Slip Roller

[12bolts]

...Very little decarburization which means the argon flood is doing it's job....

How much argon do you use in an oven that size Ray?
Do you purge it hard to flush it out and then just keep a dribble going in for the duration? Or.....

Cheers Phil

 

[Ray C]

How much argon do you use in an oven that size Ray?
Do you purge it hard to flush it out and then just keep a dribble going in for the duration? Or.....

Cheers Phil

Hi Phil...

Just a one-time shot. I rig a couple plastic tubes to feed from the bottom and vent at the top (argon is a very dense gas). The insulation batting allows me sneak those tubes in/out without too much fuss. I should install some tubes and valves... The inside is something like 1.5 cuft so, I just set the welding tank up a few notches and fill it up in a few minutes.


Ray

 

[markknx]

Nice work Ray I will be following this one.

 

[markknx]

Ray I just got thetime to view you vidios. Now I want one of those. The wife may just have to wait a little longer for that second honeymoon. Ha Ha

 

[Ray C]

Ray I just got thetime to view you vidios. Now I want one of those. The wife may just have to wait a little longer for that second honeymoon. Ha Ha

Well stand-by until later this evening and I'll make some more vids. -And just to please Marco, I'll shoot them in horizontal/landscape mode.


Ray

 

[Ray C]

Better late than never, they say... I got a late start on this last night.

I'm re-making the bearing holders because one of the originals sustained a slight crack during the heat treating. The crack didn't go all the way through but nonetheless, I no longer trusted either part. I packed the holes but, it wasn't enough. There was a high chance of this happening -and it did.

The first parts were bored on a manual lathe and these were bored with the mill as shown. There are trade-offs. The bore from the lathe-produced parts were perfect from the get-go. With the CNC mill, the bore varied between 1.2485 to 1.2495. It was supposed to be 1.250. The plan from the onset was to pass a reamer through to make them perfect. On the flip side, setting-up the part on the CNC is very easy -just establish the origin and press go. It's an even trade-off in my opinion.

In these videos, the paths were setup for a slow feed rate to provide enough time to video the motions and let you see in slower-motion the path movements. Whenever I watch videos of the real-pros doing this, I pay close attention to the fine points of the path motions. These motions were not highly optimized and I could have gotten rid of the Z elevation clearance motion between passes but, since this a "one-off" situation, its not worth the effort. The parts could have been cut at twice the feed rate if I so wished -and still not come anywhere close to stressing the machine.

Here are some vids -and heads-up, the audio on the 3rd vid is shot in the foot.

http://www.youtube.com/watch?v=9lwwi1W2pfw
http://www.youtube.com/watch?v=lZbBFFsEPc8
http://www.youtube.com/watch?v=VlKbEQjH8QQ


Here's a close-up of the finished parts with absolutely no post touch-up or deburring. Fresh out of the mill. I wasn't careful setting the Z when doing the finish pass on the large outer radius to thin-out the shell. You can see some artifacts of my carelessness. No harm done but, I must say, this typical of what happens when I'm not focusing on my work and fiddling-around with video cameras...




Ray

 

[Tony Wells]

Ray, just for the sake of discussion, long parts are preferably done vertical. I know you didn't build your furnace with that in mind, and that's fine. There aren't all that many heat treaters who have long part capability. I used to send parts 6-8 feet long regularly to a couple I know of. The were 41xx series alloy, and tubular to boot. Laying them down just wasn't working. We built a 100 ton rolling frame straightening press early on in this work to make do. Since we brought them in ejector drilled, we couldn't simply leave them over size and turn them straight. There was a drift requirement. When they were bowed, we had to roll them on vee blocks (ball bearing style, these were sometimes heavy), use an ultrasonic thickness mic and bent them so that the holes were straight before we turned them. It was a little mind bending at first, having to make the thick walled side run out on the plus side the correct amount to make the hole straight. Sometimes this took a couple of iterations, because they would move when we turned them.

 

[zmotorsports]

Ray, just for the sake of discussion, long parts are preferably done vertical. I know you didn't build your furnace with that in mind, and that's fine. There aren't all that many heat treaters who have long part capability. I used to send parts 6-8 feet long regularly to a couple I know of. The were 41xx series alloy, and tubular to boot. Laying them down just wasn't working. We built a 100 ton rolling frame straightening press early on in this work to make do. Since we brought them in ejector drilled, we couldn't simply leave them over size and turn them straight. There was a drift requirement. When they were bowed, we had to roll them on vee blocks (ball bearing style, these were sometimes heavy), use an ultrasonic thickness mic and bent them so that the holes were straight before we turned them. It was a little mind bending at first, having to make the thick walled side run out on the plus side the correct amount to make the hole straight. Sometimes this took a couple of iterations, because they would move when we turned them.

I don't know the answer to this which is why I am asking so go easy on me as I have very little to no experience with heat treating.

That said, wouldn't lying them horizontally give you a more uniform heating throughout the part? I would think standing them vertically would allow the parts to be hotter at the top of the part due to the heat rising and therefore not be as even temperature throughout the part. I would think the same physics of heat apply inside an oven as they do outside. Please explain.

Again, I am only asking because I don't know, not criticizing.

Mike.

 

[Tony Wells]

Fair question, Mike. Yes there can be a temperature gradient inside a furnace. It isn't as much as one may think though. As well insulated as these furnaces are built, and the location of the heat source is chosen, it's not a big factor. At the acceptable temperatures and soak times, there is minimal convection. Some processes use an open bath of molten salt to minimize any temperature differential. Good size and shape retention is obtainable with that method.

Most of the distortion will actually occur during the quench phase of the process, where almost no matter how you approach it, one end of the part cools faster than the other. Larger quench baths help, but do not eliminate that. Most commercial quench baths have temperature control anyway, so as long as it stays within bounds, things a pretty consistent.

 

[zmotorsports]

Tony, thank you very much for explaining that.

Mike.