CO2 MOLDING

Prepared By:-Rahul Kumar Sinha &

Garima MishraVI Sem Metallurgy

WHAT IS CO2 MOLDING??

• Carbon Dioxide molding is a sand casting process that employs a mixture of sand and liquid silicate(3-4%) also known as water glass as binder.

• The sand molding mixture is hardened by blowing gas over the mold.

THE PROCESSThe equipment of the molding process include CO2 cylinder,

regulator, hoses and hand held applicator gun or nozzle.Any existing pattern can be used for the molding purpose

which can be placed in the mold before the mold is hardened.

The sand is mixed with the liquid sodium silicate in a standard muller and is packed into flasks.

It remains soft and moldable until it is exposed to a flow of CO2

gas, after which it hardens.After the mould is fully rammed, CO2

is introduced through vents in the metal pattern.

Na2SiO3 + CO2

Na2CO3 + SiO2

(colloidal)

This hardens the adjacent sand, and the pattern can now be withdrawn .

• Note : In addition, care must be taken to prevent the carbon dioxide in the air from hardening the sand before the mould-making process is complete.

APPLICATIONS OF CO2 MOLDING

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.

ADVANTAGES OF CO2 MOLDINGCompared to other casting methods cores and molds

are strong.Reduces fuel cost since gas is used instead of to other

costly heating generating elements.Reduces large requirement for number of mold boxes

and core dryers.Provides great dimensional tolerance and accuracy in

production.Moisture is completely eliminated from the molding

sand.This process can be fully automated.

DISADVANTAGES OF CO2 MOLDING

If excess moisture is contained in the sand, anything above 0.5% moisture could impair the performance and give poor results.

Another drawback with CO2 is the rental payments on the gas bottles, plus the purchase expense of gas cylinder regulators, required to deliver the correct line gassing pressure.

The mould has to be broken apart to retrieve the casting and is generally discarded after each use, presenting a sand waste disposal problem.

THANK YOU!