position tolerances

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POSITION TOLERANCES USED TO SPECIFY THE REQUIRED LOCATION ACCURACY FOR FEATURES OF SIZE ONE FEATURE CONTROL FRAME CAN BE USED TO SHOW THE POSITION OF A SINGLE HOLE OR AN ENTIRE PATTERN OF HOLES MOST COMMONLY USED FOR HOLES/SLOTS

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Page 1: Position Tolerances

POSITION TOLERANCES

USED TO SPECIFY THE REQUIRED LOCATION ACCURACY FOR FEATURES OF SIZE

ONE FEATURE CONTROL FRAME CAN BE USED TO SHOW THE POSITION OF A SINGLE HOLE OR AN ENTIRE PATTERN OF HOLES

MOST COMMONLY USED FOR HOLES/SLOTS

Page 2: Position Tolerances

POSITION TOLERANCES

DATUM FEATURES ARE IDENTIFIED –

LOCATES THE DATUM REFERENCE FROM WHICH THE HOLE LOCATIONS ARE MEASURES

BASIC DIMENSIONS LOCATE THE TRUE POSITIONS FOR THE HOLES

FEATURE CONTROL FRAME DEFINES THE SIZE OF THE TOLERANCE ZONE

Page 3: Position Tolerances

POSITION TOLERANCES

Page 4: Position Tolerances

POSITION TOLERANCE

A POSITION TOLERANCE

ZONE WILL USUALLY HAVE

A DEFINED SHAPE, SIZE, LOCATION, AND ORIENTATION.

PAGE 165

A DIAMETER SYMBOL INDICATES SHAPE

Page 5: Position Tolerances

BASIC DIMENSIONS & TRUE POSITIONS

THE TRUE POSITION IS THE LOCATION ON WHICH TO CENTER THE SPECIFIED TOLERANCE ZONE.

Page 6: Position Tolerances

POSITIONRELATIONSHIPS

Page 7: Position Tolerances

THE NEED FOR POSITIONAL TOLERANCES

Page 8: Position Tolerances

FEATURE CONTROL FRAME

Page 9: Position Tolerances

POSITIONAL TOLERANCING

Page 10: Position Tolerances

THE EFFECTS OF MATERIAL CONDITIONS ON POSITION

Page 11: Position Tolerances

RFS APPLIED TO POSITIONAL TOLERANCING Page 166

THE SPECIFIED TOLERANCE VALUE REMAINS CONSTANT REGARDLESS OF THE PRODUCED SIZE OF THE TOLERANCED PART

Page 12: Position Tolerances

MMC APPLIED TO POSITIONAL TOLERANCING

IF THE CONTROLLED FEATURE IS PRODUCED AT ANY ALLOWABLE SIZE OTHER THAN MMC, THE POSITION TOLERANCE VALUE INCREASES AN AMOUNT EQUAL TO THE MMC.

Page 13: Position Tolerances

HOLE POSITIONING AT MMC

Page 14: Position Tolerances

LMC POSITIONING

THE POSITION TOLERANCE VALUE INCREASES AN AMOUNT EQUAL TO THE DEPARTURE FROM LMC

Page 15: Position Tolerances

HOW FIT AFFECTS POSITION TOLERANCES

DEPARTURE FROM MMC INCREASES LOCATION ERRORS

THE PERMITTED POSITION TOLERANCE INCREASES BY EXACTLY THE SAME AMOUNT AS THE FEATURE DEPARTS FROM MMC

Page 16: Position Tolerances

POSITION TOLERANCING USING AXES

Page 17: Position Tolerances

DATUM REFERENCES FOR POSITIONING

MEASUREMENTS TAKEN FROM THE DATUM REFERENCE FRAME MAY BE SIGNIFICANTLY DIFFERENT FROM MEASUREMENTS FROM THE ACTUAL PART-

USE MEASUREMENTS FROM THE DATUM REFERENCE FRAME

Page 18: Position Tolerances

POSITIONAL TOLERANCING

Page 19: Position Tolerances

POSITION TOLERANCES RELATIVE TO DATUM FEATURES

Page 20: Position Tolerances

POSITIONING HOLES

Page 21: Position Tolerances

MMC TOLERANCE USING DATUMS

Page 22: Position Tolerances

ZERO POSITIONING TOLERANCES

Page 23: Position Tolerances

POSITIONING SLOTS

Page 24: Position Tolerances

TOLERANCE ZONE

ROUND TOLERANCE ZONES PROVIDE AN INCREASED TOLERANCE ZONE COMPARED TO SQUARE TOLERANCE ZONES

PAGE 175

Page 25: Position Tolerances

COMPOSITE POSITION TOLERANCES

A COMPOSITE TOLERANCE HAS ONLY ONE POSITION TOLERANCE SYMBOL

PAGE 184

Page 26: Position Tolerances

COMPOSITE POSITION TOLERANCES

Page 27: Position Tolerances

COMPOSITE TOLERANCES

WHENEVER DATUM REFERENCES ARE SHOWN IN THE SECOND LINE OF A COMPOSITE TOLERANCE, THEY MUST BE REPEATED AS SHOWN IN THE FIRST LINE WITH THE SAME MATERIAL CONDITION MODIFIERS.

Page 28: Position Tolerances

COMPOSITITE TOLERANCING

Page 29: Position Tolerances

CONTROLLING COUNTERBORES

Page 30: Position Tolerances

COUNTERBORE HOLE POSITIONING

Page 31: Position Tolerances

HOLE PATTERNS

Page 32: Position Tolerances

HOLE PATTERNS

Page 33: Position Tolerances

PATTERNS

Page 34: Position Tolerances

PATTERN AT MMC

Page 35: Position Tolerances

CHECKING POSITION

Page 36: Position Tolerances

CHECKING POSITION

Page 37: Position Tolerances

CHECKING POSITION

PAGE 172

Page 38: Position Tolerances

CHECKING POSITION

PAGE 173

Page 39: Position Tolerances

FEATURES VS.POSITIONING

Page 40: Position Tolerances

FLOATING FASTENER

Page 41: Position Tolerances

FLOATING FASTENER

T = TOLERANCE

H = HOLE DIA AT MMC

F = FASTENER DIA AT MMC

Page 42: Position Tolerances

FLOATING FASTENERPRACTICE CALCULATION

Page 43: Position Tolerances

FLOATING FASTENER –EXAMPLE 2

CALCULATE THE POSITION TOLERANCE FOR A FLOATING FASTENER APPLICATION.GIVEN HOLE DIAMETER = .328 +/- .004”FASTENER DIAMETER = .312” MMCT = H – F

.324 - .312 = .012

T = .012”

Page 44: Position Tolerances

FIXED FASTENER

FASTENER LOCATION CAN BE FIXED BY THREADS, PRESS FIT, OR TAPER THAT PREVENTS MOVEMENT OF THE FASTENER

Page 45: Position Tolerances

FIXED FASTENER CALCULATION

PAGE 170

Page 46: Position Tolerances

FIXED FASTENER CALCULATION

CALCULATE THE POSITION TOLERANCE FOR A FIXED FASTENERHOLE DIA = .296 +/- .003”FASTENER DIA = .250” MMC

T = (H – F) /2

T = (.293 - .250) /2

T = .043/2

T = .0215

Page 47: Position Tolerances

FIXED FASTENER

Page 48: Position Tolerances

COAXIAL HOLE PATTERNS

COAXIAL HOLES CAN HAVE DIFFERENT DIAMETERSA COMPOSITE TOLERANCE CAN BE APPLIED TO COAXIAL HOLES OF DIFFERENT DIAMETERSTHE ALIGNMENT OF THE COAXIAL HOLES MUST BE ACCURATE ENOUGH TO INSERT THE SHAFT THAT PASSES THOUGH THEM.

PAGE 199

Page 49: Position Tolerances

COAXIAL FASTENERS

Page 50: Position Tolerances

COAXIAL POSITIONING

Page 51: Position Tolerances

CONCENTRICITY

CONTROL OF ONE AXIS TO ANOTHERONLY USED WHEN THIS IS THE ONLY MEANS TO MANUFACTURE A USEABLE PARTCOMMON MISTAKE TO USE A CONCENTRIC TOLERANCE INSTEAD OF A RUNOUT TOLERANCE

PAGE 203

Page 52: Position Tolerances

CONCENTRICITY

APPLIED TO A CYLINDER OR ANY OTHER SYMMETRICAL SHAPE WITH AN AXIS

Page 53: Position Tolerances

CONCENTRICITY

Page 54: Position Tolerances

SYMMETRY

PAGE 201

A CONDITION WHERE FEATURES ON EACH SIDE OF A CENTER LINE OR CENTER PLANE ARE EQUAL

COMMONLY USED

ON HOLE PATTERNS

Page 55: Position Tolerances

SYMMETRY

CAN BE APPLIED TO FEATURES OF SIZE

SHOWS THAT THE RAIL IS SYMMETRICALLY LOCATED TO THE BASE OF THE PART

Page 56: Position Tolerances

SYMMETRY

Page 57: Position Tolerances

SYMMETRY

Page 58: Position Tolerances

SYMMETRY AT MMC

Page 59: Position Tolerances

CHECKING INTERFERENCE

Page 60: Position Tolerances

PROJECTED TOLERANCE ZONE

Page 61: Position Tolerances

PROJECTED POSITION TOLERANCE

Page 62: Position Tolerances

PROJECTED POSITION TOLERANCE

Page 63: Position Tolerances

BONUS TOLERANCES

USED TO INCREASE THE AMOUNT OF ACCEPTABLE ERROR

CAN BE USED TO REWORK HOLES THAT ARE OUT OF TOLERANCE BY REDRILLING HOLES TO A LARGER DIAMETER

ALLOWABLE INCREASE IN THE TOLERANCE IS KNOWN AS THE BONUS TOLERANCE

Page 64: Position Tolerances

BONUS TOLERANCES

THE BONUS TOLERANCE AND THE SPECIFIED POSITION TOLERANCE ARE ADDED TOGETHER TO DETERMINE THE ALLOWABLE POSITION TOLERANCE.

Page 65: Position Tolerances

BONUS TOLERANCE

Page 66: Position Tolerances

BONUS TOLERANCES

POSITION TOLERANCES APPLIED TO EXTERNAL FEATURES ARE AFFECTED BY MATERIAL MODIFIERS IN THE SAME MANNER AS TOLERANCES ON HOLES/INTERNAL FEATURES

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