Foundry Chemicals & Consumables
Bentonite
Sodium and calcium bentonite used as the binder in green sand moulding.
Bentonite is a clay-based binder added with water to green sand, giving plasticity and green strength. It is common in iron and steel casting. Sodium bentonite provides high swelling and hot strength; calcium bentonite swells less and has different green strength and flowability, and is also used in activated form.
In a sand system, bentonite level is tracked through green compression strength, permeability, compactability and active clay value. Fresh bentonite is added continuously to compensate for clay burned out and deactivated. Use together with a carbonaceous additive (coal dust) improves surface finish.
Because it absorbs moisture, it should be stored dry. Respiratory protection is advisable because of dust.
Product details
- Types
- Sodium bentonite, activated calcium bentonite
- Form
- Fine powder (milled)
- Packing
- 25 kg bag, 1 tonne big bag; bulk (silo) on request
- Storage
- Dry area, on pallets
Applications
- Green sand moulding (grey and ductile iron)
- Steel casting green sand systems
- Binder make-up in sand systems