Coolant or Air Blast

[bigprody]

I have an application where I am going to be doing about 2 1/2 hrs of High-speed milling in annealed A-2 . I will be using a 3/8 "Helical" end mill, 10% step over, .500 DOC. The speeds/feeds are worked out with the help from their calculator. So the question is Air Blast or Coolant?

[jlw™]

air blast... all day baby

[jlw™]

literally, it'll run all day.

[crazy^millman]

Air blast no coolant it will shorten the tool life if you use coolant the whole thermal shock to the . Make sure the air is getting the chips out of the way. I have been recommend air knifes to customers for large volume chip movement like 3 to 5 yards a shift. Exair makes some nice ones.

[Matthew Hajicek - Singularity]

1 hour ago, C^Millman said:

Air blast no coolant it will shorten the tool life if you use coolant the whole thermal shock to the . Make sure the air is getting the chips out of the way. I have been recommend air knifes to customers for large volume chip movement like 3 to 5 yards a shift. Exair makes some nice ones.

Interesting.  Which of their part numbers, and how is it applied?

[Sticky]

Contrary to what is hip right now, there is no hard and fast rule about air or coolant. I recommend you try both if it is going to be a repeat job, you might find some tools and or operations perform better one way or another. We use through the spindle airblast using TSC style holders and tools, works great, especially with endmills with a hole through the axial center.

A few potential problems exist with air that need to be kept in mind depending on the type of work you are doing.

-Airblast typically puts more heat into the workpiece, which can affect tolerancing.

-Machining dry leaves "dust" all over the part and inside the machine, this can cause problems with in process inspection.

 

I often find that we do both airblast and TSC on steel parts, often roughing is done with air, and all finishing, drilling and tapping is done with TSC. We are mostly processing 35RC+ steels and stainless materials with tolerances of +/- .0002"

[crazy^millman]

18 hours ago, Sticky said:

Contrary to what is hip right now, there is no hard and fast rule about air or coolant. I recommend you try both if it is going to be a repeat job, you might find some tools and or operations perform better one way or another. We use through the spindle airblast using TSC style holders and tools, works great, especially with endmills with a hole through the axial center.

A few potential problems exist with air that need to be kept in mind depending on the type of work you are doing.

-Airblast typically puts more heat into the workpiece, which can affect tolerancing.

-Machining dry leaves "dust" all over the part and inside the machine, this can cause problems with in process inspection.

 

I often find that we do both airblast and TSC on steel parts, often roughing is done with air, and all finishing, drilling and tapping is done with TSC. We are mostly processing 35RC+ steels and stainless materials with tolerances of +/- .0002"

Sticky I was using air 20 years ago so what some might be calling hip I was doing some time ago. I had to be taught coolant is not always the best way. I took an air gun and took a zip tie and strapped it over the handle and then zip tied it to the side of the spindle and could get 10 times the life out of a tool running it with air that way verses coolant. When you are cutting for days on some parts it is nice to have something that will hold up, but guess I was hip back then and didn't realize it.

I use to run a positive Mil-Tec face mill for 8 hours in HRS and never once put the 1st bit of coolant to it again almost 25 years ago.

[bigprody]

Thanks for all the info. We usually go with air blast for the HS roughing. I just have not machined too much tool steel, this job has quite a bit of HS time in A-2. It looks like air for roughing, coolant for finishing.

[crazy^millman]

33 minutes ago, bigprody said:

Thanks for all the info. We usually go with air blast for the HS roughing. I just have not machined too much tool steel, this job has quite a bit of HS time in A-2. It looks like air for roughing, coolant for finishing.

Does the machine have a spindle chiller? You will need to watch heat creep into the spindle from the tool and holder getting hot. I have sometimes put a off position Thru Spindle with coolant to cool down the tool and spindle when my machine didn't have a spindle chiller. Heat gun is your best friend and you can just hit the spindle while it is running normal stuff and when you are running dry. If you see it starts to go up then you will have to see what is better poor tool life, but not heating up of the spindle a little heating up, but not that is hurting the machine. That is where looking at all factors as part of the process is key. Not just blanket statements.

[crazy^millman]

21 hours ago, Matthew Hajicek™ - Conventus said:

Interesting.  Which of their part numbers, and how is it applied?

Matt, I will have to go back and look it up. We have chips going every where on certain applications for a customer and this proved to be an effective means to help keep the chips washed down with air. Not a coolant machine strictly mist or air on this and many others for the customer.

Here is one system I have seen in these applications for misting parts do an excellent job. Yes SS and Ti parts are being done this way.

Unist

[nickbe10]

23 minutes ago, C^Millman said:

That is where looking at all factors as part of the process is key. Not just blanket statements.

In Europe where the environmental regs are stronger they have been running mostly dry for decades now. At first of course all the machinists rolled their eyes when the regs came out. Then people started to think about it. Eliminating coolant, now we save money not buying coolant, no more hazardous waste disposal no more coolant floods, no more processing chips before recycling....etc....and it was embraced and they are still way ahead of us on this.

So there is a lot to be said for running dry as much as possible.

24 minutes ago, C^Millman said:

Yes SS and Ti parts are being done this way.

back when I was running large Ti hogout parts (mid 90s) Stellram applications manager sent me a copy of a Masters thesis which looked at mist systems for Ti. When set up correctly the amount of mist is just enough so that it is entirely vaporized by the heat generated leaving dry chips and part. Pages of heat transfer calculations but quite interesting.

Have been running 15-5 at 700 sfm with an airblast since about that time too.......

[F10Brandon]

2 hours ago, bigprody said:

air for roughing, coolant for finishing.

That's pretty much my motto

[Leon82]

MQL is option also

[huskermcdoogle]

The only material I have never been able to master dry is structural steel.  Certain ops like milling, no problem, all day long.  But drilling 5xd, through a plate stack consistently with inexperienced operators, forget it, trust me I tried.  Needed the coolant pressure to get the chips out (thru air wasn't enough), and the walls were still galled up, but darn did I have stable long tool life.  We were working on implementing mist through tool, MQL wasn't really the best term for it as the lube and air aren't mixed at the tool, little heavy on the lube side to get anything out of it, but our tool shop was slow in putting coolant tubes into the holders so we never tested it in the main 5xd application.  I think it would work, and likely get equal or better tool life.  I ran the crap out of those drills and never burned a corner on them, it was always built up edge right in the middle of the lip that took them out.  IIRC we were running double the recommended high speed for those drills and just below the max on feed.  My brain wouldn't let me go any faster. 

Also had trouble finishing some bores at high speeds dry.  Chips liked to weld to the bore and cause the inserts to chip out.  Overall in that material it was more productive time wise to drill, finish bore, and tap with coolant than without.  Even after having to clean off the parts afterwords.  (large fabricated chassis)  

Anyway, toolsteels and aluminum, all do very well dry or with MQL in my experience.