Instruction manual

OPERATING_MANUAL_MC20V.DOC 18.03.11 KS Seite 21
Open the casting chamber and remove the flask and the flask holder.
3.10. Important information about direct induction heating
Direct induction melting is necessary on metals with high temperature melting points,
such as Pt, steel etc. High temperatures do not allow use of graphite crucibles
because of quick burning under standard atmosphere. Also direct induction melting
is necessary on metals, which reacts unwanted with graphite.
An Induction Coil, used in our systems, creates streamlines of electrical field, with an
specific direction.
Fieldlines on an induction coil
If now a conductive material like metal is brought into this induction field, metal
absorbs energy, it couples. This metal is separated in an unconductive ceramic
crucible in between.
As bigger now the working surface of the metal, as more energy can be absorbed, as
quicker melting can happen.
This is why metal parts should be placed rectangular to field line = horizontal, to
provide optimal absorption of energy.
So it makes sense to place metal plates horizontal, also bigger wires couple more
energy in horizontal position.
This is a typical application what does not work with a MC15.
Here are 20g of small thin Platinum sheets.
Miscues:
- 20 grams of Platinum melt only as one piece
- the material is standing vertical (IIII).
Much better would lying horizontal (==) to cross fieldlines!
Please take care that this metal parts have enough distance to crucible’s wall to
prevent disruption of crucible by extension of the metal pieces before melting.
Please also take notice, that induction melting systems need a certain amount of
volume to absorb enough energy for melting. The MC20V with direct induction
heating needs a filling level of at least 20% of the crucible’s volume. Thin wires,
chipping do not have enough volume and should be compressed (by a press) or
better, charged into already molten metal.
At direct induction melting please notice following hint:
If a too voluminous piece of metal will given to already molten metal, molten metal
can „freeze“, it becomes solid again. If this form-fitting metal now is heated-up again,
it expands can can disrupt the crucible.
Hint: load complete amount of metal in cold crucible or charge only small pieces into
molten metal