Turning AR400 Plate

Rogue_Machinist · Jul 14, 2021

So I used the search function and dont think this has been posted and the one post nobody really answered the question. I need to turn AR400 Plate with a 5° angle on the edge. But I cant find any speeds and feeds for it online and the company. The first plate I cut was fine the angle was fine, but it looks blistered. And the second one I cut completely cut wrong. I dont understand how I can go from one being correct and one being wrong. Any input on this matter would be great. More Details
Rough .040" DOC leaving .005" finish cut
6.5" O.D. x 1/2" thick.

I could do them manually but having to cut as many as I need to it just makes sense to do them in the CNC. Thank You.
Included photo was the first part I ran, finish is not super important but rather get them right. Grinding them is NOT an option.

escapethewrmhole · Jul 14, 2021

Turning AR400 on the CNC is best done with CBN. It can be done with carbide but it's very slow and unproductive.

You can find AR400 on most tool manufacturer's tool suggestion tools online.

wmpy · Jul 14, 2021

I'm not familiar with AR400, so I looked it up. It seems it's a high carbon steel in the 40-43 HRc range.

I think we need more information in order to help you. What insert are you using? Do you have a separate rougher and finisher? You say the second one cut wrong- in what way? Did the insert get damaged? Are you drilling those holes after the turning? Facing over those holes could definitely cause some problems.

My guess is that you should be in the 300-400 sfm range with a general purpose steel cutting insert. The .005" doc on the finish is probably too low unless you're using a very sharp insert. But, I don't see a reason to use a sharp insert on this application.

Rogue_Machinist · Jul 14, 2021

These plates are cut out on the laser and the holes are there pre turn. I have to face to make them parallel with the blanchard ground side. And I dont have access to CBN inserts, my company will not pay for them, I am using a 2025 WNMG 423 Rougher .062 Tool Nose Rad. And finishing with a .015 tool nose rad. And the second plate seemed to have cut almost as if I suddenly had a decrease in cutting force. Inserts looked fine. I checked them. And I only have .005" on the face to use. So hence the .005" finish cut. I am roughing at 300RPM .007"/rev and finishing at 350rpm .005"/rev. I didnt find any cutting guides for speeds and feeds so I didnt even know where to being. I usually mill AR plate. Ive never had to turn it.

Mtndew · Jul 15, 2021

nissan300ztt said:
I am roughing at 300RPM .007"/rev and finishing at 350rpm .005"/rev. I didnt find any cutting guides for speeds and feeds so I didnt even know where to being. I usually mill AR plate. Ive never had to turn it.

What sfpm? Rpm means jack squat.

Rogue_Machinist · Jul 15, 2021

Mtndew said:
What sfpm? Rpm means jack squat.

400SFM is what I use for 4140 and I was told its similar. As I said I normally mill AR plate. Turning it is leaving lots to be desired.

Mtndew · Jul 15, 2021

nissan300ztt said:
400SFM is what I use for 4140 and I was told its similar. As I said I normally mill AR plate. Turning it is leaving lots to be desired.

AR400 is tough stuff. IMO it's only like 4140 when the 4140 is heat treated to 50Rc.

I could be thinking of AR500 though. It's been a long time since I turned this stuff but I do remember having to machine it a lot slower than you'd think.

I'd start out around 250sfpm. Keeping your feed and d.o.c. the same-ish.

AARONT · Jul 15, 2021

Any chance to getting a little more material left to finish with? .005" isn't much. I would shoot for .01" minimum, if not .015".

Rogue_Machinist · Jul 15, 2021

AARONT said:
Any chance to getting a little more material left to finish with? .005" isn't much. I would shoot for .01" minimum, if not .015".

unfortunately no. These were lasered out of 1/2" ar400 plate material. I need to nail these parts come Monday or Tuesday

petersen · Jul 15, 2021

The hardness is irregular in many of the AR400 steels resulting in that

blotchy or mottled finish appearance. Some look and feel like hardwood grain.

A grinding lick may be the practical remedy at this point.

If you could have your blanchard grinder grind both sides to finish thickness,

you would not have to turn the interrupted cut through the hole pattern.

That would be efficient.

A lot of difference among different sources of those AR400 class BORON STEELS.

We made many tons of wear plates; milling a 6" wide path .375 deep in 1" AR plate.

Starting in the early 1990's with "Jalloy" type AR360.

In the mid '90s we discovered "Hardox 400" and life got easier.
It machined more consistently and more easily than the 360.

After 9/11 , A R steels became scarce and we couldn't get Hardox for a couple years.

We tried many others. A Bethlehem product was said to be "same as Hardox".......Wasn't

We tried some from a west coast mill that produced the wood-grain finish.

When Hardox came back as "450" it still machined more easily than the others.

petersen

escapethewrmhole · Jul 16, 2021

petersen said:
The hardness is irregular in many of the AR400 steels resulting in that

blotchy or mottled finish appearance. Some look and feel like hardwood grain.

A grinding lick may be the practical remedy at this point.

If you could have your blanchard grinder grind both sides to finish thickness,

you would not have to turn the interrupted cut through the hole pattern.

That would be efficient.

A lot of difference among different sources of those AR400 class BORON STEELS.

We made many tons of wear plates; milling a 6" wide path .375 deep in 1" AR plate.

Starting in the early 1990's with "Jalloy" type AR360.

In the mid '90s we discovered "Hardox 400" and life got easier.
It machined more consistently and more easily than the 360.

After 9/11 , A R steels became scarce and we couldn't get Hardox for a couple years.

We tried many others. A Bethlehem product was said to be "same as Hardox".......Wasn't

We tried some from a west coast mill that produced the wood-grain finish.

When Hardox came back as "450" it still machined more easily than the others.

petersen

What petersen here said is my experience as well.

I have milled a ton of AR400 and AR500 wear plates. The material is notoriously inconsistent riddled with hard spots and yields that seem to be in the range of 150-200ksi. The machinability of AR400 plate is poor. Mostly because of the inconsistency.

For turning I use CBN, for milling carbide at around 180 sfm to start to figure out the batch of material I've got.

This can not be compared to 4140. This is very much an H group material.

wmpy · Jul 16, 2021

Since you said that you do have experience milling AR400, can you put the part in the mill and face off the .005", then put it in the lathe to cut the angle? This would save you from making the interrupted cut in the lathe, which can be really challenging in hard materials.

I know you said that CBN is not going to happen, but what about ceramic? Or what other grades of inserts do you have available to you? That 2025 grade you mentioned is a Sandvik grade for stainless if I'm not mistaken. Do you have any other Sandvik grades like 4305 or 4315? I think those would work better.

Rogue_Machinist · Jul 16, 2021

wmpy said:
Since you said that you do have experience milling AR400, can you put the part in the mill and face off the .005", then put it in the lathe to cut the angle? This would save you from making the interrupted cut in the lathe, which can be really challenging in hard materials.

I know you said that CBN is not going to happen, but what about ceramic? Or what other grades of inserts do you have available to you? That 2025 grade you mentioned is a Sandvik grade for stainless if I'm not mistaken. Do you have any other Sandvik grades like 4305 or 4315? I think those would work better.

I will look around Monday. Also it seems that this plate is like this. After posting this question a few other groups im with they have all said. That blotchiness is just the material not being normalized after rolling. So im assuming this is how its going to cut. I will recommend Hardox for next time, however, last time we made these parts was 2007. And the guy who ran them then has passed away. I will definitely go through my inserts. Would a ceramic insert with no chip breaker be a better option? I have some of those.

Rogue_Machinist · Jul 16, 2021

wmpy said:
Since you said that you do have experience milling AR400, can you put the part in the mill and face off the .005", then put it in the lathe to cut the angle? This would save you from making the interrupted cut in the lathe, which can be really challenging in hard materials.

I know you said that CBN is not going to happen, but what about ceramic? Or what other grades of inserts do you have available to you? That 2025 grade you mentioned is a Sandvik grade for stainless if I'm not mistaken. Do you have any other Sandvik grades like 4305 or 4315? I think those would work better.

Oh and I do have a bunch of 4035 WNMG Trigons I dont know who makes them.

petersen · Jul 16, 2021

"Next time" ... With that amount of stock removal, having your Blanchard grinder flip

them over and finish the thickness will save you a lot of trouble.

petersen

Rogue_Machinist · Jul 16, 2021

petersen said:
"Next time" ... With that amount of stock removal, having your Blanchard grinder flip

them over and finish the thickness will save you a lot of trouble.

petersen

That is likely what I will suggest and then just cut the angle to eliminate the interrupted face cut.

BRIAN.T · Jul 18, 2021

Are those holes lasered out or drilled? If laser, I would take an old countersink and try to c-sink the scale off before turning. Putting a .030 chamfer on those holes will prevent you from turning thru the extra hard stuff. Also I'm not lathe expert, but finished .005 with a .015 radius isn't right... Right? You're not forming a proper chip. Try a radius equal or less than stock remaining.

register · Jul 21, 2021

How did this turn out?

Turning AR400 Plate

Hot Rolled

Aluminum

Hot Rolled

Hot Rolled

Diamond

Hot Rolled

Diamond

Stainless

Hot Rolled

Cast Iron

Aluminum

Hot Rolled

Hot Rolled

Hot Rolled

Cast Iron

Hot Rolled

Cast Iron

Hot Rolled

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