[SEL] How Babbit Works-will not stick to iron/steel

[Richard Strobel]

Thank you Richard and all who replied..neat stuff!!

RickinMt.


----- Original Message ----- 
From: "Richard Allen" <linstrum55 at yahoo.com>
To: "Stationary Engine List" <sel at lists.stationary-engine.com>
Sent: Friday, April 15, 2005 9:33 AM
Subject: [SEL] How Babbit Works-will not stick to iron/steel


> Rick Strobel's thread "Wire in main bearing caps":
>
> Babbit bearing alloys have one property that is both a blessing and a
> curse. Babbit contains antimony and occasionally arsenic, bismuth, and
> phosphorus as well. These four additives are all members of the "Group
> V" family of elements and all share similar properties. One property is
> that they will not stick to iron or steel, and a very good example of
> this property can be found in the well-known silver solder alloys
> called Silphos and Phoscopper used for copper tubing. They work great
> on copper but when used on iron or steel they appear to work great, but
> on cooling, the phosphorus-containing silver solder falls off! This
> property is useful because Silphos and Phoscopper are themselves
> fabulous bronze bearing alloys as well, and to cast them a steel
> mandrel is machined to size, polished, the phosphorus silver solder
> cast around the mandrel, and then the mandrel pressed out. Babbit does
> the exact same thing, so to get it to stay inside a steel or cast iron
> bearing shell it has the familiar staking holes, screws, wires, and/or
> pins that physically "cage" or lock it in place. One recommended
> procedure for preparing a shell for casting is to flux it with sal
> ammoniac (ammonium chloride) or zinc chloride and tin it with 37% lead
> 63% tin solder. However, I found out the hard way to NEVER rely on the
> tinning to keep the bearing in the shell! The tinning is ONLY to
> facilitate the flow of the babbit into the shell so it makes intimate
> contact with the backing shell and to prevent air pockets. You must use
> staking holes, screws, or the wires that Rick mentioned to keep the
> bearing in place. Now, the good part of babbit not sticking to iron or
> steel is that particular property is what makes it such a fabulous
> bearing alloy! Without antimony or any of the other mentioned
> additives, the babbit would gall or smear and become cold soldered to
> the cast iron or steel crankshaft bearing surface, with immediate
> destruction of the bearing. Besides the traditional antimony content, I
> have also worked with babbits that contain arsenic, phosphorus, and
> bismuth, which all work very well, with the exception that bismuth
> babbit has a maximum operating temperature of about 180°F that
> precludes its use in high speed or hot-running engines. Arsenic is
> probably the best additive for babbit, but because of the hysteria
> associated with it as a violent poison it is nearly impossible to
> obtain and its equally deadly "brother" antimony is used instead. Of
> course, from over 165 years of excellent service for machine bearings,
> the tin-lead-copper-antimony babbit alloys have proven themselves to
> 100% satisfactory! By the way, until about the year 1839 babbit was
> simply called pewter. It was Mr. Isaac Babbit (American inventor,
> 1799-1862) who improved pewter specifically for use in high performance
> marine steam engines. See:
>
> http://www.americanbabbittinc.com/history_of_babbitt_bearings.htm
>
> Work and play safely!
>
>
> Rich
>
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