GC EUROPE Fujivest Super - Manual (Page 15)

15
Focus Edition from GC
2.3 Investing
2.3.1 Working time (see 1.3)
The working and pouring time for each investment
material is stated in their individual ‘Instructions
for Use,’ however it must be understood that
this is calculated for material stored and used
at normal room temperature of 21 - 23°C.
Temperature variations will result in a longer
(if cooler) or shorter (if warmer) working times.
2.3.2 Investing , filling the moulds
Invest using a thin stream of material and low
frequency (gentle) vibration, once the ring is filled
stop the vibration immediately and do not touch
the investment until set. The optimised consistency
of GC Europe’s phosphate bonded investments
means that they possess excellent flow properties
rendering strong vibration unnecessary.
2.3.3 Investing under pressure
We do not recommend high pressure investing
as this may lead to a
delayed setting
(especially when
the compressed air
temperature is low)
which can result in a
rough casting surface
and increased risk
of fining on the cast
objects.
2.4 Setting
2.4.1 Setting time
The optimal setting time prior to insertion in
the furnace is normally 20 min, however please
always check the most recent ‘Instructions for
Use.’ The setting time is based on the material
being stored and used at a room temperature
of 21 - 23˚C, as said previously variations in this
temperature may affect the setting time and
expansion.
Best results are then normally obtained by placing
the casting ring immediately into a preheated
burnout furnace. Prior to putting the investment
into the burnout furnace it is essential to make
sure that it has fully set, as unset investment
material is likely to cause casting defects such as
distortion and/or rough surfaces.
Lengthening the setting time before putting the
mould into the furnace is a technique often used
when a lot of investing is done late in the day and
the casting is to be undertaken the next morning,
this is the so called “over night” burn-out technique.
This longer setting period will usually work but can
result in an over expansion, a reduction of surface
smoothness and increased risk of cracking.
If the filled investment ring does need to be
left for an extended period prior to burnout it is
better to put it into a plastic container or
bag which will help retain humidity within the
investment material, it can be inserted into
the burnout furnace and processed with the
conventional step heating method.