Lathe work on hardened material

[patooyee]

I'm a amateur machinist, stress being on amateur.

I'm trying to cut some hardened shafts on my lathe and am having one hell of a time. Right now I am doing it with a minor degree of success, going as slow as I can bear to watch, going through bits quickly, there's some minor sparking. Its taking hours to do simple stuff that would take minutes on a non-hardened piece. Anyone got any advice?

 

[Elliott]

Carbide bits should cut it unless it's really hard, I've got a diamond insert that I use on really hard junk but most of the time carbide will get the job done.just remember you want the heat in your chip not the part or cutter, you will get this by speed and feeds

 

[patooyee]

Thanks, I'm using HSS bits right now so that could be a big part of my problem.

I don't think I trust myself with diamond.

I am correct to expect to have to go slower than unhardened though?

 

[Hudson1]

Carbide bits. Quality counts.

 

[kmcminn]

Yeah, carbide inserts are the minimum needed on hardened material. That high speed tool is probably close to same hardness as that shaft your are cutting which isn't going to work. Even with the proper tooling cutting hardened material can be a bitch to say the least. The steel with carbide braised on the end turning tool's generally aren't the best either. You may want to make sure your tool is not above the centerline, and rubbing instead of cutting.

 

[patooyee]

Carbide bits. Quality counts.

Are these considered quality?

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=943268&PMAKA=340-1208

 

[kmcminn]

Are these considered quality?

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=943268&PMAKA=340-1208

I prefer the 4 sided inserts with a 1/32 radius cutting tip iirc. I don't know that particular one. We used kennametal also. The salesman that came around would point us to the right insert for our holder if we were having issues with tool life or just wasn't working good for what we were doing. You can get into some money pretty quick when you start busting 10 dollar inserts.

 

[patooyee]

I've used those in the past and liked them but cheaped out on my last buy because I never cut anything hardened. Of course now I need to cut hardened stuff and I'm out of the carbide bits.

 

[mdo817]

Kennametal KC-730 are my choice

 

[Blase]

Depending on how hard your shaft is and what types of cuts you are making Ceramics might be the way to go. Any straight cuts in material with a hardness of 50HRC ceramics are the way to go. They can be difficult to get the hang of using but man do they cut! Oh and they throw tons of sparks too. lol

 

[patooyee]

Well, I needed some more of the carbide bits anyway so I went ahead and got them ordered. I guess I'll give them a try and go from there.

 

[09zkrankin]

Re:

Yup, carbide or ceramic is the way to go for anything hard. You will also find that if you pony up for carbide tooling that your non hardened stuff will come out much nicer. Hss is just too hard to keep good and sharp and you tolerances and finish will show it

Sent from my SAMSUNG-SM-G890A using Tapatalk

 

[pholmann]

Anneal it and then re-heat treat it when your done.

 

[offroadr1]

Like patrick said. My machinist does this regularly. Anneal it, work it then have it heat treated again.

 

[pholmann]

You can re heat treat it yourself. Heat to glowing red then quench in oil.

 

[patooyee]

So to anneal I heat to red and let cool slowly?

And to re-treat I heat back to red and quench it? I would do this with a torch presumably? What kind of oil?

I thought heat treating was a bit more complicated than that?

The parts I'm working with right now are cheap and plentiful. It might be a neat experiment.

 

[kmcminn]

You can re heat treat it yourself. Heat to glowing red then quench in oil.

You don't nessacarily quench it in oil it depends on the material it could be oil, air or brine.

 

[kmcminn]

So to anneal I heat to red and let cool slowly?

And to re-treat I heat back to red and quench it? I would do this with a torch presumably? What kind of oil?

I thought heat treating was a bit more complicated than that?

The parts I'm working with right now are cheap and plentiful. It might be a neat experiment.

It is more complicated than that. You need to research what material it is. You generally heat it up to critical temp then quench it a certain way.

 

[pholmann]

You don't nessacarily quench it in oil it depends on the material it could be oil, air or brine.

I'm listening. Always up for some new knowledge.

 

[pholmann]

Generally to anneal it you heat it up and bury it in a bucket of sand and let it cool slowly.