Serrated Roughing End Mill vs Chip Breaker End Mill

[teddyg43t]

Hello,

I am curious of the main difference in application for these two types of roughing end mills stated in the title.

Application: We are currently running a 1/2" End Mill, 1.5" LOC, 3 Fl. , ZRN Coated, 37 Degree Helix Solid Carbide end Mill with Chip Breaker for roughing out various pockets in a 1.5" Mic 6 Cast Aluminum Plate. We need to remove about 80 lbs. of MTL x 16 plates and this end mill is working well. Running HSM/Adaptive Toolpaths, about .15" RDOC, 1.25-1.4" ADOC, 200-150 IPM ish.

Would a serrated rougher work better? When and why would I pick one over the other. MTL considerations, price, time, ect?

Thanks,

Ted

[seth.madore]

For roughing, especially in aluminum, I LOVE the chip breakers. Why? Chip management and flushing. I am able to push faster speeds, my conveyor doesn't get jammed  up, and I have to empty my chip bucket a lot less, as there is now less air being piled in.

There is less recutting of long chips, as the coolant is able to better flush away the small chips. The one downside is that they tend to go everywhere and the rollers on my door tend to find a good deal of them

[sunderlandjoe]

Serrated chip breakers have gone the way of the dodo, they're not overly useful as they will require you to do a toolchange to a finishing endmill.

Chip breaker (splitter) endmills are the modern variant of it. Stick with them, they're awesome. They will rough and finish with the same tool without a massive build up of swarf.

[CGPM]

I ASSUME that you mean corncob vs rougher/finisher.  If so then a corncob will greatly reduce the cutting pressure and the part lifting pressure of the end mill.  This is great when you are limited by how well you can hold onto your part.  A corncob is a rougher and a rougher/finisher is pretty much a finish end mill, plain and simple.  Also ZrN can alow you to increase the feed by 20% vs uncoated, given you can flush the chips out fast enough, and greatly improve tool life.  Keep in mind that slotting you can feed a good 3/8" corncob end mill at .04" per tooth, really, if you can clear the chips fast enough.  If you haven't tried a few do so, there is nothing like them for roughing aluminum.  Maritool is the best bang for the buck and MA Ford is one of the best performers, but the MA Fords come standard uncoated.  I keep a 3/8", 1/2" and a 3/4" corncob permanently loaded in Maritool stubby sidelocks, they are that good.  I haven't used a rougher/finisher in years, there just isn't much difference between them and a finisher.

I generally don't bother with adaptive toolpaths with corncobs but if you do run at least a 50% stepover, at least.  And do try increasing the chip load to see how fast they can go.

[teddyg43t]

So as I am understanding the Corn Cob (serrated rougher) is great for slotting and reducing cutting forces. This seems like a great tool for harder materials with larger tools (3/4" +)/longer reach roughing.

We are currently using a 1/2" with Chip breaker (this is not a corncob end mill) and it is nicely breaking the chips for swarf management, reducing cutting forces, and increasing our speeds. Here is a link to the chip breaker so you know what I am talking about. 

https://www.mscdirect.com/webapp/wcs/stores/servlet/product/details/85646370

Regardless we have to come in with a 1/2" finish end mill to finish the floors and the side walls as the adaptive strategy accompanied by the very fast feeds and speeds (150-300 IPM) leaves a pretty bad surface finish on both the floor and the walls. 

So overall, would a corncob end mill (serrated rougher) out perform a Chip breaking end mill in roughing applications on aluminum? Maybe just for slotting? It sounds like they would outperform a chip breaker in steels/harder materials.

We also bought one of the Clean-Tec chip fans by Lang Tec. Life saver for these plates. Blows 60 lbs of chips off it, plus about 5 gallons of coolant in the pockets in 60 seconds. I would spend 15 minutes trying to blow them off with an air gun! Not to mention getting soaked in coolant and chips.

[seth.madore]

The biggest annoyance I find with the old school "corncob" roughers is the chip size is TINY. We're talking grains of sand size. They go everywhere, fall through conveyors, clog up coolant filters. Nasty.

Having run both, I'd take a chipbreaker any day. That said, there is a LOT less pressure on part and tool with a carbide corncob.

[teddyg43t]

That is some exact information I am looking for. Seems like I'll stick with the chip breaker on Al. and move to a corncob if we really need to reduce our cutting forces. Our machine is plenty powerful to run up to a 3/4" End Mill in Aluminum at max feeds/speeds all day long. Haas VM6 with 12k spindle 4o Taper.

[CGPM]

After trying the corncob style I quite using the rougher/finishers, since I can make parts faster with them which = more $ per hour.  I still have some Destiny Diamondback rougher/finishers, I just NEVER find a use for them.  Usually being able to hold onto the part limits how hard I can run the cutters, since the parts start to move.  I don't have a chip conveyer and the coolant filter has no problem catching all the chips, it is a 5 micron bag.

Do yourself a favor and get a couple to try out.  Play with the first one bumping the feed and stepover up until you have problems, you will be amazed at how fast they can remove aluminum.  3/8" mill burried with a .04" chipload is not a joke, it's normal with these. 

[teddyg43t]

Posted last week by Harvey tool. Sounds like I should stick with chip breaker on Aluminum. Also shows that there are quite a few different names for these 2 classes of end mills.

https://www.harveyperformance.com/in-the-loupe/chipbreakers-vs-knuckle-rougher-end-mills/