QUALITY  

Oxidation Process

Oxidation is a process that creates a lubricant oxide film to prevent soldering and adhesive wear in high pressure die casting tools.
The iron oxide film Fe₂ O₃ and Fe₃ O₄ created on the die surface with a thickness of 2-5 µm acts as a barrier between molten metal and die surface therefore prevents soldering which occurs with mechanical locking and also by intermetalic layer formation.
It is strongly recommended to apply oxidation before the first shot of the dies which has complicated figure therefore poor lubrication and cooling because of the design. The major effect of oxidation in such complicated die is to prevent directly interaction between die surface and molten metal at the areas which are poor of lubrication.

Another effect of oxide film is decreasing the wetting angle of molten metal and minimizing the thermal shock during solidification of molten metal and so delays the thermal fatigue cracks. The temperature of the process is near to the last tempering temperature so the stresses, created by the final machining like grinding and EDM are minimized with the process and maximum resistance to heat checking can be achieved.
Oxidation is applied as a final process before the first shot and no other machining is applied after oxidation.

• Minimize the adhesive wear that occur due to soldering,
• Decreases the wetting angle of molten metal and minimizing the thermal shock, increase heat checking resistance,
• Oxide film acts as naturel lubricant and makes it easy to pull out the product from the mold,
• Minimize the surface defects that occur due to soldering,
• Minimizes final machining stresses at the surface and provides the best performance to thermal fatigue.