Help with DOC/feed&speed/best order of operations?

Thanks mksj, I'll check those out. Im currently doing research on different inserts for aluminum. I'm ashamed I just used whatever insert I found and didn't put anymore thought into it. Insert choice is confusing to me, I guess WNMG are used for finishing? I suppose having a .030 nose makes sense for that? 80 degrees seems more rigid for roughing though? I'd assume smaller nose and smaller angle would mean more prone to breaking in deep cuts but what do I know... What is the best shape/nose/angle for turning aluminum at about .100-.150 DOC? And with these inserts being rated so high as far as SFM goes how can a 20+ year old manual lathe keep up? Do I just punch it and run at 1000 rpm and X amount of IPM? I think I baby the old girl a little as I'm not sure what she'll do at the highest rpms and feed rates it can get to {max 1500 rpm}. Also would say ceramic hold up better to heat as I'm not using coolant of any kind during these heavy cuts.

Sorry for all the noob questions, I spent 3 years in machining class during high school and graduated a 2 year Machine Tool Technics program at a technical collage and feel like I retained less then I should've. They focused heavily on CNC. Now it's been oh 8 years since then and I really never used my degree. I'm a machinist at a little mom and pop factory with all manual machinery and before getting back into the industry haven't touched one since 1st year of tech school. I remember a lot but want more.
 
WNMG can be used for a wide range of turning, it is more dependent on the insert used. As it is a negative rake tool holder, it is usually used for heavier and higher Hp lathes. When machining aluminum you use an insert with a positive cutting edge that is sharp, thus reducing the Hp needed. You can get pretty aggressive on aluminum, Using my whimmpy 2Hp lathe w/o coolant, on larger aluminum stock (say 2.5") I might start out at 600-800 RPM (~400-500 SFM) with a 0.1" DOC, I feed a bit slower, start out with something like 0.003-0.004"/rev., you can increase the speed as the diameter goes down. I usually take a final pass(s) of around 0.020" or 0.010", depends on the tolerance, the lathe and the setup. I do find using my Korloy WNMG331 inserts I can shave very fine dimensions in the diameter, as they cut as opposed to push the material. The final feed/finish will be dependent on the nose diameter of the insert. Probably need to get familiar with the setup and see what works for you. You could do your initial passes to remove material with a bit less speed with a bit more feed. My other main insert is an 80 degree CCMT, neutral rake holder is used in lower Hp lathes. They hold up very well, but I normally do not have it setup with inserts for turning aluminum.

As far as machining your part, I am not a seasoned as others as to give specific recommendations.
Korloy.jpg

A fellow hobbyist/machinist "Firestopper" also uses WNMG and you can see the results in the following post turning down 3" aluminum round stock: https://www.hobby-machinist.com/thr...ox-pan-brake-rebuild.63891/page-2#post-549325
 
Today I ran with a Valenite CNMP 432E VC-5 insert at 700rpm .0035 feed rate at .100+ DOC. Happy chip formation, great finish, but the part still got very warm after multiple passes, too hot to hold your hand on it. Guessing that's unavoidable when not using coolant and taking aggressive cuts. Had to hold off on final pass as my diameter kept shrinking as it cooled. Now to just find the best order in which to cut everything so it runs true along the entire part. Thanks for the help!
 
You must log in or register to reply here.
Back
Top