Re: [CAD_CAM_EDM_DRO] Re: What makes a machine CNC ready?

turbulatordude wrote:

>--- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers <rogersmach@...> wrote:
>
>
>>Another thing being over-looked is the type of materials for each.
>>
>>
>Acme screws are soft and generally not heat-treated at all, ballscrews
>are case heat treated to 65-72 rockwell
>

72 Rockwell C scale? Yikes, that's HARD!

>And, since wear can only occur when the oil film is not sufficent to
>keep the nut and screw from contacting, or if there is debris in the
>oil, life of the screw *can* be longer than the ballscrew.
>
>
>

Actually, the wear is not abrasion but fatigue, due to the compressive
loading of
the balls. Eventually, the material right where the balls roll fatigues
and starts
to break up. That normally takes millions of balls rolling past the same
spot.
This is the same failure mechanism as on ball bearings, and why they get
rough,
instead of just loose.

Jon