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FEAR Our greatest fear is not that we are inadequate, but that we are powerful beyond measure. It is our light, not our darkness, that frightens us. We ask ourselves, Who am I to be brilliant, gorgeous, handsome, talented and fabulous? Your playing small does not serve the world. There is nothing enlightened about shrinking so that other people won't feel insecure around you. ~Quoted selectively from Marianne Williamson and Nelson Mandela

Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

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Page 1: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

FEAR

Our greatest fear is not that we are inadequate,but that we are powerful beyond measure.

It is our light, not our darkness, that frightens us.We ask ourselves, Who am I to be brilliant,gorgeous, handsome, talented and fabulous?

Your playing small does not serve the world.There is nothing enlightened about shrinking

so that other people won't feel insecure around you.

~Quoted selectively from Marianne Williamson and Nelson Mandela

Page 2: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

Tolerances, Limits and Fits

A succession of rude jokes

Page 3: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

Tolerances, Limits and Fits

The Importance of Fitting In

Page 4: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

Tolerances

• A convention to define leeway in manufacturing

Page 5: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

Limits

• Maximum Thresholds that may not be exceeded in manufacture

Page 6: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

Fits

• The manner in which items fit together, and the behaviour of this

Page 7: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

Why Tolerances?

• No dimension can be “accurately machined”

• Thermal instability of material

• Greater accuracy requires more precision tooling and time, which is costly

• Function of fit must be considered

Page 8: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

Conventions of Notation

Page 9: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

Further Conventions of Notation

Page 10: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -
Page 11: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

Conventions

• Nominal size is the “actual” vernier sizeWe tend to base our calculations on the hole size – tooling

• Capital ‘H’ refers to holes

• Lower case letters a to z refer to shaft

• Numbers refer to magnitude of displacement from nominal

Page 12: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -
Page 13: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

Types Of Fits

• Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft.

• Transition fit - A fit provides either a clearance or an interference. The tolerance zones of the hole and the shaft overlaps.

• Interference fit - A fit provides an interference. The tolerance zone of the hole is entirely below that of the shaft.

• Source: Hong Kong University of Science and Technology

Page 14: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -
Page 15: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

The MicrometreMeasured with a micrometer

Item

Anthrax Spore 6 μm

Diameter of Bacterium 1 - 10 μm

Discernable Gap 20 μm

Human Hair 70 μm

Sheet of Paper / Coat of paint 100 μm

Page 16: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -
Page 17: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -
Page 18: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -
Page 19: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

Tolerance:

• Nominal : 48mm

• H8 f7

Page 20: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -
Page 21: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -
Page 22: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -

CalculationNominal Plus Minus

Hole 48 39 -25

Shaft 48 +0 -50

48+.039(-)0

48 - .025 - .050

Hole

Shaft

48+.039(-)0

48 -0.025-0.050

Page 23: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -
Page 24: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -
Page 25: Tolerances, Limits and Fits · Types Of Fits •Clearance fit - A fit provides a clearance. The tolerance zone of the hole is entirely above that of the shaft. •Transition fit -