Alternatives to brass plug for bearing cup welding

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bgkast
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Alternatives to brass plug for bearing cup welding

Post by bgkast » 23 Feb 2015, 12:01

Are there other materials that could be used? A 6-inch rod of brass in the appropriate size is just under $40 from Mcmaster Carr! :shock: Aluminum maybe? or Steel? The idea is just to act as a heat-sink and to give the cup some structure while it is welded, right?

Midlana1
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Re: Alternatives to brass plug for bearing cup welding

Post by Midlana1 » 23 Feb 2015, 12:42

Exactly; the idea is to keep the cup from distorting due to welding heat, else the bearing may not drop in.

Aluminum should work, though there might be a concern that since its melting temperature is lower than steel, it might melt and "hook" itself into the cup. Probably worth a try though.

Steel? It should work as long as the cup isn't heated high enough to melt into the plug.

John
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Re: Alternatives to brass plug for bearing cup welding

Post by John » 24 Feb 2015, 14:29

I would think copper would be the best material for this and brass is already a step down from ideal. Copper has a thermal conductivity that is about 8 times better than steel and about twice aluminium which in turn is about twice as conductive as brass which is about twice as conductive as steel. Copper is incompatible with steel, it wont dissolve into steel to form a solid solution with the steel or fuse with the steel. So it shouldn't alter the alloy of the material it sits against. Its melting point is 1980 F to steels 2700 F approx. So not too far apart considering it's fantastic thermal conductivity. Melting point of aluminium is only around 1000 F so that could be a problem. For brass its about 1700 - 1800 F depending on the alloy. The coefficient of thermal expansion of aluminium is about twice that of steel to Coppers around 50% greater than steel with brass somewhere in between the two. Having a thermal expansion for the plug greater than the cup should be helpful in keeping it tight which will aid thermal transfer and help control weld shrinkage. This would be a draw back of using a steel plug. The plugs temperature should always be lower than the cup so a steel plug would develop a looser fit when welding and so might not prevent distortion or act as a very good heat sink. How far you can depart from the ideal and still be adequate I don't know.

Midlana1
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Re: Alternatives to brass plug for bearing cup welding

Post by Midlana1 » 25 Feb 2015, 06:40

Good points about copper, except his issue was the expense of the material, and copper will be even more than brass. Bgkast, can you find someplace that sells really small chunks of the stuff - you don't need much.

bgkast
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Re: Alternatives to brass plug for bearing cup welding

Post by bgkast » 25 Feb 2015, 11:50

I may try to hit the local scrap yard this weekend and see what I can find.

dpkilty
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Re: Alternatives to brass plug for bearing cup welding

Post by dpkilty » 25 Feb 2015, 12:16

http://www.onlinemetals.com/

If I just need small amounts of stuff I hit them up. Usually a little cheaper than McMaster Carr for "cut to length" material.

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