Problem- Milling Inconel welded parts

[gepperta]

I need help with up to date suggestions for milling reconditioned gas turbine parts that have been welded with Inconel. I do not have the exact alloy name. I remember years ago we would take as deep a cut as possible because of work hardening and go very slow otherwise. I also remember using a sulphur free cutting oil that had the consisitency of honey, but I can't remember the name.

[PixMan]

Valenite has a new grade of carbide insert for milling high-temp alloys. I've had good luck with their PDMX 0905ZEER51 grade VP2003 inserts on their V556 high-feed mill. It's not depth of cut that keeps the material from work-hardening, it's staying in the feed. NO DWELLS!

I'm running 200 sfm in Inco 718 @ 42Rc. Though it's a shallow depth of cut (.060), it's feeding at .024 inches per tooth. Gets the job done quick! There are ceramic grades that work well too, so I hear, but I'm afraid to apply the speeds they specify for fear of changing the temper of the workpiece. I can't imagine what a shower of sparks would do to the workpiece (or the cutter for that matter.)

[gepperta]

Thanks for the help. I called Kennametal and spoke with them about 1/2 dia
whisker reinforced ceramic inserts, grade KY4300. They suggest 870 SFM and then watch the fireworks. My problem is milling small air foil shaped pockets, so he recommended solid carbide end mills grade KC 635 at 100-200 sfm and .0002-.003 fpt.

.024 fpt is quite aggressive. How does the finish look when you are done?

[USMCPOP]

My son TIG welded gas powerplant turbine blades for awhile at Alstom. The base blades were Inconel 738 and were built up using Inconel 625 filler.

[PixMan]

Originally Posted by gepperta .024 fpt is quite aggressive. How does the finish look when you are done?

Parts look stunning if you add a wiper insert or two. Otherwise, between a 125 and 250 microinch finish.

The low depth-of-cut is easy on the workpiece while the high feed rate moves the heat off with the chips. This method is what many mold shops have turned to for faster removal of cavities. I don't know the configuration of your parts, so "Ask your doctor if high feed milling is right for you".

[crabbass]

watch the video on youtube. I think it was called High speed Machining Inconel 750. This looks like it is being ran in a pretty robust machine with a #50 taper.