sand test and it’s different types for casting process

Sand test used to determine foundry sand properties for casting method. In this sand reject for two reason such as sand defects due to sand property and metallurgical defects. In this defects arise from sand testing and making the additives. The green sand is made from silica sand, pitch powder and binder. It can be standard to maintain small amount of rejection.

The following sand test method performed to molding.

  • Moisture content of sand test
  • Clay content test
  • Refractoriness sand test
  • Strength test
  • Permeability test
  • Flowability test
  • Mould hardness test

Moisture Content of sand test:

Moisture content Sand test
Moisture content Sand test

In this moisture content test method to determine amount of moisture by dry a mold sand weight amount of 20 to 50 grams of mold sand and with constant temperature upto 100⁰c above one hour. Then cooled with room temperature and reweight the mold sand.

The moisture content will be evaporated in the sand molding. Due to loss of moisture, the weight of molding sand loose together , gives the some amount of moisture expressed as percentage of original sand.

The moisture content tester as shown in figure. It tester contain the pan with infrared bulb. In this pan above placed weight sand and infrared heating bulb is switched on & determine the time require, the mold sand is weighted together.

Clay Content Test:

The clay content test is determined an amount of clay in test process. In this test to take 20 micron clay particles per 0.0008 inch diameter, dried sample such as molding sand with 50 gm, which is put in distilled water  with 1% of NaOH solution. In this mixture is stirred for five minutes to allow settle. Then the dirty water is remove together, and process is repeated until to get the clear water. In this process washes away. All clay in it the mold sand is dry and weighted the Clay content.

Grain Fineness sand test:

The grain fineness test method is to find the size of the silica sand particles. It fine grain sand associate with good surface finish & strength of mold will high and lower permeability.

mechanical-shaker

It carried out on dry silica sand weight of 50 gms and free from the clay. When the top sieves of mechanical shaker, the sand is placed with 6, 12, 20, 30, 40, 50, 60, 70, 140, 200 and 270 per mounted on table. In this sieve having meshed together. It sieve series placed with top to bottom in order of fineness. The free silica is shaked together in this shaker within 15 minutes or above after that weight of Sand retained for each sieve is obtains and also retained sand for each sieve multiplied by 2 and give % of weight retained.

Refractoriness sand test:

In this test of mold sand is evaluated by heat the standard sand specimen with high temperature based on sand type. It this specimen (heated specimen) are to allow cooled to room temperature and it examined along with a microscope for surface characteristic or scratching with steel needle. The specimen of sand placed into furnace, then it temperature raise 100⁰c to 1300⁰c. And wait 3 minutes and taken from oven for examination use of microscope for evaluate surface characteristic.

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