Flat aluminum chip sticking to bit tip

[vitals]

Hi everyone,

I have a PRS Standard, and I'm stumped. I've been routing aluminum for a couple years, with a variety of tools. Right now I'm using a 3/16" Belin tool for aluminum, and every cut I make ends up leaving a thin aluminum disc on the end of the tool. It doesn't blow or fall off on it's own (unless I touch it with a piece of soft wood), and ends up jamming the z-axis when it tries the next plunge.

I've run into this before when drilling holes near the same width of the tool, but this happens on profile paths as well. It routes the shape out, lifts up, and there's a thin aluminum chip stuck to the tool.

I've never seen this happen (even with my other Belin and Onsrud tools)

If anyone else has experience this, I'd love to know what you found out.

- Keith Watkins

[Rob Gunn]

Keith, The best machning fluid I ever found for machining aluminum was kerosene. Please keep in mind that it is flammable and you certainly would NOT want to let the machine run unattended but it will help keep the cutter clean. A hand held spray bottle would do the job.

[Brady Watson]

...every cut I make ends up leaving a thin aluminum disc on the end of the tool. It doesn't blow or fall off on it's own (unless I touch it with a piece of soft wood), and ends up jamming the z-axis when it tries the next plunge.

One of the cardinal rules when cutting aluminum is that you NEVER plunge straight down into the work. This includes drilling. All profile cuts should be done with a smooth ramp that gradually allows that Belin bit route down on an angle gradually into the work. Same for when you need to drill - use a smaller dia bit with an Inside Profile strategy with helical/spiral ramp into the work. Both of these options are available in the Vectric products (PartWorks, VCarvePro, Aspire).

-B

[donek]

What series aluminum are you cutting? Is this a new bit? Newly sharpened?

[Simops]

Guys can I jump in, hopefully not hyjacking the thread, but with a related aluminium cutting issue.....

Lately I have been getting annoying melted like swarf apoearing along a long profile cut in aluminium (cutting 80 thou aluminium) with spiral O upcut 1/4" bit. This melted swarf is stuck to the aluminium (like it ha been welded).

I've changed the grade of aluminium to a 6 series so maybe this is the cause or maybe I have stuffed up my feed or speed.......using 1"/sec at 12KRPM with about 5 passes to full depth....this seemed to work before??

Cheers

[MogulTx]

I have had some aluminum that was SUPPOSED to be 5052 start doing that melty thing on me. I have found it to happen only in ONE area of a large sheet... It has happened several times over teh last couple of years. It is not consistent from one end to the other and is not consistent from one piece to another. I think this may be due to poor consistency of the aluminum alloy and or temper of the materials ...

To resolve it, I have used a shallower cut. I always ramp in to every aluminum cut. I always use my dust collector to force air past my bit and my material. When the material cuts poorly, I use WD-40 as a cutting fluid. I also make sure I am using a good bit- and once aluminum welds to the bit, I put it in the resharpen pile.


You MAY have other issues, but it could be quality and consistency of the material. The above parameters should solve your troubles... Use your "regular" cutting speeds that you use for aluminum. ( which will be significantly slower and with shallower cuts and ramps) than for other materials.

[Simops]

Thanks.....it maybe that I need to do more passes and slower and accept the increased cutting time.
5 passes equates to 16 thou depth but I might try to 7 then 10 if needed to get a clean cut??

Cheers

[donek]

5052 is a horrible material to cut. I'd avoid it at all costs.

the recommended feed rate for most aluminum cutting O-flutes I have seen is 1.2ips and a pass depth of 0.050in. The only time I have had to modify this is if my router is underpowered. If you're running a PC 3.25HP router or equivalent, I would not change these values, but look for other sources such as aluminum series, bit sharpness, or bit selection. I also run my PC router at full speed (I think that's 18000 rpm). I don't bother with air or dust collection. If it starts to gum up, I replace or sharpen the cutter.

If you sharpen your cutter, be sure to remove an entire 0.050in from the length. This is the portion of the cutter doing all the work, so you won't get to a fresh section of cutter unless you grind that much or more off the bottom of the cutter.

[Simops]

I'm using a 2.2hp spindle with brand new onsrud bit out of the box.
The grade of aluminium is important and think some of the blame rests there....it is very hard to get the grade you want over the retail counter....in many cases the vendor has no idea of the grade they are selling!

I got this latest batch from a supplier that supplies to aircraft fabrication and was told that this 6 series grade was best for fabrication....but not sure now that is correct for router fabrication!!!!!

Cheers

[MogulTx]

Michael,

I cut 5052 ALL the time. For solids of any thickness, I usually use .02" ( .5mm) per pass, spiral ramped. I usually use around 1.4ips. And use the dust system to pass more air over the bit and if you have any issues at all, have some wd40 (or similar) handy to spritz onto the cutting path.

"6 series" may equate to our 6061-T6. The "T6" designation is a "temper" in the metal. The "6061" is the alloy designation. It cuts well on my machine. One thing I forgot to mention is that the aluminum must be held down well. I often use scews for this. If it is possible to align it with an edge and clamp over the edge- then I'll do that. Have used screws and DS tape... it all works. But if you are going to spritz a coolant onto it, it will affect the DS tape, if you use any significant amount of coolant. ( I only use a little and only on the cut line.)

[Simops]

MGM, it is the 6061-T6 that I used recently and the one giving trouble! Your feed and speeds are similar to mine and I always ramp in! I also use my ducted dust system. I haven't used wd40 but will try to see if it makes a difference with this grade......I'll try anything to get rid of that annoying melted slag on the side of the cut and bit. Note this is only happening on long profile cuts!!

Cheers

[donek]

I'm using a 2.2hp spindle with brand new onsrud bit out of the box.
The grade of aluminium is important and think some of the blame rests there....it is very hard to get the grade you want over the retail counter....in many cases the vendor has no idea of the grade they are selling!

I got this latest batch from a supplier that supplies to aircraft fabrication and was told that this 6 series grade was best for fabrication....but not sure now that is correct for router fabrication!!!!!

Cheers

Pretty much anything I obtain has the series printed on it. In the states we have online supplier such as onlinemetals, industrial suppliers and even recyclers. All of them are familiar with the material and grade they are selling. I think I would pursue a different supplier. Most will work with you and price based on the quantity you purchase.

Which onsrud bit? An O-flute for plastic is different from an O-Flute for aluminum.