7.2 Dimensions, Allowances and Tolerances Flashcards
What is a dimension?
A measurable limit of some kind
What is the nominal size?
An approximate dimension that is used for general identification
What is the basic size?
The theoretical size from which size limits are derived by applying allowances and tolerances
What is the actual size?
The measured size
What is tolerance?
The total amount that a dimension is allowed to vary
What are the 2 types of tolerance?
- Bilateral
- Unilateral
What is a Bilateral tolerance?
- Means they can be +/-
- Applies for most tolerances
What is a Unilateral tolerance?
Can only be for one way, either + or -
What is clearance?
The space between mating parts
What is the fit?
The dimensional relationship between 2 parts
What can the 2 types of fit be referred to as?
Loose or tight fit
What is a clearance fit?
Allows for sliding or rotating between the parts
What is an interference fit?
When the dimensions of the 2 parts overlap
What is the allowance?
The minimum clearance space intended between 2 parts
What is a limit?
The maximum or minimum dimension formed when maximum or minimum tolerance is considered
What must the different standards for hardware have?
The same fits and clearances, may be slight difference in tolerance
What is workmanship?
- The skill of a craftsman
- Quality
- The product or result
- Attitude
- Duty of care to self
- Duty of care to others
- Duty of care to equipment and tools being used
- Working to a high standard
What does any deviation away from the AMM require?
Correct approval
When is a reamer used?
When a smoother finish in the hole is required
