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IndustryArena Forum > MetalWorking > MetalWork Discussion > New To Milling Questions
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  1. #1
    Join Date
    May 2021

    New To Milling Questions

    Hi folks,

    I am getting started in the CNC world and I am struggling with understanding how to determine feeds and speeds. I have milled several parts with a NON-Ferrous 4tooth 1/4" endmill and it has done a pretty good job. I am running it at 6000rpm and about 20ipm at a 1/8" depth of cut .0032" chip load. It seemed to run really well and it had a pretty good finish but about 10 parts in I noticed a little chip out of the very bottom so it will still work but my tolerance is off on a hole around 015" or .007" per side. So I had an old HSS 4flute 1/4" endmill laying around that I tried and at these same settings I welded it to the part.
    Can someone just push me to getting my initial settings figured out so I can calculate the other parts of the equations? There are so many different takes out there that I cannot figure out a basic starting point to get the correct settings. Also most everything I machine is mild steel.

  2. #2
    Join Date
    Jul 2018

    Re: New To Milling Questions

    Hi Rufus - Are you using a router or a Mill? If so which one? are you flood cooling? Tool suppliers have charts for their bits to guide on cutting parameters. I have also found FSWizard to be good. Peter

  3. #3
    Join Date
    May 2021

    Re: New To Milling Questions

    Hi Peter, I am using a Mill and I am using coolant. Long story but I inherited a bunch of HSS endmills from my grandfather and I have no clue the manufacture.. He was a gun smith in the old days so I have attempted to use 1 or 2 as a test which has failed. I have purchased GWizzard Calculator which gives you a small indication of f&s but I seem to be not understanding how to get the surface speeds correct. There is a huge difference between the HSS and NON Ferris bits I have used. If I could just get over the hump to understand the speeds I think I can calc the feeds and plunge rates but this seems to be my hang up. I will definitely look at the FSWizard.

  4. #4
    Join Date
    Feb 2009

    Re: New To Milling Questions

    CAD, CAM, Scanning, Modelling, Machining and more. http://www.mcpii.com/3dservices.html

  5. #5
    Join Date
    Apr 2004

    Re: New To Milling Questions

    What do you mean by "non-Ferris" bits? Are you talking about endmills intended for use on non-ferrous metals like aluminum and brass? Or did you mean ones that don't contain any steel, like tungsten carbide endmills? Are you sure that what you've got are really endmills, and not drill bits or reamers? If you're plunging them into the work, are you sure they're the center-cutting type? Some only cut on the side, and can't plunge. 4-flute endmills are primarily intended for ferrous metals; aluminum is usually machined with 2 or 3 flute cutters.
    Andrew Werby

  6. #6
    Join Date
    May 2017

    Re: New To Milling Questions

    Hi Rufus Toad,

    Aluminum is gummy and you generally want a 2 or 3 Flute End Mill to ensure the chips evacuate, otherwise the chips clog up the flutes and it can completely fail (like welding to the part or blowing up). You can definitely make a 4 Flute End Mill work but there is less room in the flutes for the chips to evacuate. With a 2 or 3 Flute End Mill in slotting Aluminum you want to be at 50% Axial DOC so your 1/8" DOC is good but with 4 Flutes you will want to lighten your DOC to 30%-40% Axial DOC or .075"-.100". Here are the speeds and feeds I'd be at:

    Carbide End Mill:
    SFM: 500-2,200
    RPM: 8,000
    CLPT: .001"-.002" (Start at .001")
    IPM: 24

    HSS End Mill: same as above but 400 SFM or 6,000 RPM
    SFM: 400
    RPM: 6,000
    CLPT: .001"-.002" (Start at .001")
    IPM: 24

    A High Performance 3 Flute End Mill for Aluminum as they are designed with a sharp cutting edge as well as more room in the flutes for chips to evacuate. If you would like a recommendation on this let me know!

    Also, here is a quick speed and feed chart we created that could help (the End Mills Speeds/Feeds are for Carbide End Mills):
    Speed/Feed Cheat Sheet

    Hopefully this helps!


  7. #7

    Re: New To Milling Questions

    Jumping into CNC milling and figuring out feeds and speeds definitely takes a bit of trial and error, especially with different materials like mild steel, which you’re working with. For mild steel using a 1/4" HSS endmill, you might want to start with lower RPMs, around 3000, and a feed rate of about 15 ipm. See how your machine handles that and tweak it from there.

    Remember, it’s all about making small changes and seeing how your part turns out. Don’t stress too much because everyone goes through some adjustments to find what works best.

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