A little background first...
I work at a fairly small shop, we have two departments. Lathe and Mill. Two owners, each owns his own section. With the mills (where I work), we used this stuff called Trim E190. It worked well, but smelled awful and the rust inhibitors were sub-par.
In the lathe dept, Cimcool was used for all 3 CNC lathes.

Due to the rust problems, we switched the coolant in one of the mills to Cimcool. My experience with it has been awful. Yet the owner of the lathe dept says it is the greatest coolant.

Here is the situation:
3960RPM
.312" ISCAR ball insert cutter, 2 flute.
410 Stainless steel
Feeding at 50IPM @ .036"

The finish is awful. We have run thousands of these parts with excellent results, never has the finish been so lousy. According to the Vee Gee Refractometer, coolant concentration is 6.5%.

Does anybody have any suggestions of how to make better use of this CImcool product?

Try refact increase to 8 or 9. I have worked with CimCool and did not like it, does not have a long sump life and turns green. I think the best stuff out there is Blazer Cut, i have never had any probs.

I also am a fan of Blaser. 4000 strong is my poison(soluable oil). We run it in our mills and our one lathe. Athough with the price of oil being so unsteady I have been searching for other alternatives.

I'll third that, Blaser is good stuff, 4000 series here too. Its a soluble, so what, I think a lot of people get too hung up on having to use a "synthetic".

Msomerville, I wouldn't get too worried about the price of oil affecting coolant, its really only a small bit of the price. If worse comes to worse, drop back to the 2000 series and save the 2 bucks a gallon, though I wouldn't, since we switched to the 4000 series, I don't think I've smoked a single drill.

Phantomcow, I've never run across crappy coolant leaving a crappy finish, but I'm sure its possible. The lathe guy probably likes it because its all he knows, and in a lathe, I'm guessing at least 50% of the time, the coolant is doing more cooling than lubricating so it probably wouldn't be as noticable that its not doing its job.

Personally, with an inserted milling cutter, I would ditch the coolant and crank it up. I haven't worked with any 400 series lately, but with 304 and 316 and my most hated 321, I have much better results(tool life) and faster machine times running dry with inserted cutters and carbide endmills.

Blaser is tha bomb.

Take away the blaser for something cheaper and all hell will break loose in the shop.

Possibly look into a mist setup, I cut stainless all the time using my mist setup with Acculube 2000 the stuff works great, very good lubricity in gummy materials such as stainless, I blow it on all my cuts in a 5 axis machine, from soft steel to hardened S-7 to aluminum and everything in between, the stuff is expensive it's about 70$ a gallon but considering I use about an ounce a day it's not that bad.