Re: [ATM] OT: Machinist Question

[Richard <cnc@cncservo.co.uk>]

Hi Thomas,

Wednesday, February 14, 2007, 3:37:02 AM, you wrote:

TAM> What materials are self lubricating?

Gunmetal, Bronze and to a lesser degree Brass. Also impregnated
sintered materials such as Oilite. Some of the harder modern plastics
too, but its not really my field. There are also lubricant filled
plastics such as Nylon containing up to 6% hard grease.

TAM> I can not lubricate because dry grit will be passing through the valve.

Trouble with any material that is softer than the abrasive in that
application is that it is likely to pick up grains of abrasive and act
like a lap on whatever it is contact with. Nasty design challenge
you've got there. My approach would be to set rule number one as no
clearance anywhere is smaller than twice the maximum grain size. May
be worth a search of the patents database to see how the abrasives
industry do it. They must have already solved these problems.

-- 

Best regards,
  Richard in the UK

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