1. IMS Engineering College, Ghaziabad - Delhi NCR LIMITS,FITS,AND TOLERANCES AND SURFACE ROUGHNESS SUBMITTED TO Prof. DEEPAK SHARMA SUBMITTED TO DIVYANSHU VERMA ME-1 1214340058

2. 1- Standardization 2- Interchangeability (a)definition (b) advantages 3- Limits and Fits (a) Terminology (b) Types of Fits (c) Basis of Limit system (d) Limit gauge 4- Surface roughness 5- Preferred numbers TOPICS COVERED

3. Standardization The main purpose of standardization is to establish mandatory or obligatory norms for the design and production of machines so as to reduce variations in their types and grades and to achieve quality characteristics in raw materials, semi-finished and finished products. In standardization, the concept of preffered numbers helps to reduce unnecessary variations in sizes

4. Benefits of Standardization Better product quality, reliability, and longer life service. Mass production of components at low cost. Easy availability of parts for replacement and maintenance Less time and effort required to manufacture. reduction in variations in size and grades of an article.

5. Interchangeability Definition - Situation where two or more items are so similar in functional and physical characteristics that they are considered equivalent in performance and durability. Each is capable of replacing the other(s) without causing a need for alteration or adjustment to fulfill the same requirement.

6. Examples Nuts and boltsRims Tires

7. Advantages For Interchangeable Manufacture Replacement: One such part can freely replace another, without any custom fitting (such as filling). Easy to Assembly: This interchangeability allows easy assembly of new devices Repairing: Easier repair of existing devices. Minimizing time and cost :Minimizing both the time and skill required of the person doing the assembly or repair. Rapid Manufacturing :Machine tool enables the components to be manufactured more rapidly

8. Limits and Fits LIMITS:‐ These are two extreme permissible sizes of dimension between which actual dimension is contained. FITS:‐It is the relationship existing between mating parts with respect to amount of play or interference which is present when they assembled together. It is the degree of tightness or looseness between two mating parts to perform definite function

9. Terminology for LIMITS & FITS 1. Size:- It is a number expressed in a particular unit in the measurement of length. 2. Basic Size:- It is the size based on which the dimensional deviations are given. 3. Actual Size:- It is the size of the component by actual measurement after it is manufactured. It should lie between the two limits of size. 4. Limits of size:- These are the maximum and minimum permissible sizes of the part. 5. Maximum limit:- Is the maximum size permitted for the part. 6. Minimum limit:- it is the minimum size permitted for the part limit of size.

11. Tolerance - the difference between the upper limit and lower limit of a dimension is called Tolerance. When both tolerances on one side,system is said to be Unilateral. when tolerances is allowed on both of nominal size, said to be Bilateral

12. Deviation:- It is the algebraic difference between a size, to its corresponding basic size. It may be positive, negative or zero. Upper Deviation:- It is the algebraic difference between maximum limit of size and its corresponding basic size. Lower Deviation:- It is the algebraic difference between minimum limit of size and its corresponding basic size. Actual Deviation:- It is the algebraic difference between actual size and its corresponding basic size

13. Fit- is the relationship that exists between two mating parts, a hole and shaft with respect to their dimensional difference before assembly. Three types of fit are given hereunder

14. Types of fits Clearance Fit : In clearance Fit shaft is always smaller than the hole Interference Fit: It is also called Press or force fit, In this fit shaft is always larger than the hole

15. Continued.. Transition Fit: it is called sliding Fit. It occurs when the resulting fit due to the variations in size of the male and female components due to their tolerance, varies between clearance and interference fits. The tolerance zones of shaft and hole overlap

16. Hole basis - Hole is keep constant and the shaft diameter is varied. The actual size of the hole is within the tolerance limit Shaft basis -Shaft is kept constant and the hole diameter is varied. The actual size of a hole that is within the tolerance limits is always less than the basic size. Basis of limit system

17. Limit gauge It inspection tool used to check a workpiece against its allowed tolerances. A Go-No gauge refers to an inspection tool used to check a workpiece against its allowed tolerances. Its name derives from its use: the gauge has two tests; the check involves the workpiece having to pass one test (Go) and fail the other (No Go).

18. Surface roughness and its measurement Each type of cutting tool leaves its own individual pattern which therefore can be identified. This pattern is known as surface finish or surface roughness.

19. Continued

20. Continued… SymbolsSurface roughness (Ra) in microns V8 to 25 VV1.6 to 8 VVV.025 to 1.6 VVVVLess than.025 According to the indian standard following symbols are used to denote the various degree of surface roughness

21. Preferred numbers In industrial design, preferred numbers (also called preferred values) are standard guidelines for choosing exact product dimensions within a given set of constraints. Product developers must choose numerous lengths, distances, diameters, volumes, and other characteristic quantities. the series of preferred numbers are designated as R5,R20 and R40 respectively. R5: 1.00 1.60 2.50 4.00 6.30 Example - If our design constraints tell us that the two screws in our gadget should be placed between 32 mm and 55 mm apart, we make it 40 mm, because 4 is in the R5 series of preferred numbers.

22. Preferred numbers of the basis series according to ISO3

23. Thank you