2 4 Hitchhiker’s Guide to Geometric Dimensioning …

1 Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 1 Hitchhiker s Guide to Geometric Dimensioning & tolerancing Thomas Allsup Co-Chair of North Texas SolidWorks Users Group Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 2 Presentation Available Download Now We survived another SolidWorks World. Last session of the conference. They announced where 2014 would be at this morning. If you are still here and have your brain engaged then this must be important to you. You can find this and other GD&T and technical PowerPoint presentations on our website. Proceedings with audio will be available in a few weeks. Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 3 Thomas Allsup About the Presenter Sixth time SWWorld Attendee Third time presenter. Co-chair of North Texas SolidWorks Users Group BSME Oklahoma State University MSME University of Texas at Arlington Partner at Anida Technologies, , a Dallas based engineering consulting company.

2 GD&T Aficionado Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 4 Previously at SolidWorks World Three makes a is it In 2009, How to Spell GD&T started our discussion of Geometric Dimensioning and tolerancing concentrating on the fourteen basic symbols using the FOPRL chart. In 2010, How to Spell GD&T Part II: Revenge of the Circled Letters concentrated on the modifiers in GD&T symbols. Now in 2013, we are ready for the next exciting chapter in the GD&T Saga where we will answer the question To GD&T, the Universe, and Everything. Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 5 Agenda Don t Sweat the Small Stuff, It s All Small Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 6 Updated FOPRL Chart Now based on ASME Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 7 When Do I Add Geometric Dimensioning and tolerancing Dassault Syst mes | Confidential Information | 4/26/2014 | ref.

3 : 3DS_Document_2012 8 How Do I Interpret Geometric Dimensioning and tolerancing . Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 9 Tolerance Zones versus Shapes My money is on Shapes kicking Zones Total Wide Tolerance Zone Cylindrical Tolerance Zone Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 10 Sign Language Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 11 Exceptions Mostly Harmless Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 12 Rule #1 of GD&T states that the Geometric form of a feature can vary so long as it stays within the limits of its size tolerance. Another way of saying this rule is to say size tolerance is the primary control of a feature and that GD&T is a refinement within that tolerance. The first magnitude of control is size. Lesson in GD&T Dassault Syst mes | Confidential Information | 4/26/2014 | ref.

4 : 3DS_Document_2012 13 GD&T symbols refine the shape or Geometric control that starts with simply checking the dimensions of the part to the drawing. The best example to illustrate this is not from the GD&T standard but from the surface finish callout. What s Rule #1 Mean? Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 14 Surface finish is a measurement of the surface roughness. Surface roughness height is measured: microinches (millionths of an inch) micrometers (millionths of a meter) Roughness spacing is measured in inches or millimeters. Surface Roughness Surface Finish Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 15 AMaximum Roughness Average BMinimum Roughness Average CMachining Allowance DLay Symbol ERoughness Sampling Length FMaximum Waviness Height Rating GMaximum Waviness Spacing Rating Surface Roughness Symbol Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 16 Surface Roughness Removal of Material Do Not Remove Material Method Not Specified Remove Material Dassault Syst mes | Confidential Information | 4/26/2014 | ref.

5 : 3DS_Document_2012 17 Perpendicular to surface indicated (wink) you like this symbol =Parallel to surface indicated XAngular in both directions MMultidirectional CCircular with center on surface indicated RRadial with center on surface indicated PNondirectional, pitted, or protuberant Surface Roughness Surface Lay Symbols Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 18 You don t start by inspecting the surface finish of a plate. Initially you would measure the length, width, and thickness and make sure the dimensions are in tolerance. If the parts don t match the tolerances then it doesn t make sense to waste time checking how the surface is finished. The last inspection step would be to check the surface finish. Surface Roughness is a refinement of the limits of size. Surface Roughness Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 19 If the first rule of GD&T states that the Geometric form of a feature can vary so long as the feature stays within the limits of its size tolerance then we better understand limits of size.

6 The limits of size are the minimum acceptable measure value and maximum acceptable measured value for a dimension. Geometric tolerancing should only be added when form must be more accurately controlled or to convey functional/interchangeability requirements. Rule #1 Revisited Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 20 Min Max .625 .675 .550 .650 40 45 0 .750 .475 .525 .95 .08 .18 has no tolerance Limits of Size Example Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 21 What is the difference in connotation in a limits dimension and a bilateral toleranced dimension? Isn t . , the same as .125 .025? Answer #1: Limits of acceptable dimensions are identical for both. Answer #2: Manufacturing people don t target .125 when they see limits but rather the tool safe side and let wear bring them down to the other extreme. Answer #3: What should the CAD model show for limit dimensions?

7 The average is not really the target so why not show it at the either the minimum or maximum values? Opinion Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 22 Section : If CAD/CAM database models are used and they do not include tolerances, then tolerances must be expressed outside of the database to reflect design requirements. This section clearly states that models may include tolerances hence paving the way to eliminating conventional drawings someday! ASME CAD/CAM Data Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 23 In Section Cited Standards now has ASME (reaffirmed in 2008) Digital Product Definition Data Practices. Provides guidance to 3D model with embedded dimensions and tolerances. Numerous new citations back to this standard. This topic came up in Austin during one of my Primer lectures and I wanted to mention that the embedded 3D data has been allowed since 1984 but now it is really well documented.

8 ASME CAD/CAM Data Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 24 The next stop on the GD&T primer train is the Tolerance Zones and Shapes station. These sound like the same thing but they are two separate but related items for tolerances. Let s start with the easy one - zones. Tolerance Zones and Shapes Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 25 All controls can have TOTAL WIDE TOLERANCE ZONES. Except Concentricity. Only five can have a CYLINDRICAL TOLERANCE ZONES: Position Orientation Parallelism, Angularity, Perpendicularity Straightness Concentricity requires CYLINDRICAL TOLERANCE ZONE. Tolerance Zones Position tolerance zones for holes and bosses are always cylindrical tolerance zones. Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 26 Tolerance Zone Symbology Total wide zone is default You put the diameter symbol here. f .014m U j Y Dassault Syst mes | Confidential Information | 4/26/2014 | ref.

9 : 3DS_Document_2012 27 Cylindrical zone sounds easy - it s a circle or cylinder within with which the feature must reside to be acceptable. What shape is a total wide zone? Here s where it gets complicated and one of the reasons I originally built the FOPRL chart - let s look at the shapes. Tolerance Zone Shapes Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 28 Each Geometric control has it s own total wide tolerance shape that is suggested by it s name. Form Straightness: between two lines Flatness: between two planes Circularity: between two circles Cylindricity: between two cylinders Tolerance Zone Shape: Form Total Wide Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 29 For all three orientation controls, the surfaces must lie between two planes. Parallel Angularity Perpendicular Hold it a second, we just said flatness control was between two planes. Tolerance Zone Shape: Orientation Total Wide Dassault Syst mes | Confidential Information | 4/26/2014 | ref.

10 : 3DS_Document_2012 30 Profile Line: between two curves that are the shape of the feature Surface: between two surfaces that are the shape of the feature Runout Full indicator movement Tolerance Zone Shape: Profile / Runout Total Wide Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 31 Position: depends on the geometry it controls Between resultant and virtual conditions and fixed / floating fastener theory, there s a day s worth of topics on positional tolerances. Symmetry: two planes Concentricity: cylindrical Tolerance Zone Shape: Location Controls Total Wide Dassault Syst mes | Confidential Information | 4/26/2014 | ref.: 3DS_Document_2012 32 Rule 1 has four (count em four) exceptions: Stock parts : Bars, sheets, tubing, structural shapes Parts subject to free state variation Add note to a surface or feature: PERFECT FORM AT MMC NOT REQUIRED. Straightness tolerance on features of size with MMC applied. Straightness is the important exception at the end.