babbit welding for journal bearing

Date 10-25-2005 17:22

Hello Alfred-
Is this a bearing repair or new?

I have had good repair results by:
U.T. existing babbit bearing to determine extend of bond quality.
If bond is acceptable it can be welded, if bond is not acceptable, it will not improve by welding. Lack of bond areas are more difficult, since all babbit material is removed in the unbonded areas, the shell is tinned there, and then the shell can be welded over. There are a few grades of babbit, and the babbit weld filler material used depends on the original bearing material chemistry. I would not recommend welding lead based babbit unless special lead fume safety venting equipment is in place. common bearings found here are ASTM B23 Grade 2 (tin based). I have purchased that grade in 1/8" dia. and 5/32" dia. solid wire on 15 pound spools. I use the GTAW process, low heat, 100% argon, stringer passes, weld it in the flat position ONLY, and peen each pass emediately after welding using a small ball peen hammer. Important: Care to be taken not to overheat the bearing shell during the welding process. Stop and cool shell with fans or air cool. Overheating of the steel or cast iron shell can cause good bond to pop and fail. I also have seen oxy fuel torches used for welding, but only in very large shells, again this method is easy to overheat the shell. Use a copper bar or shoe as a dam to assist in building up edges. Skip around the ID to spread out the heat. U.T. inspect after completed first machining clean up cut. Good Luck

By alfred aryadi e (*)

Date 10-26-2005 01:28

Dear bill,
the prosess is repair the remaining babbit. we use GTAW, 100% argon and inspected by Penetrant
we have problem with surface porosity .
ussualy we just add the remainning babbit on the bearing
would you give me the specification of filler rod of babbit welding that you use?do you use Thermal spray wire from Sulzer MEtco, too? as a i said, we use Thermal spraying wire material ( sprabbabit A) with spec: Sn 7.5Sb 3.5Cu 0.25Pb

Thank you

By Bill M

Date 10-26-2005 13:20

Use fairly low amps and do not make a very large dia. puddle with the tig torch. Try tig welding the babbit wire onto a piece of clean bright brass. You should not get any porosity. If you are sucessful on the brass, and still get porosity on your bearing, the problem is a contaminated babbit bearing base material. try pre-machining the bore to bright metal before weld overlay. I do not have any experience welding thermal spray wire, i only use only grade 2 babbit in wire form for welding. Grade 2 babbit is 88-90% tin, 7-8% Antimony, 3-4% copper, trace balance.
see:
http://www.aimalloys.com/solder_products/babbitt_metal.htm