regardless of Feature Size)is the default case for Features of Size under ASME Y14.5.There is no notation associated with it in the 1994 revisions to the standard.,Where MMC or LMC is not specified,Assume RFS.,RFS requires the characteristics of a feature to be gauged without reference to its size dimension(presuming that size dimension is in-spec!).,RFS conditions cannot be checked with Go/,NoGo,gauging like MMC,it requires variable gauging to establish the position of axis or,centreplane,.Consequently it is generally more expensive and therefore Non-Preferred,End of section test,Give three benefits of using GD&T?,Explicitly defines measurement,datums,for the part,Provides control of,Mating Conditions,not just Tolerances.,Supports CAD definition of nominal form,Describe the difference between a Feature and a Feature-of-size?,A Feature is typically a flat plane,A Feature of Size must have a size dimension,eg,a Pin,hole slot etc.,Describe a Pin diameter that is at MMC,in terms of its variation from Nominal size?,A Pin Described as being at MMC would be at top-limit of diameter spec,ie,would be as large as allowed by the drawing.,What does RFS stand for?,Regardless of Feature Size,What does it mean?,That any tolerance applied at RFS ignores the size of the feature it is applied to,Section 2 Rule One (,Perfect form at MMC,),MMC?,MMC(Maximum material condition)is when Holes are smallest and pins are biggest,It is therefore Worst Mating Condition,(because you always want the hole to be bigger than the pin,Right?),Perfect Form at MMC?,10.0,0.5,Ring Gauge,At Least material condition,the Mating envelope is not affected by form errors.,Our ring gauge still fits over the feature despite the form errors.,9.5,mm,Least Material Condition,Perfect Form at MMC?,10.0,0.5,But at Maximum material condition,any form errors will take the Mating envelope out of spec.,10.,5,To maintain the Mating envelope(so we can assemble the part)each part must have,Maximum Material C