WIELAND Dental WILAVEST quick Mode D'emploi page 14

Speed-preheating
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Once the investment material has reached its highest temperature caused by the setting reaction, the casting
ring should be placed in a burnout / preheating furnace.
This will be 20 minutes after beginning mixing. The ring is then placed in the furnace with the crucible former
face down.
Caution!
With speed-preheating, the furnace door must remain closed for a minimum of 15 minutes after the
casting rings have been placed inside. (Danger: Flames issuing from the furnace may cause burns!)
Casting ring size
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3
The best castings are produced by heating the furnace
to final temperature and then placing the casting ring
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in it immediately after the 20 minutes have elapsed.
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Caution!
Switch the preheating furnace on early enough, so that the final temperature is reached 20 minutes
after investing. If the preheating temperature has not been reached by this time, the speed
preheating method cannot be used. In this case, we recommend allowing the casting ring to cool to
room temperature and preheating it in stages using a conventional cycle. In this case, the ring must
be placed in a cold furnace.
If the ring is not to be preheated on the same day, it must be sealed with wax or Vaseline,
otherwise the investment material will dry out. The moisture required for burning out the wax
completely would then be missing.
Conventional preheating in stages
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Place the casting ring in a cold furnace:
Heat to 280 °C at a heat-rate of 3°C / min.
Hold at 280°C for 30 minutes.
Heat to final temperature at a heat-rate of 7 °C / min.
Hold at final temperature for the correct period for the size of ring.
If several casting rings have been placed in the preheating furnace, each hold-time must be prolonged by
10 minutes. After casting, bench-cool the rings to room temperature. Once the castings have been sandblasted
or pickled, continue processing them as usual.
Where a very ductile alloy has been used, we recommend using a pickling agent to clean the framework and
to gently remove the investment material from the framework.
Setting time
20 min. (from beginning mixing)
Furnace temperature
Gold casting alloys: 700 – 750 °C
Bonding alloys: 800 – 950 °C
(according to the information on the
applicable alloy labels)
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Preheating time
40 min.
50 min.
60 min.
90 min.