Non Precious Casting Trouble- Help!!!

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Janine Harris

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Hi
I am casting using a CoCr base alloy (Dsign30) for the first time. Usually I use a high content gold alloy, lower melting point etc, etc.... but I cant seem to cast the metal!

Its been a long time since Ive cast with non precious and I tried twice so far:

825 burnout, with crucible in oven, remove crucible, drop in ingot, use 10PSI LPG and 40PSI O2.
This just melted into a blob with a lot of oxide.

Second 875 burnout with crucible in oven, with 20PSI LPG and 50PSI O2. Hardly melted the alloy and it just stuck to the exit hole in the crucible.

How hot does it have to be and how long should I be melting the alloy for? Using a centrifugal casting machine. Thanks :)
 
sidesh0wb0b

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where are you located?
I'd be happy to help if I can. pm me and I'll give you my number

it's easier on the phone instead if running through all the questions here
 
Bumfrey

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Hi Janine.
I used Dsign 30 for a while before i found bego 230. They cast just the same but the bego is a little more economical.
I go by eye using the torch, as the readouts are busted, but you need to turn it up high so it sounds like a freight train to get the metal melted to cast. It take longer than the high gold alloys, but i find it easier and have 0 miscasts.
Do not drop the ingot in the crucible put any old alloy and new ingots IN the burnout oven. This helps to get the temp up before you even start.
Hope this helps. Welcome to the board.
 
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o my burnout s set at 925-950.
 
Bumfrey

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C
Alphvest speed
Yes.
Sorry was busy.
 
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Result?
Success?
Janine????
 
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Janine Harris

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Sideshow Bob I'm located in Sydney. How about you? Probably different ends of the world?! Thats why I'm just replying now- just woke up!!! My email is [email protected] if thats easier?
Its at degrees C. I used Alphavest speed.
Third try resulted in 875 burnout with 35PSI Propane 90PSI O2. It cast, but was still a miscast with it clearly STILL not being hot enough!!!
I will try 925 burnout today and really up the PSI so, as you say Bumfrey, it will sound like a freight train!!! It was pretty roaring yesterday tho.
I do seem to remember heating up the non precious alloy in the furnace first all those many moons ago when I was living in the U.K.
I will try that today and let you know. Thing is think my torch only casts at max 1500 degrees C. Which is only just hot enough.
Manufacturer says I could try a casting flux but dont really want to start doing that!
 
RDA

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Bumfrey is right about the torch sound. Also, going from a high noble/noble alloy to NP can be confusing on what the "melted" alloy should look like. NP usually only slumps and does not pool like high noble/noble alloys. Using a larger multi-orifice torch tip is also helpful. If you are using a traditional casting unit, crank it up one more wind than you would for your HN or noble alloys.
 
Bumfrey

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Multi-orifice torch tip is a must. Keep trying, when you get it its easier than high noble imo. Cast thinner than HN as well.
 
sidesh0wb0b

sidesh0wb0b

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yeah opposite side of the pond, US here.
let us know how you do, though your torch is fine. the melting range for dSign 30 is 1145C-1165C....casting temp being 1240-1350C. Ivoclar said to use a flux? thats strange, though it shouldnt hurt anything. but i dont think you should need it.

first advice.....agreed with Bumfrey....preheating the crucible and metal will help (but have your torch ready when you pull it out of the furnace, you dont want an oxide layer forming). also be sure you are using the proper multi-orifice torch tip.
2nd, your oxygen doesnt need to be much more than 2x your LP setting. i have never cast dSign 30, but its not far from other type 5 alloys ive cast. generally speaking 20psi LP : 40psi Oxy. start by lighting just LP and open the flame up a bunch. then turn on your oxygen wide open. back the flame down on the LP until you get the cones where they should be and you hear that loud loud hissing noise. this does 2 things, #1 it ensures you have proper oxygen flowing through the flame, and #2 if you follow this step every time you will get the SAME flame every time you fire it up. only changes in the regulators will be needed to adjust your flame.
3rd, be sure you are casting with fresh alloy. i dont know the advice on this particular alloy but im guessing its not to use any more than 50% old alloy.
4th, any reheated alloy should be well sandblasted to remove all oxide layers, and any nasty spots of burnt alloy should be removed
5th, as stated above, an extra wind on your centrifuge will be needed for these types of alloys. the required force to move the semi-fluid mass is greater than high gold content alloys.
6th,due to the nature of the NP alloys, they rarely pool and become a nice fluid mass. they basically just slump, sometimes looking like a raisin or wrinkled mass of metal.
7th, before doing any of this please be sure you have proper eye protection! these alloys require a nasty flame that can do serious retina damage very quickly :)

hope this helps you some, keep us posted
 
Sydceramist

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Hi Bumfrey, I use alphavest also, what do you recommend for liquid ratio for a long span bridge? say 6-8 units. I find rocking even though wax up is perfect an resin is used for connectors and such. Thanks
 
Bumfrey

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Hi Bumfrey, I use alphavest also, what do you recommend for liquid ratio for a long span bridge? say 6-8 units. I find rocking even though wax up is perfect an resin is used for connectors and such. Thanks
About 20-25% water.
That sounds more like warping than incorrect ratio imo. Long bridges are always a little tricky though.
 
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thanks 20-25% wow ok I have been going with 13.5ml L, 1.5ml W, I use thick feeding sprues an wax sticks as sprues not coil, no button, vent channels, all I am left with is either ratio or the rapid program. Thanks
 
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thanks 20-25% wow ok I have been going with 13.5ml L, 1.5ml W, I use thick feeding sprues an wax sticks as sprues not coil, no button, vent channels, all I am left with is either ratio or the rapid program. Thanks
Try using a PLASTIC rod parallel to your bridge. Sprue to each unit from the plastic rod. /then one or two thick sprues of wax from the plastic rod to the button. Like this but with a plastic rod parallel to the bridge. It made a big difference for me. Might be worth a try. I use leftovers from a plastic airplane kit that my kids use.
Hope it helps let me know.
Peace.
 

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Bumfrey

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^ Not a photo of my work, was the fastest way to show you without opening the lab back up.
 
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They are not perfect all the time, but they are better then before i did them this way. Some drop onto the retainers without any easing. I love it when that happens.
 
AGV

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"I used Dsign 30"

Bumfrey,

Do you use d-sign porcelain?. Have you had craks and delaminations? I have a lot, and want to change to another combination.
 
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I used Dsign30, but now i use bego 280 like i stated i think. OO i said 230 i meant 280. I use In-line and have zero problems. I did up my first opaque temperature by i think 80-100 will have to look that up.
In-line is great at fast buildups that match the shade guide. Dsign is better porcelain but harder to use. My main work is production work. I am also trying to go metal free.
 
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I guess it worked out in the end Janine.......
 

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