[TheForge] new question, quenching oil

[David E. Smucker]

The primary oil I use for oil quenching is used hydraulic oil.  Hydraulic 
oil today is generally straight mineral oil with R & O additives.  (R & O, 
is Rust and Oxidation).  It has worked very well for me.  I thin it a bit by 
adding diesel oil but other wise use it straight from a hydraulic oil change 
on the tractor.  It DOES NOT smell near as good as using one of the cooking 
oils but I avoid the best I can breathing the fumes from quenching.  It is 
much cleaner than used motor oil with much lower additive package.  I use a 
15 gallon beer keg for my quench container so I have about 14 gallons in the 
keg.  The top was cut out and I have a fabricated lid to drop in place in 
case of fire.

Most likely the best quench oil are the commercial ones -- cost is around $ 
80 for 5 gallons.  Some of the knife maker supply houses sell these oils.  I 
know of no industrial heat treaters that use cooling oil for quenching.

One note of special care with quench oil -- you can collect water in the 
bottom of your container and never know it -- from say storing your contain 
outside of the shop and collecting rain.  If you drop by mistake hot metal 
into such a container you can cause the water in the bottom to boil and blow 
oil out of the contain in one big burp.  Makes for a mess, and serious fire 
risk.

Dave
----- Original Message ----- 
From: "lee robbins" <naturadoc1 at yahoo.com>
To: <theforge at mailman.qth.net>
Sent: Monday, November 12, 2007 10:37 AM
Subject: [TheForge] new question, quenching oil


> has anyone had any experienced quenching oil hardening
> steel in hydraulic oil. i emptied my backhoe after
> draining the system to fix a pipe and added fresh oil
> and the old stuff seems perfect. I wonder if anyone
> has had experience with this and if there is any
> reason to avoid it.
>
> Lee Robbins
> Flying tortoise forge studio
>
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