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Coating the inside of telescoping aluminum tubing?

I am building a piece of equipment using 6061 T6 that uses a telescoping frame to adjust for height and has a secondary aspect that uses 1/2 inch rods sliding into a length of extruded aluminum 6061 t6. I will be powder coating the finish on the outside but am not sure what I need to do for the inside telescoping piece or for the rods and mating section.

The size of the largest piece will be triangular roughly 18 X 20 X 3 so it would be slow to anodize a bunch of pieces, but I am also concerned with the chromate process and its durability. I am also interested in minimizing my regulatory issues if possible.

I am just starting out as a manufacturer and your input is appreciated. Since the inside aspect of the tubing will remain open to the elements, how would I seal the chromate deposited inside the tubing if chromating provides a strong enough surface.

If I powder coated the inside of the tubing, would it be durable enough to withstand the sliding of the mating piece?

I am using weight plates mounted on one aspect, is standard anodizing or chromating with a powdered topcoat tough enough to prevent from being defaced or would these areas warrant hard coating?

Thank you in advance for your input. Shawn Arstein

Shawn Arstein
Product designer - San Antonio, Texas
January 26, 2011

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January 31, 2011

Aluminum against aluminum is normally a problem.
No one can tell from your description of what will not work as it also involves loads, cycles and times.
It is very difficult to apply any coating on the inside of a tube other than a dip coating, which most do not like wear.
You may need to go to bushings or seals with lube trapped inside of the tube.

James Watts
- Navarre, Florida