Ductile Iron Surface/Roughness Finish

[JustinMEEE]

Hello everyone,
I am wondering how surface finishes or surface roughnesses are typically specified for ductile iron shafts. More specifically, I am dealing with bearing surfaces in a forced lubrication system. There will be aluminum rods attached to the ductile iron shaft in a crank-piston mechanism. In other words, the two bearing surfaces will be aluminum and ductile iron with oil constantly supplied.
I've found Ra, Rp, and Rv values to describe the surface roughness, but what are typical values?
Also, I am aware that when grinding ductile iron there will occur a cat-tongue effect on the ground surface. When this occurs the shaft can be reliably rotated with the cat-tongue hairs, but not against them. The two methods I've found to eliminate this effect is either using a super finish or grinding in both directions. My remaining question is: "How is this cat-tongue effect quantified?"
To summarize, does anybody know how to quantify, measure, and specify surface roughness on ductile iron bearing surfaces in forced lubrication systems?

Thanks,
Justin

 

[unclesyd]

I would get in touch with the following companies and discuss your requirements.

http://store.flexbar.com/merchant2/...LX&Product_Code=16023&Category_Code=Suf-Rough

http://www.gaging.com/garmicrofinishcomparators.htm

I would also contact the DIF society to see what literature they have. At one time they had a very good brochure that discussed your OP in some detail.

http://www.ductile.org/

 

[SincoTC]

Have you tried searching for tribology?

here's an organisation in the States

http://www.stle.org/