definition of interference & clearance fits

[pmover]

ok fellow gearheads, i searched in my mark's handbook and via internet without success.

please advise definition and examples of interference fit and clearance fit when applied to flexible couplings.

as time passes...

ok, i now found clearance and interference fit in mark's handbook under "tolerance".

more time investigating...

also, i now found further information at:

http://www.engineersedge.com/gdt.htm

i do not quite understand the concept of interference fits and its application.

thanks!
-pmover

 

[BillPSU]

Fits were standardized by ANSI B4.1-1967(R1987). A better source for information on fits is the Machinery's Handbook.
There are two main categories of interference fits LN, Locational Interference fit, and FN, Force fit.

LN fits are for applications where maintaining a location is necessary such as the press fit on a dowel pin. LN fits are designated LN1, LN2, and LN3, with increasing limits of interference as the number gets larger.

FN fits are designated FN1 light drive fit, FN2 medium drive fits, FN3 Heavy drive fits, and FN4 and FN5 are normally shrink or expansion fits due to driving forces.

The design engineer must establish the desired level of interference in the assembly and then can use the standard fits to determine part tolerances.

 

[diamondjim]

Those of us who wear belts and not
suspenders have some idea of interference
fits, and the old problem of how tight is
tight. We have to rely on field experience
to establish whether the range meets our
intent and no more than enough to meet that
requirement as the costs rise considerably
with greater interference fits. I really
like the drill or machine chucks to be
able to adjust or control the fits rather
than having to rely on matched assemblies.

 

[gearguru]

Similar topics were discussed here in the past. The Machinery's Handbook has also a lot of information, but not per my opinion unnecessary complicated.
Try to search using the "ISO Fits" in this forum and also on Google. The ISO (metric) fits are the "daily bread" of any engineer in metric countries.
I found one thread where you can find some info:
thread404-34842
Unfortunately, the excellent German web site with metric fit "calculator" mentioned in that thread does not exist anymore.