Aluminum for Diamond turning op.

[1MadMax]

I have an aluminum mirror that has very high surface irregularity and roughness requirements which is being diamond turned. We are trying to determine if there is an aluminum available in an 11" or 12" stock diameter that could be substituded for 6061 T6 (our current mat'l of choice) to improve our D.T. machined results ... any suggestions?? Stability is of greater concern than strength.

thank you, Max

 

[1MadMax]

I don't know about the tool stick-out, my thoughts are the more its extended the greater the likelyhood for vibration. The haze occurs when the system (assembled unit) is imaged, I believe it is "general" in nature.

 

[unclesyd]

Stick-out and extension are the same thing.

How are you addressing the speed as you traverse the larger disk?

 

[sreid]

Have you checked that the feed rate and spindle RPM will give you a less than 10 nm record groove depth?

 

[1MadMax]

The speed and feed for cutting the large mirror has been an item of concern for me. I suspect that a constant rpm is being used and this is contributing to the surface roughness. We are doing more analysis on the last 4 produced to see if there is a better/worst zone to the surface condition.
The record groove depth I don't know. My understanding is that the machines are capable of speed and feed compensation for large diameters ... whether this is being used properly (or at all) is something else to be investigated. Do either of you have experience with that machine function? I understand the theory but haven't had experience with it and practise doesn't always equal theory!
thanks, Max