Quench Plates

i4Marc

i4Marc

Joined
Oct 19, 2011
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I was looking at different materials for quench plates. Does it matter whether you use aluminum, copper, brass, iron or some other material? If I choose aluminum, does it matter if it is 6061, 7075 or some other alloy? Which materials, and specific formulas of those materials are best?
 
You want the fastest transference of heat possible,so copper is best but way expensive,aluminum next relatively cheap and alloy doesn't matter,steel will work but not as well but can be found as scrap. With most air quenching steel you have about 3-4 minuets to get past the pearlite nose.But faster is better.
I use 12X12X1-1/2" aluminum

Stan
 
I was able to find a 12"x12"x1" plate of aluminum on ebay a number of years ago for a good price. I bought in and cut it in half to make 2 12"x6" plates. Good enough to heat treat 1-2 knives at a time before you need to cool them off. Just a note, 1" plate aluminum doesn't cut very easily with common hand tools :b I cut as much as I could with my band saw, and then had to cut the rest by hand. Took a long long time.

--nathan
 
Contact area is important so whatever you choose needs to be good and flat. I recommend you find some ground jig plate scraps.

While it is true that aluminum conducts heat three times faster than steel, it only has one third the thermal mass so it heats up faster during the quench (which slows quench speed). So, while aluminum is still the better choice, I have found that steel works pretty good for a lot of applications.

If you're quenching stainless, you're probably going to want the fastest quench plates you can get, so go with thick flat aluminum for that.
 
not to butt in... but a theoretical quandry... would it improve cooling if the aluminum were grooved much like a heat sink??? helping to speed the transference of heat into the air by increasing the surface area of the alumium exposed to the air versus the aluminum against the blade???
 
The mass of the aluminum is what pulls the heat out of the steel quickly. Slotting or fin-ing the aluminum would remove mass. My thought is that it would slow down the cooling capacity of the plates at any given time, but it would help the plates recover from quench more quickly by giving the heat up to the air. If you had sufficient thickness (say 1.5"), you could still have the 1" mass of the plates with 1/2" fins to help the plates cool between quenches.

--nathan
 
I bought some 1" thick aluminum that was 6" x 48" and cut into a few peices 2 feet long and keep them in the freezer till needed.
 
silver_pilate said:
The mass of the aluminum is what pulls the heat out of the steel quickly. Slotting or fin-ing the aluminum would remove mass. My thought is that it would slow down the cooling capacity of the plates at any given time, but it would help the plates recover from quench more quickly by giving the heat up to the air. If you had sufficient thickness (say 1.5"), you could still have the 1" mass of the plates with 1/2" fins to help the plates cool between quenches.

--nathan
Click to expand...

X2 :thumbup:
 
Thanks everybody. Would say, 2" or 2.5" thick aluminum be as effective as something like 3/4" copper?
 
I am thinking about taking my quench plates and machining in channels and then making a sealed cover plate and pumping water through them like Nathans platen chillers. Already havee the pump and sump system for my platen chiller.
 
i had been thinkingabout that and a "4 link " setup to mount th4em in with a one lever closer for years
not sure i have the skills to make it happen tho
more likly since i have a 1/4 thick shet of copper i might bolt it to the face of my Al plates. let the copper suck heat fast and the al dissipate it form the copper
 
butcher_block said:
i had been thinkingabout that and a "4 link " setup to mount th4em in with a one lever closer for years
not sure i have the skills to make it happen tho
more likly since i have a 1/4 thick shet of copper i might bolt it to the face of my Al plates. let the copper suck heat fast and the al dissipate it form the copper
Click to expand...

It may not matter for surface areas that large and temperatures that high, but in computers hybrid copper / aluminum heatsinks don't work well at all unless they have a very good thermal interface. Think lapped to each other and held together with pressure. Barring that, a good conducting thermal interface material goes a long way (on high end computers we use stuff like special ceramic or silver paste). Again though, that is dealing with smaller surface areas and much smaller temperature gradients. Just food for thought.
 
I understand the process of plate quenching, but one thing bugs me.

If, as mentioned above, the plates need to be flat and have considerable mass to quickly transfer heat, how does this effect the quenching of a pre-ground blade. If the plates only contact the flats of the ricasso and spine, but do not contact the bevels, wouldn't this adversely affect the quench? Can you only plate quench flat, profiled, but not yet ground blades?

Thanks,

-Peter
 
I've quenched many fully ground blades. Remember, we are talking about air cooling steels in general. The plates will still draw a great deal of heat out through the ricasso and the contacting portions of the tang and spine. The heat drawn from those areas in turn draws heat from the blade. Ultimate, even with a relatively small contact area to the plates compared to the overall surface area of the knife and the additional layers of high temp SS foil in between, you'll still get a much faster cooling than air alone.

--Nathan
 
Bigblue17 said:
I understand the process of plate quenching, but one thing bugs me.

If, as mentioned above, the plates need to be flat and have considerable mass to quickly transfer heat, how does this effect the quenching of a pre-ground blade. If the plates only contact the flats of the ricasso and spine, but do not contact the bevels, wouldn't this adversely affect the quench? Can you only plate quench flat, profiled, but not yet ground blades?

Thanks,

-Peter
Click to expand...

Peter, I wonder too. Everything gets cooled eventually, but surely the flat portions towards the spine are cooling faster. Isn't that the opposite of what one does when differentially hardening? It is the equivalent of putting clay on the edge. and leaving the spine bare.

If possible you would want to hold the plates so they touch the primary bevel and that edge cools fastest, right?

Or is this just a theoretical and not a practical problem?
 
Bigblue17,

No problem with the side track. As long as information is being passed along I'm paying attention! But I am still shopping for QP materials so if we could come around to answering the question at some point that would be appreciated. ;)
 
gotmike said:
not to butt in... but a theoretical quandry... would it improve cooling if the aluminum were grooved much like a heat sink??? helping to speed the transference of heat into the air by increasing the surface area of the alumium exposed to the air versus the aluminum against the blade???
Click to expand...

I'd think you'd want to groove the outside faces of the aluminum, not the contact surfaces. Grooves and fins are for air-cooling the sink itself (think motorcycle engines and CPU heat sinks) as the mass and contact surface of the sink pulls heat out of the part.
 
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