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I Forge Iron

Lubrication while hot cutting


JNewman

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I am forging a bunch of tools right now and one of the last steps is to nip off the cutting edge.  I have my small hydraulic press set up  with top and bottom 90degree cutting edges. The edge is only just over 1/8" thick but is 2" wide.    I can easily cut 1" square in one shot with this setup but the extra width and the fact the heat dissipates so fast because they are so thin, I need a really good heat to cut these off in the thin narrow pieces and even then I have to bend  them back and forth a couple of times or quench them and break it off. 

 

After the first 75 or so I decided to try lubricating the cutting edges with a mixture of oil and graphite.  Now some of them pop right and the rest break off with a hammer blow or two.  It is amazing the difference the lubrication makes. 

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  • 2 weeks later...

If you are nipping off the end to eliminate fish lips..you can simply hit back into the end of the steel and drive the lips back in before they need more work. I try and go back in the forge before I lose color so it does not take so long to reheat, I hit the ends before going back for heat.

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I am cutting surplus material off the ends so i end up with a consistent product.  I do have things I forge extra material out to eliminate the forming of fish lips, I then cut off the extra material.   I have other things I hot cut in half  to make 2 parts.  This leaves me with a conical end on the stock which prevents any folding over. 

 

Just hitting the ends in can be difficult when you are working with 2-3" alloy steels.  All of these jobs are done entirely with power hammers and presses the material just does not move enough by hand. 

 

I have 5 gallons of the  Henkel product and I do use it for some things and often use the graphite oil mixture until the tool heats up enough to use the Henkel stuff.  I have a job I just finished where I was pushing 2 different shaped  bolsters together with a press to straighten the work flatten the one face and upset the material slightly between the bolsters.  The bolsters are both hardened 4140 and was having problems with galling between the work and the one bolster leaving metal deposited on the bolster.  On some pieces where there was a bit of a twist or bend in the piece the hot work scrubbed against the bolster and this is where I often had the galling.   I used the Henkel product and found I was getting more galling than I was with the graphite oil mixture.  Maybe I don't have the henkel stuff mixed rich enough.  I used 1 1/2 large paper coffee cups worth of the chemical in a garden sprayer with the rest water.  It is the colour of canned iced tea or weak coffee.  For a lot of the open die tools I use the henkel stuff cools the tool enough that it can be hard to keep them hot enough to flash off the water. 

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JNewman

In the axle shop where the henkel product was sprayed as a mix in water at about 5% to water we sprayed between every single hit, and at 6 seconds between hits the water was needed o keep the die cool. At my home shop I run 50:50 and dip hot cuts, my touch mark and drifts.

The goal is not what the mix looks like, but more that the water flashs off removing heat, and then leaves a tan light chocolate like coating that is dry.

Properly used this stuff is like ball bearing for hot work tools.

We did have an extreme reverse extrusion job, Mil-spec that used an exotic alloy.This we reverse extuded in a 4 post hydraulic press that was probably a little slow, and temp control was hard given the forge, so we only had about 1 in 60 stick and freeze in the tooling causing a loss of 50% of the tooling when salvaging. That one used graphite in a road tar emulsion, about like toothpaste.

For upsetter dies the Henkel lube was magic.

If you are getting galling try a heavier mix to get that solid film coating, may have to reapply every part.

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