Die casting for aluminium alloy, including magnesium-aluminium-zinc alloy is a very mature production process. The die-casting products are widely used in cars, telecoms, motorcycles, machinces, household appliances, etc. Heat and melt the alloy materials(the melting point of aluminium is 660.4℃ ), then pour it into the mould cavity, it will shortly cool into solid phase. To make sure that the die-casting products are smoothly released, the mould release agent must be sprayed onto the surface of the mould cavity before the injection of the melted alloy materials.
The release agent for die casting is essential for the production process. Due to the difference of the sizes, structural complexity and the requirements for the post processing of the die casting products, the requirement for the release agent is also different.
A suitable release agent should meet the following standards:
1. An excellent releasing media.
As an effective material for isolating the metals, silicone oil is an ideal choice. The silicone oils should be high temperature resistance, it will not affect the post-processing, such as the coating of the aluminium products.
2. Water-based.
Because when the mould is at high temperature, all the solvent based release agent is not suitable. Taking water as an dispersion media, water will be quickly evaporated at high temperature, and the effective component of the release agent will be uniformly distributed on the surface of the mould cavity. It will form uniform film, and get strong adhesion ability, high temperature resistance and excellent releasing property.
3. Be emulsified with suitable emulsifiers.
The chosen emulsifiers should be high temperature resistant, it should avoid being carbonized at high temperature to make sure of the cleanness of the die casting products and the mould cavity.
4. No corrosion to the die casting products and mould parts.
5. The volatile matter has no smoke and it should be non-toxic, does not harm the operators.
When you are using the mould release agent and face the following problems, then it is time for you to change the release agent.
1. Your die casting products or mould are contaminated. That is because your selected mould release agent contains some organic materials which are not high temperature resistant, so they will be carbonizated or become polyers with macromolecul and then be adheded to the surface of the die casting products or the mould.
2. After releasing, the surface processing property of the die casting product is affected. For example,shrinkage cavity appears during the coating process and the flake of the coating falls off, etc.