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Siam Casting Powders Ltd.
SIAM CASTING POWDERS LTD.
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SCP - TECHNICAL DATA
Jewellery Trouble Shooting Casting problems
Flashing or Finning
Cause : Incorrect powder/water ratio (too much water)
REMEDY :
Use correct amount of water (especially important with vacuum investing machines)
Cause : Work time of investment too long. Slurry start to set while still under vacuum.
REMEDY :
Ensure the work time is fully used.
Normally 8 minutes.
Cause : Casting the material with too much force.
REMEDY :
For centrifugal casting, use the correct
spin For vacuum casting, reduce pressure.
Cause : Moving flask too soon
REMEDY :
Leave the flasks for at least 1 hour.
Cause : Moulds allowed to dry out before burn out.
REMEDY :
If not burning out the same day, keep moulds wet by covering with wet sacking.
Bubbles
Cause : Investment too thick. Too little water.
REMEDY :
Use correct powder/water ratio.
Cause : Vacuum pump/tank faulty.
REMEDY :
Ensure equipment is regularly serviced
and adequate for the task.
Water marking
Cause : Incorrect powder/water ratio (too much water)
REMEDY :
Use correct amount of water (especially important with vacuum investing machines)
Cause : Work time of investment not used up.
REMEDY :
Ensure the work time is used up and slurry temperature is 20 – 30 °C.
Cause : Investment powder expired(too old)
REMEDY :
Do not keep investment too long time.
Blister
Cause : Dewax soak time not long enough.
REMEDY :
Extend time for dry dewax at least 3 hours
(temperatures between 150 to 250°C)
Cause : Flasks dewaxed at too high temperature.
REMEDY :
Do not exceed 250°C during dry de-wax.
Wax will boil and erode investment surface.
Cause : Flasks put in furnace too soon after investing.
REMEDY :
Leave flasks undisturbed for a minimum of one hour before de-wax.
Rough surfaces
Cause : Rough waxes.
REMEDY :
Use too much powder on the rubbers.
Cause : Flasks dewaxed at too high temperature..
REMEDY :
Do not exceed 250°C during dry de-wax.
Wax will boil and erode investment surface.
Cause : Steam de-wax for too long..
REMEDY :
Steam, de-wax for a maximum of 1 hour.
Steam will erode surface of the casting.
Cause : Flasks overheated during burn out..
REMEDY :
Ensure maximum burn out temperature
does not exceed 750 °C
Cause : Metal temperature too hot.
REMEDY :
Reduce metal casting temperature.
Rough surfaces
Cause : Usage of low quality metal.
REMEDY :
Do not use more than 50% recycled alloy
and ensure it is clean.
Cause : Reaction with investment temperature. (Flask temperature too hot)
REMEDY :
Reduce flask temperature down, Specially
on big design.
Cause : Overheating the metal.
REMEDY :
Reduce metal casting temperature.
Cause : Temperature inside furnaces over.
REMEDY :
Ensure the quality of Thermocouple can control temperature.
Shrinkage porosity
Cause : Incorrect spruing
REMEDY :
Sprues should be attached to the heaviestpiece of the casting.
Thereshould be sufficient sprues to ensure the casting is adequately fed.
Cause : Flask temperature too cold.
REMEDY :
The flask temperature should be just hot enough to achieve complete fill.
Incomplete casting
Cause : Metal or flask temperature too cold.
REMEDY :
Increase casting temperatures. If the
metal or flask is too cold, the metal will
freeze before completely filling the mould.
Cause : Improperly sprued.
REMEDY :
the sprue system should be designed
to allow the metal to enter easily and
without restriction.