Limits, Fits, & Tolerances Flashcards
Module questions from the current module as well as last years module.
What is the tolerance of 1.500 + /- .003
0.006
Calculate the limits of size for 1.875 +/- .010
1.865-1.885
If a shaft is 85.05 +/- .05 and the hole is 85 +/- 1, calculate the fit.
Transition fit
What is the meaning of FAO
Finish All Over
What is the meaning of MMC
Maximum Metal Condition
What is the meaning of A/F
Across Flats
Name two pieces of information found in a revision block.
1) Date
2) Description of revision
3) Revision number
4) Author
Name the three basic fits.
1) Clearance
2) Transition
3) Interference
What is allowance based on?
Maximum Metal Condition
The kind of tolerance, where the variation is in one direction only is called…
Unilateral tolerance
When the variation in size can be in either direction from the basic size, the tolerance is called…
Bilateral tolerance
Define: Allowance
An allowance is the intentional difference between mating parts at maximum material condition (MMC).
Define: Clearance fit
A clearance fit means the shaft will always fit into the mating hole. In other words, the diameter of the shaft will always be smaller that the diameter of the mating hole, even if both parts are at MMC.
Define: Interference fit
An interference fit is the opposite of the clearance fit. The diameter of the shaft will always be larger that the diameter of the mating hole, even when the shaft is as small as it can be and the mating hole is as large as it can be.
Define: Transition fit
A transition fit means the mating parts may have some clearance or some interference when assembled. At MMC there is interference between the parts, but when the parts are less than MMC there will be a smaller degree of interference or have some degree of clearance between the parts.
What is the meaning of HRMS
Hot Rolled Mild Steel
What is the meaning of CRMS
Cold Rolled Mild Steel
What is the meaning of SS
Stainless Steel
What is the meaning of MS
Mild Steel
What is the meaning of MST
Machined Steel
What is the meaning of ASSY
Assembly
What is the meaning of BC
Bolt Circle
What is the meaning of BCD
Bolt Circle Diameter
What is the meaning of BHC
Bolt Hole Circle
What is the meaning of CBORE
Counterbore
What is the meaning of CHAM
Chamfer
What is the meaning of CLA
Centre Line Angle
What is the meaning of CL
Centre Line
What is the meaning of CSK
Countersink
What is the meaning of DIA
Diameter
What is the meaning of DWG
Drawing
What is the meaning of SF
Spotface
What is the meaning of STL
Steel
What is the meaning of SYM
Symmetry
What is the meaning of TPF
Taper Per Foot
What is the meaning of TPI
Taper Per Inch
What is the meaning of TR
Taper Ratio
What is the meaning of TYP
Typical
Define UNC & UNF thread series
UNC - National Coarse
UNF - National Fine
Thread designation “A” is a ___________ fit.
External (Alpha)
Thread designation “B” is a ___________ fit.
Internal (Bitch)
Class of thread fit 1A - 1B is for what type of fit?
Used for loose fits
Class of thread fit 2A - 2B is for what type of fit?
Used for commercial fits, fasteners, interchangeable parts.
Class of thread fit 3A - 3B is for what type of fit?
Used for high precision fits, close snug fit.
Define: Roughness
Roughness is defined as having irregularities in the surface texture. The average roughness is designated in micro inches, micrometers, or roughness grade numbers from N1-N12.
Define: Revision
Revision is a change or correction on the original drawing. The revision number is enclosed in a circle or triangle.
Define: Reference dimension
The reference dimension is presented on the drawing for information only. It is not used in the manufacturing of the part.
