anyone harden PTG dies in kiln?
- Thread starter alinwa
- Start date
Joe Woosman
Member
Al, couple of comments:
First, from your previous posts, I gather you are person that is focusing on the utmost of precision in your die machine work. Heat treating these ultra precise dies with a kiln and foil wrap would be like taking your shinny new BR rifle and rope dragging it behind you to the bench. It'll still resemble a BR rifle but you probably aren't going to take as much pride in it anymore.
Your SS foil I assume you would use to wrap the part as to protect the surfaces from the atmosphere of the heat treat oven. A trick we use when we have to wrap parts due to not having an atmospheric controlled oven is to put a small strip of paper in the foil bag with the part. The paper burns the oxygen out of the bag and reduces surface damage to the part. The problem I run into with these foil bags is after hitting your temps, you have to open the bag and get the part into a quench. I've found this to be QUITE challenging to do in a precision manner.
Your quench bath would likely be in oil. If you drop the die in to where it lays on the bottom of the container, it's not going to cool consistently and you'll likely introduce more warp or distortion in the die than if it could be suspended in the oil. Regardless of your method, you will end up needing to do some polishing to make them look pretty again.
You likely will see warp and shrinkage if you get as meticulous measuring them after heat treat as you did before.
Sorry to not be more encouraging. Good luck with them.
First, from your previous posts, I gather you are person that is focusing on the utmost of precision in your die machine work. Heat treating these ultra precise dies with a kiln and foil wrap would be like taking your shinny new BR rifle and rope dragging it behind you to the bench. It'll still resemble a BR rifle but you probably aren't going to take as much pride in it anymore.
Your SS foil I assume you would use to wrap the part as to protect the surfaces from the atmosphere of the heat treat oven. A trick we use when we have to wrap parts due to not having an atmospheric controlled oven is to put a small strip of paper in the foil bag with the part. The paper burns the oxygen out of the bag and reduces surface damage to the part. The problem I run into with these foil bags is after hitting your temps, you have to open the bag and get the part into a quench. I've found this to be QUITE challenging to do in a precision manner.
Your quench bath would likely be in oil. If you drop the die in to where it lays on the bottom of the container, it's not going to cool consistently and you'll likely introduce more warp or distortion in the die than if it could be suspended in the oil. Regardless of your method, you will end up needing to do some polishing to make them look pretty again.
You likely will see warp and shrinkage if you get as meticulous measuring them after heat treat as you did before.
Sorry to not be more encouraging. Good luck with them.
Joe Woosman
Member
I just checked out those die blanks on the PTG website. They say "Heat treating is generally not necessary".... Then they say.... "However, if heat treating is desired, heat to 1650 - 1700° and then allow to cool slowly for 3 to 6 hours." This is a stress relieving process, NOT a hardening process and you would want to do it prior to finish machining. Not sure if that was your intentions. I first assumed a hardening process.
Gene Beggs
Active member
Using Newlon and Bald Eagle die blanks, I have made a few wildcat sizing dies for my experiments. Although the non-hardened dies work fine they leave a frosty appearance on cases and I'm sure will not last as long as those that are properly heat treated.
Like Alinwa, I wish I could find a way to harden them myself without breaking the bank.
Suggestions?
Gene Beggs
Like Alinwa, I wish I could find a way to harden them myself without breaking the bank.
Suggestions?
Gene Beggs
Joe Woosman
Member
Gene, one possibility is case hardening with a product like Kasenit. (Assuming you have the 12L-14 dies). Just need a torch to harden. I understand there is not much distortion created in the 12L-14 material. You would need to polish out the surfaces after so I would plan on the diameters opening up a touch. A rough guess would be maybe up to .0005". I haven't actually done it so I'm not sure.
colchester
Member
What about melonite treatment? I have not priced it so it might fall under "breakin the bank" not sure. Would it work, would there be concern over dimensional changes?
OK OK OK
You'se all gotta' bear with me, I'm NOT a metallurgist and anything I do know about treating steels goes back to gunsmithing school and "carbon steels" YES I've made knives and scrapers and springs and such, from carbon steel. YES, I know a liddle about heating/quenching/drawing back to color. I can and have made chisels, punches and knives. Even made a filet knife from a file and got it to flex and to hold an edge, 30yrs ago, but NO-NO-NO!!!! I don't know about some of these "modern" alloys. I recently spoke to someone who useta' be on this board and they talked of "most steels nowadays" being "air hardening."
AS I UNDERSTAND IT you harden this PTG 4140 alloy by bringing it to temp, soaking, and letting cool in the foil, in the furnace for 3-6 hrs.
I'm making some superlative dies from PTG blanks.
I WILL NOT use un-hardened dies.
I called Whidden yesterday, they'll attempt to please me for just under 300.00 a pop, they claim they can do it and maybe they can but currently they fit their dies differently than I do.
Neil Jones makes me happy, but timing is always a problem.
Meloniting has other problems.
My question is, "DO YOU harden these dies as described? I will not quench them. All the dies I've had done in past were "vacuum hardened" and as I learn more I'm realizing that quite possibly this means "thrown into the fire in a SS bag."
Has anyone actually DONE THIS?
al
You'se all gotta' bear with me, I'm NOT a metallurgist and anything I do know about treating steels goes back to gunsmithing school and "carbon steels" YES I've made knives and scrapers and springs and such, from carbon steel. YES, I know a liddle about heating/quenching/drawing back to color. I can and have made chisels, punches and knives. Even made a filet knife from a file and got it to flex and to hold an edge, 30yrs ago, but NO-NO-NO!!!! I don't know about some of these "modern" alloys. I recently spoke to someone who useta' be on this board and they talked of "most steels nowadays" being "air hardening."
AS I UNDERSTAND IT you harden this PTG 4140 alloy by bringing it to temp, soaking, and letting cool in the foil, in the furnace for 3-6 hrs.
I'm making some superlative dies from PTG blanks.
I WILL NOT use un-hardened dies.
I called Whidden yesterday, they'll attempt to please me for just under 300.00 a pop, they claim they can do it and maybe they can but currently they fit their dies differently than I do.
Neil Jones makes me happy, but timing is always a problem.
Meloniting has other problems.
My question is, "DO YOU harden these dies as described? I will not quench them. All the dies I've had done in past were "vacuum hardened" and as I learn more I'm realizing that quite possibly this means "thrown into the fire in a SS bag."
Has anyone actually DONE THIS?
al
Al when you heat treat in a vacuum furnace you usually choose an alloy that is air quenched for the same reason you can't quench a part in oil that is wrapped in foil. Your hands (unless you are 1 bad mamba jomba) cant take the heat to reach in to the furnace & handle a 1700-1800 degree part to dunk it in oil. And besides that, when the part hit the atmosphere it would start to scale immediately. Hence the reason for a vacuum. The quench cycle is also done while under vacuum. Bite the bullet Al. Somebody told me once that there is a chemical hardening process but I've never checked into it to see if they knew what they were talking about.
Ya' lost me there, I can't gain a sense of what you're saying.....???
Here's what Kiff sez, "you wrap the parts in foil with some paper and cook 'em, now let them cool slowly."
What am I missing?
BTW, the chemical hardening process may be 'meloniting.' This process certainly does the job. It's done clear on the other end of the country from me though, turnaround is measured in, at very least, weeks. More probably months. Otherwise there's case hardening which I've done a little of but not dies.
geo.ulrich
Member
it will take a whole bunch more than a .0005 thousands to clean up more like ,002-,003 I do a lot of heattreating I would say go for the tool wrap I use a small piece of wood instead of paper it will slowly burn through whole process and you won't get the decarb.quench in oil with die vertical to minimize warpage part warps when one side is cooled faster than the other. george
geo.ulrich
Member
probably gas carburizing works well but not exactly cost effective for one piece. george
Joe Woosman
Member
George, I don't know you or your background and I don't mean anything as an attack... But, I know of some high quality BR dies being made from case hardened 12L-14. The dies are made using chamber type reamers and are polished after hardening. Tight tolerances are held. On a Kasenit article I read it was stated a polished surface could be restored with steel wool. I can't see that removing much material. I have no first hand knowledge beyond that.
As far as the wood in the bag, it won't burn without oxygen so I'm not sure why it would continue to burn through the process. I have seen the paper burn into the metal a bit so I would imaging wood could be worse.
So what you all are telling me is that Kiff is all wet, that 4140 needs a traditional liquid quench to get hard?
What I'd do with this if it were say a steel bearing roller is heat it up to 1650-1700 for an hour or so and let it cool slowly, then REHEAT IT to 1550 or so, QUENCH IT by dropping it into an oil bath and final grind it to shape.
What I'd do if it were a tool is heat it, quench it, polish it and "draw it back" to a certain color.....
But it AIN'T a roller. And I CAN'T final grind it and I'm SCARED to quench it...... and I've had people tell me I can get 55-60RC with "air cooling" whatever that is.......'cept in a "vacuum" created by crimping into a .002 thick #321 SS bag. Several of the people have told me "it's pretty simple" but I ain't gonna' dump a grand on a furnace just to make stuff cherry red for quenching in oil/water/onion juice
HELP!!
al
What I'd do with this if it were say a steel bearing roller is heat it up to 1650-1700 for an hour or so and let it cool slowly, then REHEAT IT to 1550 or so, QUENCH IT by dropping it into an oil bath and final grind it to shape.
What I'd do if it were a tool is heat it, quench it, polish it and "draw it back" to a certain color.....
But it AIN'T a roller. And I CAN'T final grind it and I'm SCARED to quench it...... and I've had people tell me I can get 55-60RC with "air cooling" whatever that is.......'cept in a "vacuum" created by crimping into a .002 thick #321 SS bag. Several of the people have told me "it's pretty simple" but I ain't gonna' dump a grand on a furnace just to make stuff cherry red for quenching in oil/water/onion juice
HELP!!
al
Here's what I found online, this agrees with my experience with "carbon steels"
Have I just been completely misunderstanding those guys re "heating and air cooling"????
If this is the process, heat/quench/temper then I'm back to sending the dies out, for heat treat OR for melonite (probably melonite once I'm sending them)
From an online site, for 4140
HEAT TREATING
Heat to 1500-1600° F and hold 1-1/2 hour per inch of greatest thickness. Quench into 150° F oil.
TEMPERING
Temper immediately after quenching, before the part has cooled to below 150° F. Parts should be held 1 hour per inch of thickness, 2 hours minimum. A single temper is sufficient. The following tempering table may be used as a guide. However, since .112" dia. specimens were used for this test, it may be found that heavier sections are several points lower.
Tempering Temp. (F) As-quenched
Hardness Rc
60
400
57
500
53
600
49
700
46
800
42
900
38
1000
34
1100
31
1200
27
1300
23
_________
Have I just been completely misunderstanding those guys re "heating and air cooling"????
If this is the process, heat/quench/temper then I'm back to sending the dies out, for heat treat OR for melonite (probably melonite once I'm sending them)
From an online site, for 4140
HEAT TREATING
Heat to 1500-1600° F and hold 1-1/2 hour per inch of greatest thickness. Quench into 150° F oil.
TEMPERING
Temper immediately after quenching, before the part has cooled to below 150° F. Parts should be held 1 hour per inch of thickness, 2 hours minimum. A single temper is sufficient. The following tempering table may be used as a guide. However, since .112" dia. specimens were used for this test, it may be found that heavier sections are several points lower.
Tempering Temp. (F) As-quenched
Hardness Rc
60
400
57
500
53
600
49
700
46
800
42
900
38
1000
34
1100
31
1200
27
1300
23
_________
Now here's another one, for "air hardening steels" from EHow
this is more like what I've been hearing, with the final temper being done in the wife's oven.......
Slowly raise the temperature of the furnace to 1450 degrees Fahrenheit, at a rate of 3/4 hour per inch of steel thickness, allowing the steel tool to gradually rise in temperature.
Raise the temperature of the furnace up to 1700 degrees Fahrenheit or 1800 degrees Fahrenheit, depending on what tool steel alloy you are using. Let the tool steel sit in this temperature for 30 minutes. Remove the tool steel and allow it to sit exposed to the air in a safe location, on a heat-resistant surface so that it can harden as it cools down.
Wait two hours for the tool steel to cool down to 150 degrees to 125 degrees Fahrenheit. Temper the tool steel by raising its temperature back up to 390 degrees Fahrenheit in the forge. Remove the steel from the heat. Wait another two hours for it to cool down to 150 degrees and raise its temperature back up to 390 degrees to temper it twice. This allows the steel to harden uniformly.
Read more: Simple Instructions for Air Hardening Tool Steel | eHow.com http://www.ehow.com/how_8067979_simple-air-hardening-tool-steel.html#ixzz2Q1SzsTUX
and there's that word again, "simple"
this is more like what I've been hearing, with the final temper being done in the wife's oven.......
Slowly raise the temperature of the furnace to 1450 degrees Fahrenheit, at a rate of 3/4 hour per inch of steel thickness, allowing the steel tool to gradually rise in temperature.
Raise the temperature of the furnace up to 1700 degrees Fahrenheit or 1800 degrees Fahrenheit, depending on what tool steel alloy you are using. Let the tool steel sit in this temperature for 30 minutes. Remove the tool steel and allow it to sit exposed to the air in a safe location, on a heat-resistant surface so that it can harden as it cools down.
Wait two hours for the tool steel to cool down to 150 degrees to 125 degrees Fahrenheit. Temper the tool steel by raising its temperature back up to 390 degrees Fahrenheit in the forge. Remove the steel from the heat. Wait another two hours for it to cool down to 150 degrees and raise its temperature back up to 390 degrees to temper it twice. This allows the steel to harden uniformly.
Read more: Simple Instructions for Air Hardening Tool Steel | eHow.com http://www.ehow.com/how_8067979_simple-air-hardening-tool-steel.html#ixzz2Q1SzsTUX
and there's that word again, "simple"
Never heard anyone refer to 4140 as a tool steel let alone an air hardening tool steel. Not saying it won't work. What I've seen of hardened 4140 was oil quenched. Air hardening tool steels I've been around and used are the A, S and D types. I've made a few dies of another sort (planishing and power hammer) out of S7. Lots of punches and misc tooling out of A and D.
I've case hardened Newlon 12L14 dies in a foil wrap and didn't have to polish more than .0005" total and it was under that if I remember the last time. A quick low pressure 40 psi bead blast and minor interior polish is all it took.
I've case hardened Newlon 12L14 dies in a foil wrap and didn't have to polish more than .0005" total and it was under that if I remember the last time. A quick low pressure 40 psi bead blast and minor interior polish is all it took.
Last edited:
Joe Woosman
Member
Based on everything I have ever seen pertaining to the heat treat hardening of 4140...... YES. I will always welcome being corrected though. The process of taking the material to 1650-1700F followed by a slow gradual cooling most closely resembles the annealing process for 4140. Every hardening process, (besides surface treatments), I have seen for 4140 has been a heat/quench/temper process. Maybe it forms some sort of shallow surface hardening I've never heard of and is not published in the heat treating data I've seen. If you find something out different please report back so we know.
geo.ulrich
Member
Joe, 12L14 would need to be carberized ,which would not affect finish other than polish or lapping.kasenit leaves a extremely rough surface as it trying to add carbon to surface it gets real bad this is from experience.as for the wood I've doing this for 35+ yrs it just kind of smolders surfaces look great when parts come out.not sure of your backround mine is real easy to check. george