What's new
What's new

Turning / boring bronze bushings

RJT

Titanium
Joined
Aug 24, 2006
Location
greensboro,northcarolina
We are turning the OD and boring the ID of SYMN SCS-610-6 bronze bushings and getting quite a bit of wear on every insert (carbide) we have tried. Would ceramic or CBN or diamond be an option? What is working best right now is a DCLNR holder 431KC5010 insert at 200 surface feet for the OD (finishing) and SCLPR holder 2150KC5010 at 100 surface feet for the ID (1/2 inch boring bar finishing a .7500 hole 3 1/4 deep). We are not taking a lot of material off, the busing is near net shape, but constantly adjusting for wear. We are making it work but looking for a better solution. Machine is a Doosan Puma lathe, plenty stout enough for this size work (1 1/4 OD) . We turn lots of A-2 and D-2 and don't have the wear problem that this bronze gives us.
 
I'd try a diamond insert, it's going to hold up better presuming everything on the machine is good (in other words, no looseness or incorrectly set up tools).

To save wear, you might try roughing with carbide, finish with the diamond. But it might be fine to rough with too, within its parameters.
 
No. Those are for steels and irons.

Diamond or carbide. And of course HSS.

Ceramic, agreed, as they usually have an edge prep that wouldn't be ideal for a bronze. But a sharp edge CBN might be fine, I can't think why it wouldn't work.

[I have some sharp CBN inserts, unless they're misidentified PCD]
 
I’ve done some Oilite bronze bushings and used cermet inserts with good results. I don’t know how my bronze compares to yours and my volume wasn‘t high enough to see any wear, but it worked quite well.
 
We are turning the OD and boring the ID of SYMN SCS-610-6 bronze bushings and getting quite a bit of wear on every insert (carbide) we have tried. Would ceramic or CBN or diamond be an option? What is working best right now is a DCLNR holder 431KC5010 insert at 200 surface feet for the OD (finishing) and SCLPR holder 2150KC5010 at 100 surface feet for the ID (1/2 inch boring bar finishing a .7500 hole 3 1/4 deep). We are not taking a lot of material off, the busing is near net shape, but constantly adjusting for wear. We are making it work but looking for a better solution. Machine is a Doosan Puma lathe, plenty stout enough for this size work (1 1/4 OD) . We turn lots of A-2 and D-2 and don't have the wear problem that this bronze gives us.
How different is this from oilite?
Oilite recommends PCD-Diamond.
https://oilite.com/best-machining-practices (I think they meant inches per turn, not inches per minute)
Also you should be using a high positive rake insert/holder. Negative rake tooling on impregnated bronze just closes all the pores.
But honestly a sharp carbide insert should be sufficient. When we did shaft bushings for ships it was primarily just brazed carbide in the turning centers and lathes, although the edges were sharp and polished enough you could cut yourself with them.


How much are you taking off in roughing and finishing passes?
How much wear are we talking exactly? Comping every other part? Every 100th part?
You make it sound excessively bad, but something can't be right. We machine down 86# blocks of G10/FR-4 to about 12# (lots of internal removal) and the uncoated carbide cutters last about 3 parts before they need to be resharpened. It's a solid 2+ hours of non-stop cutting per part.

While I was pondering. I did look up the standards for both.
Oilite: SAE 660 (Al/Sb/Cu/Fe/Pb/Ni/P/Si/S/Sn/Zn)
610-5: SAE 841 (https://www.avivametals.com/products/sae-841-sintered-bronze-oil-impregnated) (C/Cu/Fe/Sn)

Metallurgically speaking, this stuff should be noticeably softer than Oilite/C93200.
 
Last edited:
He may just be surprised by how abrasive bronze it. I know cutting gear teeth, it wears out a hob faster than alloy steels and same turning the blanks, it goes through inserts worse than steel. If he's thinking bronze is like brass, well, sooprize sooprize.
My understanding, is usually that's because of the copper/tin interface and nickel content in the most common bearing bronze. Which gets even worse in nickel bronze (95510/95500). I've never had the pleasure of mucking with Manganese Bronze, but I bet it's just a joy /s.
His particular material doesn't actually have any tin. And not enough iron to consider the carbon content making hard pockets (1% iron, 1.75% carbon). I wouldn't even call it a bronze. Selenium is for copper like sulphur is for stainless, adds to the machinability. Which is why I'm surprised this material is so bad.

OP should explain this wear in more detail.
 
No. Those are for steels and irons.

Diamond or carbide. And of course HSS.

There's no rule that says ceramics are only for ferrous materials...

But yes, a typical ceramic for those will have very poor geometry for bronze.

Positive geometry cermets (the type that are for high speed finishing of steels) work well in the harder bronzes, just don't push the feed too hard.

I've never tried CBN in bronze, mainly because I've never had a need to, can't see why it wouldn't work but it would limit the DOC and feedrate possible.
 








 
Back
Top