Aluminum-to-Aluminum Gauling

[debequem]

What options are available to prevent galling and seizing between a nut and a bolt both made from aluminum?

I would assume anodizing would be one option?

I have an aluminum post about 1.5” diameter with a fine pitch thread that needs a removable cap made from the same material and thread size.

[Evan]

Anodizing will work but it will have to be hard anodizing, not decorative anodizing if the part is to be removed and replaced more than a few times. Otherwise your options are limited. Absent anodising your best bet for threads is to use an insert of different material in the aluminum cap. Straight aluminum against aluminum simply won't work. The natural oxide layer is only a few molecules thick and when it rubs off the parts cold weld together.

If you use anodizing take care to allow for part growth. This reduces the ID and enlarges the OD of parts.

[SGW]

Another consideration is the alloy(s) you use. Some are a lot more prone to galling than others, and I think there are alloys designed to reist gallling. There may be information about that on some of the aluminum manufacturer websites (Alcoa, etc.)

[Frank L]

We have used beeswax for a clean thread lube.

[lbender]

debequem,

If you are going to the trouble of hard anodizing, then ask about PTFE filled as added galling resistance.

[Allan Dimmock]

Hi! This is my first post, so i hope I don't make a fool of myself ! (I hope to save making a fool of myself until later)

I am looking to make some carb slides and was considering hard anodised aluminium running in the aluminium carb bore. However, it occurred to me that a soft anodise treated with PTFE might work. Are PTFE molecules small enough to enter the pores of the anodise ? Would a product like Slick 50 ( a PTFE based oil treatment sold in the UK) be able to enter the pores in the same way as a decorative dye ? Would the PTFE stay put in the presence of petrol ? The makers of the PTFE oil treatments claim that their products enter the boundry layer of engine parts, so I guess there is some possibilty of this working.

[lbender]

Allan Dimmock,

Both hard and soft anodize are porous at the end of the anodize cycle. Commerical anodizers typically "seal" parts as the final step in the process. The seal material can be colored or teflon or any number of other speciallized treatments. By the time you get the part back, it is too late to get good penetration. So no, post treatment is not the same.

[PTSideshow]

Would a high temp anti sieze work they have aluminum and a high temp made from copper.
A guy that I use to work with used it on all manner of bolts and nuts to keep them from siezing. I know I have used them on the lug nuts, studs and rims on the truck to keep them from bonding together.

------------------
Glen
Been there, probally broke it doing that

[wierdscience]

In this day and age yu can have aluminum parts coated with Teflon pretty cheap.Tef coat one side anodize the other,just a thought.

[Frank L]

This reply is to Allan Dimmock about the carb slides.
Most anodizing on slides does not appear to me to be "hard". Why would you need a hard finish? Slides have relatively little side loading and with and air filter should see very little grit.
As an alternative search the web for gun finishes. You may find one you like. I don't recall the site I have checked out more than once.
Are you working on Mikuni carbs? What are you trying to attempt? Just curious as I ride bikes and sleds.
Have fun with your project! Frank