CASTING DATA CENTER

Problem Cause Solutions
Bubbles In correct water / powder ratio (Investment too thick. Too little water) Recommended water to powder ratio Vacuum mixing 38:100 / Conventional mixing 40:100
Work time of investment not too less Appropriate time: 2-3 mins
Work time of investment not too long Work cycle too long. Investment is starting to thicken while still being vacuumed Bubbles
Vacuum machine faulty-Vacuum leaks
Flashing or Finning
Incorrect water/ powder ratio (Too much water) Recommended water to powder ratio Vacuum mixing 38:100 / Conventional mixing 40:100
Failure of conveyor belts
(Centrifugal casting) Over pressure (Vacuum casting)
Spin speed is too fast. Torque setting have to match spin speed.
Mixing time not long enough Appropriate time : 3-4 mins
Overheat metal melting
Rough surfaces Stream de-wax for too less Appropriate time 60 mins
Stream de-wax for too long Appropriate time 60 mins
Flasks put in furnace too soon after mixing Appropriate time 45-60 mins
Furnaces temperature is too high
Dewax too low temperature/ Lost wax time not long enough *Burnout Oven Burnout temperature : 220°C250°C
Appropriate time :
60 mins
Sand Casting Less mixing time Appropriate time 2-3 mins
Over casting temperature
Furnaces Temperature is too high
Lost wax process not long enough Appropriate 60 mins
Cleanliness of wax piece White bensin
Finning Furnace temperature is too high
Incorrect water/ powder ratio (Too much water) Recommended water to powder ratio Vacuum mixing 38:100 / Conventional mixing 40:100
Furnaces failure
Moving flask too soon after mixing Appropriate time 45 mins
Investment cracking Room temperature is too low/ Too much humidity
Incomplete casting Defective patturn-Wax tree too hight The maimum tree height should be between 0.5 inch shorter than the fill level of the flask.
Flaws in a plaster mould
Failure of conveyor belts (Centrifugal casting)
Over pressuer (Vacuum casting)
A mixture of plaster and group up old moulds
Incorrect water/ powder ratio (Too much water) Recommended water to powder ratio Vacuum mixing 38:100 / Conventional mixing 40: 100
Gas porosity Incomplete burnout * a minimum of ten hours
Furnaces failure Calibrate it once every 3-4 months
Problem Cause Solutions
Mould overfills Air pressure too high (depend on master piece) Reduce air pressure
Wax too hot 72-75°C is recommend temperature
Plates held with uneven pressure/not covering mould Heil plates firmly, distributing pressure evenly over entire mould surface
Mould held too long at nozzel Hold for less time
Mould not filling Air pressure too low Adjust air pressure
Wax not hot enough Adjust temperature
Nozzle plugged Remove and clean
Mould held too tightly Hold without squeezing
Uneven pressure caused by dirty plates Clean plates so surfaces are flat
Air trapped in mould Make air releases cuts(vents) in mould
Be sure wax pot is more than ½ full
Air bubble in pattern Air pressure too high Adjust air pressure
Wax pot low on hot Add wax. Be sure that wax pot is more than ½ full
Wax too hot or cold Adjust temperature and stir wax to release trapped air
Mould held at wrong angle to nozzle Held mould on the same plane to nozzle
Wax brittle Wax too hot Check temperature of wax pot
Wax has been reused Use new wax. Use no less than 90% new wax with reused. Try avoiding using old wax
Mould cooling too long before opening Inject fewer mould during production cycle
Using unsuitable wax Use wax that is suitable to type of pattern being produced
Wax discoloured(brownish) Wax too hot Clean wax pot (stream or soak in percloethylene) : add new wax
Patterns bend easily, wax stick to mould Wax too hot Adjust temperature
Opening mould too soon or mould too hot Prolong cooling period by working more mould
Wax keeps flowing after mould is filled Dirt inside the nozzle Remove and clean nozzle
Problem Cause Solutions
Cut mould does not seal evenly(warping) Rubber used in packing has begun to vulcanise Use new rubber
Mould under packed Use sufficient rubber. Close platens down so they are in contact with the mould frame
Mould over packed Tighten vulcaniser ½ turn past first resistance. Repeat every two minutes until platens are in contact with frame and handle cannot be turned without resistance. Allow 15 minutes at 155°C
Voids in mould (air entrapment) Model not filled in with rubber Pack rubber piece into and around model
Mould not cured for recommend time Tighten vulcaniser ½ turn past first resistance. Repeat every two minutes until platens are in contact with frame and handle cannot be turned without resistance. Allow 15 minutes at 155°C for every 6 mm. For intricate mould all 20 minutes at 145°C for every 6 mm.
Platen not at curing temperature Preheat vulcaniser to 155°C for 10-15 minutes
Mould delaminates after curing Surface of strips not clean Use new strips. Do not contaminate surface with hands and protect from eatraneous dirt or dust
Rubber is old Use new rubber
Mould not cured long enough Use correct times and temperatures