ductile iron as a bearing

[enfield]

Can anyone help with this
we have a bearing currently its scintered iron with a steel shaft the length/ dia ratio is 35mm/16mm

The lubrication is scanty and the shaft if a reciprocating in nature, The lube temp is 90 degc tending to 120 sometimes. The oil used is 60W sae at approx 0.038 gallons pr min ( I know we need 0.041 working on that )

Now to get to the point we would like to change to a harder material . and one of the choices is grey iron class 40 ish or a ductile Iron .

The thing is I ( singular) have no experience of ductile Iron nor can find any reference to it as a bearing material. Can anyone advise , or offer a differing solution...

The wear in the original bearing is substantial, I have tried a bronze one with a higher Brinell but the same occurred....
The lubrication system is pretty hard to change ....we are working on it ,,,,,

Thank you in advance

Stephen

 

[patprimmer]

What's wrong with going to a synthetic oil with lower viscosity. It will stand up to the temperature, and should flow more readily, or is the flow limited by pump capacity rather than bearing clearance

Regards
pat

 

[enfield]

The pump capacity is the limiting , the dia of the plunger is 11mm and it rotates at 1/12 engine speed and is a double acting pump (i think ..will check)
Stephen

 

[Tmoose]

Does your excessive wear appear in patterns that point to a geometry problem like misalignment either "machined-in" or resulting from thermal or operating distortion? An edge-riding bearing can not be blamed for wearing out.

Increasing hardness gets me about a 50% reduction in wear. Achieving decent lubrication gets me 1000% reduction in wear. There may be some easy gains there.

Lower grade Iron with lots of graphite flakes provides some solid lubricant effect to provide an edge in wear resistance over the higher grades when lube conditions are poor. Similarly, bronzes with lots of lead survive scanty lubrication, where the harder bronzes with no lead wear fast and even can gall.