Pressing a bushing, wall thickness of material being pressed into.

I have a 0.24" diameter headless bushing in bronze with a wall thickness of 0.025". I wish to press this (with arbor press) into 0.5" thick 6061 Al. What would be the minimum wall thickness of the Al that I could use? For that matter, is there a rule of thumb which would be appropriate for such things MOST of time? Thank you very much in advance.

Welcome aboard

I can't help you of wall thickness but if it's thin, then in your shoes I'd forget the press fit and use Loctite.

jimaginator said:

I have a 0.24" diameter headless bushing in bronze with a wall thickness of 0.025". I wish to press this (with arbor press) into 0.5" thick 6061 Al. What would be the minimum wall thickness of the Al that I could use? For that matter, is there a rule of thumb which would be appropriate for such things MOST of time? Thank you very much in advance.

Click to expand...

math does not seem to add up.
.24" ID bushing? in a plate with a .5" hole would have ~.13" walls.

did you really mean .24" ID bushing with OD of .29 into a 1/2" long tube of aluminum?

you said only "bronze", but I suspect the sintered bronze "oilite"?

any rate... oilite bushings are very soft they will not stand much more than .001" interference in a .5" bore.

there is no minimum wall thickness of the aluminum. wrap it in some foil for all I care. what does it need to be in a tiny ring for?

what's the application?

Real thin bushings can be done with heat and cold.

Thank you for the reply.

Thank you for your reply. The OD, not ID, of the bushing is 0.24", I should have specified that. The walls of bushing are 0.025". There is no 1/2" long tube of aluminum involved. Instead, there is a 0.5" thick plate of Al into which the bushing will be pressed. My inquiry was as to how close to the edge of the Al I could safely be. Thank you.

Do an internet search for "Calculating Hoop stress." Please specify "id and od in inches," in the descriptions.

The answer to your question depends on the strength of the aluminum, but also on more than just the distance from the edge.

To simplify it, imagine your bronze bushing (and you should tell us if it is Oilite or solid bronze) pressed into another bushing. If both bushings were steel, and had the same wall thickness, and the interference (amount by which the OD of the inner bushing is bigger than the ID of the outer) is 1 part in a thousand (that would be .001" on a 1" bushing), then the inner bushing will compress by about .0005" and the outer stretch by about .0005" Since the elastic modulus of steel is about 30,000,000 psi/in/in, the stress in both parts will be about 15,000 PSI, compression in the inner bushing and tension in the outer. These stress levels would be acceptable for almost any steel under almost any conditions. This very simplified example ignores loss of interference by mashing-down (a technical term) of surface roughness of both parts.

You can look up the elastic moduli of your materials. .0003" interference on a 1/4" OD bushing is all you want, but I do not know what facilities you have for making a hole to accurate size, nor for measuring. If the wall of your part is thin on one side and much thicker on the other, then the thicker will support more of the spreading force, relieving some of the stress on the thinner, but I would recommend NOT making the thinnest wall any thinner than would be needed to support the stress from insertion of oversized bushing in another bushing of uniform wall, PLUS the service stress from whatever your machine does.

The more you tell about your application, the better the advice you will get here. One thing that sometimes earns snide and unhelpful replies is a question from someone obviously without much mechanical knowledge that asks for only one tiny detail, as if the questioner knows everything else. As perhaps my reply illustrates, there are no simple questions, and you cannot get a good answer without knowing lots of details about the whole situation. A person who knows little often reveals that by assuming that the question is simple and surrounding details do not matter.

ok, for your purpose the hole will not expand at all. Your putting the the thin wall bronze up against the nearly infinitely thick "wall" of the aluminum plate.

on the at size I'd ream or bore the hole .0005" or less undersize. .001" is probably too much interference. Really it's up to whatever your willing to shrink the ID by because that is where all of the movement will happen.

at that size differential expansion is a crapshoot because it's unlikely you can measure or make the sizes that precisely and the difference in expansion will be to small to notice.

locltite bearing mount glue....sparing amounts.



I'd glue/locktite it very sparingly in place. if an oilite sintered material at that thin wall I would worry about the locktite migrating through toth eID.

Thanks to all who replied, very helpful info.

jimaginator said:

I have a 0.24" diameter headless bushing in bronze with a wall thickness of 0.025". I wish to press this (with arbor press) into 0.5" thick 6061 Al. What would be the minimum wall thickness of the Al that I could use? For that matter, is there a rule of thumb which would be appropriate for such things MOST of time? Thank you very much in advance.

Click to expand...

Thanks to all who replied, very helpful info.