Need help with machining this part...

spin-tek · Dec 30, 2013

The print calls out for a .060" saw cut on this part & having trouble with part (see picture below) after machining. Top flange thickness is only about .030" after saw cut. I'm using a 5" x .0625" thk saw & taking 4 equal passes to machine that feature. Part is aluminum 6061.

Any help would be appreciated.

Trung

Nmbmxer · Dec 30, 2013

What form of stock did you start with? If you cut them from plate there can be a lot of residual stress that would make it curl up like that. How is the part faced off? I would try see if a process change to that op changes the warp.

spin-tek · Dec 30, 2013

The part was first machined on a cnc lathe with round bar stock. I believe it was part off with a .187 width cut off tool from the lathe.

toolsteel · Dec 30, 2013

Which direction are you working in the z axis? On the upper slot are you starting from the top and stepping your way down? Is there fixturing involved, or are you grabbing it in a vise?

Limy Sami · Dec 30, 2013

Because the ''top'' has distorted and not the second, it looks like a possible effect of heat on the surface from the previous operations, if parting off I'd look at taking a couple of facing cuts before starting on the next part.

Mtndew · Dec 30, 2013

I wonder if you put a slight corner radius on that sawcutter if it will help prevent the lip from moving on ya.

spin-tek · Dec 30, 2013

toolsteel said:
Which direction are you working in the z axis? On the upper slot are you starting from the top and stepping your way down? Is there fixturing involved, or are you grabbing it in a vise?

I'm holding onto the 1.590" OD in a vise & saw cutting in the -Y- axis.

Limy Sami said:
Because the ''top'' has distorted and not the second, it looks like a possible effect of heat on the surface from the previous operations, if parting off I'd look at taking a couple of facing cuts before starting on the next part.

After the part was part off from the lathe, there was an additional .020" that was faced off using a turning/facing tool. Maybe that's not enough to get rid of the possible effect from the part off tool.

Mtndew said:
I wonder if you put a slight corner radius on that sawcutter if it will help prevent the lip from moving on ya.

Just tried, got the same result.

gregormarwick · Dec 30, 2013

As Limy said, the saw is not distorting the second slot at all, which suggests that you are creating some stresses on the front.

Try facing more off, then try facing none at all. That will prove whether it's the part off or the facing that's causing it.

toolsteel · Dec 30, 2013

I assume you have plenty of good coolant going through there....You said you were taking multiple passes to get the width correct.......does this happen on the very first pass through?

byawor · Dec 30, 2013

I see the dreaded "prototype" on the print, hope you got paid lots in advance to screw with this. If it came to our shop we would be too busy. Also I see you are using a .0625 blade but print calls for .060 slot, is that ok?
Bob

upnorth5axis · Dec 30, 2013

When did the top get distorted. before or after you cut the 2nd slot. also check your coolant concentration.

reedeprintice · Dec 30, 2013

looks like a heat problem , but its super thin . Can you do it in 3 different cuts maybe ?

upnorth5axis · Dec 30, 2013

carbide or HHS Cutter? what speed and feed are you running?

spin-tek · Dec 30, 2013

gregormarwick said:
As Limy said, the saw is not distorting the second slot at all, which suggests that you are creating some stresses on the front.

Try facing more off, then try facing none at all. That will prove whether it's the part off or the facing that's causing it.

We tried facing off .090" off top & ran the saw & it still had the same problem.

toolsteel said:
I assume you have plenty of good coolant going through there....You said you were taking multiple passes to get the width correct.......does this happen on the very first pass through?

Using flood coolant. Looks like it happened on the 3rd pass (pics below).

byawor said:
I see the dreaded "prototype" on the print, hope you got paid lots in advance to screw with this. If it came to our shop we would be too busy. Also I see you are using a .0625 blade but print calls for .060 slot, is that ok?
Bob

Print calls out .06" with a tolerance of +/- .010"

upnorth5axis said:
When did the top get distorted. before or after you cut the 2nd slot. also check your coolant concentration.

Top's distorted before 2nd slot was cut. Coolant concentration is at 8-9%

reedeprintice said:
looks like a heat problem , but its super thin . Can you do it in 3 different cuts maybe ?

Currently using 4 pass to cut

spin-tek · Dec 30, 2013

upnorth5axis said:
carbide or HHS Cutter? what speed and feed are you running?

HSS saw. I've tried a few speeds & feeds with the same results.

S600 / F18.
S600 / F9.
S2000 / F15.

Any suggestion on speeds & feeds?

solidworkscadman · Dec 30, 2013

Wire EDM it, if all else fails

peanut · Dec 30, 2013

might not make any difference, but can you try cutting by 8 passes instead of 4?

specfab · Dec 30, 2013

I might venture to guess that with the type of saw you are using, once you bury the saw body in the cut, the chips in the gullets between the teeth are forcing the thin section to deflect, especially if they get wedged between the slot wall and the cutter. You might have different results with a carbide-toothed slotting saw with a relieved body to give some additional chip clearance. .030 thickness isn't very stiff to resist bending from any sort of stress.

rockfish · Dec 30, 2013

I second the wire edm idea. I used to never think about wire edm, waterjet, laser, etc., but I'm starting to take a harder look at that stuff. We had some tricky parts that we knew we would have a hard time holding/machining without distorting the part, and we sent them out for wire edm. The results were amazing, and at a reasonable cost.

Frank

toolsteel · Dec 30, 2013

Is a stagger tooth cutter available in that size? you may have a chip issue going on. Stagger tooth would give better clearance for the chips, I have had good luck with stagger tooth cutters .125 and thicker......not sure if they go down to .0625 or not.

Need help with machining this part...

Plastic

Stainless

Plastic

Titanium

Diamond

Diamond

Plastic

Diamond

Titanium

Hot Rolled

Hot Rolled

Stainless

Hot Rolled

Plastic

Plastic

Hot Rolled

Aluminum

Titanium

Titanium

Titanium

Similar threads