tools getting scrapped, CRAP!

[Bob W.]

There is a production job we have here and we have run it for some time.  This job is steel and involves a $300 custom form tool made of solid carbide.  We have a long history with this job and the tools ALWAYS last at least 30 minutes.  This latest batch we decided to send to Guhring for coating and so far we have lost four tools immediately when the carbide touches steel.  The flutes simply fly off.  Any idea what the issue might be?  These were really poorly packaged when they were shipped back.  All tools were in sleeves but not much padding in the box.

[Bob W.]

Here is a picture of how they were shipped back.  This is about $3000 worth of custom form tools.

[Tyler Robotson]

Do you have any from an old batch ? could send out for hardness testing against these new ones

[crazy^millman]

Brazed on? I suspect they got them to hot when they coated them and broke the silver solider loose from the carbide to the tool steel. Yes I have had that happen and yes it sucks.

[Bob W.]

Brazed on? I suspect they got them to hot when they coated them and broke the silver solider loose from the carbide to the tool steel. Yes I have had that happen and yes it sucks.

No, these are solid carbide tools.  My only guess is a change in the carbide grade or rough handling during shipping?  I mean these flutes just come right off with no bang or anything, like there are micro fractures present.  What could cause that?

[specv]

Bob, Im with Ron on this one, i think heat is your issue. Are they PVD coated or CVD coated?

PVD involves heat for application and CVD involves chemical application. Either that or the carbide got too hot when they ground the tools. You might be able to have them magnaflux tested to see if there are cracks.  

[kccadcam]

Bob, Im with Ron on this one, i think heat is your issue. Are they PVD coated or CVD coated?

PVD involves heat for application and CVD involves chemical application. Either that or the carbide got too hot when they ground the tools. You might be able to have them magnaflux tested to see if there are cracks.  

That's my thoughts also, Or else bad grain structure in the blanks.

Bad packaging you normally see chips or broken teeth. (that's still unacceptable the way they were packaged)

[Bob W.]

These are nano-si coated (Guhring) and it is a 950 degree process so heat shouldn't be the culprit from a coating standpoint.  I will be calling my tool grinder tomorrow to get their take.

[kccadcam]

Balzers has been good to me.....

http://www.coating-guide.balzers.com/web/en

[THEE THAINZ™]

Do you know who supplied the blanks from your previous tools compared to the ones that fail? If they are using an inferior binder or sub straight it could be the problem. When they break off do they look as though they run in an granular manor (straight)? 

[Aaron Eberhard]

Yeah, talk to your tooling guy...  I've been through this a few times, the first time was "Oh, we changed to a higher tungsten content alloy, we thought you'd be happy because it was tougher!"  Of course, it was stronger, but more brittle, so they failed and failed FAST.   With this one, the flutes didn't physically separate, they only lasted about 30 minutes of cutting when I normally got 6 hours or so.

The second time their supplier changed the blanks, and they had no knowledge of it (apparently it would grind just like the other stuff), but it appeared to be a grain/crystallization issue in the blanks.  It drove the tool makers nuts trying to track this one down.  This one was interesting because the flutes separated, and it almost looked like a clean "cut" at the root until you looked really close (magnified it). 

 

So yes, I've had this exact problem, although in those situations it had nothing to do with heat I've ran into the stuff Ron has mentioned too a few times, but never with a "solid carbide" tool..

[Zoober]

We just went thru that with Internal Tools key cutters. Internal analyzed them and said it was a bad batch of carbide. They replaced them all, and thanked us (big discount) for bringing it to their attention. Handled like pros.

[crazy^millman]

Yeah with Solid Carbide all the points the guys brought up would be my thoughts on it. Heat will do some weird things, but with Solid Carbide I am going to say the points mentioned above will be my next thoughts.

[Sticky]

Sounds like bad carbide. I've been through this. Heat doesn't do much to carbide, I'd feel safe in ruling that out.

[Newbeeee™]

Carbide from one supplier certainly isn't the same as from another supplier.

It's all down to the micrograin and then the heat treatment - carbide when 'green' (soft) can be easily turned prior to hardening.

 

I cannot believe it is down to the handling.

It maybe to do with the guhring process.

It's probably due to this batch of tools being totally different grade from previously supplied.

[metalmansteve]

I used DuraMill end mills for years to rough my nickel parts.  All of a sudden their end mills would snap on the first or second part.  They came out but couldn't explain it other to say it must have been a 'bad batch' of carbide.  My situation wasn't that bad because I could just pop in another brand of cutter.  Being custom tools, I feel for you.  It's not like you don't have other things to deal with.

[Guest]

Carbide from one supplier certainly isn't the same as from another supplier.

There's only a few actual carbide mfr's on the planet. Sandvik being one.

[Newbeeee™]

There's only a few actual carbide mfr's on the planet. Sandvik being one.

To be more specific, carbide cutters from one company certainly aren't the same as from another supplier

 

We were doing a stainless 303 part before crimbo. 2.25dia x 5" long round bar on the 4th axis with a centre, milled out to be rectangular with the inside hogged out (think large matchbox but bigger - ohhh I lurve the highspeed toolpaths).

This is all done with the one 12mm dia cutter.

We have tried a few different makes of 4 flutes in the past, and even a couple of 5 flutes. The 5 flutes we tried increasing the feedrate for the extra tooth and they have blown up quicker, or the same tool life but are more expensive to buy.

So we settle for YG 4flute and have been using them for a couple of years and get 15 parts out of each tool before junking.

In walks our tool rep - 'you need to try the Garr V5 - run it at same everything but up the feed on the override to allow for the extra tooth'.

We did the remaining 51 parts with the tool, knocking 5+ minutes off each part.

 

This was just after we had run a similar (but bigger) part with the same method/process, but out of 304. Made the job 10 times before with never a problem, but this batch we were blowing up cutters - so we put it down to bad material (mill certs obviously said all was well) and we were limping through the job at 80% federate on all tools (except drilling @ 100%).

Our rep came in and said 'you need to try the Garr V5'. So we did and the thing had been cutting sweet for 30 seconds and then the biggest bang - like a mini explosion. I'd never heard a cutter snap like it before.

So in this instance the Garr was no benefit as it must have been inclusions (carbites?) in the material, but all the other cutters that had gone, had chipped the teeth turning them into a spot drill. But not the Garr - it had snapped clean off at the shank, but was so noisy, to me, it 'sounded' like it was a lot finer micrograin and a lot harder cutter.