Limits, Fits & Tolerances

Tolerances Training

Contents•Introduction•Fits•Tolerancing•Tolerances•Modifiers

Tolerances Training

Guide to GD&T– Variants Still AllowedGuide to GD&T– Variants Still Allowed

GEOMETRIC DIMENSIONING & TOLERANCING

ANSI Y14.5M – R1988 STANDARD

History:•Since 1900•Widely used during WW2•Automotive Industry •Standardisation 1982

Tolerances Training

Engg. Intent – Dimension &ToleranceEngg. Intent – Dimension &Tolerance

GD&T

•Define the GEOMETRY of the part precisely

•Communicate the product Function & Design Relationship

•Process Variation

Whys?

Tolerances Training Dimensioning

• Defines the SIZE of a feature

• Defines the LOCATION of a feature

Dimension

Basic Size Size Limit

Function defines Tolerance, Tolerance defines Process

Tolerances Training

Hole Based System Hole Based System

Fits

Transition Fit Interference Fit

Shaft

Hole Zero Line

•Press – For Non Fe – Allows removal•Drive - For Fe Medium , Non Fe Light – Allows removal•Force/Shrink – High Interference

H6/p5 , H7/p6 H6/r5 , H7/r6 , H6/s5 , H7 / s6H6/u5 , H7/u6

•Clearance – Very Small Clearance•True - Zero Clearance , Slight Interference tolerated•Interference – Slight Interference

H6/h5 , H6/h6 H7/h6 ,H7/h7H8/h7 , H8/h8H9/h8 , H9 / h9H11/h9 , H11/h11H8/b9 , H8/a9

H6/j5 , H7/j6 , H8 /j7H6/k5 , H7/k6 , H6/k7H6 /m5 ,H7/m6 , H8/m7

H6/g5 , H7/g6 H6/f65 , H7/f7 , H7/e7 , H8 / e8H8/d8 , H8/d9

Location & Assembly Fit

ShaftHole Zero Line

Hole Zero LineShaft

ShaftShaft

Running & Sliding Fit

Shaft

Hole Zero Line

•Stationary parts•Location – Precision / Close /Normal/Loose•Assembly – Slack / Positional Fit

•Precision – Small Clearance - Location• Close Running - Shafts• Normal Running – Large Shafts , Brgs•Loose Running – Medium clearance Pulleys,PBs•Slack/Positional – Large Clearance - Not used

Tolerances Training Tolerancing

Bilateral Tolerances : •20 +/-0.018

•20 +0.013 / - 0.015

Unilateral tolerances :•20 +0.018 /0

•20 –0.012/-0.016

Tolerances Training

Tolerance stack – Proper dimensioning keyTolerance stack – Proper dimensioning key

Tolerance Stack up

15+/-0.2 10+/-0.2 10+/-0.28+/-0.2

28+/-0.6

43+/-0.2

33+/-0.2

15+/-0.2

25+/-0.2

28+/-0.4

Chain Method:• Point to Point• Shifting reference•Cumulative effect on tolerance

Base Line Method:• Single Reference • Reduced cumulative effect on tolerance

Direct Method:(Combination)• Direct Reference • Least cumulative effect on tolerance

33+/-0.2

15+/-0.2

25+/-0.2

28+/-0.4

Tolerances Training

Function defines Tolerance, Tolerance defines ProcessFunction defines Tolerance, Tolerance defines Process

TolerancesTolerances

FormForm •Limits deviation of an individual parameter from it geometrically ideal form

ProfileProfile •Same as Form

PositionPosition •Limits the deviation of the relative position of two or more parameters

ProcessProcess •Limits the deviation of a “ Fundamental”parameter ( Like Temp, Pressure Time

Tolerances Training

5 Types5 Types

Types

Form

Straightness

Flatness

Circularity

Cylindricity

ProfileProfile of a Line

Profile of a Surface

PositionOrientation

Location

Angularity

Perpendicularity

Parallelism

True Position

Concentricity

SymmetryRun OutCircular Run - Out

Total Run - out

Tolerances Training

Always look at the mating partAlways look at the mating part

Modifiers

“Modifiers” •Modify the specified tolerance •Influence the tolerance zone•Defined by the function

M

L

RFS

Common Modifiers

MMC - Maximum Material Condition

LMC – Least Material Condition

S Regardless of Feature Size

Reference

S

SR

R Radius

Spherical Radius

Spherical Diameter

Tolerances Training Notations

Toleranced Element/Parameter

0.02 A

Tolerance Symbol

Tolerance Symbol

Datum ( When required)

A

Reference Datum

Datum Symbol

25 Nominal Dimension

Axis as Datum Surface Line as Datum

Tolerances Training Feature Control Frame

Position Tolerance Zone Symbol

BA0.2 M CM

Shape of Tolerance Zone

Size of Tolerance Zone Primary Datum

Secondary Datum

Tertiary Datum

Material Condition ModifierSecondary Datum

Material Condition Modifier

Tolerances Training

Function drives Modifiers Function drives Modifiers

Modifiers

E=mC2

E=cM2

Tolerances Training

Tolerance Zone does not ChangeTolerance Zone does not Change

Modifiers

RFS – Regardless of Feature Size•The tolerance value is unaltered “Regardless of Size” of toleranced parts

Application•Holes with Zero Clearance•Shaft /Hole combination for Interference fits

Tolerances Training

Process Control Size Vs PositionProcess Control Size Vs Position

LMC

LMC – Least Material Condition - SIZE conditions•The Feature of size : It has the Least Material within the size limits specified

Rules:• External Features – Subtract the tolerance •Internal Features – Add the tolerance

25

20

12 +0.2 / - 0.1

BA0.2 CL

C

B

A

Actual LMC Position Applied11.9 12.2 0.2 -0.1

12 12.2 0.2 012.1 12.2 0.2 0.112.2 12.2 0.2 0.2

ToleranceSize

Tolerances Training

Process Control Size Boss Vs HoleProcess Control Size Boss Vs Hole

LMC

25 +2

BA1 CL

BA0.2 CL

LMC – Boss & Hole

C

B

12 - 0.5

A75

60

25

12

Boss Tol. Zone 1

Hole Tol. Zone 0.2

Tolerances Training

Bonus ZoneBonus Zone

Modifiers

MMC – Maximum Material Condition - SIZE conditions•The Feature of size : It has the Maximum Material within the size limits specified

Rules:• External Features – Add the tolerance •Internal Features – Subtract the tolerance

Application•Clearance holes ( Mounting/Assembly)

Eg; Position Tolerance of the hole increase as the hole size increases

Tolerances Training

Classic Case- Bell Crank & SleeveClassic Case- Bell Crank & Sleeve

Modifiers at MMC

A

A0.02 M

25

0.0

0/-0

.018

18

0.0

0 /-

0.0

13

A

A0.02 M

25

0 .0

2/0

.00

18

0.0

13/0

.00

FeatureShaft Dia1

Shaft Dia2

Pos Tol of SD1

Delta of SD2 Allowable

At MMC 25 18 0.02 0 0.02At LMC 24.982 0.02 0.018 0.038At Inter 24.99 0.02 0.01 0.03

FeatureBore Dia1

Bore Dia2

Pos Tol BD1

Delta of BD2 Allowable

At MMC 25 18 0.02 0 0.02At LMC 25.02 0.02 0.02 0.04At Inter 25.01 0.02 0.01 0.03

Tolerances Training Modifiers MMC On HoleM

Datum

A0.2 M

Hole

60

10 +0.2 / 0

20 +0.1 / 0

A

0.4

Actual MMC Position Allowable10.2 10 0.1 0.2

Size Tolerance

Tolerances Training Modifiers at MMC On Datum M

Datum Hole

A0.2 M

60

10 +0.2 / 0

20 +0.1 / 0

A

0.3

Actual MMC Position Allowable20.1 20 0.1 0.15

Size Tolerance

Tolerances Training Modifiers MMC On Hole & Datum M

Datum

0.2 M

Hole

60

10 +0.2 / 0

20 +0.1 / 0

A

A M

0.6

Actual Datum

MMC Datum

Actual Hole MMC Hole Position Allowable

20.1 20 10.2 10 0.1 0.3

Size Size Tolerance

Tolerances Training

Datum Ref. Frame is Theoretical Datum Ref. Frame is Theoretical

Datum

•Origin from which a Location of a feature is defined

• Origin from which the shape of a feature is defined

• Theoretical “Perfect geometry” ( Point , Line or Plane)

Tolerances Training

Manufacturing & Inspection w.r.t.specified datum Manufacturing & Inspection w.r.t.specified datum

Datum

A

AExternal Datum

A

Datum Simulator

Datum Simulator

Datum Simulator

Internal Datum

Tolerances Training

Controls Form of Cylindrical/Conical Surfaces- Applies to Entire SurfaceControls Form of Cylindrical/Conical Surfaces- Applies to Entire Surface

DEFINITION : Straightness is a condition where the surface or an axis of an element is a straight line.

TOLERANCE ZONE : Straightness tolerance•Specifies a tolerance zone within which the considered surface/axis or derived median line must lie. •Straightness tolerance is applied in the view where the parameter to be controlled is represented by a straight line.

REFERENCE TO DATUMS : No reference datum.

MMC, LMC, RFS TO FEATURE : Applicable if the tolerance applies to the axis or center plane of a feature or size. Not applicable if the toleranced feature is a surface.

MMC, LMC, RFS TO DATUMS : No datum reference

.

PERFECT FORM AT MMC : Applicable when the tolerance is applied to a surface. "Perfect from at MMC not required" may be specified.

Especially useful when the part is subject to small deformations under its own weight or internal stresses.

STRAIGHTNESS 0.21

Tolerances Training

Straightness: Applied to the Surface Cylinder

•The surface must lie within the specified tolerance zone•The dimension of perfect form at MMC (1.510).•Each longitudinal element must lie within two parallel lines 0.002 apart.

STRAIGHTNESS 0.21

Tolerances Training

Neck

Bow

Barrel

STRAIGHTNESS 0.21

Tolerances Training

Cylinder Liner Tier 2Cylinder Liner Tier 2

STRAIGHTNESS 0.21

Tolerances Training

Note effect of Size Tolerance Note effect of Size Tolerance

Straightness tolerance is• Applied in the view where the elements to be controlled are represented by a straight line.• Tolerance zone is constrained into the plane of projection of the view where it is called.•For each linear element on the surface, the tolerance zone of straightness may be

oriented differently, as long as it stays in the correct plane.

STRAIGHTNESS 0.21

Tolerances Training

Direction is in the ViewDirection is in the View

Straightness: Applied to a plane surfaceMeasurement Direction

STRAIGHTNESS 0.21

Tolerances Training

Combined Straightness “is” FlatnessCombined Straightness “is” Flatness

The tol. notation is attached to a leader line to the surface or to an extension line of the surface.

STRAIGHTNESS 0.21

Tolerances Training

Controls Form deviation of plane surfaces – Qualifies surface for primary datumControls Form deviation of plane surfaces – Qualifies surface for primary datum

FLATNESS

DEFINITION Flatness is the condition of a surface having all the elements of which in one plane.

TOLERANCE ZONE The flatness tolerance specifies a tolerance zone defined by two parallel planes within which the surface must lie.

REFERENCE TO DATUMS No reference datum.

MMC, LMC, RFS TO FEATURE

Not applicable.

MMC, LMC, RFS TO DATUMS Not applicable.No reference datum

PERFECT FORM AT MMC Where the surface under consideration has a size dimension, the flatness tolerance must be less than the size tolerance.

Flatness 0.05

0.05/100

Tolerances Training

•The surface must lie between two parallel planes 0.25 apart.•The surface must be within the specified limits of size.

Flatness 0.05

Tolerances Training

Flatness – Primary Datum/Seat/Sealing faceFlatness – Primary Datum/Seat/Sealing face

Flatness 0.05

Tolerances Training

Datum , Seat DefinitionDatum , Seat Definition

Flatness 0.05

Tolerances Training

Defines DatumDefines Datum

DEFINITION Circularity is a condition of a surface of revolution where a. (For a Cylindrical/Round feature other than a sphere,) all points of the surface intersected by any plane perpendicular to the axis are equidistant from that axis; b. For a sphere, all points of the surface intersected by any plane passing through a common center are equidistant from that center.

TOLERANCE ZONE A circularity tolerance specifies a tolerance zone bounded by two concentric circles within which each circular element of the surface must lie, and applies independently at any plane.

REFERENCE TO DATUMS

No reference datum.


Not applicable.

MMC, LMC, RFS TO DATUMS

Not applicable.No reference datum

PERFECT FORM AT MMC The circularity tolerance must be less than the size tolerance, except for parts subject to free state variation.

CIRCULARITY/ROUNDNESS 0.05

Tolerances Training

The tolerance zone of circularity is expressed as the radial difference between two concentric circles

The circularity tolerance applies at each circular section of the diameter independently

CIRCULARITY/ROUNDNESS 0.05

Tolerances Training CIRCULARITY/ROUNDNESS 0.05

Tolerances Training

“Combined effect” of Straightness & Roundness“Combined effect” of Straightness & Roundness

DEFINITION Cylindricity is a condition of a surface of revolution in which all points of the surface are equidistant from a common axis.

TOLERANCE ZONE A Cylindricity tolerance specifies a tolerance zone bounded by two concentric cylinders within which the surface must lie.

REFERENCE TO DATUMS

No reference datum.


Not applicable.


Not applicable.No reference datum

PERFECT FORM AT MMC

Applicable. Cylindricity tolerances cannot violate the maximum boundary of perfect form at MMC of the associated size tolerance.

Application Functional applications that require a true cylinder such as rotating shaft journal and bearing diameters, pistons and piston bores. Also used to qualify datum diameters. Used only when the size tolerance does not provide appropriate form control.

Cylindricity 0.03

Tolerances Training

•The tolerance zone of Cylindricity is made of two concentric cylinders. •The leader line from the tol. notation may be shown in either view.

Cylindricity 0.03

Tolerances Training Cylindricity 0.03

Tolerances Training

DEFINITION A profile is the outline of an object in a given plane. The profile tolerance specifies a uniform boundary along the true profile within which the elements of the line must lie. It is used to control form or combinations of size, form, orientation, and location.

TOLERANCE ZONE The tolerance zone established by the profile of a line tolerance is two-dimensional, extending along the length of the considered feature. This applies to the profiles of parts having a varying cross section, such as the tapered wing of an aircraft, or to random cross sections of parts where it is not desired to control the entire surface of the feature as a single entity.

REFERENCE TO DATUMS

In most cases, profile of line tolerance requires reference to datum in order to provide proper orientation, location, or both, of the profile. With profile of a line tolerance, datum may be used under some circumstances but would not be used when the only requirement is the profile shape taken cross section by cross section. An example is the shape of a continuous extrusion.


The specified tolerance can only apply on an RFS basis.


The datum reference can only apply on an RFS basis.

Application Typically used to control profiles of parts having a varying cross section.

Line Profile 0.1

0.1 A

Tolerances Training

Effect of SizeEffect of Size

Form Tolerance Line Profile

Each line element of the surface between points C and D, at any cross section, must•Lie between two profile boundaries 0.16 apart in relation to datum planes A and B.•Be within the specified limits of size.

Tolerances Training

DEFINITION A profile is the outline of an object in a given plane. The profile tolerance specifies a uniform boundary along the true profile within witch the elements of the line must lie. It is used to control form or combinations of size, form, orientation, and location.

TOLERANCE ZONE The tolerance zone established by the profile of a surface tolerance is three-dimensional, extending along the length and width (or circumference) of the considered feature or features.

REFERENCE TO DATUMS

Profile of surface tolerance requires reference to datum in order to provide proper orientation, location, or both, of the profile. With profile of a line tolerance, datum may be used in some circumstances but would not be used when the only requirement is the profile shape.





TYPICAL USE Typically used to control parts with a surface of revolution, or castings with surfaces defined by profile tolerances .

Surface Profile 0.05

A0.05

Tolerances Training

Note Effect of Size ToleranceNote Effect of Size Tolerance

The surface between points D and E must •Lie between two profile boundaries 0.25 apart.•Perpendicular to datum plane A, •Equally disposed about the true profile and positioned with respect to datum planes B and C.


Tolerances Training

Gen 1 Bell Crank Gen 1 Bell Crank


Tolerances Training

•Each surface must lie between two common parallel planes 0.08 apart.•Both surfaces must be within the specified limits of size.


Tolerances Training

Position Tolerance

Tolerances Training

DEFINITION Defines a zone within which the•Center• Axis•Center plane of feature of size is permitted to vary from a true (theoretically exact) position

TOLERANCE ZONE A position tolerance specifies one of the following: 1. A tolerance zone defined by two parallel planes related to specified datum.2. A cylindrical tolerance zone related to specified datum, within which the axis of the considered

feature must lie.3. A spherical tolerance zone related to specified datum, within which the center of the considered

feature must lie.

REFERENCE TO DATUMS

Obligatory with the PLTZF. Optional with the FRTZF.


Based functional requirements MMC, LMC or RFS, appropriate modifier can be applied on position tolerance.


Based on functional requirements MMC, LMC or RFS, appropriate modifier can be applied on the datum axis. Application of MMC, LMC and RFS is limited to features subject to variations in size.

Hole Position 0.2

Tolerances Training

ZERO POSITIONAL TOLERANCE AT MMC

Where no variations in position is allowed at the MMC limit of size, the feature control frame contains a zero for the tolerance zone size, modified by the MMC symbol.

PATTERN-LOCATING TOLERANCE ZONE FRAMEWORK (PLTZF)

Where composite controls are used, the upper segment is referred to as the pattern-locating control. The PLTZF is located from specified datum by basic dimensions. It specifies the larger positional tolerance for the location of the pattern of features as a group.

FEATURE-RELATING TOLERANCE ZONE FRAMEWORK (FRTZF)

The lower segment is referred to as the features-locating control. It governs the smaller positional tolerance for each feature within the pattern (feature-to-feature relationship). Where datum references are not specified in the lower segment of the composite feature control frame, the FRTZF is free to bee located and oriented within the boundaries established and governed by the PLTZF. If datum are specified in the lower segment, they govern the orientation of the FRTZF relative to the PLTZF.

TYPICAL USE Typically used to control the location of features in assembly.

BA0.2 CM

BA0.2 CM BA0.2 CMM

0.2 M

Hole Position 0.2

Tolerances Training

The PLTZF (Ø0.8) is located from datum (ABC) by basic dimensions. It specifies the larger positional tolerance for the location of the pattern of holes as a group.The lower segment governs the smaller positional tolerance (Ø0.25) (feature-to-feature relationship) within the pattern .The FRTZF is free to locate and orient within the boundaries established and governed by the PLTZF.Datum A governs the orientation (perpendicularity) of the FRTZF.

Pattern Location - PLTZF

Feature Realtion - FRTZF

Hole Position 0.2

Tolerances Training

Co- Axial Holes

Pattern Location - PLTZF

Feature Relation Location - FRTZF

Hole Position 0.2

Tolerances Training

Gen 1 Bell CrankGen 1 Bell Crank

•C-D Defines X-Axis

Hole Position 0.2

•E Defines Y-Axis •B Defines Perpendicularity

Tolerances Training Hole Position 0.2

Tolerances Training

DEFINITION The median points of all diametrically opposed elements of a surface of revolution lie on the same axis (or center point) of a datum feature.

TOLERANCE ZONE A concentricity tolerance is aCylindrical (or spherical) tolerance zone whose axis (or center point) coincides with the axis (or center point) of the datum feature(s).

REFERENCE TO DATUMS

One datum feature (axis or center point).

APPLICABILITY OF MMC, LMC, RFS TO FEATURE


APPLICABILITY OF MMC, LMC, RFS TO DATUMS


TYPICAL USE Typically used to control ………..

Concentricity 0.04 A

Tolerances Training Position Tolerance Concentricity

Regardless of feature size, ( within size tolerance)•All median points of diametrically opposed elements of the slot must lie within Ø0.4 cylindrical tolerance zone.•The axis of the tolerance zone coincides with the axis of datum feature A.

Tolerances Training

Use Either as DatumUse Either as Datum

Position Tolerance Concentricity

Tolerances Training

Use a Spigot Locator Use a Spigot Locator

Position Tolerance Concentricity

Tolerances Training

DEFINITION The median points of all opposed or correspondingly-located elements of two or more feature surface lie in the same axis or center plane of a datum feature.

TOLERANCE ZONE

A symmetry tolerance is two parallel planes whose axis (or center plane) coincides with the axis (or center plane) of the datum feature.

REFERENCE TO DATUMS

One datum feature (center plane).





Symmetry 0.05 A

Tolerances Training

Regardless of feature size,( within Size Tolerance) all median points of opposed elements of the slot must •Lie between two parallel planes 0.8 apart.•The two parallel planes being equally disposed about datum plane A

Symmetry 0.05 A

Tolerances Training

Gen1 Bell CrankGen1 Bell Crank

Symmetry 0.05 A

Tolerances Training Position Tolerance Angularity

DEFINITION Condition of a surface, center plane, or axis at a specified angle from a datum plane or axis.

TOLERANCE ZONE A angularity tolerance specifies one of the following: 1. A tolerance zone defined by two parallel planes at the specified basic angle from one or more datum planes or axis, within which the surface or center plane of the considered feature must lie.2. A tolerance zone defined by two parallel planes at the specified basic angle from one or more datum planes or axis, within which the axis ot the considered feature must lie.3. A cylindrical tolerance zone at the specified basic angle from one or more datum planes or axis, within which the axis of the considered feature must lie.4. A tolerance zone defined by two parallel lines at the specified basic angle from one or more datum planes or axis, within which the line element of the surface must lie.

REFERENCE TO DATUMS

One or more datum features. Relation to more than one datum feature is specified to stabilize the tolerance zone in more then one direction.


Based on functional requirements MMC, LMC or RFS, appropriate modifier can be applied on angularity tolerance. Application of MMC, LMC and RFS is limited to features subject to variations in size.


If the functional requirements of some applications require MMC, LMC or RFS, appropriate modifier can be applied on the datum axis. Application of MMC, LMC and RFS is limited to features subject to variations in size.

PERFECT ANGULARITY AT MMC

Where no variations of angularity at MMC size limit of feature, the feature control frame contains a zero for the tolerance, modified by the symbol for MMC.

TYPICAL USE Typically used to control orientation between planes surfaces.


Regardless of feature size,the feature axis must •Lie within a 0.2 diameter cylindrical zone inclined 60º to datum plane A.•Be within the specified tolerance of location.

Angularity : Applied to Cylindrical Feature


The surface must •Lie between two parallel planes 0.4 mm apart which are inclined at 30º to datum A.•Be within the specified limits of size.

Angularity : Applied to Plane Surface

Tolerances Training Position Tolerance PerpendicularityDEFINITION Condition of a surface, center plane, or axis at a right angle to a datum plane or axis.

TOLERANCE ZONE 1. A tolerance zone defined by tow parallel planes perpendicular to a datum plane or axis, within which the surface or center plane of the considered feature must lie.2. A tolerance zone defined by two parallel planes perpendicular to a datum axis, within which the axis ot the considered feature must lie.3. A cylindrical tolerance zone perpendicular to a datum plane, within which the axis of the considered feature must lie.4. A tolerance zone defined by two parallel lines perpendicular to a datum plane or axis, within which the line element of the surface must lie.

REFERENCE TO DATUMS



Based on the functional requirement MMC, LMC or RFS, appropriate modifier can be applied on perpendicularity tolerance. Application of MMC, LMC and RFS is limited to features subject to variations in size.


Based on functional requirements MMC, LMC or RFS, appropriate modifier can be applied on the datum axis. Application of MMC, LMC and RFS is limited to features subject to variations in size..

PERFECT PEPENDICULARITY AT MMC

Where no variations of perpendicularity at MMC size limit of feature, the feature control frame contains a zero for the tolerance, modified by the symbol for MMC.

Tolerances Training Perpendicularity

•The surface must lie between two parallel planes 0.12 mm apart which are perpendicular to datum plane. •The surface must be within the specified limits of size.

Perpendicularity : Applied to Plane Surface

Tolerances Training

Perpendicularity : Applied to Cylindrical Feature

Regardless of feature size,( within Size Tolerance limits the feature axis must •Lie within a 0.2 mm diameter cylindrical zone perpendicular to datum axis A. •Be within the specified tolerance of location.

Perpendicularity

Tolerances Training

Tolerances Training10

0

Tolerances Training Position Tolerance Parallelism

DEFINITION Condition of a surface, center plane, equidistant at all points from a datum plane; or axis and equidistant along its length from one or more datum planes or a datum axis.

TOLERANCE ZONE A parallelism tolerance specifies one of the following: 1. A tolerance zone defined by tow parallel planes parallel to a datum plane or axis, within which the surface or center plane of the considered feature must lie.2. A tolerance zone defined by two parallel planes parallel to a datum axis, within which the axis ot the considered feature must lie.3. A cylindrical tolerance zone parallel to a datum plane, within which the axis of the considered feature must lie.4. A tolerance zone defined by two parallel lines parallel to a datum plane or axis, within which the line element of the surface must lie.

REFERENCE TO DATUMS



Based on functional requirements MMC, LMC or RFS, appropriate modifier can be applied on parallelism tolerance. Application of MMC, LMC and RFS is limited to features subject to variations in size.


Based on functional requirements MMC, LMC or RFS, appropriate modifier can be applied on the datum axis. Application of MMC, LMC and RFS is limited to features subject to variations in size..

PERFECT PARALLELISM AT MMC

Where no variations of parallelism at MMC size limit of feature, the feature control frame contains a zero for the tolerance, modified by the symbol for MMC.


The surface must •Lie between two parallel planes 0.12 mm apart which are parallel to datum plane.•Be within the specified limits of size

Parallelism : Applied to Plane Surface

Tolerances Training

Parallelism : Applied to Cylindrical Feature

Regardless of feature size,the feature axis must •Lie within a 0.2 mm diameter cylindrical zone parallel to datum axis A.•Be within the specified tolerance of location.

Position Tolerance Parallelism

Tolerances Training Position Tolerance Run-out

DEFINITION Runout is a composite tolerance used to control the functional relationship of one or more features of a part to a datum axis. The types of features controlled by runout tolerance include those surfaces constructed around a datum axis and those constructed at right angles to a datum axis.

TOLERANCE ZONE Each considered feature must be within its runout tolerance when the part is rotated about the datum axis. The tolerance specified for a controlled surface is the total tolerance or full indicator movement (FIM).

REFERENCE TO DATUMS





The specified datum can only apply on an RFS basis.

TYPICAL USE Typically used to control circularity and concentricity simultaneously.

Tolerances Training Position Tolerance Run-out

Run-Out: Circular / Radial Run- Out

At any measuring position, each circular element of these surfaces must be within the specified run-out tolerance (0.02 mm FIM) when the part is rotated 360º about the datum axis with the indicator fixed in a position normal to the true geometric shape.

Tolerances Training

Run-Out: (Circular / Radial) Total Indicated Reading

The entire surface must lie with the specified total run-out tolerance zone (0.02 mm FIM) When the part is rotated 360º about the datum axis with the indicator placed at every location along the surface in a position normal to the true geometric shape without reset of the indicator

Tolerances Training

Run-Out: (Circular / Radial) Total Indicated Reading

Tolerances Training

Run-Out: Face- Total Indicated Reading- Example

Tolerances Training

Tolerances Training

Building Blocks

Tolerances Training

TemplateTemplate

Types

Straightness

Flatness

Circularity

Cylindricity

Profile of a Line

Profile of a Surface

Angularity

Perpendicularity

Parallelism

Concentricity

True Position

Symmetry

Circular Run - Out

Total Run - out

25 +2

BA1 CL BA0.2 CL

M

Limits, Fits & Tolerances

Design

Transcript of Limits, Fits & Tolerances