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Basic Knowledge Relevance of Die Casting Release Agents

| Editor: Nicole Kareta

The use of die casting release agents represents an essential process step in the production of cast parts, as the so-called mold release agent prevents components from sticking to the mold or the metal from being soldered to the mold. What else is worth knowing about die casting release agents?

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The correct composition of casting release agents depends on the metal used.
The correct composition of casting release agents depends on the metal used.
(Bild: gemeinfrei / Unsplash)

As a rule, release agents are sprayed onto the wall of the die casting mold. This separates the metal from the mold and also simplifies the demolding of the casting. In addition, die casting release agents offer numerous other functions and advantages which have a positive influence on the entire production process:

  • Improved flow of molten metal
  • Easy removal thanks to homogeneous coating
  • Good lubrication of moving parts
  • Improvement of economic efficiency due to lower material requirements
  • Shortened cycle time due to cooling properties
  • Continuously high product quality
  • Reduced scrap rates
  • Increased mold life

Composition of Die Casting Release Agents

Basically the agents can be used for various metals such as aluminum, zinc, magnesium and their alloys, whereby the correct composition depends on the respective variant. It is therefore particularly important that the metal to be demolded is neither physically nor chemically compatible, otherwise the release agent could be absorbed. In addition, the release agent ingredients have an influence on the cycle times of the casting process and on the quality of the cast components.

The main components of die casting release agents can be divided as follows:

  • Mineral oils
  • Ester oils
  • Silicone oils
  • Waxes
  • Surfactants

While the content of paraffins and aromatics in mineral oils is still high, ester oils make a positive contribution to the environment as they leave a low CO2 footprint and are a renewable resource. Silicone oils have excellent lubricating properties and high thermal resistance, making them well suited for use in die casting. The use of waxes is limited due to the high temperatures in die casting. Surfactants are used to emulsify the materials and form a bond between water and oils or waxes.

In die casting, water-based release agents are mainly used, as the molds are cooled by the heat of water evaporation. In addition, solvent-based products pose a risk of explosion and are harmful not only to the environment but also to health.

Die Casting Release Agents Must be Dosed Correctly

Less is more or better too much than too little? When it comes to the dosage of die casting release agents in die casting, popular life mottos should be avoided. Here it is a matter of sure instinct, because if too little release agent is used, the casting can stick to the mold, leading to defects in the building component. Too much release agent cannot evaporate quickly enough, causing porosity in the metal.

Development of Die Casting Release Agents

The formulation of die casting release agents still follows the motto "trial and error". However, due to the extremely short injection times in die casting, there are still no suitable measuring methods with regard to temperature, heat exchange and viscosity drop. This means that die casting release agents can only be developed with the aid of practical tests.

Henkel offers one example of this: Based on its own experience, the company has launched a release agent onto the market that was developed using the company's patented siloxane technology and combined with a new approach to biostability. Bonderite L-CA CP 799 has been specifically developed for structural castings where no heat treatment is required, providing a foundry solution for the automotive industry. The product provides improved casting performance, antibacterial protection and excellent surface finish.

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