Strange tearing/surface finish Titanium facing - Pics included

[JearBear]

Hey All,

A few weeks ago I faced about 30 of these 1"x2" Titanium 6Al-4V parts using a 1.5" 45 degree shellmill with some SEHT 43 YBG205 Inserts. Left about .01" for the cut and ran the tool down the centerline of the part (Surface finish is paramount on this part and the machining lines need to be centered and aesthetic). SFM was 250 and CPT was .003". Surface finish came out amazing, no issues whatsoever....however...

Now, same batch of parts again, same tool, coolant, workholding, feeds/speeds, and material. But now I'm getting this strange tearing/wrinkled look on the surface of every single part. Could this be a result of a bad batch of titanium alloy? Coolant concentration is at 12% and the inserts were rotated to some freshies just in case. I reached out to the metal supplier and they confirmed that the alloy was the same, but they did come from two different processing plants. They even sent me the certifications for both.

Machine is a Fadal3016 88HS. Coolant is QualiChem 251c, only a month old.

I changed my SFM all the way from 200-500 and the CPT from .003 to .007, with every combination of the two in-between. Still wrinkles and tearing in the surface finish.

I'm thinking I need to get some better inserts designed for titanium too, but it's odd that my current inserts would work for me before and quit on me now.

I've attached pictures of both the good and the ugly. I know both may be acceptable in almost all other scenarios, but this is part of an assembly for a high end consumer product.

Does anyone have any insight on this? Feel like I've exhausted all my options.

 

[hvnlymachining]

Have you by chance got any of the last batch for a test run? Or a piece from yet another supplier?

Looks and sounds like batch difference problem to me but difficult to be sure without trial by comparison.

If possible, maybe hardness test?

Good luck.

 

[DMF_TomB]

Hey All,

A few weeks ago I faced about 30 of these 1"x2" Titanium 6Al-4V parts using a 1.5" 45 degree shellmill with some SEHT 43 YBG205 Inserts. Left about .01" for the cut and ran the tool down the centerline of the part (Surface finish is paramount on this part and the machining lines need to be centered and aesthetic). SFM was 250 and CPT was .003". Surface finish came out amazing, no issues whatsoever....however...

Now, same batch of parts again, same tool, coolant, workholding, feeds/speeds, and material. But now I'm getting this strange tearing/wrinkled look on the surface of every single part. Could this be a result of a bad batch of titanium alloy? Coolant concentration is at 12% and the inserts were rotated to some freshies just in case. I reached out to the metal supplier and they confirmed that the alloy was the same, but they did come from two different processing plants. They even sent me the certifications for both.

Machine is a Fadal3016 88HS. Coolant is QualiChem 251c, only a month old.

I changed my SFM all the way from 200-500 and the CPT from .003 to .007, with every combination of the two in-between. Still wrinkles and tearing in the surface finish.

I'm thinking I need to get some better inserts designed for titanium too, but it's odd that my current inserts would work for me before and quit on me now.

I've attached pictures of both the good and the ugly. I know both may be acceptable in almost all other scenarios, but this is part of an assembly for a high end consumer product.

Does anyone have any insight on this? Feel like I've exhausted all my options.

..... could be crappy metal or
some cutters you get a shiny mirror like surface above certain sfpm (a lot higher sfpm)
........just saying sometimes 10 or 20% adjustment often dont see everything and
might need much larger changes to gather info and or find limits. thats and tool
life some metals you got hard spots (often small hard to see) metal dulls cutter fast.
also sometimes take finish cut with new inserts AFTER the roughing done cause
inserts dulled doing rough machining

 

[gkoenig]

I'm a neophyte when it comes to titanium, so I am asking this more as a question than anything else - but isn't 200SFM a touch on the high side?

We launched some titanium parts last year and I am still learning the most efficient way to make them, but a big AhhHa moment was when someone I trust off of here told me to just set everything to 180sfm, take a higher chip load than I think appropriate, and send it. This advice didn't make me a titanium whisperer or anything, but it went a long way to helping me out.