PPT: Limits, Fits & Tolerances | Manufacturing Engineering - Mechanical Engineering PDF Download

 Page 1


LIMITS FITS & TOLERANCES 
Page 2


LIMITS FITS & TOLERANCES 
Objectives
• To understand basics of lim it’s, fit’s &
tolerances.
• Calculate basic & gauge tolerances.
• Understand various types of gauges & their
applicability
Page 3


LIMITS FITS & TOLERANCES 
Objectives
• To understand basics of lim it’s, fit’s &
tolerances.
• Calculate basic & gauge tolerances.
• Understand various types of gauges & their
applicability
Terminology of Limit system
Page 4


LIMITS FITS & TOLERANCES 
Objectives
• To understand basics of lim it’s, fit’s &
tolerances.
• Calculate basic & gauge tolerances.
• Understand various types of gauges & their
applicability
Terminology of Limit system
?Nominal Size
• Nominal Size is a size “in a name only ” which is
used for identification. The nominal size may not
match any dimension of the product, but with in
the domain of that product the nominal size may
correspond to a large number of highly
standardized dimensions and tolerances.
– Example – ½” pipe, 1 ” pipe etc.
?Basic Size
• It is size of job, in relation to which all limits of
variations are determined. It is same for both
hole and shaft.
?Zero Line
• The line representing basic size is called as zero
line.
Page 5


LIMITS FITS & TOLERANCES 
Objectives
• To understand basics of lim it’s, fit’s &
tolerances.
• Calculate basic & gauge tolerances.
• Understand various types of gauges & their
applicability
Terminology of Limit system
?Nominal Size
• Nominal Size is a size “in a name only ” which is
used for identification. The nominal size may not
match any dimension of the product, but with in
the domain of that product the nominal size may
correspond to a large number of highly
standardized dimensions and tolerances.
– Example – ½” pipe, 1 ” pipe etc.
?Basic Size
• It is size of job, in relation to which all limits of
variations are determined. It is same for both
hole and shaft.
?Zero Line
• The line representing basic size is called as zero
line.
? Hole
• Hole is a term used to designate all internal features of
parts including those, which are not cylindrical.
? Shaft
• Shaft is a term used to designate all external features of
parts including those, which are not cylindrical
? Deviation
• It is algebraic difference between actual size of the
job and basic size of the job. Mathematically it is
represented as
• Deviation = Actual Size - Basic Size (Measured
Dimension – Theoretical Dimension)
? Lower Deviation
• It is the difference between minimum limit and basic
size of component.