Ford_福特GDT形位公差培训材料_全集.ppt

1、GD The above document also contains an electronic copy of the ASME Y14.5M 1994 Dimensioning and Tolerancing Standard.,GD Influence Fit and Finish Reduce Reworks Increase Reliability Affects Assembly Process Reduce cost,GD Past evidence, past experience, can sometimes hinder rather than assist the ne

2、w design concept Result of meeting May be documented in CAD, or paper form,GD 0,0,0,GD 1PERPENDICULARITY 2POSITION 3PROFILE,GD 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

3、 the LMC. Secondly the features “Position” must be verified. GD,GD,GD,The upper FCF is the PROFILE of the Surface, for SIZE, FORM, ORIENTATION and LOCATION controls,The Lower FCF is the ELEMENT Lines of the surface FORM control. No LOCATION or ORIENTATION is implied (No Datums of Reference),GD Funct

4、ion Cost Manufacturing Process From agreed generic tolerance data (see Cad Methods) Do Not “pick tolerances out of the air”, without documented data with which to supports your decision. Do not copy tolerances blindly from previous data,GD&T for Body Engineering,107,Diametral Features,Clearance Hole

5、s Holes with specific function,GD&T for Body Engineering,108,ClearanceHoles,Tolerance of feature size should be derived from the generic tolerance specification, unless otherwise required, and stated on the 3D model,20.0,GD&T for Body Engineering,109,Holes with specific function,20.0,Feature Size an

6、d Tolerance of Feature Size to be functionally derived and stated on the 3D model,GD&T for Body Engineering,110,Slotted Features,Clearance Slots Slots with specific function,GD&T for Body Engineering,111,Clearance,20.0,BOUNDARY,GD&T for Body Engineering,112,Slots with specific function,A,B,2.0,C,BOU

7、NDARY,20.0,GD&T for Body Engineering,113,Step 5,Final Approval of GD&T on the CAD Data,GD&T for Body Engineering,114,Final Approval of GD&T on the CAD Data,Verification required from the core team for Steps One to Four. The goal of this process should be to prevent any changes associated with incorrectly specified PMI after engineering release. This process allows input and p