GEOMETRIC DIMENSIONING

M

L

P

ST

F

A1

– MMC – MAXIMUM MATERIAL CONDITION:THAT CONDITION WHERE A FEATURE OF

SIZE 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 OF

SIZE CONTAINS THE LEAST AMOUNT OF MATERIAL WITHIN THE STATED LIMITSOF SIZE. EXAMPLE: MAXIMUM HOLE SIZE AND MINIMUM SHAFT SIZE.

RFS – 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.

– FREE STATE: THIS SYMBOL INDICATES THE PARTS MUST NOT BE RESTRICTED

DURING 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 CYLINDRICAL.

TOLERANCE 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 METAL.

DATUM REFERENCE FRAME: (THREE PLANE CONCEPT). THE CONCEPT OF USINGMUTUALLY PERPENDICULAR FEATURES OF APART TO CONTROL ITS FREE MOVEMENT IN SPACE (DEGREES OF FREEDOM). SEE DATUMSYMBOL AND DATUM TARGETS.

FREE MOVEMENT RESTRICTED MOVEMENT

LIMITS 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 LMC.

GEOMETRIC 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 COLUMN.

PITCH 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. 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 TOLERANCE

STATED TOLERANCE

DIAMETER SYMBOL (CYLINDRICALTOLERANCE ZONE)

GEOMETRIC CHARACTERISTIC SYMBOL

A B CM.005

M

FEATURE CONTROL FRAME:

EXAMPLE:ACTUAL

MMC

BONUS

.503

.500

.003

.507

.005

.500

AM

A B CM.005

WITHIN RELATIVE TO

BASIC SENTENCE STRUCTURE: WHEN USING THE ENGLISH LANGUAGE TO SAYWHAT IS IN THE FEATURE CONTROL FRAME.YOU MAY USE THE FOLLOWING CONNECTING WORDS:

EXAMPLE: THE POSITION OF THE FEATURE AXIS MUST BE WITHIN A .005TOLERANCE 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 TOLERANCE.

AT MMC THE HOLE MUST BE POSITIONED WITHIN A CYLINDRICAL TOLERANCE ZONE OF.005 DIAMETER. AS THE EXAMPLE SHOWS, THE HOLE HAS DEPARTED FROM MMC BY .003. THE .003 BONUS TOLERANCE MAYNOW BE ADDED TO THE ORIGINAL .005ZONE FOR A TOTAL OF .008 TOLERANCE.

FUNCTIONAL GAGES: DEVICES THATMEASURE THE COLLECTIVE EFFECTS OF SIZEAND GEOMETRIC TOLERANCES AT THE SAMETIME. IT REPRESENTS A SIMULATED MATING CONDITION.

BONUS 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 GROUP.

VIRTUAL CONDITION: THE COLLECTIVEEFFECT OF SIZE AND GEOMETRICTOLERANCES THAT MUST BE CONSIDEREDIN DETERMINING THE FIT OR CLEARANCEBETWEEN MATING PARTS OR FEATURES.

TO CALCULATE VIRTUAL CONDITION:

EXTERNAL FEATURES:MMC SIZE + TOLERANCE OF FORM,ORIENTATION, OR LOCATION

INTERNAL FEATURES:MMC SIZE – TOLERANCE OF FORM,ORIENTATION, OR LOCATION

A VIRTUAL CONDITION WILL EXIST ONLY FORTOLERANCES THAT CONTROL SIZE FEATURES.

* 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 Y14.5M - 1994.

GENIUM PUBLISHING CORP.ONE GENIUM PLAZASCHENECTADY, NY 12304(518) 377-8854

S Y M B O L S , R U L E S , A N D G U I D E L I N E S

YES NO

YES

YES

NO

A

A

A

A.004

SYMMETRY

A

.004 EQUALLYDISPOSED FROMCENTER PLANE

CONCEN–TRICITY

A.004.004 AROUNDDATUM AXIS

.022 ZONE AT LMC

.014 ZONEAT MMC

TRUE CENTER

.380

.620POSITION

C.620

.380

B

A

A B CM

M L

.014

.250 .004

RFSALWAYS

RFSALWAYS

OR CAN

APPLYTO A

FEATUREOF SIZE.

M

YESIF

ISSTATED

LOC

ATI

ON

YES

YES

NO

NO

A A

A

.004 A

A.004 A

CONCENTRICCIRCLES

.004 APART

TWO CONCENTRIC CYLINDERS .004 APART RFS

ALWAYS

RFSALWAYS

TOTALRUNOUT

CIRCULARRUNOUT

RU

NO

UT

NO

NO

.004

A A

.004 A

TWO LINES.004 APARTALONG TRUE PROFILE

TWO PLANES.004 APARTALONG TRUE PROFILE

DOESNOT

APPLY

DOESNOT

APPLY

MAY BEUSED

ORMAY NOT

MAY BEUSED

ORMAY NOT

PROFILEOF A

SURFACE

PROFILEOF A LINE

PR

OFI

LE

YES

YES

YES

.004 A

.004 A

A

A

A15˚

.004 A

TWO PARALLEL PLANES.004 APART

A

A

TWO PARAL–LEL PLANES.004 APART

TWO PARALLEL PLANES .004APART

90˚

15˚ M

YESIF

ISSTATED

M

YESIF

ISSTATED

M

YESIF

ISSTATED

M LOR CAN

APPLYTO A

FEATUREOF SIZE.

M LOR CAN

APPLYTO A

FEATUREOF SIZE.

M LOR CAN

APPLYTO A

FEATUREOF SIZE.

ANGULARITY

PERPEN–DICULARITY

PARALLELISM

OR

IEN

TATI

ON

FACTS TO REMEMBER FACTS TO REMEMBER

TYPE SYMBOL AS SHOWNON DRAWING

TOLERANCEZONE

MMC LMCOR RFS

DATUMUSED

FUNCGAGEUSED

TOLERZONE

TYPE

A

D

G

H

J

A

D

G

H

J

A

D

G

H

J

C

D

E

F

B

E

G

H

J

J

G

H

A PARALLEL LINES B PARALLEL LINES C PARALLEL LINES D PARALLEL PLANES E PARALLEL PLANES F PARALLEL PLANES G PARALLEL PLANES H PARALLEL PLANES J CYLINDER ZONE

NO

NO

NO

NO

NO

NO

NO

.004

.005.500

.004

.500 .005

.004

.500 .005

.004

.500 .005

TWO PARALLELLINES .004APART

TWO PARALLELPLANES, .004APART

TWO CONCEN–TRIC CIRCLES .004 APART

TWO CONCEN–TRIC CYLINDERS.004 APART

M

YESIF

ISSTATED

DOESNOT

APPLY

DOESNOT

APPLY

DOESNOT

APPLY

M LOR CAN

APPLYTO A

FEATUREOF SIZE.

CYLINDRICITY

CIRCULARITY

FLATNESS

STRAIGHTNESS

FOR

M

.004 A

H

J

D

B

E

A

A