Hi there,
I’ve been using my CRP4848 machine very successfully on plastics and woods for years. I am continuing to struggle with Aluminum. I have yet to cut a piece successfully and I just don’t know where I am going wrong. I use the CNC Cookbook GWizard tool to calculate speeds and feeds and yet, I constantly am breaking bits.
Current project is 0.105 thick (11 gauge basically) 5052 Aluminum sheet. I am using a full carbide bit, 1/4" shank, 1/8" cutting diameter, 1/2" cutting length single flute upcut bit with 1" stickout (I’ve used SPEtools, Amana, several other brands, but they all have this same spec). The calculator tells me that for this bit, with a cut depth of 0.10 inches, at 16K RPM and using a feedrate of 75IPM, I should get 0.000374" bit deflection and a chipload of 0.00456ipt with a tool torque of 6.12 oz/in. Using aluminum cutting fluid misted on.
The first set of holes are all 1/8" diameter so basically it’s just a straight plunge. Those work perfect, the spindle sounds good, everything works. As soon as it moves to make a cut with ANY horizontal component, the bit instantly snaps off.
I can’t imagine I am THAT far off spec from the calculator. This same calculator has worked perfectly for achieving efficient cuts in all other materials. What could I be overlooking here? I have selected 5052 aluminum as the material in the calculator.
Any help very much appreciated… this is getting expensive at up to $40/bit
Thanks.
James
5052 is really miserable, abrasive, and gummy. I’ve not had great luck with it either, but, single O flute, mist coolant and maybe half that DOC should work.
Forgot to mention, 6061 is what 90% of people are milling, or if you are lucky, Mic6. 5052 is good for bending, but if I need 5052, I just use send cut send.
I don’t specifically need 5052, it’s just what the store carries I pick up my sheets from. The plates I am cutting are very simple, but they do have 1 tight bend in them so 6061 isn’t a good choice unless I go through the hassle of annealing that spot where the bend is first.
I did try 0.05 DOC with 45ipm last night. It does cut, but I am finding 2 things… 1 is that the upcut is leaving a terrible ragged edge on the top, the bit is not cleaning it up even with a finish pass, and 2, when I get to the bottom of the cut, instead of cutting the metal, the bit is pushing it down into the holding tape so I don’t have a complete cut but rather what looks like a stamped depression on the bottom surface.
I did check cut send cut, I may have to go that route but wow, that’s expensive for the 8 little pieces I need to hammer out!
I am waiting for some new bits to arrive this morning that have a different design to the upcut. Hoping that maybe they will have a better chance. I am not having any gumming issues (well, the metal that sticks with the part is gummy, but no gumming up in the bit), and the chips that do get cut and ejected look pretty good.
Sounds like I am barking up a tree that never going to give me great results, but I’d settle for just getting this cut and having to clean up and sand it if I can get that far!
One last question… I did halve the DOC but I also halved the IPM. I am hesitant to increase my IPM back up, but what about potentially running something like a 0.02 DOC at 75IPM? Will I have better luck that way or will I start running into heating issues?
OK thanks Loren. I’ll try those settings. I have been using WD-40 as the coolant/lubricant thus far. Alcohol would be a nicer solvent to use since I wouldn’t have to clean up the mess after
I know the machine is “light” compared to industrial sized machines but I never considered it as light as desktop versions. I have a 7hp spindle and NEMA34 motors on this machine so bending/flexing is more of a worry than powering the head through things!
I will try your settings and fluid and see what happens. Thanks for the suggestion.
James
