The mold coating is a continuous film on the surface. After special treatment, it is used to protect the mold from rust and scratch by sharp hard objects. The coating material can be gaseous, liquid, or solid. Its type and state are usually determined according to the substrate to be sprayed. What coatings can be applied on die casting mold and injection mold? In this article, let’s go over three common types of mold coatings and their benefits.

What are the Benefits of Mold Coating?

After vacuum coating, the surface hardness of the die can be increased by 5 to 10 times, which can greatly reduce the surface wear. Especially when used for high-precision machining, it can obtain very excellent surface quality. After the cold stamping forming and drawing dies are coated with vacuum coating, the friction force can be significantly reduced, and the scratch and wear in processing can be significantly reduced. Therefore, the service life can be increased and the cost can be greatly reduced. Mold coatings can improve the slip properties, surface hardness, wear resistance, and corrosion resistance. 

– Reduce the friction coefficient and reduce the machining forces

– Improve the surface hardness and greatly prolong the service life of the die

– Prevent product galling and strain and improve product quality

– Save the trouble of unloading, polishing, and then installing the mold, and improve the efficiency

Types of Mold Coatings - PVD Coatings, CVD Coatings, and TD Coatings for Molds

What is CVD Mold Coating? 

CVD (chemical vapor deposition) and PVD (physical vapor deposition) technology are widely used in die surface treatment. Among them, CVD coating technology has more excellent high-temperature oxidation resistance and strong coating adhesion. It has a good application effect in high-speed steel trimming die and extrusion die. However, due to the many advantages of PVD in other aspects and its continuous expansion in coating materials in recent years, its performance has gradually been better than CVD in more and more aspects. CVD (chemical vapor deposition), as its name suggests, uses gaseous precursor reactants to generate solid films through atomic and intermolecular chemical reactions. Compared with PVD, CVD has another advantage that ordinary PVD technology is difficult to catch up with at present, that is, the most commonly used CVD coating material – aluminum oxide (Al2O3). Aluminum oxide has very good physical and chemical stability, is hard and wear-resistant, and is very low cost, but it is difficult to realize on ordinary PVD due to the constraints of the generation process.

What is PVD Mold Coating?

PVD is the abbreviation of physical vapor deposition. It refers to that under vacuum conditions, using low-voltage and high current arc discharge technology, using the gas discharge of vacuum coating equipment to evaporate the titanium plate and ionize the evaporated material and gas, and using the acceleration of electric field to deposit the evaporated material and its reaction products on the workpiece. PVD coating is widely used in the mold industry because of its excellent performance, such as hard height, high wear resistance, strong corrosion resistance, high-temperature resistance, adhesion resistance, and so on. PVD is a process that employs titanium nitride to create an exceptionally durable and hard-wearing coating. PVD coatings are far more resistant to wear than conventional gold plating.

What is TD Mold Coating?

TD coating refers to the super hardening treatment technology of the TD die surface, which adopts the principle of metal carbide diffusion coating TD (thermal diffusion carbide coating process). It is to place the workpiece in borax molten salt and its special medium at a certain treatment temperature, and produce a chemical reaction between the metal in the special molten salt and the carbon and nitrogen atoms in the workpiece, It diffuses on the surface of the workpiece to form a metal carbonization layer of vanadium, niobium, chromium, titanium and so on. The TD treatment process is complex, which requires processing equipment, furnace, technical process parameters, and rich production experience to successfully produce qualified mold coating.