GEOMETRIC DIMENSIONING

1 GEOMETRIC DIMENSIONINGMLPSTFA1 MMC MAXIMUM MATERIAL CONDITION:THAT CONDITION WHERE A FEATURE OFSIZE CONTAINS THE MAXIMUM AMOUNT OF MATERIAL WITHIN THE STATED LIMITSOF SIZE. EXAMPLE: MINIMUM HOLE SIZE AND MAXIMUM SHAFT SIZE. LMC LEAST MATERIAL CONDITION:THAT CONDITION WHERE A FEATURE OFSIZE CONTAINS THE LEAST AMOUNT OF MATERIAL WITHIN THE STATED LIMITSOF SIZE. EXAMPLE: MAXIMUM HOLE SIZE AND MINIMUM SHAFT REGARDLESS OF FEATURE SIZE: THIS IS THE DEFAULT CONDITION FOR ALL GEOMETRIC TOLERANCES. NO BONUSTOLERANCES ARE ALLOWED. FUNCTIONALGAGES MAY NOT BE USED. PROJECTED TOLERANCE ZONE: WHEN THE SYMBOL IS SHOWN, IT MEANS THE STATED TOLERANCE ZONE IS EXTENDED BEYOND THE SURFACE OF THE PART, NOT WITHIN THE PART. STATISTICAL TOLERANCE: ATOLERANCE FOR A PART OF AN ASSEMBLY BASED ON THE RESULTS FROM A STATISTICAL CALCULATION. THE DESIRED RESULT IS LARGER TOLERANCES.

2 FREE STATE: THIS SYMBOL INDICATES THE PARTS MUST NOT BE RESTRICTEDDURING INSPECTION. DATUM SYMBOL: THIS SYMBOL IS ATTACHED TO A PLANE OR SIZE FEATURE THAT MUST BE CONTACTED FOR MACHINING AND INSPECTION. BASIC DIMENSION: THESE DIMENSIONS HAVE NO TOLERANCE. THEY ONLY LOCATE A TOLERANCE ZONE. DIAMETER SYMBOL: THIS SYMBOL REPLACES THE WORD "DIAMETER." IT SHOULD BE USED ANYWHERE THERE IS A DIAMETER ON THE DRAWING, AND WHEN A TOLERANCE ZONE IS ZONES: ALL TOLERANCE ZONES SHOWN IN THE FEATURE CONTROLFRAME ARE TOTAL. EXAMPLE: FLATNESSWITHIN .004 MEANS THAT TWO PARALLELPLANES NO MORE THAN .004 APARTDEFINE THE TOLERANCE ZONE. DATUM TARGETS: USED TO LOCATE SPECIFIC POINTS, LINES, OR AREAS ON PARTS USED FOR SUPPORT FOR MACHINING AND INSPECTION COMMONLYUSED ON RIGID PARTS LIKE CASTINGS ANDFORGINGS AND NON-RIGID PARTS MADEFROM PLASTIC, RUBBER, OR SHEET REFERENCE FRAME: (THREE PLANE CONCEPT).

3 THE CONCEPT OF USINGMUTUALLY PERPENDICULAR FEATURES OF APART TO CONTROL ITS FREE MOVEMENT IN SPACE (DEGREES OF FREEDOM). SEE DATUMSYMBOL AND DATUM MOVEMENT RESTRICTED MOVEMENTLIMITS OF SIZE RULE: WHERE ONLY A SIZE DIMENSION IS GIVEN. a) THE SIZEDIMENSIONS AT ANY CROSS SECTION MUSTBE WITHIN THE SIZE TOLERANCE. b) THESURFACE(S) SHALL NOT EXTEND BEYONDTHE PERFECT FORM DEFINED BY THE MMCSIZE. c) THE FORM MAY VARY WITHIN AN ENVELOPE BETWEEN THE MMC AND TOLERANCE RULE: GEOMETRICTOLERANCES ARE UNDERSTOOD TO BE APPLIED RFS. IF MMC OR LMC ISREQUIRED, IT MUST BE PLACED IN THE FEATURE CONTROL FRAME. SEE MMC, LMC,OR RFS DIAMETER RULE: TOLERANCES THAT APPLY TO SCREW THREADS APPLY TO THE AXIS OF THE THREAD DERIVED FROMTHE PITCH CYLINDER. IF ANOTHER PART OF THREAD IS TO BE USED TO DERIVE THEAXIS, IT MUST BE STATED BENEATH THEFEATURE CONTROL FRAME.

4 ANY OTHER FEATURE THAT HAS A PITCH DIAMETER MUSTHAVE THE DATUM FEATURE STATED. TERTIARY DATUM(ONE POINT MIN)SECONDARY DATUM(TWO POINTS MIN)PRIMARY DATUM(THREE POINTS MIN)MODIFIER FOR THE STATED TOLERANCESTATED TOLERANCEDIAMETER SYMBOL (CYLINDRICALTOLERANCE ZONE) GEOMETRIC CHARACTERISTIC CONTROL FRAME:EXAMPLE:ACTUAL TO BASIC SENTENCE STRUCTURE: WHEN USING THE ENGLISH LANGUAGE TO SAYWHAT IS IN THE FEATURE CONTROL MAY USE THE FOLLOWING CONNECTING WORDS: EXAMPLE: THE POSITION OF THE FEATURE AXIS MUST BE WITHIN A .005 TOLERANCE ZONE AT MMC RELATIVE TO DATUM FEATURES A, B, AND C. BONUS TOLERANCE: WHEN MMC IS SHOWN MODIFYING A PARTICULARTOLERANCE, THE STATED TOLERANCEAPPLIES ONLY WHEN THE FEATURE BEINGCONTROLLED IS AT MMC. THE BONUS ISTHE DIFFERENCE BETWEEN THE ACTUAL SIZEAND THE MMC SIZE AND MAY BE ADDEDDIRECTLY TO THE ORIGINAL MMC THE HOLE MUST BE POSITIONED WITHIN A CYLINDRICAL TOLERANCE ZONE DIAMETER.

5 AS THE EXAMPLE SHOWS, THE HOLE HAS DEPARTED FROM MMC BY .003. THE .003 BONUS TOLERANCE MAYNOW BE ADDED TO THE ORIGINAL .005 ZONE FOR A TOTAL OF .008 GAGES: DEVICES THATMEASURE THE COLLECTIVE EFFECTS OF SIZEAND GEOMETRIC TOLERANCES AT THE SAMETIME. IT REPRESENTS A SIMULATED MATING TOLERANCES AND FUNCTIONAL GAGES: DIRECTLY APPLICABLE TO ANY GEOMETRIC CHARACTERISTIC THAT IS MODIFIED BY .SHIFT: AS A DATUM FEATURE OF SIZE,THAT IS GEOMETRICALLY CONTROLLED,DEPARTS FROM MMC, ADDITIONAL TOLERANCE MAY BE CONSIDERED FOR THE CONTROLLED FEATURES. THIS ADDITIONAL TOLERANCE DOES NOT ADD DIRECTLY TO THE ORIGINAL TOLERANCE BUT MUST BE APPLIED TO THE PATTERN OF FEATURES AS A GROUP. IT IS CONSIDERED A TOLERANCE THAT ALLOWS THE CONTROLLED FEATURES TO SHIFT AS A CONDITION: THE COLLECTIVEEFFECT OF SIZE AND GEOMETRICTOLERANCES THAT MUST BE CONSIDEREDIN DETERMINING THE FIT OR CLEARANCEBETWEEN MATING PARTS OR CALCULATE VIRTUAL CONDITION:EXTERNAL FEATURES:MMC SIZE + TOLERANCE OF FORM,ORIENTATION, OR LOCATIONINTERNAL FEATURES:MMC SIZE TOLERANCE OF FORM,ORIENTATION, OR LOCATIONA VIRTUAL CONDITION WILL EXIST ONLY FORTOLERANCES THAT CONTROL SIZE FEATURES.

6 * THIS COLUMN INDICATES POSSIBLETOLERANCE ZONES THAT MAY BE USED WITHTHE VARIOUS CONTROLS. THE DIFFERENT TOLERANCE ZONES ARE SHOWN ALONG THEBOTTOM OF THIS CHART. THIS CHART IS PROVIDED FOR INFORMATIONAL PURPOSES ONLY. THE INFORMATION IS BASED UPON ASME - PUBLISHING GENIUM PLAZASCHENECTADY, NY 12304(518) 377-8854 SYMBOLS, RULES, AND EQUALLYDISPOSED FROMCENTER PLANECONCEN AROUNDDATUM ZONE AT ZONEAT MMCTRUE CANAPPLYTO A FEATUREOF APARTTWO CONCENTRIC CYLINDERS .004 APARTALONG TRUE PROFILETWO APARTALONG TRUE PROFILEDOESNOTAPPLYDOESNOTAPPLYMAY BEUSEDORMAY NOTMAY BEUSEDORMAY NOTPROFILEOF A SURFACEPROFILEOF A .004 ATWO PARALLEL APARTAATWO PARAL LEL APARTTWO PARALLEL PLANES .004 APART90 15 MYESIFISSTATEDMYESIFISSTATEDMYESIFISSTAT EDMLOR CANAPPLYTO A FEATUREOF CANAPPLYTO A FEATUREOF CANAPPLYTO A FEATUREOF DICULARITYPARALLELISMORIENTATIONFACTS TO REMEMBERFACTS TO REMEMBERTYPESYMBOLAS SHOWNON DRAWINGTOLERANCEZONEMMC LMCOR RFSDATUMUSEDFUNCGAGEUSEDTOLERZONETYPEADG HJADGHJADGHJCDEFBEGHJJGHA PARALLEL LINESB PARALLEL LINESC PARALLEL LINESD PARALLEL PLANESE PARALLEL PLANESF PARALLEL PLANESG PARALLEL PLANESH PARALLEL PLANESJ CYLINDER PARALLELLINES.

7 004 APARTTWO PARALLELPLANES, .004 APARTTWO CONCEN TRIC CIRCLES .004 APARTTWO CONCEN TRIC APARTMYESIFISSTATEDDOESNOTAPPLYDOESNOTAP PLYDOESNOTAPPLYMLOR CANAPPLYTO A FEATUREOF