Preservation of Castings

[Peter J.Heizmann]

There have been numerous discussions concerning castings, mostly in the Technical threads. They have varied from restoring-to-properties. What has not been discussed is the unintentional destruction of a cast part.<P>This can happen at various phases of restoration, or, mechanical work. One thing for certain, it has happened in the "industrial use of iron castings". I have been called out on quality complaints (more times than I care to remember), wherein, the customer says our castings are failing due to fractures. Not to belabor the subject, the following is a classic:<P>--An un-named account complained, that after putting big machining dollars into our castings, they fractured when a serial number was stamped using a die. Turned out, they machined the section of the number from 1/2" raw casting dimension down to 3/8", thus weakening it to the point any blow would cause cracks.<P>My pointers to enthusiasts that are either in a junk yard using a sledge hammer to free up a part, an enthusiast that is sweating trying to free up a starter motor housing with a hammer, the enthusiast that throws a cast part across the garage floor thinking the part is cast so it can take the shock:<P>--Temperature: In a junk yard smacking a part in i.e.- 30 degree weather can cause hairline cracks that the eye will not see.<P>Ductile Iron is basically a mild steel. Guess what: At 0-degrees it becomes brittle if stresses are put onto the part.<P>--Throw a thin sectioned cast bracket, manifold, etc., and guess what: You can cause cracks.<P>--Do not think just because a cast part is bolted to a solid item, such as a block, and I will smack it with a sledge to free it up it should work. The same: It can crack. (I shutter to think that a "hard to find part" is ruined by doing this.<P>My point is be careful how you treat them. Human nature is to think just because the part feels "heavy" to the touch it cannot be ruined if I get mad and throw it while frustrated.<P>Just a tip.<P>Regards, Peter J.<P> <p>[ 03-31-2002: Message edited by: Peter J Heizmann ]

[1937hd45]

This topic brings back bad memories. While disassembling the fromt end of my 1962 Lyndwood, I desided to mark the cast aluminum friction shocks L & R with a letter punch. Should have done it while they were on the car. One light tap and it broke the inner ear off. I was lucky to find another pair at a flea market. But the original was distroyed.