03. dimensional tolerances

1.  PART AND ASSEMBLY DRAWINGS

2.  SURFACE CHARACTERISTICS

3.  DIMENSIONAL TOLERANCES

4.  FITS

5.  GEOMETRIC TOLERANCES

6.  DIMENSIONING

7.  THREADED FASTENING

8.  SHAFT AND PIPE JOINERS

9.  BEARINGS

10. GEARS 1: DEFINITION

11. GEARS 2: HELICAL

12. GEARS 3: BEVEL

13. BELTS AND CHAINS

14. WELDED JOINTS AND RIVETS

3. DIMENSIONAL TOLERANCES

DIMENSIONAL TOLERANCES DEFINITIONS | ANNOTATION| ISO

Industrial Drawing CC 2015 Ramón Rubio

These are called shafts

These are called holes



These are the names we should be familiar with.

shaft

hole



We can indicate dimensional tolerances in this way



TOLERANCE GRADES

But the ISO groups recommend us to use tolerance grades…



Where do they come from? TOLERANCE GRADES

(IT stands for International Tolerance)



Tolerance on a shaft or a hole can also be calculated by using the formulas provided by ISO.

iKT ×=

T is the tolerance (in mm)

DDi 001.045.0 3 += (unit tolerance, in mm)

21DDD = (D1 and D2 are the nominal sizes marking the beginning and the end of a range of sizes, in mm)

( )( )66.110 ITITnK −=

Tolerance Designation (ISO R286)



Example: Calculate the tolerance on the shaft (D=25 mm and IT grade of 7) using the formulas given in ISO standards.

i = 1.3073 mm

( )( ) 166.110 67 == −Kmm 0.021m 91.20 ==×= µiKTs

Tolerance Designation (ISO R286)



With ITs we will know the tolerance, but not the position (in the hole or in

the shaft) It will be defined by deviations …

We use CAPITAL letters for holes…



We use small letters for shafts…



Remember H and h positions!



Tolerances in drawing:

nominal size + zone + grade



What is meant by the tolerance 40g8?



1. Draw the zero line and the shaft tolerance


You must know that “g” is below the zero line



2. Calculate its TOLERANCE (IT grade-basic size table – slide 5)


IT8 ø40


Zero line





IT8 39µ ø40


Zero line





IT8 39µ ø40

3. Evaluate deviations (fundamental deviation table – slide 12)

g8 es= ø40


Zero line





IT8 39µ ø40


g8 es=-9µ | ei ø40


Zero line





IT8 39µ ø40


g8 es=-9µ | ei=es-t=-9-39=-48µ ø40


Zero line





IT8 39µ ø40


g8 es=-9µ | ei=es-t=-9-39=-48µ ø40

4. Solution: Maximum limit of size: 40-0,009=39,991 mm Minimum limit of size: 40-0,048=39,952 mm


Zero line




We can also indicate the minimum and maximum values

1.  PART AND ASSEMBLY DRAWINGS

2.  SURFACE CHARACTERISTICS

3.  DIMENSIONAL TOLERANCES

4.  FITS

5.  GEOMETRIC TOLERANCES

6.  DIMENSIONING

7.  THREADED FASTENING

8.  SHAFT AND PIPE JOINERS

9.  BEARINGS

10. GEARS 1: DEFINITION

11. GEARS 2: HELICAL

12. GEARS 3: BEVEL

13. BELTS AND CHAINS

14. WELDED JOINTS AND RIVETS

3. DIMENSIONAL TOLERANCES

03. dimensional tolerances

Engineering