CASTING PROBLEMS

FLASHING

Possible Fault Cause	Solution
Incorrect Water or Powder Ratio	Ensure Correct Ratio P:W Conventional Mix 40:100 Vacuum Mix 38:100
Incorrect Burnout Cycle	Follow recommended burnout cycle. Ensure furnace ramp does NOT exceed 250°C/Hr. Ensure first stage burnout temperature is kept in the range 220°C - 250°C and is held for 4.5 hours minimum. If problem still occurs increase hold time.
Excessive Casting Forces	Centrifugal casting: Lower torque and RPM settings. Vacuum casting: Reduce over pressure.
Disturbed Flask during setting	After investing bench set and do NOT move flask, strip base or remove tape for a minimum of 90 minutes.
Over working investment	Ensure all flasks are poured and removed from vacuum tank and put on bench to set by max. 9 minutes from starting mixing.
Waxes too close	Waxes too close together creating a very thin wall of investment. Waxes too close to side or top of flask; ensure min. 5mm gap to top and sides of flask.
Slurry too hot or cold	Adjust slurry temperature to 21°C +/- 1°C by increasing or decreasing water temperature.
Moulds dried out before burnout	If flasks are left on bench for more than 4 hours before burnout place a damp towel over the tops of the flasks to stop them drying out. Do NOT leave flasks in furnace overnight before burnout.
Flask base leak during investing	Ensure good seal between wax sprue and base. It is suggested that it be sealed with molten wax.