Sand testing of sand casting (2)

2) Test Material Clay:

The amount of clay is determined by the test subject of clay a clay in the sand molding of 50 grams defined as particles when suspended in water, fail to resolve at the rate of one inch per min to complete. Clay consists of particles smaller than 20 microns, against 0.0008 inch dia.

3) Test Finer Grain:

The AFS Grain Fineness number (AFS-NBA) is one means of measuring the fine grain of sand system. NBA is a measure of the average particle size (or grain) in a sample of sand. The finer grain of sand molding measured using a test called sieve analysis. The test is carried out in shaker power driven a number of sieves equipped with one over the other. 1. A representative sample of the sand is dried and weighed, then passed through a series of progressively finer sieves (screens) and they are agitated and tapped a 15-minute test cycle. The series is put in order from top to bottom fineness. 2. The sand keep each sieve (grain too large to pass through) is then weighed and recorded. 3. The weight of each sieve to keep out three calculations to get the AFS-NBA.

4) Test refractoriness:

Refractoriness is considered the molding sand by heating the specimen AFS standard sand to the high temperature ranges depending on the type of sand. The heated sand test pieces are cooled to room temperature and examined under a microscope where surface characteristics or by scratching it with a steel needle. If silica sand grains remains sharply defined and easily give way to the needle. Sintering is not yet set in. In the actual experiment the boat porcelain sand specimen submitted in electric furnaces. Is usual practice to start the test from l000 ° C and temperature in steps of 100 ° C raise to 1300 ° C and in steps of 50 ° over 1300 ° C till sintering the grain silica sand held . At each level of temperature, it is kept for at least three minutes and then taken out of the oven for examination under the microscope to evaluate the surface characteristics or by scratching it with a steel needle.