GC EUROPE Fujivest Super - Manual (Page 34)

34
Cause Remedy
- Too early and/or too fast burnout procedure - Lengthen the time of bench setting before
investment mould is placed in furnace.
Consult the instruction for use for the correct
setting time, end-temperature and heating
up schedules
- Investment mould burnt out and allowed to
cool for too long prior to casting
- Cast as soon as possible after removing from
furnace
- Investing was continued when the
material had begun to set or the mould was
disturbed during setting
- Leave the mould to bench set completely
away from vibration, do not pour
investment when its consistency is not
correct or it begins to set
- Blockage of the main sprue hole during
early burnout by high melting pattern
materials, causing a build-up of pressure
within the mould
- Select pattern and sprue materials that melt
easily and burn out without difficulty; coat
plastic sprues with wax in order to allow wax
to drain away and plastic to expand for
optimal burn-out. It is preferable to use
hollow sprue systems
- Too many patterns - Avoid placing too many patterns, use a
larger sized investment ring
- Patterns placed too close to ring wall or near
to the top of the ring
- Space patterns 5 mm from investment
mould wall and top of mould
- Mould is not porous enough for gases to
escape
- Scrape the top of the investment mould
before burnout
- Use of excessive pressure/force during
casting procedure
- Reduce pressure (number of turns/pressure)
- Invested with metal ring without liner - It is advised to use the GC New Casting
Liner when using a metal ring (consult the
instruction for use)
5
Investment cracking
(fins on the castings, miscasting ….)