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Does grease in the electrolyte cause problems?

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  • Does grease in the electrolyte cause problems?

    The reason I am asking is this: I saw the agitation post by NeoMoses and liked his idea of a pump. So I bought the same pump and set up it up essentially the same way.

    All seemed to work well for a little while, although shortly after getting it together I noticed the solution had streaks in it, which I realized was grease from the pump. Then I began to have problems, unevenness mostly, and a chalky residue that was noticeable after dying and then drying. After sealing, the residue would wipe off some off the time, but on the black it was more difficult. The only thing I changed in my process was the adition of the pump.

    I came to the conclusion that the grease was the probable cause of the problem(s), so I took the pump out and cleaned the grease out of it, skimmed what I could from the tanks, and wiped the tank sides down around the solution line. This didn't make any noticable improvements.

    Latter I added a little detergent a couple drops of Dawn dish soap and a few sprinkles of the SP cleaner, figuring I had little to loose as I was expecting a change to new solution was the only thing to fix this. It got a lot better, so I decided to tear the setup down to completely clean the whole thing up properly and replace the solution since I had reason to believe I had isolated the problem. I found the pump was shot, which wasn't a total surprise since I had removed the lubricant, it ran maybe a total of 72 hours as I had left it on over night a couple of times.

    I bought a Little Giant 2-MD-HC high corrosive magnetic drive 510 GPH pump to replace it, and just assumed the pump chamber would be free of a need of grease and would solve the problem. Today I was looking it over, and found it uses grease in the pump chamber too, as it is mechanically very similar to the smaller Lifetech 4550, (although heavier duty in construction and is not submersible), and the armature and impeller run on a fixed ceramic shaft. I cleaned the grease from it, and ran it for a few seconds on the bench, and could sense that the armature was chattering on the shaft and will likely fail if run like this. The solution may get rid of the chatter, but that?s probably too much too expect and it would still probably fail soon. I may try running it in water some to experiment anyway.

    I realize many use air for agitation and some cooling, which I haven?t ruled out. I have a small oil-less compressor, which I can use, but I would really prefer the pump. For one thing, I expect I will want to set up a titanium coil chiller in the not so distant future and assumed I could plumb it into the system.

    After all this, I am left with the question of what pumps are suitable for an anodizing tank, and now wonder if the grease was the root of the problem or not? I may have been better off to get the chiller/heater unit sold on the site here, I would have to assume that it doesn?t have any lubrication issues that are incompatible.

    I apologize for the long post, but wanted to include enough information to up the odds of getting good answers. Any comments that would help answer my questions would be appreciated.

  • #2
    The presence of any grease or oil in the electrolyte is very bad. This alone will probably cause you to flunk the sheeting test.

    I have a Model 3-MDX, which is slightly smaller than yours but appears otherwise identical. I've haven't yet used it for anodizing, I intend to use it in series with a 1/4 HP chiller, that has it's controller modified so that it will chill down to 0 deg. C. Small scale hardcoat experiments, obviously. Anyway, I took it apart and it has some sort of silicone (?) lubricant in it too. The lube has to go.

    Contact customer service at Little Giant and see what they say. Tell them the acid in question is 5% by volume sulfuric, I'm sure they will ask.. Your pump (and mine) should be fine for this. Please post what you find out.


    • #3
      I haven't noticed the grease in my tank, and I've had that pump submerged for almost 4 consecutive weeks now. No problems yet, but I'm not going to fool myself and think that there won't be any ever. We'll see how long mine lasts. However, I have left the grease on the impeller shaft. I would expect it to continue to turn, but if I see the grease on the surface of my bath, I'll be forced to try a different agitation solution.


      • #4
        Fibergeek, thanks for confirming the answer about grease.

        I am running a test batch tonight, after setting it all back up. The pump does not sound bad now, it appears the liquid does help. Of course there are still issues that need to be answered for long term, so I will talk to Little Giant and do some other investigation.

        NeoMoses, I may not have described it exactly right last night. The grease didn't make a film like oil would, but kind of floated around in little gobs. There was an unmistakable accumulation of grease film around the waterline on the tank and cathode though.

        Thanks for the comments and help. I will post back with what I learn.


        • #5
          Since I find myself in the same situation as M_D; I'm concerned and a little perplexed, it seems to me, that most processes where acid solutions are pumped won't respond well to the presence of grease (any kind of grease) not just anodizing. I wonder if this is a preservative, intended to be removed before use.

          NeoMoses' observation that some grease belongs on the impeller shaft makes mechanical sense. We must be doing something wrong.


          • #6
            First, I need to clarify this paragraph I wrote, as it seems contradictory and confusing: "NeoMoses, I may not have described it exactly right last night. The grease didn't make a film like oil would, but kind of floated around in little gobs. There was an unmistakable accumulation of grease film around the waterline on the tank and cathode though. "

            What I meant was there wasn't an oil slick floating on the solution surface, but there was a film that collected on the tank and cathode at the water line.

            I?ll add this about the first pump, the first day after use it would not start. I disassembled it expecting to find that the electrolyte had permeated the motor. What I found instead was the armature had seized to the ceramic shaft. It appears it may have been a reaction between the grease and acid/water. That is when I cleaned the pump up, but the damage to the solution was done.

            I haven't had time to call Little Giant yet, but as this is important to me I will do so and post all that I learn.

            I did do a batch of perhaps 30 parts last night, and feel there was certainly a problem that was cured (until the next mishap, of course). I dyed the parts 3 colors, black, blue, and red. I still have a problem with the black and red.

            The black problem is more noticeable, checking the part a few minutes into the dyeing process reveals a nice clean surface, but as it remains in the dye longer to build a solid color it builds a film of dye that clings to the part that cannot be rinsed off with normal water pressure. I wipes off though. If left to dry, it leaves a chalky dulled surface. This concerns me, as it will not be practical to clean part in this manner on an extended basis. For the red, it does the same thing but not as bad. It may be the dyes was contaminated from the electrolyte tank, so I will mix a little batch of fresh dye and give that a try. I have seen on various occasions the chalking on parts we send out for to be anodizing, so I know there are issues that need to be controlled, only I need to isolate them. I have read the Caswell trouble shooting section, which may help as I have time to work through it.