Corrosion between machine table and 6061 subplate: Real World results

[Matt@RFR]

There are a shit ton of threads talking about corrosion between machine tables and aluminum sub plates. To the best of my searching ability, nobody has ever shown pictures of actual results after some time... Until now!

Haas VF-2
6061 Sub plate, raw machined surface on table
Pretty sure I put a very thin layer of motor oil on the table
3.5 years:



Obviously we've scraped all the chips and loose rust out in the picture of the table, but no real cleaning has been done at all. There is actually ZERO corrosion at the interface around all the bolts. It's only in between the bolts where there is slight corrosion, but I'm super happy with this. After repairs (stupid X axis...) it's going to get put back together exactly as before.

But wait! There's more! After 3M pad cleaning:



And some pitting in the T-slot sections:

 

[Kapster]

Thanks for the pictures! What kind of coolant do you use?

 

[Matt@RFR]

I meant to mention that. We use Oemeta Hycut, which is their 2 part coolant, and we mainly cut plastics and aluminum with some 304 and various steels thrown in for good measure, and a rare smattering of Titanium.

 

[kazlx]

Nice! I did spray a film of LPS3 on my table before setting my vises, so I'm hoping that helps keep it nice.

 

[Matt@RFR]

Nice! I did spray a film of LPS3 on my table before setting my vises, so I'm hoping that helps keep it nice.

We've been using LPS on our vises and it works well. I am tempted to use it on the subplate when it goes back on, but the engine oil worked so well that I don't want to take a chance on anything else.

I'll update in another 5 years.

 

[Vancbiker]

That worked pretty well. Probably the only thing I have seen do better is aerosol Cosmoline. You have to be pretty quick at putting the subplate, vise, or fixture on after spraying so it doesn't harden on you before getting everything bolted down. The trade off for better protection is the difficulty of disassembling later. It kind of "glues" things together. Jack screws or a pry point is nice to have when the time comes.

 

[G00 Proto]

I worked very briefly for a horrible company making aerospace parts... crookeder than a dog's hind leg, but that's a story for much later.

They had sacrificial aluminum sub-plates on all of their machines. I have no idea what they did for pre-treatment, but I bet is was superficial. On some of the machines, the corrosion was very bad. But on a couple of the machines, they anodized the plates before bolting them down (because they thought it looked cool in pictures). For some reason the anodized plates did not corrode the table whatsoever. I was only there briefly (I literally gave 45 minutes notice... a personal record), so I never delved deeper, but I almost wonder if it isn't galvanic corrosion between the aluminum and the cast iron exacerbated by any electrolytes in the coolant (in that shop, the electrolytes were probably urine and chew spit).

 

[kazlx]

I worked very briefly for a horrible company making aerospace parts... crookeder than a dog's hind leg, but that's a story for much later.

They had sacrificial aluminum sub-plates on all of their machines. I have no idea what they did for pre-treatment, but I bet is was superficial. On some of the machines, the corrosion was very bad. But on a couple of the machines, they anodized the plates before bolting them down (because they thought it looked cool in pictures). For some reason the anodized plates did not corrode the table whatsoever. I was only there briefly (I literally gave 45 minutes notice... a personal record), so I never delved deeper, but I almost wonder if it isn't galvanic corrosion between the aluminum and the cast iron exacerbated by any electrolytes in the coolant (in that shop, the electrolytes were probably urine and chew spit).

Well, anodize is non-conductive, so I would assume that only helps the situation.

 

[sheys]

I will second Matt's experience. I've had a 6061 subplate on a 30x16 VMC for 12 years now and when I pull it off (every 3 years or so) the table looks like Matt's. A few minutes with scotch-brite and most of the staining is gone. I haven't yet seen anything I'd call "corrosion".

I do mostly aluminum with steel and brass thrown in. Blaser 2000 coolant. I put a thin film of way oil on the plate when I reinstall it. My machine regularly sits for weeks at a time with no use, though I couldn't say whether that's better or worse for the situation. The plate started at 1.5" thick and skim a few mils off of it a couple times a year. At the rate I've been going it'll outlast the mill!

 

[DavidScott]

Another vote for anodizing. I have been testing a hard anodized plate and have yet to see any corrosion so I think this is the way to go if you want the best protection for your table. This is on a table where I am limited in what coolant I can use so have constant problems with corrosion under the raw aluminum fixtures. No photos but I have seen machines where the pitting was .01"-.02" deep under the aluminum plate. No idea if there was any preventive measures taken before bolting it down or how long it had been on the table, but it can get real nasty. Coolant was TrimSol.

 

[Fal Grunt]

Thanks for the real world results!

That is less corrosion than I get after removing a vise that has been sitting for a few weeks!

Where did I put that quote...

 

[Cycle1000]

You had me @ shit ton
I used motor oil when I first started with good results but I found Gibbs 20ish years ago and use it for everything including subs. Works great. I always thought that anodizing would work also
Gary