Milling Cutter Explanations

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BillWood

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Hello,

I've been googling looking for a general mugs guide to milling cutters and also for mugs guide to roughing milling cutters but no joy.

Keen to find out if roughing cutters are only for professionals with big machines rather than my little mill/drill. (RongFu 30 2HPmotor)

Any recommended books / web pages - - youtube videos are a last resort for me due to slow internet connection.

Bill
 
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Roughing endmills work good on large machines because they allow heavy cuts and high feed rates without causing a lot of chatter. They should work on your machine, but I'm not sure they are worth the extra expense. They also tend to wear more rapidly in my experience. Hope this helps.

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I just used a roughing cutter on my bport clone and it was asking for more, I cut a half inch wide, .700inch deep slot in one pass, it would chatter with low depth of cuts, it liked the full engagement
Maybe get a fine pitch rougher because of your lack of rigidity.
 
chevydyl said:
I just used a roughing cutter on my bport clone and it was asking for more, I cut a half inch wide, .700inch deep slot in one pass, it would chatter with low depth of cuts, it liked the full engagement
Maybe get a fine pitch rougher because of your lack of rigidity.
Click to expand...
What material?
 
Roughers generally load your machine less than normal cutters for the same material removal rate. They do like heavy cuts with a somewhat reduced feed rates. I think your RF30 will like them. I normally use roughers for heavy material removal then switch to normal cutters for finishing. There are 3 main types of roughers: Course, Fine, and Finishing. The finishing rougher actually leaves a pretty good surface. They are normally M42 cobalt, and come in plain finish and various coatings. Available in both aluminum and steel cutting geometry. I have found that they last longer than normal cutters when loaded correctly, when lightly loaded they tend to rub and thus will wear somewhat quickly.

Here is a picture of a 1/2 inch rougher plowing through some 1018 at 1 IPM, about 800 RPM, .875 DOC
IMG_0562.jpg

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+1 to what Jim said.

In my experience, roughers are the way to go on smaller, less rigid machines as they are less stressful on the machine itself yet allow a more aggressive cut. I use them all the time. :)
 
Jim, how many flutes? Is it still bad practice to slot with a 4 flute rougher?
I ask because I blew up 2 4 flute roughers yesterday; .625 dia, .25 DOC in 6061 AL, about 1200 rpm, 8 ipm feed


Stan,
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20150728_000537.jpg Running though steel plate, not sure rpm but whatever hss calls for plus a little more, not sure of feed, it was slow but very fast compared to taking multiple passes
 
sgisler said:
Jim, how many flutes? Is it still bad practice to slot with a 4 flute rougher?
I ask because I blew up 2 4 flute roughers yesterday; .625 dia, .25 DOC in 6061 AL, about 1200 rpm, 8 ipm feed


Stan,
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Click to expand...

That one was a 4-flute. No real problem slotting, but don't expect an accurate on-size slot. The tool will pull to one side. I have some 3-flute aluminum cutting ones also. In aluminum, more chip clearance is a good thing.

My guess is that the feed rate was a bit high, and maybe more importantly not enough coolant. 6061 is really gummy and wants to pack into the flutes and weld it's self to the tool. It's really important to keep the tool wet. I use WD-40 in a spray mist system, with a heavy flow under those conditions, and bring up the air a bit to try to remove as much of the swarf a possible.

If you look at the broken pieces of end mill, my guess is that you will find aluminum welded into the flutes.
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