[IowaNAV]

Hi all, new to the forum. I'm an engineer with very little manufacturing training who has been teaching himself, so please take it easy on me

Backstory (feel free to skip): I lead a research group at a university, where we frequently manufacture small parts for robotics or instrument applications. We run a lot of 3D printing, and I recently rescued a 440 from a teaching lab after a student yoinked the Z-axis ball screw right out of the coupler and nobody cared to troubleshoot/fix it. I've spent the last 6 months teaching myself how to use it, and am now getting around to training some of my students to use it for their fabrication needs that cannot be met with 3D printing alone.

We do very small volume (mostly one-off) in a variety of metals and plastics - 6061 Al and mild steel being the most common. The machine came with the enclosure and flood coolant kit, and I've added an SMW fixture plate (anodized 7075 with a layer of B'laster surface shield between it and the table), fogbuster, passive probe, and some other goodies.


Here's my dilemma/question: I've been struggling with cooling/chip evacuation on Aluminum parts, fighting chip re-cutting and welding. The fogbuster helps, but now all the chips end up just sticky enough that a brush is almost useless for cleaning the machine. This is even worse with steel, where my light cuts are producing needle-like chips that make me feel like I've come out of a fight with a very small, very angry porcupine. Coolant residue (or worse, way oil that drips into the pan) mean that the shopvac, brushes, and rags don't really clean the machine up to my satisfaction.

What about washdown retrofits like this (https://www.youtube.com/watch?app=de...=9FfYtQnqr7E)? I have the flood coolant kit, but I've been hesitant to use it because I figured the fogbuster/compressed air would be sufficient and less messy. I'm not sure I want/need flood coolant for the actual cutting right now, but I'd like a way to clean the machine better. So...

(A) Will using coolant for washdown invite a lot of additional corrosion (especially under the SMW fixture plate)?

(B) Has anybody used the stock coolant pump to power a washdown sprayer on the 440?

(C) Should I just dive in and use flood coolant for both cutting and washdown?

Thanks!

[joeavaerage]

Hi,
My own built mill is all cast iron and steel, and not in anyway treated or painted. I use water soluble oil and water at around 35:1. I don't really get any corrosion,
a little surface rust but that's about it. I've had this machine in service for 3.5years with little or no rust.

I use a 1/8th hp single phase pump with a 12l tank. Had it for nine years, and it does OK, but I want better. I recently upgraded my spindle (3.5kW(S1), 3.4Nm(S1), 10krpm (rated), 40krpm (max), HSK32E tool interface)
and am now making a lot more chips. Want a much larger volume tank, about 200l, with 600 x600 gauze filter and a three phase pump producing something like 80l/min.

I really want to wash the chips 'down the drain', and you just need a lot of volume. I also have two stainless magnetically coupled (no pesky shaft seal) gear pumps that do about 5l/min but will easily get to 100psi.
I want a portion of the main coolant flow to divert through a fine gauze and/or paper filter and feed these pumps with that extra filtered coolant. They will 'squirt' out really nice and flush the chips away from
the cutzone........and that is the whole secret to milling aluminum in my opinion.

(C) Should I just dive in and use flood coolant for both cutting and washdown?

That's what I do.

I'm hoping that when I get my new tank and pump running that washdown will be quicker and more effective.

In my opinion the trick to using flood coolant well is to have really good coolant containment around the milling area, a readily accessible, readily serviceable large area filter to get rid
of chips and a large tank.

Cleaning up coolant leaks gets very old very quickly. Wrecking a part because the coolant got blocked somehow, somewhere and you did not notice it until the part and tool are wrecked
also gets very old.

Things like nozzles that constrict the flow are exactly the sort of places where chips/dross entrained in the coolant flow block up. Gauze or other filters that get too loaded with chips too regularly
are another source of leaks or overflows. Anything that minimizes leaks, blockages and overflows is highly worthwhile. University students are notoriously ham-fisted, and teaching or rather demonstrating
proper industrial coolant handling will stick with them forever.

Craig

[metalmayhem]

if you already have the flood coolant kit then I say hook it up , you'll thank yourself later .
Cutting fluids have rust inhibitors . Coolant / cutting fluid does not cause corrosion , or , it shouldn't cause corrosion if it is proper machining fluid mixed at an appropriate ratio .

What stuck out to me in your question was "additional corrosion " , does this mean you have corrosion issues .

Feeling like you fought a porcupine is the nature of the beast , best you can do is get used to having nail clippers in your pocket to pull the slivers out

[CL_MotoTech]

My mill (G0704 Conversion) rusts far less with coolant than it did without it. Surface rust basically isn't an issue. My vises come on and off the table on the regular though. I can imagine if I left a vise on for a month or more that it would get pretty nasty under it.

I find that high volume not necessarily high pressure (though it has to be more than a drip) works quite well with aluminum. High pressure is needed for deep pockets though, which is where my DIY solution lacks.

[joeavaerage]

Hi,
until a few weeks ago I used one of the very common segmented coolant nozzles with a magnetic base.
The coolant pump has modest pressure so it produced a modest volume but quite nice velocity, guessing around 1000m/s and 5l/min.

A few months ago I bought a new spindle and I am now producing a lot more and bigger chips. Where, with my 800W 24krpm spindle I might have used a 1/8th tool
now I use 6mm-8mm-10mm tools which result in much bigger chips.

With this change I was being beset with coolant blockages in the nozzle. Inside there is a 3mm -4mm plastic tube, and a right angle joint at the mag base, just ripe for any
entrained swarf to block up.

I have removed and discarded the old nozzle and now use just a 3/8 brass tube. It does not suffer the restrictions and is very VERY much less inclined to block. As a result the volume
has increased, maybe 10/l but the velocity has dropped to say 400mm/s.

Overall this new combination is better. I don't think the increase in volume is as important as its consistency. If you don't get blockages then the job is not likely to be starved of coolant.
When you are making parts where coolant plays a major role in your cutting strategy, then a temporary absence of coolant flow can wreck the job.

Rather than focus too much on either volume or velocity I would give thought to the coolant flow being consistent.

When I'm using coolant, I'm staggered at just how quickly it disappears. Its nothing for me to have to top up 8l in a days work. My guess is that when the coolant hits the high speed
spindle it mists up, and then the water evaporates. Its not impossible that the mist is escaping and permeating throughout the workshop, but I can't see it. Anyway the upshot is that you want
a good size tank otherwise you will end up with an interrupted coolant flow at some stage during the day. Consistent coolant flow is the answer to making consistent parts. Inconsistent coolant
flow is a great way to produce a lot of scrap parts and not just a few buggered tools.

Craig

[IowaNAV]

I use a 1/8th hp single phase pump with a 12l tank. Had it for nine years, and it does OK, but I want better. I recently upgraded my spindle (3.5kW(S1), 3.4Nm(S1), 10krpm (rated), 40krpm (max), HSK32E tool interface)
and am now making a lot more chips. Want a much larger volume tank, about 200l, with 600 x600 gauze filter and a three phase pump producing something like 80l/min.

I really want to wash the chips 'down the drain', and you just need a lot of volume. I also have two stainless magnetically coupled (no pesky shaft seal) gear pumps that do about 5l/min but will easily get to 100psi.

That's interesting. I think the stock coolant pump is only 1/10 HP, and the tank is about 15.5L. I might look into beefing up the pump, but your point about managing/containing coolant is well taken. The machine sees sporadic use, and may go unused for a month between projects. Like I said, we are a research lab that uses it for one-off parts when our University machine shop is slammed or we're still iterating on designs and don't want to sink the cost into having others make parts quite yet.

I'm not really hurting for better cooling (usually). I can afford to take light cuts, and the fogbuster seems to do the trick for aluminum. I just got to thinking "Hey, the coolant pump is there. Why don't I try using it primarily for washdown through a hand-held sprayer to simplify clean-up?" Who knows... I may end up realizing that flood coolant is vastly superior to my mist system and make the leap, but for my planned application, a clogged nozzle won't cost any parts or tooling.

What stuck out to me in your question was "additional corrosion " , does this mean you have corrosion issues .

I misspoke. No current corrosion (except for some surface rust on the outside of the spindle cartridge that came with it from it's old home). My question was whether I'd be inviting corrosion by using flood coolant (for cutting or for cleaning) when I have a fixture plate more-or-less permanently bolted to the table. Seems like trapped moisture might become an issue...?

My mill (G0704 Conversion) rusts far less with coolant than it did without it. Surface rust basically isn't an issue. My vises come on and off the table on the regular though. I can imagine if I left a vise on for a month or more that it would get pretty nasty under it.

I find that high volume not necessarily high pressure (though it has to be more than a drip) works quite well with aluminum. High pressure is needed for deep pockets though, which is where my DIY solution lacks.

That's reassuring. As I mentioned above, my fixture plate is intended to be a permanent addition to the table. I'll pull it for regular cleaning and to renew the rust inhibitor layer, but I don't know how well that rust shield (B'Laster Surface Shield) will hold up if moisture works its way under the plate.

The more I read, the more I feel like I'll end up trying the flood system for its intended purpose eventually, but I've been fairly happy with the mist system running TRIM mist for now - except for the sticky residue. The nozzle is very focused, and does a great job of clearing chips out of pockets. Lubrication is probably not as good in deep pockets, since less of the mist makes it to the tool itself, but it hasn't failed yet -- barring the times I was pushing some HSM paths with fairly aggressive tool engagement and bogged the machine down, leading to a lot of rubbing and welding.

Here's the current setup. First image shows the jury-rigged washdown sprayer. Second shows the fixture plate I'm worried about (without the washdown hose).

I'm going to see how well the pump moves coolant through the little PU coiled hose and nozzle first, then I'll add the coolant nozzle itself back in. My next challenge is cleaning - it turns out that the last custodians of the mill didn't empty the coolant sump completely - just enough that I couldn't tell anything was in there. Scum galore, and I swear some of it looks sentient. Going to run some simple green through, followed by a biocide before I actually fill it up with coolant.

[metalmayhem]

I misspoke. No current corrosion (except for some surface rust on the outside of the spindle cartridge that came with it from it's old home). My question was whether I'd be inviting corrosion by using flood coolant (for cutting or for cleaning) when I have a fixture plate more-or-less permanently bolted to the table. Seems like trapped moisture might become an issue...?

any trapped moisture should contain oil from the coolant which contains the rust inhibitors that I had mentioned . It's always a good practice to add a layer of waylube oil to the table before laying down a fixture plate . If it is held down flat then that protective layer of oil can last for years . What can cause corrosion is a reaction between 2 different metals , this can also be minimized by the layer of oil and it is fairly minimal of a problem anyhow .
I have aluminum fixture plates that never leave my 440's and I only swap them out every few years .for new plates The last time I swapped there was very little signs of rust and a quick stone to the tables had them looking like new again with little effort .
The important factor to preventing corrosion is keeping the coolant concentrates at the recommended ratio or higher

I think the stock coolant pump is only 1/10 HP, and the tank is about 15.5L. I might look into beefing up the pump,

I don't have the stock pumps but that should supply ample coolant for your needs

[joeavaerage]

Hi,

I may end up realizing that flood coolant is vastly superior to my mist system and make the leap, but for my planned application, a clogged nozzle won't cost any parts or tooling.

I'd be prepared to bet that you'll revisit that.

If I get an inconsistent coolant flow very often I end up with wrecked parts. That is to be sure because I have optimized the cutting to take advantage of the cooling/chip evacuation.
Interestingly it is plastics which are the most subject to wreckage to to insufficient coolant. Built-Up-Edge happens so quickly and buggers things so badly. Next worse is steel. Without cooling the tool
heats up so fast, and once it does you've just wrecked a $70 tool. I can't afford those sorts of mistakes. Aluminum is a bit more forgiving, not much mind, but some. Brass is probably the best
without coolant, it makes such nice chips, nonetheless I use coolant on brass too, the finish is just so much better.

Craig

[CL_MotoTech]

I think I used a 2600gph water feature pump for mine. It only has about 3 feet of head pressure and I run five nozzles. Flow is almost certainly limited by the 5/16 hose that feeds all five coolant nozzles. I got rid of the bendy snap hose because it was always moving or getting in the day. With TTS it's pretty ideal because tool stickout tends to be very consistent. The only time I get into issues is with drills and deep pockets. My fly cutter is always interesting. I honestly don't adjust the nozzles ever.

My tank is 45 liters but only about 32 liters of it usable coolant. 8 hours of run time will cost it about 40% of it's collant to just straight evaporation via the aforementioned atomization. It looks like smoke coming off the tool when I am full bore roughing.

I use a completely different pump for wash down. Two seperate circuits but from the same tank. There are some benefits to that. For example, I can feed hold and blast out pockets with the wash down hose. Solving that issue when it arises.

[joeavaerage]

Hi,
I need a bloody parts catcher. Just made twenty little brass washers, but can only find 14 of them. Dirty little b****tards!

Maybe some sort of sieve I can wrap around my vice, loosing these little parts is frustrating.

Craig

PS Found two in the coolant filter, where the others go I'll be damned. Just like taxes...'up and vanished'.

[joeavaerage]

Hi CL_MotoTech,

I use a completely different pump for wash down. Two separate circuits but from the same tank.

I really like the sound of that idea.

I have a 1/2hp 3 phase motor that I was going to use for the pump and direct a portion of its output through an extra filter stage, and thence through a high(er) pressure pump for jet directed cooling.
The motor is rated at 370W (1/2hp) at 1300rpm (50Hz), but I have used it with a VFD and taken it up to 4000rpm, at just over 1 hp. Not planning on pushing that hard, But I feel sure that I could get 3/4hp
reliably.

Then you came along with your idea, and now I'm thinking that I'll use the one motor but have two impellors/pumps on the one shaft. You see I was always planning on making my own pump,
not really because I need to or think that I can do better than everyone else....but because I want to try. That's the hobbyist in me speaking while the hard nosed engineer says go and buy one.

I was planning on milling the pump housing out of aluminum, I have some 32mm 6061 plate set aside for the purpose. I'm now thinking to have the shaft pass through one pump and drive
a second underneath it. The impellors I'll make out of acetal, I have plenty of that on hand, it is my preferred plastic for machining. The pump bearing, just one, will be a teflon bush, with the shaft running
through it. As it will be submerged in coolant, I'm hoping the lubricity of the coolant will mean a reasonable life span. A year would be nice......have to wait and see.

My thinking at this stage is that the teflon bush needs a reasonable bearing area, thus I'm thinking a 12mm, maybe 16mm shaft, and the length of the bush be about the same, in the region of 12mm to 16mm long.
The acetal I have in stock is 25mm (nominal). Therefore I was thinking that the larger of the two impellors would be 25mm thick, whereas the smaller of the two need only be 15mm thick.
If I stack two 32mm aluminum pumps housings atop each other then the housing with the smaller impellor would have 32mm -15mm=17mm thickness leave in the base, and that would be ideal for the teflon bush.

Might draw up a sketch or two. More anon.

Craig

[joeavaerage]

Hi,
I'm much better at making stuff than I am drawing sketches.

This is the larger of the two impellors, it is 60mm in diameter but the blade depth is 20mm. This is hopefully the larger volume output but at lower pressure.

My intention is the the second impellor will be bigger in diameter, 75mm, resulting in higher pressure but the blade depth will be 10mm, so lesser volume.

Craig

[joeavaerage]

Hi,
Just finished the second pump housing and impellor. That's me done for the day.

Craig