End mills for aluminum

[EmilioG]

is it really necessary to buy high helix end mills made for aluminum? I’ve been getting by without them but thought of buying two.

Is anyone using them with better results?
Guhring also makes a Diver series for all type of milling slots. Ramping. Angles drilling etc.

 

[mikey]

In a hobby shop, no, I don't think Hi-helix end mills are necessary. I use them and like them because they eject chips better than a standard end mill. If I was in a shop running at high speeds with flood coolant with big runs of parts, yeah, I would use them.

Try a coarse pitch Hi-helix roughing end mill from Niagara for internal pockets and slots in aluminum, Emilio. You will not want to use anything else.

 

[darkzero]

I agree, for a hobbyist or a conventional mill without crazy high spindle speeds probably no need. I do have a couple of them & they do perform much better than a 2 flute which is generally recommended for aluminum.

They're expensive though unless you score on ebay. I have recently switched to using 3 flute endmills for aluminum. Just switching to 3 flutes alone made a great improvement on surface finish, I really like them. I recommend trying some!

I have not tried the 3 flute for slotting though, I still use 2 flutes for that. The hi helix endmills I have are in 3 flute also. With my mill drill I can live without.

 

[EmilioG]

I’ll have to buy one to see for myself. Why are they so expensive?

 

[mksj]

I primarily use 3 flute high helix end mills for aluminum, they provide a very good balance of chip evacuation, finish and less vibration. I usually see much more chatter with a 2 flute, and more regrinding of chips with a 4 flute. The two significant factors that seem to make the most difference when machining aluminum is using climb cutting and some form of chip evacuation system, so either air or vacuum chip evacuation system, The type of aluminum also is a significant factor as to its gumminess, often it doesn't matter what you do, the end mill will fowl quickly. I do not find the 3 flute end mills significantly more expensive then 2 or 4 flute unless you go for some of the coated or high end brands. The other factor on the cost of end mills is how long they last, I do use carbide or cobalt 3Fl end mills and they usually last me 6 months or more. They stay sharp a long time, they usually get retired because I do something stupid and break a tip by dropping it or banging a flute. The other type of 3 flute end mill that I find works very well in aluminum is the Minicut 3Fl powdered metal 930P series endmills. Their cutter profile is a wave profile some somewhat like a fine rougher and finisher in the same end mill. I have several 3/4" ones, that work very well and in this size they are significantly less expensive then standard 3Fl high helix aluminum specific end mills. Most of my aluminum machining is done with 1/2" 3Fl high (or variable) helix end mills, they do come up on evilbay at good prices, but much less so these days. I rarely if ever use my 2Fl end mills.
http://minicut.com/hss-pm-super-cobalt-end-mills-minicut/
http://www.discount-tools.com/endmills/min-930p.cfm

As Mikey outlined, a rougher in aluminum can remove a lot of material very quickly. I have a 7/8" Niagara 5Fl fine rougher that I often use, on my last bench top mill I would take easily take very deep cuts like below which is a 0.2" DOC by 0.6" deep and the chips would fly at significant feed rates with ease. Slotting in aluminum is a bit of a different animal in my experience, you will almost always get an oversized hole if one does a plunge cut into aluminum and then proceeds to slot. This is often because of regrinding the chips in the hole. Air and light lubrication will dramatically improve the finish, ramping down into the slot as opposed to plunge and slot will also help. In general for slotting, I use and a smaller end mill to slot and then do a finishing pass around the slot to the desired width using climb cutting.

 

[Metal]

Also remember that lubrication/chip ejection is really the only thing limiting your feed rate in aluminium, so things like high helix endmills exist to get more productivity per hours out of the mill, thats typically not a problem for hobby machinists.

Also Also, metric endmills can be found and are typically cheaper than imperial

 

[wrmiller]

I'll give another vote for the 3-flute high-helix endmills, for the reasons stated above. I've been able to find them reasonable enough price-wise on eBay once in a while. Haven't looked recently though.

 

[EmilioG]

I think the use of air is a good idea to blow off chips. I've always gotten good results using almost any endmill type when milling outside edges with WD40, but will try the air.

 

[jlsmithseven]

All I've used so far is similar to the one in the picture. A roughing end mill designed for Aluminum. It did an exceptional job and felt like it was cutting much smoother than a regular HSS tool bit. Very nice thing to have if you're doing them all the time, but I agree with others that it isn't always necessary.

 

[magicniner]

I'm a big fan of single flute end mills for fine work in Aluminium,

- Nick