selfmade Internal-cooling?

[Spartan117]

Hey there,

i'm wondering if it wouldn't be possible to build an internal-cooling-adaptor?

The only critical part is the sealing between the rotating parts, i think...
I was thinking about two possibilities to solve that problem:

1. two exactly fitting cylinders that are plugged into each other. The inner one with many grooves on it, the grooves filled with grease.
But i don't believe you can achieve high pressures with this.

2. Two Rings, one mounted on the spindle and the other at the housing, that are sliding on each other. Maybe spring-loaded. They should be very abrasive-resistant. I thought about SiC and something carbon-like. Some permanent-operation-pumps are sealed this way.
The best solution, i think, but also the most expensive. The two rings for a very small pump (diam. of the motor-shaft was 10mm) cost EUR70,-


Or did someone already build such a cooling-adaptor?
No matter if it is for top-of-spindle-mount or for the tool-holder. I just need some ideas for the sealing...

Thank you very much,

Marc

[RICHARD ZASTROW]

Rotary unions are commercially available. Try to "google" rotary union or rotary coupling.
I can not remember the brand name, but I have purchased them a few years ago.

Dick Z

[Geof]

You mean the rotating seal at the top of the spindle for 'through spindle coolant'?

What rpm and what pressure are you dealing with? The two ring seals, I think they are called face seals, are fine for low pressures and rpm but as you point out they are not cheap to buy. However they are not too difficult to build and the material for the seals does not have to be exotic; my company has several shop-built barfeeds with face seals that use Delrin rotating against brass and these give excellent service at up to 300psi (20 atmospheres) and 2000 rpm. I would have no worries about running these up to two or three times the rpm if the pressure was kept below 100 psi.

If you want to deal with higher pressures and higher rpm then you need to find out about labyrinth seals; these can run at much higher pressures and speeds but they do not give perfect sealing. The layrinth seal does not have mating surfaces that actually make contact for the seal, they have interlaced closely spaced grooves between the rotating elements, which makes for a very tortuous flow path for leaking fluid. This, combined with the rotation, induces a lot of turbulence so even at very high pressures not much fluid escapes. These are expensive and are more complicated to build.