When upper deviation is +0.15 mm and lower deviation is -0.05 mm, then the tolerance for the part is _______ mm.

Concept: 

Tolerance:

• It is the difference between the maximum limit of size and the minimum limit of size.
• Or It is the difference between the upper deviation and the lower deviation.
• It is always positive and is expressed only as a number without a sign.
• So, the tolerance of a hole is the difference between the maximum diameter of the hole and the minimum diameter of the hole.
• Similarly, the tolerance of a shaft is the difference between the maximum diameter of the shaft and the minimum diameter of the shaft.

Upper deviation:

• It is the difference between the maximum size limit and the basic size.

Lower deviation:

• Lower deviation is the difference between the minimum limit of size and the basic size.

Basic size:

• It is the size based on which the dimensional deviations are given.

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 if the component is to be accepted.

Limits of size:

• These are the extremely permissible sizes within which the operator is expected to make the component.

Maximum limit of size:

• It is the greater of the two limit sizes.

Minimum limit of size:

• It is the smaller of the two limits of size.

Calculation:

Given:

upper deviation = +0.15 mm and lower deviation = -0.05 mm

Tolerance = (upper deviation) - (lower deviation)

⇒ Tolerance = 0.15 - (-0.05) = 0.20 mm