Re: Kiln/furnace advice sought

Andrew Mawson wrote:


"Peter Fairbrother" <zenadsl6186@xxxxxxxxx> wrote in message
news:C08A9DAD.C9866%zenadsl6186@xxxxxxxxxxxx Andrew Mawson wrote:


"Peter Fairbrother" <zenadsl6186@xxxxxxxxx> wrote in message
news:C08A865F.C9845%zenadsl6186@xxxxxxxxxxxx

I want to build a furnace to cast Inconel, which melts at ~ 1350 C.

I'm planning on using 1450 C as a target kiln maximum temperature, and 1550
C rated castable insulating refractory. Is this sensible?


I also need to be able to evacuate the furnace to a fairly high vacuum. I'm
looking for a cylinder with a full-diameter removable, sealable lid,
between 8 1/2 and 14 inches in diameter, and 11 and 16 inches high, which
will take a vacuum at perhaps 100 C - the insulation is on the inside, it
doesn't get very hot. Any suggestions? Something cheap.

I thought of using a small milk churn, but they are aluminium and not
entirely cylindrical, and the lid is smaller than the body.

A gas bottle could be used, but it would need a lot of work to make a
removable, resealable lid (and I'm a bit unhappy about cutting one open
anyway).

Any other suggestions? I have this image in my head of a (stainless?) steel
container of about the right size, with a lid that clips on, a small drum
perhaps, but I can't identify it.


-- Peter Fairbrother


Peter,

100 deg C difference between your max temp and your melting point looks a
bit close to me. The heat transfered from the kiln / furnace to the metal is
proportional to the difference in temperature so as the metal gets close to
melting it will take an age to heat up the last few degrees. What is your
casting temperature - obviously more than 1350 C - but what temperature do
you need for fluidity ?

What are you using as a heat source?

AWEM



Hi Andrew,

I don't know the casting temperature needed for inconels - in fact I know
very little about casting inconel at all.

I have done some casting with lower-tmperature metals, where the hot molten
metal is poured into a cooler mould and hardens quickly.

What I had in mind here was to heat both the mould and the metal to the same
high temperature, allow the metal to flow slowly into the mould, then cool.

This may be a silly idea - I am a newbie, and am having a hard time finding
references/books etc on the subject.

I don't mind going higher if needed, the figures given were just my first
thoughts, which seem to have been a bit naive.

Any further advice would be welcome.




Electric heat, resistance, but what I have only goes to 1600 C element
temperature. Thinking about using microwave/RF, but I thought to start off
easy.


-- Peter Fairbrother


I'd be interested in the heating element that takes that temperature. Kanthal
is the most common of the 'exotics' and that runs out of steam at 1350 C, and
even then the atmosphere has to be controlled so that the film of aluminium
oxide doesn't get stripped.

AWEM

It's just an idea, but I was thinking of using light bulbs - the "halogen"
ones with quartz sheaths and tungsten elements. Is this silly?

I got some 9" extra-long ones, so the ends could be outside the furnace
proper and cool-ish in use, as they have metal bits on to carry the current
etc.. I won't be running them at full power.

The middle part is just fused quartz and tungsten (and halogen and argon) -
quartz softens at 1,650 C iirc, and the tungsten goes to 3,000 C plus in
ordinary use..

I may try Super Kanthal HT (thanks Charles!) tho' if they don't work.


--
Peter Fairbrother

.

Relevant Pages

  • Re: Kiln/furnace advice sought
    ... I'm planning on using 1450 C as a target kiln maximum temperature, ... The heat transfered from the kiln / furnace ... I don't know the casting temperature needed for inconels - in fact I know ... I have done some casting with lower-tmperature metals, ...
    (uk.rec.models.engineering)
  • Re: aluminum machining? A q that is technical but not bicyclic
    ... Metals conduct heat, while plastics are insulators. ... lower temperature than your bodytemperature. ...
    (rec.bicycles.tech)
  • Re: Heat Calculation In Hot Wire TIG
    ... temperature" (that is, as the time increases, the temperature of both ... Now in order to find the heat energy required by ... dilution in Hot Wire TIG welding is 40 to 45%. ... from ambient temperature to melting temperature of metals)? ...
    (sci.engr.joining.welding)
  • Re: Foam and rescue possibilities
    ... Though its brittleness decreases with falling temperature, ... Metals are generally ductile (as opposed ... to brittle) because their ultimate strength considerably exceeds their ...
    (sci.space.policy)
  • Re: Foam and rescue possibilities
    ... science knows that the strength of a metal (or metal alloy) generally ... Though its brittleness decreases with falling temperature, ... a wide variety of structural metals *don't* get brittle when ...
    (sci.space.policy)