also...
The effective bore/bearing-length of an unmodified flanged bushing... for the same shank length and nominal small standard chamfers... is lightly longer.
As noted, the most common purpose for flat surfaces of the flange is an integral 'plain washer-bearing' to avoid superficial fretting on mating surfaces.
Also, Some flanged-bushes are installed with deliberately 'thick' flanges... which are subsequently machined simultaneously using rigid sets of milling-cutters to ensure ultra precise side-to-side positioning, face-to-face spacing and parallel surfaces.
In some cases I have see 'flat thick flanges' recessed in spot-faces [counter-bores].
Flanged bushes can also have 'countersunk-flanges'... 90, 100, 120, 130, etc countersink angles... and the top of the bush flange may be set flush-to-high with the surface.
Regards, Wil Taylor
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