PowerPoint Presentation

Basic GD & T.

Training Content:. Dimensional Control System Types of Line Hole & Thread Callouts Miscellaneous Callouts Roughness.

Dimensional Control System.

Dimensional Control System. Form Tolerance Profile Tolerance Orientation Tolerance Location Tolerance Runout Tolerance.

Form Tolerance – is referring to the tolerance zone that limits the deviation of a form element from its ideal geometry and is orientated exclusively to the tolerance element..

Characteristic narne: Straightness Control type: Form Controls the straightness of a feature in relation to its own perfect form Tolerance zone 0.1 -4 Checking method using dial gauge Zone.

Characteristic narne: Flatness Control type: Forrn Controls the flatness Of a surface in relation to its perfect for-rn L 0.1 Tolerance zone olerance Zone Checking rnethod using dial gauge V—BIock echmen.

Characteristic narme: Circularity Control type: Forrn Controls the for-rn Of a revolved surface in relation to its ov.zn perfect forrn by independent cross sections Tolerance zone Checking method using dial gauge V-B10ck.

Characteristic narne: Cylindricity Control type: Forrn Controls the for-rn Of a revolved surface Like circularity, but applies sir-nultaneously to entire surface c. 005 Tolerance zone Zone Checking rnethod using dial gauge V-B10ck.

Profile Tolerance - defines a uniform boundary around a surface within where the elements of the surface must lie. Profile is a three-dimensional tolerance that applies in all directions regardless of the drawing view where the tolerance is specified..

Characteristic narne: Profile Of a line Control type: Profile Profile of a line describes a tolerance zone around any line in any feature, curved shape. 0,25 usually of a Checking method using dial gauge & master profile Tolerance zone M Profil.

Characteristic narne: Profile of a Surface Control type: Profile Profile of a surface describes a 3-Dirnensional tolerance zone around a surface, which is an advanced curve or shape. Tolerance zone Toleraxx.ce Zoxxe Checking rnethod using CMM probe sensing usually.

3 Type of Orientation Tolerance. Orientation Tolerance - determines the orientation for the form in relation to a reference. A datum is always necessary to indicate orientation tolerance..

Characteristic narne: Angularity Control type: Orientation Controls orientation of a feature at a specific angle in relation to the prirnary daturn of its datum reference frame 0.25 A Tolerance zone Slip Ga Checking method using dial gauge.

Characteristic narme: Perpendicularity Control type: Orientation Controls the orientation of a feature vvhich is norninally perpendicular to the prirnary daturn of its daturn reference frarne Tolerance zone ii V—BIock with U—clarnp Checking rnethod using dial gauge.

Characteristic narne: Parallelism Control type: Orientation Controls orientation of a feature w'hich is nor-ninally parallel to the prirnary daturr-u of its datum reference frame. Tolerance zone Tolerance Zone Checking method using dial gauge.

3 Type of Location Tolerance. Location Tolerance - determines the location of the feature in relation to a reference..

Characteristic narne: Position Control type: Location True position in terrns of the axis. point or plane controls variations of a feature frorn a specified exact true location- Checking rnethod using CMM probe sensing ZQ.A@•• Tolerance zone ech n.

Characteristic narne: Concentricity Control type: Location It controls the central axis of referenced feature. coaxially. to a daturn axis- Checking rnethod using dial gauge Tolerance zone olera_nce V—BIock It is also called as echrnen.

Characteristic nan-me: Syrnrnetry Control type: Location It controls uniforrnity of tvuo features on a part across a daturn plane- Checking rnethod using dial gauge Buttix.g Surface.

2 Type of Runout Tolerance. Runout Tolerance - is a geometric tolerance that specifies the run-out fluctuation of a target's feature when the target (part) is rotated on an axis (specified straight line). A datum is always necessary to indicate run-out tolerance; as such, it is a geometric tolerance for features related to datums..

Characteristic narne: Circular run—out Control type: Run—out Controls circularity and coaxiality Of each circular segr-nent of a surface independently about a coaxial daturn Tolerance zone Checking rnethod using Dial gauge -2 V-B10ck echrnen.

Characteristic narne: Total run—out Control type: Run—out Controls circularity, straightness. coaxiality, and taper Of a cylindrical surface about a coaxial daturn Tolerance Checking rnethod using Dial gauge V—BIock echrnen zone.

Type of Lines.

TYPE OF LINES. Part Outline Section Line Hidden Line Center Line Dimension Line Cutting Line Break Line.

A. A – Part Outline - These are thick continuous lines and are used to represent the outline or overall shape of an object. Every edge or surface that is visible is represented by these lines..

E. D – Center Line - are used to indicate the centers of holes, arcs, and symmetrical objects. They are very thin (size), long-short-long kinds of lines..

G – Break Line - are used to show where an object is broken to save drawing space or reveal interior features. Break lines come in two forms: a freehand thick line, and. a long, ruled thin line with zigzags. are used to show where an object is broken to save drawing space or reveal interior features. Break lines come in two forms: a freehand thick line, and. a long, ruled thin line with zigzags..

Hole & Thread Callout.

c INTERNAL THREAD CALLOUT THRU WITH COUNTER SINK INTERNAL THREAD CALLOUT BLIND c THRU HOLE WITH COUNTER BORE AND COUNTER SINK THREADED HOLE - SECTION VIEW CALLOU, SECTDN A-A SECTON CC SECTDN e-B c THRU HOLE WITH COUNTER SINK SECTON C.C.

SECTION VIEW CALLOUTS SECTION A-A SIMPLE HOLE - SECTDN e.-6 SECTION C-C ynz 0-0 SECTON.

Miscellaneous Callout.

CHAMFER CALLOUT. EQUAL LEG CHAMFER CALLOUT. RADIUS CALLOUT.

Counter bore: This symbol is used to indicate a counter bore or a spot face. The symbol precedes the dimension of the counter bore, with no space Countersink: This symbol is used to indicate a countersink. The symbol precedes the dimensions of the countersink with no space. Square: This symbol is used to indicate that a single dimension applies to a square shape. The symbol precedes the dimension with no space between. Depth or Deep: It is used to indicate that a dimension applies to the depth of a feature. This symbol precedes the depth value with no space in between. Number of Places: The "X" symbol is used along with a value to indicate the number of times a dimension or feature is repeated on the drawing..

95 Statistical Tolerance: It is the assigning of tolerances to related components of an assembly on the basis of statistics. By applying statistical tolerance, tolerances of individual components may be increased or clearances between mating parts may be reduced. Between: This is used to indicate that a profile tolerance applies to several contiguous features or letters may designate where the profile tolerance begins and ends. These letters are referenced using the between symbol. Target Point: This indicates where the datum target point is dimensionally located on the direct view of the surface. Arc Length: This indicates that a dimension is an arc length measured on a curved outline. The symbol is placed above the dimension. Continuous Feature : It is used to identify a group of two or more features of size where there is a requirement that they be treated geometrically as a single feature of size..

5 OR A1 A1 All Around Symbol: This indicates that a tolerance applies to surfaces all around the part. Dimension Origin: A circle used in place of one of the arrowheads on a dimension line indicates the origin for measurement. Conical Taper: It is used to indicate taper for conical tapers. This symbol is always shown with the vertical leg to the left. Slope: It is used to indicate slope for flat tapers. Datum Target: It is a specified point, line, or area on a part that is used to establish the Datum Reference Plane for manufacturing and inspection operations..

Modifier. Least Material Condition (LMC). L. Least Material Condition : LMC describes the condition of a feature where the least amount of material exists within its dimensional tolerance. This condition exists at maximum clearance or minimum interference. Symbol: L E.g.: Smallest pin diameter, Largest hole size SHAFT Ø10 00±0 10 Here LMC 980mm HOLE ø10 10 Here LMCI 10 10 mm.

Modifier. Maximum Material Condition (MMC). Maximum Material Condition : MMC describes the condition of a feature where the maximum amount of material exists within its dimensional tolerance. This condition exists at minimum clearance or maximum interference. Symbol: M E.g.: Largest pin diameter, Smallest hole size SHAFT ø1000±0 10 Here MMC: IOU mm HOLE ØIO Here MMC 990mm.

A screenshot of a cell phone Description automatically generated.

Roughness.

Peak Line Mean Line Valley Line Sarnple length Here, Ra = The average variation frorn rnean line (green colour). Rt = Distance frorn the highest peak to the deepest valley. Rp = The highest peak above the rnean line. Rv = The deepest valley belov•v the rmean line. Rz = The average Rt over a given length..

Surface Finish • Surface finish is the allowable deviation from a perfectly flat surface, made by some manufacturing process. • Surface roughness is a property of the material surface texture, which is recognized by an uneven topography as compared to the perfectly flat surface. • All machining processes will generate some roughness on the surface. • Since, all the surfaces may not have functional requirements. So, no need to have equal finish every where. • Roughness can be measured by manual comparison against a surface roughness comparator (plate), profilometer (diamond stylus contact measurement) or optical method. • Surface finish is broken up into three components such as roughness, waviness, and form. Here, Roughness is the machined marks made on a surface by the cutting tool. Waviness is the result of the vibration of the tool and Form surface irregu larities caused by worn off machine bed or table etc..

Lay direcim Rcxaghness width Roughness He•t Waviness Height Waviness Space Roughness is the measure of finest irregularities of a surface. Waviness is the measure of surface irregularities with a spacing greater than that of surface roughness. Lay refers to the predominant direction of the surface texture..

Syrnbolic Representations: Roughness "a" obtained by any production process Roughness "a" obtained by removal Of material by machining Roughness "a" obtained without removal of any material "al" Upper and "a2" lower limit of roughness value "G" B "B" represents production method represents other than Ra value.