Photos of inserts for Aluminum ...

[wquiles]

Those ground inserts sure look sharp

 

[precisionworks]

Three awesome videos of high speed - high feed machining:

http://www.ranitool.com/YouTube2.htm

 

[tino_ale]

Hey guys,

Along with the PM1236 I got the basic TMX tool set that Matt sells in the DCMT flavor. I chose DCMT over CCMT to get more clearance/angle to access tricky situations and because I thought my 1236 should not excess what a DCMT can take.

Moving on.

I got some TMX DCGT 32.51 AK H01 aluminium inserts to work with both aluminium and titanium (later on).

When searching the recommended depth of cut / feed recommended range, I was shocked TMX specifies this :

Light to medium turning of Aluminum and non Ferrous materials
• Feed Rate = .001 – .020 ipr
• Depth of Cut Range = .040 – .200 inch

The DOC range seems huge, even the smalest recommended DOC is about 1mm of material removing ???

I thought you were supposed to use very low feed and DOC to get the best aluminimum finish ? What did I miss ?

thanks

 

[gadget_lover]

The feed rate and DOC are what you want to use in a production environment to maximize the number of parts per hour AND the life of the tool. We are not doing production, so we can do OK with slower SFM, feeds and DOC

In this specific case the leading edge is very high in relation to the chip breaker. I suspect that a light DOC will allow the aluminum to curl into a long spiral instead of coming off in small chips. I find that every insert has a sweet spot when roughing where you really remove the metal fast and you are literally showered with a fountain of small curly chips. I'd bet that the chipbreaker becomes more effective at about .040.

I looked at the chipbreaker on this page; http://www.toolmex.com/Products/custom/TechDetails.aspx?itemid=6-DCG-3212

Daniel

 

[precisionworks]

It is difficult to find an insert the does well in both aluminum and titanium. The .51 nose radius if is both extraordinarily sharp and quite delicate. I use that same insert for titanium finish cuts but limit depth of cut to not more than .25 mm. If you push it much harder than that tip life is quite short.

 

[tino_ale]

Thanks. Indeed during my first try I did not cut that deep and the aluminum would curl into long "hair" instead of breaking in chips.
Except if I took very light cuts as I thought it would give the best finish, then it would create tiny chips.
Apparently there is is a range of doc where the chip breaking doesn't work.


Now, I know I will not be using flood coolant on my lathe. My shop is small, not well ventilated and in the house... Flood coolant sounds too smelly and just too messy. So if I turn titanium I doubt I will ever take any kind of roughing cuts to avoid titanium fire. 0.25mm is 0.5mm in diameter reduction, that sounds plenty enough to me.

 

[precisionworks]

... Now, I know I will not be using flood coolant on my lathe. My shop is small, not well ventilated and in the house... Flood coolant sounds too smelly and just too messy.

WQuiles set up flood & he's never mentioned it being smelly/messy/etc. http://www.candlepowerforums.com/vb/showthread.php?364617

Titanium is best machined with flood unless you have an endless supply of inserts. Insert life machining Ti under the best of conditions (short & rigid setup, sharp fresh insert designed specifically for Ti, flood coolant at the correct mix, etc.) is much shorter than when machining most other materials. This isn't to say that Ti cannot be machined dry. Anything is possible.

I don't use flood on either the lathe or mill but rather run MQL using Acculube LB2000. IMO it's neither more nor less messy than flood but it's easier to set up on a machine tool not designed for flood (like my mill-drill). The only drawback to MQL is the cost of the applicator - the model I use for the lathe has a retail of $1305. Seems like it cost $150 on eBay. http://www.mscdirect.com/product/details/05651328

Apparently there is is a range of doc where the chip breaking doesn't work.

Most literature suggests that DOC should at least equal nose radius. Depending on edge treatment it's sometimes possible to run the DOC as small as 2/3 of nose radius & still get good chip breaking. Less than that & it gets iffy quickly.

 

[wquiles]

It is difficult to find an insert the does well in both aluminum and titanium. The .51 nose radius if is both extraordinarily sharp and quite delicate. I use that same insert for titanium finish cuts but limit depth of cut to not more than .25 mm. If you push it much harder than that tip life is quite short.

+1

Exactly what I have found as well. The best insert for Aluminum is a little too delicate but all but the lightest Titanium machining. Lately I have been using the Sanvik H13A inserts which are outstanding in Titanium, and pretty good for Aluminum.

WQuiles set up flood & he's never mentioned it being smelly/messy/etc. http://www.candlepowerforums.com/vb/showthread.php?364617

Yup. Not smelly at all. That TRIM MicroSol 585XT plus distilled water works wonders with Titanium. Now-a-days I use it for "all" metal cutting. The only time I run the lathe dry is for Delrin.

Titanium is best machined with flood unless you have an endless supply of inserts. Insert life machining Ti under the best of conditions (short & rigid setup, sharp fresh insert designed specifically for Ti, flood coolant at the correct mix, etc.) is much shorter than when machining most other materials. This isn't to say that Ti cannot be machined dry. Anything is possible.

+1

Life of my carbide drill bits and threading taps, and Titanium-specific inserts have been "dramatically" extended once I got the flood coolant running. I delayed running coolant for several years, but once I started with Titanium I quickly gave it a try, and now there is no going back, "specially" when doing cut knurling :devil:

Will

 

[darkzero]

Exactly what I have found as well. The best insert for Aluminum is a little too delicate but all but the lightest Titanium machining. Lately I have been using the Sanvik H13A inserts which are outstanding in Titanium, and pretty good for Aluminum.

Yup, I scored a bunch of H13A inserts late last year, like 80 of them. At the rate I'm going with these they will literally last me a lifetime. But hey, at under $2 per insert, who can't pass that up! And that's including shipping. The other 100 inserts behind them were just over $3 per insert, shipped from Germany.

Even though I have enough H13As at my disposal, I still use alumn specific inserts for finishing Ti too, they give me a slightly shinier finish but only noticeable when comparing side by side with the H13A finish. I'll even rough Ti with them but with different style inserts. But I like the H13A cause they're like my general purpose finisher as I use them on most of the metals I machine.

I know I will not be using flood coolant on my lathe. My shop is small, not well ventilated and in the house... Flood coolant sounds too smelly and just too messy. So if I turn titanium I doubt I will ever take any kind of roughing cuts to avoid titanium fire. 0.25mm is 0.5mm in diameter reduction, that sounds plenty enough to me.

I may follow in Will's foot steps someday & start using the flood coolant systems on my lathe, mill, & bandsaw. For now I've been doing just fine even with Ti.

Ti fire you say? As they say, yeah been there done that.....

Those battle scars are gone already, repainted the gap. Just don't get lazy with letting Ti chips & grinding dust pile up (especially the Ti dust), that alone makes a big difference. If you don't have a class D fire extingusher or can't afford one, keep a bag of sand around. Not an alternative but better than nothing & cheap, especially if you go to the sand dunes. Think Ti is bad, magnesium is even worse & topping that is ferro rod. NEVER machine ferro rod dry, ask me how I know!

 

[tino_ale]

WQuiles set up flood & he's never mentioned it being smelly/messy/etc. http://www.candlepowerforums.com/vb/showthread.php?364617

I have no experience about it obviously, just reading online it seems people usually stay away from coolant in a home shop because they don't want to worry about the coolant getting rancid, stinking (maybe it only smells after a while or gone rancid ?), having some rust issues (although I thought a coolant was specifically designed to NOT cause any rust), etc.
My machine will not see *that* much use. If I have to evacuate the cooland and dry the machine thoroughly after each use, that may be a PITA.
If none of those issues are valid, then it would indeed sounds like a no-brainer to go for it. Might take the plunge but I need to read more about it.

Most literature suggests that DOC should at least equal nose radius. Depending on edge treatment it's sometimes possible to run the DOC as small as 2/3 of nose radius & still get good chip breaking. Less than that & it gets iffy quickly.

In that case I have definetely been too shy for my first chips making attempts!
That leaves me with a question though. Say, I have a scratched OD flashlight body, and I just want to "touch up" the OD to refinish the shine. How would I do that if the smallest cut I'm supposed to take with my finish inserts is that much ? Sometimes there isn't much "meat" there. I need to experiment more DOC, feeds and speeds.

Yup, I scored a bunch of H13A inserts late last year, like 80 of them. At the rate I'm going with these they will literally last me a lifetime. But hey, at under $2 per insert, who can't pass that up! And that's including shipping. The other 100 inserts behind them were just over $3 per insert, shipped from Germany.

Well if you have too many, I could get some of them off your hands and you could recoup part of your cost ?
They would have to fit my DCGT 32.51 tool holder though (can't see the size you have from the pic)


Reading all of your experience I'm frustrated I can't get to bring the beers, sit with you for an hour while you're turning some parts, I would learn and absorb so much valuable information so much faster :huh:

 

[gadget_lover]

That leaves me with a question though. Say, I have a scratched OD flashlight body, and I just want to "touch up" the OD to refinish the shine. How would I do that if the smallest cut I'm supposed to take with my finish inserts is that much ? Sometimes there isn't much "meat" there. I need to experiment more DOC, feeds and speeds.

The smallest DOC for proper chip breaking is one thing. The coils you get when doing a finishing pass are different. You can either pause occasionally to let the string break or you can just keep it away from the flashlight. Be REAL careful about that. Those cute springy curls can be razor sharp and strong as steel. They will cut you like a knife.

If you use a tool ground to be a "shearing tool" you can get .0002 DOC and wispy swarf that floats.

Daniel

 

[tino_ale]

Be REAL careful about that. Those cute springy curls can be razor sharp and strong as steel. They will cut you like a knife.

We never can be too carefull. I have a tooth brush to evacuate any annoying coil, so my hand/fingers never get too close to them while the lathe is running.
I can see how dangerous those cute curls can be if they wrap around any part of me and get caught in a chuck jaw :green:

 

[precisionworks]

... reading online it seems people usually stay away from coolant in a home shop because they don't want to worry about the coolant getting rancid, stinking (maybe it only smells after a while or gone rancid ?), having some rust issues (although I thought a coolant was specifically designed to NOT cause any rust), etc.

There are thousands of urban legends & the flood coolant legend goes hand in hand with "never use compressed air to clean a machine tool". It seems that many experts who make these statements have limited exposure operating machine tools. You have to remember when on the error-net to believe half of what you see & none of what you hear :nana:

Flood coolant doesn't cause premature aging or hair loss but does dramatically extend insert life & often improves surface finish by eliminating or reducing slip-stick & built up edge (BUE). It also lowers chip temperature well below the ignition point of titanium. I've machined just a bit of Ti & have never had a fire as the chips never reach critical temperature.

If machining Ti without coolant (flood/mist/MQL) you may want to adjust surface speed to around 25 sfpm (for a typical 1" or 25mm body that's 95 rpm).

My machine will not see *that* much use. If I have to evacuate the coolant and dry the machine thoroughly after each use, that may be a PITA.

I don't know anyone in any shop that does that.

 

[tino_ale]

Sounds good! Just very very counter-intuitive to leave a machine "wet" before going to bed. :duh2:

 

[precisionworks]

... very counter-intuitive to leave a machine "wet" before going to bed.

I don't know how other machinists work but I was taught from Day 1 to clean my machine at the end of the shift, wipe off the ways & apply a coat of Vactra #2 way oil. You will never ever have a rust issue if this is done every time the lathe is used.

 

[tino_ale]

Ok I have tried turning 7075 Aluminum, the difference is obvious!
Chip breaking is much less a problem on 7075, and it machines shiner, less gummy than 6061.
I would say it is more pleasant to machine.

I am still not really happy about the finish I get on the OD. On the right is 6061, on the left, 7075.

I was turning at 1200rpm, and experimented different DOC and feed.
- DOC did not make much difference
- feed : the faster, the coarser the finish. Seems it was the one parameter that had the strongest impact on the finish.

The finish I get on the pics is using the slowest feed available on the PM1236.
I can still see and feel with my fingernail the feed crests on the finish. As if it was a very very fine thread, sort of.

I cannot reach the perfectly flat surface I get when facing, as the slowest feed setting on the crossfeed is much finer than on the carriage feed.

I have tried dry, using WD40, using a cutting oil. Did not make much difference.

What is the secret ?

 

[tino_ale]

Quick question : everything else being equal, would the finish differ between a C shape insert and a D shape insert for external turning and facing ?

I'm happy about my DCxT inserts so far, just curious.

 

[wquiles]

The finish I get on the pics is using the slowest feed available on the PM1236.
I can still see and feel with my fingernail the feed crests on the finish. As if it was a very very fine thread, sort of.

You "should" feel the crests somewhat. If you are using the machine to advance the cariage, you are basically threading, right?

What is the secret ?

It is a combination of things, but you get the best finish when you use Al-specific inserts with a very sharp edge. What "exact" inserts you are using?

 

[tino_ale]

You "should" feel the crests somewhat. If you are using the machine to advance the cariage, you are basically threading, right?

Well technicaly power feedding but yes I guess. I just can't seem to get the same super-smooth finish on the OD compared to facing operation (the feed is slower on the cross slide, and I'm using the slowest feed avaiable on the carriage).

It is a combination of things, but you get the best finish when you use Al-specific inserts with a very sharp edge. What "exact" inserts you are using?

I am using :
DCGT 32.51 AK H01 DCGT 11T304 AK C2 Uncoated Polished Turning Insert for Aluminum 10/pack

 

[wquiles]

I am using :
DCGT 32.51 AK H01 DCGT 11T304 AK C2 Uncoated Polished Turning Insert for Aluminum 10/pack

Awesome. Those are good.

How are you verifying that the tip of the insert is at the right height compared to the centerline of the piece? What method? What tools are you using to set it?