Need a better finish.

[ddwadley]

Hello all,

First post here - I stop in on occasion to find new ideas.

I'm a mould maker in southern Ontario for a small shop, currently programming, setting up and operating CNC machines.

My finishing machine is a Kitamura Mycenter 3xG with a 15000k spindle. I use Cimatron E 9.0 for all of my programs. We are not a production shop, focusing primarily on prototype tooling, low and high volume quality tooling as well.

I am looking for ideas on how to achieve a better finish coming down steep walls. 1-3 degree draft angles... Currently we will rough and semi finish, followed by a finishing operation.

IN this case we are discussing a hardened block of H13 50 -52 HRC. Something like a .5" or diameter solid carbide coated endmill (IMCO) with a
.03" corner rad. I will profile top to bottom at around 2200 RPM (300 SFM) and a feed rate of aprox. 35 -40 IPM. Axial DOC will be around.005"-.007" and radially leave around .003" - .005" stock for finishing.

I am not happy with the finish and would like to eliminate as much hand polishing as possible. The finish would be suitable for most needs, such as standard shutoffs, and I can achieve great surface finishes on this machine with ballnose endmills. Our tool holders are high quality with excellent TIR.

Any suggestions on new tooling, machining strategies, feeds or speeds that would improve surface finish on near vertical walls?

Thanks,

[jezx]

id slow the cutting feed after its roughed and climb mill it to <.001 over your wanted size. then do a sweep along skimming the last bit with it climbing an take the whole surface in a few passes .
i dont realy know alot about the steel you're useing , but thats what i do for some of my stuff . if it works it works if not .......

[ddwadley]

Thanks for the reply.

Due the the steep nature of the angled face, I would not be able to take a few passes sweeping along the face. You need all those shallow incrememnts so you can accurately represent the 3 degree tapered wall. What you explained is a great way to finish vertical walls, but would leave my situation a mess.