What's new
What's new

How to achieve the lowest friction surface after machining an aluminum channel?

martin_05

Hot Rolled
Joined
Mar 11, 2009
Location
Valencia, CA, USA
I have to machine a custom version of these Igus channels:

https://www.igus.com/product/723

I am basically integrating multiple channels into a single piece of aluminum in a way that can't be easily done by simply buying pre-made extrusions.

These extrusions are meant to work with low friction carriages like these:

https://www.igus.com/product/1157

Machining the slots isn't a problem. The question is about how to post-process in order to improve the surface smoothness and lower the coefficient of friction between the slots and carriage.

It will be very difficult and laborious to get in there to polish the surfaces unless I come up with a clever rig of some sort to use lapping compound to smooth it out. One thought I had on this front was to perhaps make an aluminum version of the carriage and some way to mount it to my spindle with a spring-loaded compliant holder. I would then program the machine to go back and forth after applying lapping compound to the channels. Other than making sure I don't get lapping compound in the coolant I think this could work well and might give me a controlled way to do it.

The other thought was to investigate if the surface could be made smooth through anodizing. I read this article:

Surface Roughness Before and After Anodizing |


Products Finishing


In it the author mentions that anodizing with oxalic acid produces much smoother parts.

I guess one of the questions might be: How does a company like Igus achieve a low coefficient of friction between their extrusions and carriages? Other than a highly polished die during extrusions the only thing left has to be a chemical smoothing process and/or a specialized anodization approach that smooths out the material.

I just ran a test with a mirror finish block I faced with my shell mill. Even though it looks like a mirror, when I compare the friction between that surface and the anodized Igus channel I have you can definitely tell the difference (with the same carriage). I then polished the surface with 2000 grid wet-sanding paper and cleaned it with alcohol. This made a noticeable improvement in friction (again, measured by feeling it by hand). I followed that by polishing with Scotch Brite Type S Ultra Fine pad (also wet). I can't say it made a difference. It's possible I should have done it in the opposite order.

I don't have anything finer than 2000 grit or polishing compound on hand. I'll have to order some and run a test.

Thoughts?
 
The process itself will reduce friction. There is also did Teflon electroless nickel which also might be an option for you.

Polishing would probably enhance the process, but I have never tried it to compare. Maybe some google time would dig up an answer.
 
The process itself will reduce friction. There is also did Teflon electroless nickel which also might be an option for you.

Polishing would probably enhance the process, but I have never tried it to compare. Maybe some google time would dig up an answer.

Yeah, I found local sources. I'll talk to them on Monday and see which of the two processes might be best for this application.

Thanks.
 








 
Back
Top