Moulding sand Properties.pptx

its about properties of moulding sand

1. Arya College of Engineering & IT. Kukas-Jaipur Unit –I Manufacturing Processes Moulding sand Prepared By Nikil Kumar Khandelwal Department of Mechanical Engineering

2. Moulding Sand Moulding sand is defined as granular particles resulting from the breakdown of rocks, due to the action of natural forces, such as frost, wind, rain, heat and water currents. Rocks have a complex composition and sand contains most of the elements of the rocks. Typical mixture of moulding sand contains 89% sand, 4% water and 7% clay

3. Characteristic of Moulding Sand: Moulding sands are refractory in nature and can withstand temperature of metal being poured without fusing. The moulding sand do not chemically react with molten metal. The sand has high degree of permeability and thus allow gases formed during pouring to escape. These strength, permeability and hardness of the sand mix can be varied by changing the structure of sand.

4. Types of Moulding Sand Natural Sand or Green Sand In Moist State 6-8 % Water 5-6 % Clay Having good Damping Capacity Used For Small and Medium Die casting

5. Types of Moulding Sand Dry Sand Called as “Dry Sand Mould” or Skin Dry Mould Used For Large Casting Loam sand Contains 50 % Clay Used For Heavy Casting Specially Used in Loam Mould

6. Types of Moulding Sand Parting Sand Parting sand consists of fine grained clay free dried silica sand, sea sand or burnt sand with some parting compounds Used For separating crop and drag parts without cohesion

7. Types of Moulding Sand Facing Sand It is made of silica sand and clay without the addition of any used sand. Thickness of the sand layer varies from 20 to 30 mm Graphite, mollasses etc. may be added to the facing sand. High strength and refractoriness are required for this sand.

8. Types of Moulding Sand Baking Sand Backing sand is the bulk of the sand used to back up the facing sand and to fill up the volume of the flask. Old Sand may used repeatedly It is also known as Black sand It reduces the cost of moulding

9. Types of Moulding Sand Core Sand Also Known as Oil sand This is silica sand mixed with core oil.

10. Properties of Moulding sand Flowability Flow-ability is the ability of moulding sand to free flow and fill the recesses and the fine details in the pattern. It varies with moisture content. Green Strength Adequate strength and toughness for making and handling the mould. Dry Strength Dry sand must have strength to resist erosion and also the mettalostatic pressure of the molten metal or else the mould may enlarge.

11. Properties of Moulding sand Hot Strength It is the strength of the sand above 212◦F Capacity of sand to with stand hot metal mettalostatic pressure Porosity or Permeability It is the ability of the moulding sand to allow gasses to pass through. Refractoriness It is the ability of the sand to withstand high temperature with experiencing any physical changes

12. Properties of Moulding sand Collapsibility Collapsibility is that property of the moulding sand which determines the readiness with which the moulding sand or mold Automatically gets collapsed after the casting solidifies Breaks Down in knock out and cleaning operations Adhesiveness The ability of the sand particles to get stick with another body is called adhesiveness.

13. Properties of Moulding sand Bench life It is the ability of the moulding sand to retain its properties during storage or while standing Coefficient of Expansion Moulding sand should possess low Coefficient of Expansion Durability It is the capacity to withstand repeated cycles of heating and cooling during casting operation