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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Bushing material
I want to spin a nylon shaft in a plain bearing/bushing at low rpm. Is
the choice of bushing material critical? Will brass or copper do? As a matter of general principle should the shaft and bushing be made of different material? What would happen (for argument's sake) if one spun a brass shaft in a copper bushing? Thanks, Michael Koblic, Campbell River, BC |
#2
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Bushing material
On Aug 28, 8:18*pm, wrote:
I want to spin a nylon shaft in a plain bearing/bushing at low rpm. Is the choice of bushing material critical? Will brass or copper do? As a matter of general principle should the shaft and bushing be made of different material? What would happen (for argument's sake) if one spun a brass shaft in a copper bushing? Thanks, Michael Koblic, Campbell River, BC Sorry for the screwy units, but ............bearing material is rated by PV . The P is psi and the V is surface feet per minute. Nylon is good for about 3500. So calculate what the PV is. Assuming that it is below 3500 then most any usual bearing material will do. UHMW poly is 3000 and is the only material listed in the MSC catalog as a bearing material that is lower than nylon. It does not list copper or brass but cast bronze is listed as 75,000. So I am pretty sure copper and brass are way above the nylon shaft. Dan |
#4
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Bushing material
As a matter of general principle should the shaft and bushing be made of different material? What would happen (for argument's sake) if one spun a brass shaft in a copper bushing? Michael, As a general rule of thumb, same-metal contact under pressure and motion will cause galling; the softer, the worse. Copper on copper would be a very bad bearing selections, because not only is the metal the same, it's soft. Steel on copper works. Brass is a good bit harder than copper, but contains enough copper that I think it would smear off particles and gall. Lloyd |
#5
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Bushing material
wrote in message ... I want to spin a nylon shaft in a plain bearing/bushing at low rpm. Is the choice of bushing material critical? Will brass or copper do? As a matter of general principle should the shaft and bushing be made of different material? What would happen (for argument's sake) if one spun a brass shaft in a copper bushing? Thanks, Michael Koblic, Campbell River, BC As a general principle, you want one material to be smooth and hard, and the other to be softer (but still hard enough not to deform with the pressure applied to the bearing surfaces). If both materials in a bushing have similar hardness or chemical affinity, you can get galling. Nylon will work as a bushing with most metals (unless it is glass-filled). When using nylon as a bearing material, watch out for excessive loads that deform the plastic, high temperatures, acids, and water absorption that makes nylon expand. However, if the pressure on the bushing is low and the RPMs are low, you might be able to get away with similar materials if lubricated. |
#6
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Bushing material
On Tue, 28 Aug 2012 17:53:15 -0700, "anorton"
wrote: wrote in message .. . I want to spin a nylon shaft in a plain bearing/bushing at low rpm. Is the choice of bushing material critical? Will brass or copper do? As a matter of general principle should the shaft and bushing be made of different material? What would happen (for argument's sake) if one spun a brass shaft in a copper bushing? Thanks, Michael Koblic, Campbell River, BC As a general principle, you want one material to be smooth and hard, and the other to be softer (but still hard enough not to deform with the pressure applied to the bearing surfaces). If both materials in a bushing have similar hardness or chemical affinity, you can get galling. Nylon will work as a bushing with most metals (unless it is glass-filled). When using nylon as a bearing material, watch out for excessive loads that deform the plastic, high temperatures, acids, and water absorption that makes nylon expand. However, if the pressure on the bushing is low and the RPMs are low, you might be able to get away with similar materials if lubricated. OK, thanks. The loads on this will be minimal. Did not know about nylon absorbing water. Michael Koblic, Campbell River, BC |
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