Remedying Blown out insert pocket

[CentexMachineShop]

Good afternoon.

Had a fairly significant crash this morn using a Ingersoll 6” 5N6J SEHT1504 45 deg face mill on a K&T 3K vertical. The forces involved were pretty incredible. Suffice to say it’s the worst crash I’ve had happen. Fortunately the mill appears to be fine, stripping the hold down t nuts and throwing a 8x10x2 block of steel across the shop. Unfortunately it totally smashed one insert pocket on this essentially brand new insert body. The question is what is the recommended practice, aside from replacing the face mill on abandoning the pocket altogether. It has 12 inserts, so would it be best to drop the insert 180 degrees from smashed pocket and then drop feed rate some to match a 10 insert mill or would you just run it with 11, still cutting some feed?

Curious to see what folks would do. I don’t think it’s repairable. Too bad as this was not a cheap tool.

 

[adamm]

If you just remove one insert, the insert that trails the empty pocket is going to be seeing 2x the chip load of the rest. It is going to take more wear, and be prone to failing. I think if you're going to limp it around, it would be best to evenly remove half the inserts, and run it like a 6 tooth cutter. If it would work with one insert missing, I'll assume the body actually has enough clearance that it doesn't start rubbing with half the teeth missing. Then everything is running an even chip load.

 

[4GSR]

Dad used to rebuild some of the larger face mills back when he was alive. He would build up the pocket with a high strength wire and I have the compound tilt rotary table he would set it up on. Indicate in on a good pocket then proceed to recut the damage pocket. There's not much you can do about reheat treating the repaired pocket back to its original hardness. So knowing that, it's eventually going to wear out quicker than the others. I've seen people leave out the inserts on damaged pockets and keep running. May have to reduce the feed rate by one less cutting edge... Ken

 

[CarbideBob]

Not much that can not be fixed here.
Goggle tool holder repair.
Some places will use a tig rad that goes on hard. This is more expensive since remaching the pocket more difficult.
Some charge a flat rate of 1/2 the new cost regardless of damage and some charge by the amount of work to be done.
Ultra-Dex and others have an entire department that do this stuff all day long. This business was how Ultra-Dex got started with a handful of B-ports in an old gas station.
It is an art. The hardest part is the welding.
At one time I had 4 guys who did this full time. Sandblast, bench grind away the mushed, tig, recut new pocket.
The auto plants used to wreck a lot of cutter bodies and toolholders.
Bob

 

[Milland]

Was this a "bolt to the spindle" cutter body, or pull stud/draw bar?

Regardless, I'd encourage you to check the spindle nose bearings, unless the machine "is what it is" and even if the bearings were damaged there's no repairing them.

 

[CentexMachineShop]

I think this is what I’m going to try to do. I appreciate the comments. Very unfortunate as this thing had less than prob 500hrs of milling on it

 

[Milland]

What happened to cause the crash?

 

[CentexMachineShop]

Was this a "bolt to the spindle" cutter body, or pull stud/draw bar?

Regardless, I'd encourage you to check the nose spindle bearings, unless the machine "is what it is" and even if the bearings were damaged there's no repairing them.

Luckily it was not a bolt on type! Was on an K&T-made nmtb50 1.5 pilot shell arbor and it partially sheared through both integral .625 keys. Checked the spindle run out and it was still at .00025 at gage line which is what I got last time I checked it 7-8 years ago. Fingers crossed. Noise was incredible, but machine didn’t notice. Was pretty dicey. Still not quite sure what caused it. I suspect I hit a super hard spot in the 8620 hot rolled plate and my fixturing wasn’t up to the task ? It’s almost as if plate was lifted into cutter momentarily. Wish it had been filmed in slow motion to see

 

[CentexMachineShop]

I think this is what I’m going to try to do. I appreciate the comments. Very unfortunate as this thing had less than prob 500hrs of milling on it

50hrs *** major difference

 

[CentexMachineShop]

If you just remove one insert, the insert that trails the empty pocket is going to be seeing 2x the chip load of the rest. It is going to take more wear, and be prone to failing. I think if you're going to limp it around, it would be best to evenly remove half the inserts, and run it like a 6 tooth cutter. If it would work with one insert missing, I'll assume the body actually has enough clearance that it doesn't start rubbing with half the teeth missing. Then everything is running an even chip load.

Should have enough clearance. SEHT1504 stood up on point

 

[michiganbuck]

We had a shop Stegman Tool that would weld up a blown pocket, rebuild it, re tap if needed, and bring it back to spec.
Now Stegman is a big outfit and likely would not do a one-up

A good toolmaker likely could do the same.

Likely the part surface finish will show the missing insert. If still Ok then worth a try

 

[Milland]

It’s almost as if plate was lifted into cutter momentarily. Wish it had been filmed in slow motion to see

If there was an inclusion in the stock it might still be visible in the carnage. Of course, you'll need to separate out the carbide and body shrapnel...

 

[CentexMachineShop]

We had a shop Stegman Tool that would weld up a blown pocket, rebuild it, re pat in, and bring it back to spec.
Now Stegman is a big outfit and likely would not do a one-up

A good toolmaker likely could do the same.

Likely the part surface finish will show the missing insert. If still Ok then worth a try

Maybe I’ll give this a try. If it’s low or high guess I can drop to insert and go back to square one. Screw hole 5mm for mounting the insert is smashed flat. No clue where screw went. Looks like it got compressed .25 or so from original height not so much bent backwards. Very odd. Basically like someone took a sledge and beat the hell out of it

 

[CentexMachineShop]

If there was an inclusion in the stock it might still be visible in the carnage. Of course, you'll need to separate out the carbide and body shrapnel...

Appears to be a pocket containing a partially melted ball bearing and charcoal looking stuff. Customer supplied Material came from speedy metals

 

[GregSY]

Why would the hardness of the holder (or lack thereof) cause it to wear out faster? It seems the steel is just backing the insert and doesn't see any wear itself.

 

[Garwood]

Appears to be a pocket containing a partially melted ball bearing and charcoal looking stuff. Customer supplied Material came from speedy metals

Wow! I'd be pretty upset.

 

[CentexMachineShop]

Why would the hardness of the holder (or lack thereof) cause it to wear out faster? It seems the steel is just backing the insert and doesn't see any wear itself.

I assume it’s from the abrasion of the swarf/chips? Good question. Guess it’s common in super high production environments. Only have seen one completely worn out and it was an old sandvik coromant we used to mill welds, ie slag and all on an old k&t 2H The body looked sand blasted or like it’s was pitted from corrosion by the time we chunked it

All I know is this Ingersoll cutter body is harder than a coffin nail

 

[CentexMachineShop]

Yeah luckily the customer is a bulldog, prob will go looking for a refund and hawk them for it. Not my fault.

 

[Milland]

Appears to be a pocket containing a partially melted ball bearing and charcoal looking stuff. Customer supplied Material came from speedy metals

Welcome to the joys of machining. Whether it's parts wrecked by platers, bad stock, or poorly made drawings - it's always our fault, and our cost.

I'd ask your customer for the invoice and certs (if any) for that plate, and have a talk with Speedy.

 

[gbent]

Damage porn! We want pictures! Abscess in plate, too.