Carbon dioxide moulding process 1

casting

1. Carbon dioxide moulding process Prepared by: Zanzmera vipul Pande jayprakash

2. Introduction Co 2 Casting is a kind of sand casting process. In this process the sand moulding mixture is hardened by blowing gas over the mould. In addition, one can be sure of getting dimensionally accurate castings with fine surface finish. But, this process is not economical than green sand casting process. The process is basically a hardening process for moulds and cores.

3. Process The principle of working of the co2 process is based on the fact that if co2 gas is passed through a sand mix containing sodium silicate, the sand immediately becomes extremely strongly bonded as the sodium silicate becomes a stiff gel. This gel is responsible for giving the necessary strength to the mould.

4. The sand used for the process must be dry and free from clay. Suitable additives such as coal powder, wood flour, graphite may be added to improve certain properties like collapsibility. The suitable sand mixture can then be packed around the pattern in the flask or in the core box by machines or by hand. When the packing is complete, co2 is forced into the mould at a pressure of about 1.45 kgf /cm2(142 kn /m2) . The gas is inert upto 15 to 30 seconds. The volume of co2 required can be calculated if the quantity of sodium silicate present is known.

5. As a thumb rule, for every 1 kg of sodium silicate, 0.50-0.75 kg of gas is required. Over gassing is wasteful and results in deteriorating the sand. Patterns used in this process may be made of wood, metal or plastic. Carbon dioxide casting is favoured both by the commercial foundry men and hobbyist for a number of reasons. In commercial operations, foundry men can assure customers of affordable castings which require less machining.

6. The moulding process which can be fully automated is generally used for casting process that require speed, high production runs and flexibility. In home foundries this is one of the simplest process that improves the casting quality .

7. Co2 casting process is ideal where speed and flexibility is the prime requirement. Molds and cores of a varied sizes and shapes can be molded by this process. Applications

8. This process has many advantages in comparison to other forms of castings some of them are as follows: Compared to other casting methods cores and moulds are strong. Reduces fuel cost since gas is used instead of to other costly heating generating elements. Operation is speedy. Moulds and cores can be immediately after processing. Great dimensional accuracy can be attained than other moulding or core making process. Semi-skilled labour can be used. This process can be fully automated. Advantages

9. Difficulty in reclaiming used sand. Bench life of sand mixtures is much shorter than for most other mould and core mixes. Disadvantages

10. Thank you