Die-cast tool coating is one of the essential parameters of the entire process, which is often misunderstood or overlooked. In aluminum die casting, tools are likely to be exposed to corrosion due to coming in contact with the tool surface to heat checking, casting alloy, and oxidation while pouring at high temperatures. While performing the die casting, the goal is to finish the casting with no additional operation.
However, it is essential not to compromise with the final finish and the physical characteristics that might get affected during the process. Hence, a die-cast coating is done to save the produced components from failing after a short run. Let us understand what die casting coating is and what makes it essential.
Die cast tool coating offers various insulating properties to the metal and reduces thermal shock during the casting. These shocks can lead to roughness and defect in the final product, which may appear on the casting and make it less stable.
Standard PVD coatings include-
- Titanium Nitride (TiN)
- Titanium Carbonitride (TiCN)
- Chromium Nitride (CrN)
- Titanium Aluminum Nitride (TiAlN)
PVD coating like Chromium Nitride is mainly used in die casting. When molten aluminum attacks the h13 tool steel and drains the iron out of the steel, welding starts to happen. This makes the cavities and pins start weakening, and quickly get defective.PVD coatings provide hard barriers to prevent the molten aluminum from reaching the steel and create a perfect environment to keep the components in the right shape.
Another reason these coatings are the best possible solution is the washout and erosion that come with die cast tooling. CrN combats these issues and keeps the shape intact.
HOW TO CHOOSE THE RIGHT COATING MATERIAL?
While choosing the right PVD or CVD coating material for your application, here are some of the characteristics you can consider.
The harder a material or surface is, the longer a tool will last. Titanium Carbo-Nitride (TiCN) offers higher surface hardness, increasing the tool life. For non-ferrous material, it can keep durability last longer than other alternatives.
Friction causes heat, which leads to short coating life or failure. However, the heat can be lessened with a surface lacking irregularities and coarseness. Therefore, choose higher surface lubricity to increase speed compared to non-coated material.
A wear-resistant coating protects against scrapes. However, materials may not be hard, but the processes during production may lead to a breakdown of edges and parts.
Factors like surface preparation, binding agent, and choosing compatible material can increase the protection of the die-cast tools.