Limit, Fit & Tolerance PDF

Limit, Fit & Tolerance Present By : Ankurkumar Jasani ❖ Content Definitions of Limit, Fit and Tolerance Type of Dimensions Type of Tolerance Fundamental Deviation Type of Fit Basic System...

Limit, Fit & Tolerance Present By : Ankurkumar Jasani ❖ Content Definitions of Limit, Fit and Tolerance Type of Dimensions Type of Tolerance Fundamental Deviation Type of Fit Basic System Tolerance Grade Tolerance Calculation Geometrical Tolerance Basics Prepared By : Ankurkumar Jasani 2ˎ˗  ❖ Introduction + 0.3 30.3 Simplest definition of Limit, Fit & Tolerance : 30 - 0.2 29.8 ▪ Limit : is the maximum and minimum sizes of a part. The lower limit is the smallest size that the part can be, and the upper limit is the largest size that the part can be. ▪ Tolerance : is the allowable variation from the nominal size of a part. The tolerance is the difference between the upper limit and the lower limit. Hole : 30 H7 (30+0.00/+0.021) Shaft : 30 g4 (30-0.007/-0.013) ▪ Fit : is the relationship between two parts that are designed to fit together. The fit is determined by the combination of the limit, fits and tolerances of the two parts. Prepared By : Ankurkumar Jasani 3ˎ˗  ❖ Product Design Considering Factors Product Design Operational Durability & Functional Aspects Aspects dependability Manufacturing Aspects Economic Aspects Aesthetic Aspects Marketing Aspects Prepared By : Ankurkumar Jasani 4ˎ˗  ❖ Manufacturing Aspects while product designing : Manufacturing Aspects Tolerances, Manufacturing Type of Fit Cost of Dimensions of Process & it’s Between Parts Manufacturing mating parts sequence Prepared By : Ankurkumar Jasani 5ˎ˗  ❖ Need of Limit and Tolerance : Ideal conditions demand for parts without any kind of dimensions variation, but in actual practice it is impossible due to following reasons, 1. Variations in the properties of material being machined introduce errors. Deflections of workpiece. Thermal deformation etc. 2. The production machines themselves have some inherent inaccuracies build into them and have the limitations to produce perfect parts. Forced vibrations and chatter. Tool bearing clearance etc. 3. It is impossible for an operator to make perfect setting, some error may creep in, while setting tools and workpiece on the machine. Tool deflection Tool wear, fixture/clamping error etc. 4. Environment effects Prepared By : Ankurkumar Jasani 6ˎ˗  ❖ Limit & Tolerance role in manufacturing. ▪ The Limit and Tolerance is a compromise between accuracy required for proper functioning and the ability to economically produce this accuracy. ▪ Unnecessary tight tolerance make parts more expensive to produce and increase cost of parts assembly. Production Cost ▪ There is no reasons to apply ±0.0002 mm tolerance when ±0.002 mm will do. ▪ Because tolerance and production cost have inversely proportion relationship. ▪ Old basic rule “do not specify higher accuracy than is really needed” and “Tolerance must be as large as Tolerance possible and as small as necessary”. Prepared By : Ankurkumar Jasani 7ˎ˗  ❖ Interchangeability : ▪ Interchangeability is the ability of two or more parts to be exchanged or substituted for each other without affecting the functionality of the assembly. In simple terms, it means that two parts that are interchangeable are exactly the same size, shape, and fit. ▪ Interchangeability is achieved by manufacturing the parts to very close tolerances, so that they have the same dimensions. This is done through a variety of manufacturing methods, such as machining, casting, forging, stamping etc. ▪ Best Examples : ▪ Nut & Bolt, ▪ Bearing, ▪ Valve, ▪ Bottle Cap, ▪ Car Components, ▪ Bike Components and Many more … Prepared By : Ankurkumar Jasani 8ˎ˗  ❖ Advantage of Interchangeability : ▪ Increased efficiency: Interchangeability allows for the mass production of products, which can lead to increased efficiency and productivity. ▪ Reduced costs: Interchangeability can help to reduce costs by eliminating the need for special tools and fixtures. ▪ Readily available replacement component in the market. ▪ Assembly process requires lesser skill. ▪ Reduce cost and labor time by allowing easy maintenance as well as easy field repair. Prepared By : Ankurkumar Jasani 9ˎ˗  ❖ Type of Dimensions : 1. Mating Dimensions or Functional Dimensions : Certain surfaces are in contact when mating parts are assembled these dimensions are called mating dimensions and have been machined and required high degree of accuracy. 2. Free Dimensions or Non-functional dimensions : The surface which are not in contact these dimensions are called free dimensions. These need not be machined to high degree of accuracy, and these have no effect of the quality performance of the component or assembly. Prepared By : Ankurkumar Jasani 10ˎ˗ ❖ Type of Dimensions : Prepared By : Ankurkumar Jasani 11ˎ˗ ❖ Type of Dimensions : Prepared By : Ankurkumar Jasani 12ˎ˗ ❖ Type of Dimensions : Prepared By : Ankurkumar Jasani 13ˎ˗ ❖ Type of Dimensions : Prepared By : Ankurkumar Jasani 14ˎ˗  ❖ Type of Size : 1. Design size : Design size is calculated during the designing process of the component It may not be a whole number. i.e., 49.6333 mm 2. Nominal size : It is determined solely from design calculations. If the strength and stiffness requirements need a 50mm diameter shaft, then 50mm is the nominal shaft size. If it has to fit into a hole, then 50 mm is the nominal size of the hole. 3. Basic size : Basic size is the size in which all limits are given If a shaft basic size is 50 mm and limit of ±0.02 is given, then 50 ±0.02 OR 50h8 is called basic size. 4. Actual size : It is the size of actual component by actual measurement after it is manufactured It should be lie between two limits of size. i.e., 50.013 mm Prepared By : Ankurkumar Jasani 15ˎ˗  ❖ Limit ▪ Limits are the two extreme permissible sizes, of a given dimension. ▪ The highest permissible size is called High limit and ▪ the lowest permissible size is called Low limit. ▪ Limits are determined according to basic size and fit required ▪ Example : ▪ In this case, ▪ Basic Size : 20 mm ▪ High Limit : 20 + 0.03 = 20.03 mm + 0.03 ▪ Low Limit : 20 - 0.02 = 19.98 mm 20 - 0.02 Prepared By : Ankurkumar Jasani 16ˎ˗  ❖ Tolerance : ▪ The algebraic difference between high limit and low limit is called tolerance. ▪ and has an absolute value without sign. ▪ or in other words we can say that ▪ tolerance is the amount of tolerable inaccuracy for a given dimension. ▪ Example : ▪ In this case, ▪ Basic Size : 20 mm ▪ High Limit : 20 + 0.03 = 20.03 mm + 0.03 ▪ Low Limit : 20 - 0.02 = 19.98 mm 20 - 0.02 ▪ Tolerance : 20.03 – 19.98 = 0.05 mm Prepared By : Ankurkumar Jasani 17ˎ˗ ❖ Type of Tolerance : Tolerance can be divided in to 4 main types : 1. Unilateral 2. Bilateral 3. Compound tolerance 4. Geometric tolerance Prepared By : Ankurkumar Jasani 18ˎ˗ ❖ Type of Tolerance - Unilateral : 1. Unilateral Tolerance : ▪ If the variation in the size is permitted in one direction only. ▪ i.e., either in upper side or in lower side of the basic size is known as unilateral Tolerance - 3.0 +0.0 - 2.0 +0.2 30 30 Prepared By : Ankurkumar Jasani 19ˎ˗ ❖ Type of Tolerance - Bilateral : 2. Bilateral Tolerance : ▪ If the variation in the size is permitted on the both sides of the basic size. ▪ i.e., upper side and lower side of the basic size is known as Bilateral Tolerance +3.0 +0.6 - 2.0 -0.2 30 30 20ˎ˗ ❖ Type of Tolerance - Compound : 3. Compound Tolerance : ▪ Compound tolerance is determined by the established tolerances ▪ i.e., the combination of more than one type of tolerances are called compound tolerances, the different types of tolerances may be angular, lateral etc. ▪ For Example: ▪ In figure tolerances on dimension / are dependent on tolerances of L, h and θ. ▪ This compound tolerance on ‘l’ is the combined effect of these three tolerance. The minimum tolerance on ‘l’ will be corresponding to L-b, θ-∝ and h+c. ▪ In practice, compound tolerance should be avoided as far as possible. Prepared By : Ankurkumar Jasani 21ˎ˗ ❖ Type of Tolerance - Geometrical : 4. Geometrical Tolerance : ▪ Geometrical tolerances are associated with certain geometrical features like flatness of a plane surface, straightness of a cylinder, squareness of a square shape, roundness etc. Diameters of the cylinders need to be concentric with each other. For proper fit between the two cylinders, both the centers to be in line. This information is represented in the feature control frame. Feature control frame comprises three boxes. First box On the left indicates the feature to be controlled, represented symbolically (example concentricity) Centre box indicates distance between the two cylinders, centers cannot be apart by more than 0.01 mm (tolerance) Third box Indicates that the datum is with X Prepared By : Ankurkumar Jasani 22ˎ˗ ❖ Type of Tolerance - Geometrical : Prepared By : Ankurkumar Jasani 23ˎ˗ ❖ Type of Tolerance - Geometrical : Prepared By : Ankurkumar Jasani 24ˎ˗ ❖ Allowance : It is the difference between the basic dimensions of the mating parts. When the shaft size is less than the hole size, then the allowance is positive and When the shaft size is greater than the hole size, then the allowance is negative. Maxi. Allow. = Max. Hole dia. – Min Shaft dia. Mini. Allow. = Min. Hole dia. – Max shaft dia. 25ˎ˗  ❖ Allowance Example : The slot and the mating parts have basic dimensions of 0.500 inches. Lower and upper limits of the slot are 0.498 and 0.502 inches, correspondingly; lower and upper limits of the mating parts are 0.495 and 0.497 inches. Maxi. Allow. = Max. Hole dia. – Min Shaft dia. Mini. Allow. = Min. Hole dia. – Max shaft dia. Key Upper Limit : 0.497 Maxi. Allow. = 0.502 – 0.495 = 0.007 Key Lower Limit : 0.495 Mini. Allow. = 0.498 – 0.497 = 0.001 Keyway Upper Limit : 0.502 Both Value are positive hance fit will be Keyway Lower Limit : 0.498 clearance. 26ˎ˗ ❖ Deviation : ▪ Upper deviation : It is the algebraic difference between the maximum limit of the size and the corresponding basic size is known as upper deviation ▪ Lower deviation : It is the algebraic difference between the minimum limit of the size and the corresponding basic size is known as lower deviation ▪ Actual deviation : It is the algebraic difference between the actual size and the corresponding basic size is known as actual deviation + 0.01 + 0.02 ▪ Example : Basic Size : 25 ▪ Acceptable Limit : 25.010mm and 25.020mm ▪ Actual Size : 25.012 ▪ Actual Deviations : 25.012 – 25.000 = 0.012 mm ▪ Lower Deviation : 0.010mm and Upper Deviation : 0.020mm Prepared By : Ankurkumar Jasani 27ˎ˗ ❖ Deviation Nomenclature : 28ˎ˗ ❖ Deviation Nomenclature : 29ˎ˗ ❖ Fundamental Deviation: ▪ It can be defined as one of the two deviations which is conventionally chosen to define the position of tolerance zone in relation to the zero line. 30ˎ˗ ❖ Zero Line / Line of Zero Deviation ▪ In a graphical representation of limits and fits, a straight line to which the deviation are referred The zero line is the line of zero deviation and represents the basic size By convention, when the zero line is drawn horizontally, positive deviations are shown above and negative deviation below. Prepared By : Ankurkumar Jasani 31ˎ˗ ❖ Type of Fit : ▪ It is the relationship or degree of tightness that exists between two mating parts, a hole and shaft with respect to their dimensional difference before assembly. ▪ There is 3 type of fits : ▪ 1. Clearance Fit ▪ 2. Interference Fit ▪ 3. Transition Fit - Hole Limit - Shaft Limit 33ˎ˗ ❖ Clearance Fit : ▪ For clearance fit, the limits of the mating dimensions are so selected that if the parts are made within the limits, there will be always a positive allowance, between the mating parts. ▪ Example : ▪ According to the amount of the clearances, the ▪ Vernier Caliper Sliding jaw clearance fit is divided into the following groups: ▪ Nut and bolt assembly 1. Slack running fit ▪ Bush bearing 2. Loose running fit ▪ Ram of shaper machine 3. Easy running fit ▪ Pivot Fitting 4. Normal running fit ▪ Riveting 5. Close running fit 6. Precision sliding fit 34ˎ˗ ❖ Clearance Fit : ▪ For clearance fit, the limits of the mating dimensions are so selected that if the parts are made within the limits, there will be always a positive allowance, between the mating parts. 35ˎ˗ ❖ Clearance Fit : ▪ Slack running fit ▪ This is the loosest type of fit, with the largest clearance between the hole and shaft. It is used in applications where accuracy is not important and where the parts may be exposed to contamination. For example, a slack running fit might be used for a pivot that is not subject to high loads. ▪ Loose running fit ▪ Easy running fit ▪ Normal running fit ▪ Close running fit ▪ Precision sliding fit Prepared By : Ankurkumar Jasani 36ˎ˗ ❖ Clearance Fit : ▪ Slack running fit ▪ Loose running fit ▪ This is a slightly tighter fit than a slack running fit, with a smaller clearance. It is used in applications where accuracy is not of the utmost importance and contamination may be a problem. ▪ Example uses in engineering: Fits exposed to dust contamination, corrosion, thermal and mechanical deformations. Pivots, latches, etc. ▪ Example fits: H11/c11, H11/a11, H11/d11 (all hole-basis), C11/h11, A11/h11, D11/h11 (all shaft-basis) ▪ Easy running fit ▪ Normal running fit ▪ Close running fit ▪ Precision sliding fit Prepared By : Ankurkumar Jasani 37ˎ˗ ❖ Clearance Fit : ▪ Slack running fit ▪ Loose running fit ▪ Easy running fit ▪ This is a fit with a clearance that is even smaller than a loose running fit. It is used in applications where the parts need to be able to move freely and with little resistance. For example, an easy running fit might be used for a piston in a cylinder. ▪ Normal running fit ▪ Close running fit ▪ Precision sliding fit 38ˎ˗ ❖ Interference Fit : ▪ A fit which provides an interference, is called interference fit In this case the limit sizes of the hole and the shaft are so chosen that if the hole and the shaft dimensions are made within the specified limits, the shaft dimensions will always be bigger than the hole dimension. ▪ Examples : ▪ According to the amount of the clearances, the ▪ Fitting of coupling on shaft, clearance fit is divided into the following groups: ▪ Fitting of ferrous and nonferrous sleeve, 1. Shrink fit ▪ Fitting of railway type on wheel. 2. Heavy drive fit ▪ Fitting of Clutch disc 3. Light drive fit ▪ Permanent Flange Prepared By : Ankurkumar Jasani 39ˎ˗ ❖ Interference Fit : ▪ A fit which provides an interference, is called interference fit In this case the limit sizes of the hole and the shaft are so chosen that if the hole and the shaft dimensions are made within the specified limits, the shaft dimensions will always be bigger than the hole dimension. Prepared By : Ankurkumar Jasani 40ˎ˗ ❖ Transition Fit : ▪ A fit which may provide either a clearance or an interference is called transition fit. in this type the tolerance zone of the hole and the shaft overlap so it is not possible to give guarantee when two mating parts are to be assemble to give guarantee when two mating parts are to be assembled with transition fit, whether they will fit with a clearance or an interference. ▪ Example ▪ According to type and amount of allowance the ▪ Fitting of keys, ▪ transition fits are divided into following groups ▪ Fitting of small a.f. bearings 1. Push Fit ▪ Belt Pully on shaft 2. Light keying Fit ▪ Demountable fit of hub 3. Medium keying Fit 4. Heavy Key Fit 41ˎ˗ ❖ Transition Fit : ▪ A fit which may provide either a clearance or an interference is called transition fit. in this type the tolerance zone of the hole and the shaft overlap so it is not possible to give guarantee when two mating parts are to be assemble to give guarantee when two mating parts are to be assembled with transition fit, whether they will fit with a clearance or an interference. 42ˎ˗ ❖ Tolerance Zone vs Fit : 43ˎ˗ ❖ Fit vs Allowance Comparisons : SL No. Fit Type Min. Allowance Max. Allowance 1 Clearance Fit Positive Positive 2 Interference Fit Negative Negative 3 Transition Fit Negative Positive Maxi. Allow. = Max. Hole dia. – Min Shaft dia. Mini. Allow. = Min. Hole dia. – Max shaft dia. Prepared By : Ankurkumar Jasani 44ˎ˗ ❖ Hole Basis System and Shaft Basis System : ▪ Hole basis is the system of fits where the minimum hole size is the basic size. ▪ In the example, the fundamental deviation for a hole basis system is indicated by the uppercase letter “H”. ▪ The hole basis fits have four preferred hole tolerances H11, H9, H8, and H7. ▪ Shaft basis is the system of fits where the maximum shaft size is the basic size. ▪ In the example, the fundamental deviation for a shaft basis system is indicated by the lowercase letter “h”. ▪ The shaft basis fits have four preferred shaft tolerances h11, h9, h7, and h6. Prepared By : Ankurkumar Jasani 45ˎ˗ ❖ Hole Basis System : 46ˎ˗ ❖ Shaft Basis System : Prepared By : Ankurkumar Jasani 47ˎ˗ ❖ Hole Basis System : 48ˎ˗ ❖ Hole Basis System and Shaft Basis System vs Fit : Prepared By : Ankurkumar Jasani 49ˎ˗ ❖ ISO Codification : ▪ The ISO System of Limits and Fits (referred to as the ISO system) is covered in national standards throughout the world, as shown by the following list: ▪ Global - ISO 286 ▪ India - IS 919 - 1963 ▪ USA - ANSI B4.2 ▪ Japan - JIS B0401 ▪ Germany - DIN 7160//61 ▪ France - NF E ▪ UK - BSI 4500 ▪ Italy - UNI 6388 ▪ Australia - AS 1654 50ˎ˗ ❖ Fundamental Deviation: ▪ It can be defined as one of the two deviations which is conventionally chosen to define the position of tolerance zone in relation to the zero line. 51ˎ˗ ❖ Fundamental Deviation: ▪ The symbols used for the fundamental deviations for the shaft and hole are as follows : Hole Shaft ▪ Upper deviation (E cart superior) ES es ▪ Lower deviation (E cart inferior) EI ei ▪ The various 28 fundamental deviation are represented for Hole by : ▪ A, B, C, CD, D, E, EF, F, ,FG, G, H, JS, J, K, M, N, P, R, S, T, U, X, Y, Z, Za, Zb and Zc ▪ Excluding I, L, O, Q, W and adding CD, EF, FG, Js, Za, Zb, Zc - 28 nos ▪ The various 28 fundamental deviation are represented for Shaft by : ▪ a, b, c, cd, d, e, ef, f, fg, g, h, js, j, k, m, n, p, r, s, t, u, x, y, z, za, zb and zc ▪ Excluding i, l, o, q, w and adding js, cd, ef, fg, za, zb, zc - 28 nos. cd, CD, ef, EF, fg, FG for sizes up to 10 mm which for fine mechanism and horology. 52ˎ˗ ❖ ISO Codification : Prepared By : Ankurkumar Jasani 53ˎ˗ ❖ Fundamental Deviation: Prepared By : Ankurkumar Jasani 54ˎ˗ ❖ Fundamental Deviation: Prepared By : Ankurkumar Jasani 55ˎ˗ ❖ Tolerance Grade : ▪ International tolerance grade (IT) : ▪ The classification system OR a series of tolerances that vary with the basic size to provide a uniform level of accuracy within a given grade. ▪ It is an indication of the level of accuracy. ▪ There are 20 grades of tolerances for size from 0 to 500mm. ▪ It is denoted by the combinations IT01, IT0, and IT1 to IT18. ▪ There are 18 grades of tolerances for size from 500 to 3150mm. ▪ It is denoted by the combinations IT1 to IT18. Prepared By : Ankurkumar Jasani 56ˎ˗ ❖ Tolerance Grade : ▪ IT01 to IT4 - For production of gauges, plug gauges, measuring instruments ▪ IT5 to IT7 - For fits in precision engineering applications ▪ IT8 to IT11 - For General Engineering ▪ IT12 to IT14 - For Sheet metal working or press working ▪ IT15 to IT16 - For processes like casting, general cutting work Prepared By : Ankurkumar Jasani 57ˎ˗ ❖ Tolerance Grade : Prepared By : Ankurkumar Jasani 58ˎ˗ ❖ Tolerance Grade : Prepared By : Ankurkumar Jasani 59ˎ˗ ❖ IT Grade Values (as per ISO 286) : Prepared By : Ankurkumar Jasani 60ˎ˗ ❖ IT Grade Explanation : INTERNATIONAL TOLERANCE GRADES Values In IT5 IT6 IT7 IT8 IT9 IT10 IT11 IT12 IT13 IT14 IT15 IT16 Microns Values For D 7i 10i 16i 25i 40i 64i 100i 160i 250i 400i 640i 1000i In mm ▪ 𝒊 = Tolerance standard 𝟑 ▪ Where 𝒊 = 𝟎. 𝟒𝟓 ∙ 𝑫 + 𝟎. 𝟎𝟎𝟏 ∙ 𝑫 ▪ This value indicate tolerance of that size. Prepared By : Ankurkumar Jasani 62ˎ˗ ❖ Fundamental Deviation from Chat as per ISO 286 : Prepared By : Ankurkumar Jasani 63ˎ˗ ❖ Example : 3 ▪ Fit : 50 H7/g6 Where 𝑖 = 0.45 ∙ 𝐷 + 0.001 ∙ 𝐷 ▪ Means : D = (30𝑥50) = 1500 = 38.72 𝑚𝑚 ▪ Basic size : 50 3 𝑖 = 0.45 ∙ 𝐷 + 0.001 ∙ 𝐷 ▪ Hole tolerance : H7 3 𝑖 = 0.45 ∙ 38.72 + 0.001 ∙ 38.72 ▪ Shaft Tolerance : g6 𝑖 = 1.56 IT7 = 16i ▪ For Hole : IT7 = 16 x 1.56 ▪ Fundamental deviation is H IT7 = 24.977 ~ 25 Micron Hole Upper deviation is 0.025 mm ▪ Lower deviation is 0 Upper limit is : 50.025 mm ▪ Upper deviation as per IT7 grade ▪ IT7 = 16i Lower Limit is : 50.000 mm Upper Limit is : 50.025 mm Prepared By : Ankurkumar Jasani 64ˎ˗ ❖ Example : 3 ▪ Fit : 50 H7/g6 Where 𝑖 = 0.45 ∙ 𝐷 + 0.001 ∙ 𝐷 ▪ Means : D = (30𝑥50) = 1500 = 38.72 𝑚𝑚 ▪ Basic size : 50 3 𝑖 = 0.45 ∙ 𝐷 + 0.001 ∙ 𝐷 ▪ Hole tolerance : H7 3 𝑖 = 0.45 ∙ 38.72 + 0.001 ∙ 38.72 ▪ Shaft Tolerance : g6 𝑖 = 1.56 IT6 = 10i ▪ For Shaft : IT6 = 10 x 1.56 ▪ Fundamental deviation is g IT6 = 15.6 ~ 16 Micron ▪ Upper Deviation : -2.5 x D0.34 Shaft lower deviation is FT + IT6 mm Lower deviation : 0.009 + 0.016 = 0.025 mm ▪ = - 2.5 x 38.720.34 ▪ = 8.66 Micron Upper Limit is : 49.991 mm Online ▪ =~0.009 mm Lower limit is : 49.975 mm Calculator Prepared By : Ankurkumar Jasani 65ˎ˗ ❖ Example – 50 H7/g6 : Source: amesweb.info Prepared By : Ankurkumar Jasani 66ˎ˗ ❖ Q1 - Find out Answer : ▪ When upper deviation is +0.08 mm and lower deviation is +0.03 mm, then the tolerance for the part is ______. ▪ The tolerance is the difference between the upper deviation and the lower deviation. ▪ In this case, ▪ the upper deviation is 0.08 mm. and ▪ the lower deviation is 0.03 mm. ▪ Therefore, the tolerance is ▪ 0.08 - 0.03 = ▪ 0.05 mm. Prepared By : Ankurkumar Jasani 67ˎ˗ ❖ Q2 - Find out Answer : ▪ When upper deviation is +0.15 mm and lower deviation is -0.05 mm, then the tolerance for the shaft and hole both. ▪ The tolerance is the difference between the upper deviation and the lower deviation. ▪ In this case, ▪ the upper deviation is 0.15 mm ▪ and the lower deviation is -0.05 mm. ▪ Therefore, the tolerance is ▪ 0.15 - (-0.05) = ▪ 0.2 mm. Prepared By : Ankurkumar Jasani 68ˎ˗ ❖ Q3 - Find out Answer : ▪ The diameters of the hole and shaft are specified respectively as 50±0.05 mm and 50–0.04 mm. The fit is a: ▪ Hole : ▪ Lower limit of hole = 50 mm - 0.05 mm = 49.95 mm SL Min. Max. ▪ Upper limit of hole = 50 mm + 0.05 mm = 50.05 mm No. Fit Type Allowance Allowance 1 Clearance Fit Positive Positive ▪ Shaft : 2 Interference Fit Negative Negative ▪ Lower limit of shaft = 50 mm - 0.04 mm = 49.96 mm 3 Transition Fit Negative Positive ▪ Upper limit of shaft = 50 mm + 0.00 mm = 50.00 mm ▪ Max Allowance : UH – LS = 50.05 – 49.96 = 0.09 mm ▪ Fit is Transition Fit ▪ Min Allowance : LH – US = 49.95 – 50.00 = -0.05 mm Prepared By : Ankurkumar Jasani 69ˎ˗ ❖ Q4 - Find out Answer : ▪ 𝐼𝑛 𝑎𝑛 𝑖𝑛𝑡𝑒𝑟𝑐ℎ𝑎𝑛𝑔𝑒𝑎𝑏𝑙𝑒 𝑎𝑠𝑠𝑒𝑚𝑏𝑙𝑦, 𝑎 𝑠ℎ𝑎𝑓𝑡 𝑜𝑓 50+0.04 +0.03 −0.01 𝑚𝑚 𝑚𝑎𝑡𝑒𝑠 𝑤𝑖𝑡ℎ 𝑎 ℎ𝑜𝑙𝑒 50−0.02 𝑚𝑚. ▪ 𝑇ℎ𝑒 𝑚𝑎𝑥𝑖𝑚𝑢𝑚 𝑖𝑛𝑡𝑒𝑟𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑖𝑛 𝑡ℎ𝑒 𝑎𝑠𝑠𝑒𝑚𝑏𝑙𝑦 𝑖𝑠 ▪ Hole : ▪ Lower limit of hole = 50 mm - 0.02 mm = 49.98 mm SL Min. Max. ▪ Upper limit of hole = 50 mm + 0.03 mm = 50.03 mm No. Fit Type Allowance Allowance 1 Clearance Fit Positive Positive ▪ Shaft : 2 Interference Fit Negative Negative ▪ Lower limit of shaft = 50 mm - 0.01 mm = 49.99 mm 3 Transition Fit Negative Positive ▪ Upper limit of shaft = 50 mm + 0.04 mm = 50.04 mm ▪ Max Allowance : UH – LS = 50.03 – 49.99 = 0.04 mm ▪ Max Interference is ▪ Min Allowance : LH – US = 49.98 – 50.04 = -0.06 mm ▪ 0.06 mm 70ˎ˗ ❖ Q5 - Find out Answer : ▪ A medium force fit on a 75 mm shaft requires a hole tolerance and shaft tolerance each equal to 0.225 mm and a Minimum interference of 0.0375 mm. Determine the proper hole and shaft dimension with the basis hole standard. ▪ Shaft diameter = 75 mm ▪ Min. Shaft = 75.225 + 0.0375 ▪ Hole tolerance = 0.225 mm ▪ Lower Shaft = 75.2625 mm ▪ Shaft tolerance = 0.225 mm ▪ Upper Shaft = 75.2625 + 0.225 ▪ Maximum interference = 0.0375 mm ▪ Lower Shaft = 75.4875 mm ▪ Hole Upper Limit = 75.225 mm ▪ Hole Lower Limit = 75.000 mm Shaft ▪ Min. Interference = Max. Hole – Min. Shaft 75.225 Hole ▪ -0.0375 = 75.75.225 – Min. Shaft 75 71ˎ˗ ❖ Q6 - Find out Answer : ▪ Calculate the fundamental deviation and tolerances, and hence the limits of size for the shaft and hole for the fit 60 H8-f7. (Diameter steps are 50mm & 80mm). ▪ Use This : 3 𝑖 = 0.45 ∙ 𝐷 + 0.001 ∙ 𝐷 Prepared By : Ankurkumar Jasani 72ˎ˗ ❖ Q6 - Find out Answer : ▪ Calculate the fundamental deviation and tolerances and both Limits of size for the shaft and hole for the fit 60 H8-f7. (Diameter steps are 50mm & 80mm) ▪ Shaft diameter = 60 mm ▪ D = 50 𝑥 80 = 63.25 ▪ IT7 = 16𝑖 = 16 x 1.853 = 29.64 μ ▪ 3 𝑖 = 0.45 ∙ 𝐷 + 0.001 ∙ 𝐷 ▪ Shaft Upper Limit : -5.5D0.41 ▪ 3 𝑖 = 0.45 ∙ 63.25 + (0.001 ∙ 63.25) ▪ Shaft Upper Limit : -5.5 ∙ 63.250.41 ▪ 𝑖 = 1.79 + 0.06325 ▪ Shaft Upper Limit : -30.11 μ ▪ 𝑖 = 1.853 ▪ Shaft Upper Limit : 60.000 - 0.030 ▪ IT8 = 25𝑖 = 25 x 1.853 = 46.32 μ ▪ = 59.970 mm ▪ Hole Upper Limit = 60.046 mm ▪ Shaft Lower Limit : 59.970 - 0.029 ▪ Hole Lower Limit = 60.000 mm ▪ = 59.941 mm Prepared By : Ankurkumar Jasani 73ˎ˗ ❖ Q7 - Find out Answer : Prepared By : Ankurkumar Jasani 74ˎ˗ ❖ Q7 - Find out Answer : Prepared By : Ankurkumar Jasani 75ˎ˗ ❖ Geometrical Tolerance : ▪ Geometric tolerance refers to the allowable variation in the shape, orientation, and location of features on a part. ▪ It takes into account not only the individual dimensions but also the relationships between them. ▪ Geometric tolerancing uses symbols and control frames to communicate the desired tolerances on engineering drawings. ▪ Sometime called ▪ Feature-based Dimensioning & Tolerancing ▪ Or ▪ True Position Dimensioning & Tolerancing Prepared By : Ankurkumar Jasani 76ˎ˗ ❖ Geometrical Tolerance : ▪ GEOMETRICAL TOLERANCING ON TECHNICAL DRAWINGS ▪ Global : ISO 1101 : 1983 ▪ Indian - IS : 8000 (Part 1) : 1985 ▪ TECHNICAL DRAWINGS — GEOMETRICAL TOLERANCING — TOLERANCING OF FORM, ORIENTATION, LOCATION AND RUN-OUT — VERIFICATION PRINCIPLES AND METHODS — GUIDELINES ▪ Global - ISO 5460 : 1985 ▪ Indian – IS 15054 : 2001 Prepared By : Ankurkumar Jasani 77ˎ˗ ❖ Tolerance Conditions : MMC and LMC ▪ Maximum material condition (MMC) is the condition of a part when it contains the most amount of material. ▪ The MMC of an external feature such as a shaft is the upper limit. ▪ The MMC of an internal feature such as a hole is the lower limit. ▪ Least material condition (LMC) is the condition of a part when it contains the least amount of material possible. ▪ The LMC of an external feature is the lower limit of the part. ▪ The LMC of an internal feature is the upper limit of the part. Prepared By : Ankurkumar Jasani 78ˎ˗ ❖ GD&T Category : ▪ There are 14 geometric characteristic symbols. ▪ They are categorized with the type of geometric control 1. 4 - Form 2. 2 - Profile 3. 3 - Orientation 4. 3 - Location 5. 2 - Run-out Prepared By : Ankurkumar Jasani 79ˎ˗ ❖ GD&T Category : Prepared By : Ankurkumar Jasani 80ˎ˗ ❖ Modifier and it’s symbols: Prepared By : Ankurkumar Jasani 81ˎ˗ ❖ Feature Control Frame : ▪ Prepared By : Ankurkumar Jasani 82ˎ˗ ❖ Feature Control Frame Reading : ▪ For More Details : https://www.gdandtbasics.com/straightness Prepared By : Ankurkumar Jasani 83ˎ˗ ❖ GD&T Video : Video Link : https://www.youtube.com/watch?v=G7wnGeR_69k 84ˎ˗ ❖ Thanks Note : For Any Clarification and Correction, Please reach out Mr. Ankurkumar Jasani (Assist. Manager, Training Mechanical) [email protected] | +91 72053 65968 85ˎ˗