Small sized vacuum furnace advice

[marcus4]

Hello, I decided to buy furnace for small in house batches. I need it for Permalloy small thin parts (transformer laminations).
By search I found several manufacturers, mainly from China and they offer relaivelly cheap options (from 3-5k$) but I'm not sure about parameters I have to define. Ok, my heating space can be small, like 20x15x15 cm, I need continous 1200c for 4 hours and protection gas option, but what else? Vacuum level numbers are confusing me, the furnaces mentioned above can reach so called "ultimate vacuum" what is approx 10pa. Is that good enaugh? Can you please give me some advices and of course, does Chineese manufacturers can reach quality good enaugh to stand with proven Europian and American manufacturers?
Bottom line, I don't need it for the commercial work, more for experiments and small batches. For the larger quantities we will still use specialized HT companies.
Thanks

 

[MagBen]

vacuum anneal thin premalloy needs less than .001 torr (.1 Pa), i do not call 10 PA as a vacuum furnace. However, free leak chamber is more important, you can purify first then add Ar atmosphere, but ideally use dry H2 to anneal. H2 will have extra benefits to lower the impurity level which is key for high permeability.

 

[EdStainless]

Look at the pumping system. For a small unit like this it will likely be a turbo pump back by a vane pump.
Make sure the pumps are from a reputable western supplier. They are a big issue in the long run.
Is AVS still making furnaces here in the US? I believe that they were in Mass and specialized in small units.
I would want a stainless inner shell, all metal hot zone (no graphoil or fiber), and 1mTorr ultimate pressure.
There are standards for leak up rate. On this small of a unit it will be near zero.
Other issues, cold trap in the vacuum line before the pumps, placement of thermocouples, and provision for load measurement TCs.
Then there is the control system, both the controllers and how power is delivered. The controllers should be programmable and control heating, vacuum, and purge gasses.
Work like this is often done with a small Ar flow during heat up, a hold temp where high vac is pulled, and then a small hydrogen backfill for the soak.

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P.E. Metallurgy, Plymouth Tube

 

[marcus4]

Hi guys, thanks a lot for tips and technical details I have to ask from the manufacturers. I hope I can find something close as described. Cheers!