● There are many types of binders are mixed with sand core. Binder should be selected on the basis of the characteristics that are most suitable for your particular use.
● Some binders require any baking becoming tight at room temperature, such as rubber cement, Portland cement and sodium silicate or water glass.
● In foundry operations in several large and small foundries, sodium silicate binder is popular because it can be hardened almost immediately blowing carbon dioxide gas through the mixture.
● process hardens the sodium silicate / CO2 via the following reaction:
● binds the silica gel made individual sand grains together. Oil binders require heating or baking before they develop strong enough to withstand the molten metal.
● stickers require heat also sulfite. Most popular sulfite product stickers on the wood pulp industry.
● Many liquid binders made from starches, cereals and sugars. They are available with countless number of trade names.
Good binder will have the following properties;
- Collapse quickly when metal starts to shrink.
- Not have a heart condition during baking.
- Maintain strength during storage time.
- Absorption at least in the mold or moisture when in storage.
- Withstand normal handling.
- Deploy correctly and fairly across the sand mixture.
- Should the production mix can be formed easily.