Plaster for Ceramics and Industry Use

SSS Caster / Gypsum for Glass Molding

• What is the basic process for glass molding using the caster?Open

  The basic procedure is as follows

  • 1.Create a Model (rubber, clay, wood, etc.).
  • 2.Create a Cavity (pour casting gypsum and demold)
    ＊Reinforce by tying the surroundings with wire.
    ＊Mixing with ceramic fibers or SUS fibers is also effective.
  • 3.Add Glass Powder to the wet gypsum mold (from baby powder size to fist size, standard 40 mesh per inch).
  • 4.Dry overnight at 150-200℃.
  • 5.Heat gradually to 830-850℃ over 5-6 hours, for large items, hold for 1-2 hours.
    (Note:Depending on the technique and glass conditions, 680-1000℃).
  • 6.Cool down to room temperature over 3 days for small items and 4 days for large items.
  • 7.Deburr and polish.
  • 8.Completion.

• What are the methods and processes for using the caster?Open

  

  1.Creation of the original model

  •   Materials used: wood, plaster, silicone rubber, metal, etc.
  •   Note: Wood and plaster molds require water absorption prevention treatment with lacquer or varnish.
  •   Note: For original models with undercuts, use elastic materials like silicone rubber.

  2.Release Agent

  •   Materials: machine oil, Vaseline, machine oil mixed with kerosene + stearic acid
  •   machine oil + (0.1 – 0.5%) methylene chloride
  •   Note: Excess release agent can cause bubbles in the final product.
  •   Note: Insufficient release agent can cause adhesion to the original model.

  3.Water Mixing Ratio

  •   50% (100 parts plaster + 50 parts water)
  •   Note: Use drinking water for the process.

  4.Mixing

  •   Methods: hand mixing, mechanical mixing, vacuum mechanical mixing (vacuum mechanical mixing is the most
      suitable). Mix for 4-6 minutes. Insufficient mixing can lead floatation and reduce strength.
      Approximately 850 milliliters of mold can be made from 1 kg of caster.

  5.Pouring

  •   Pour the mixture quietly into the original model after mixing. During this process, apply vibrations to the mold or
      use a brush to raise bubbles to the surface of the mold.

  6.Demolding

  •   Perform demolding when the mold temperature reaches its maximum. Using compressed air can make removal
      easier.

  7.Drying

  •   Leave the mold indoors for about 3 hours after demolding.
    1.   From room temperature to 100℃: 1 hour
    2.   From 100℃ to 150℃: 1 hour
    3.   From 150℃ to 250℃: 1 hour
      Increase the temperature over a total of 3 hours.
    •   Note: Drying time can vary greatly depending on mold size, ventilation in the drying machine, number of molds
        in the drying machine, and their placement within the drying machine.
    •   Note: It is crucial to measure the temperature at the center of the mold using a thermocouple.
    •   Note: The mold is considered dry when the temperature at its center exceeds 200℃.

  8.Casting

• What is the method for aluminum casting?Open

  

  • Notes1: For reduced pressure: Depending on the shape of the product, please attach the same type of decompression device to the upper part as well.
  • Notes2: The appropriate reduced pressure is 24-30 mmHg (a vacuum gauge is required).
  • Notes3: The effective decompression time is the first 30 seconds immediately after casting, and it should be maintained for 2-3 minutes in general.
  • Notes4: There is also a method to apply decompression to the entire mold after casting.
  • In the drying machine, gradually lower the mold temperature to about 80℃ over more than 3 hours.
  • Adjust the vacuum gauge reading to around 20-30 cmHg before casting.
  • Notes5: The demolding time should be at least twice as long as that for sand molds.