Properties of Moulding Sand Part-2

Properties of Moulding Sand:

 Moulding Sand

5. Cohesiveness or Strength:

The ability of the sand particles to stay with one another is named cohesiveness. The strength of the sand depends upon how cohesive the sand particles are. The sand should have sufficient strength in order that it can easily capable to retain its shape during conveying, turning or closing and pouring. If it's not of appropriate strength than it'll not be ready to hold its shape and therefore the mould may damage during pouring of molten metal. Low strength sand results in pouring casting defects in metals. To avoid pouring defects, the sand should be of sufficient strength to supply mold of desired shape and also retain this shaped even when the molten metal is poured in the moulding cavity.

6. Green Strength:

The strength of sand possessed by it in its green or moist state is named green strength. The mould with adequate green strength retains its shape and don't collapse even when the pattern is far away from the moulding box.

7. Dry Strength:

The strength possessed by the sand in its dry or baked state is named dry strength. Enough dry strength allows the sand to face up to erosive forces thanks to molten metal and helps to retain its shape.

8. Refractoriness:

The ability of the moulding sand to face up to the heat of the molten metal without fusing into it's called refractoriness. The moulding sand must have enough refractoriness property to supply excellent quality of casting free from defects. The sand with lack of refractoriness melts and gets fuse within the casting and spoils the standard of the cast metal. The refractoriness is that the measures of sinter point of the sand not its freezing point.