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Hot spray protection for die-casting molds, applicable working conditions, comparison between PVD coating and nitriding

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  • Release time: 2026-11-07

Hot spray protection for die-casting molds, applicable working conditions, comparison between PVD coating and nitriding
Thermal spraying is another type of surface protection solution, completely different from PVD coating process, and many customers confuse the two. Xinfeng Machinery distinguishes the applicable scenarios.
1、 Principles of Thermal Spraying Process and Coating Types
Thermal spraying is the process of melting powder/wire at high temperatures and depositing it onto the surface of the mold cavity through high-speed spraying. The coating thickness is generally 0.05-0.3mm, which is much thicker than 2-4 μ m for PVD. Commonly used: WC tungsten carbide spraying, nickel based alloy spraying, ceramic spraying. The advantages are thick coating, wear resistance, suitable for strong erosion and abrasive wear conditions.
2、 Comparison of advantages and disadvantages of thermal spraying PVD AlTiN
Advantages: Thick coating, abrasion resistance, suitable for areas with high silicon content and continuous erosion of ADC12 silicon slag; Local wear and tear can be repaired on-site, without the need to send it to a professional PVD factory. Shortcomings: The coating porosity is relatively high, the anti sticking aluminum is average, and the upper limit of high temperature resistance is lower than AlTiN; The surface roughness is poor, and the subsequent polishing workload is large. The mirror appearance cavity is not suitable. The appearance of the alloy wheel mold is rarely sprayed with thermal spray, and the flushing area of the sprue and runner is occasionally selected.
3、 Suitable and unsuitable application locations
Suitable for strong erosion and abrasive wear areas such as sprues, sprues, barrels, splitter cones, and sliding block wear-resistant plates. Not suitable for: exterior cavity, requiring anti stick aluminum, A356 long-term high-temperature working surface; Pores are prone to storing aluminum, forming stubborn aluminum adhesion. Thermal spraying has weaker adhesion than PVD and is prone to peeling and flaking at locations subjected to alternating thermal shocks.
4、 Combination ideas of thermal spraying, nitriding, and PVD
Nitriding as a base enhances substrate support, followed by thermal spraying for better adhesion. Single thermal spraying is rarely used for cavity forming surfaces and is more commonly used for flow channel systems. Many low-priced solutions use thermal spraying instead of PVD, which looks good for short-term wear resistance. However, after being put into production for a period of time, aluminum is trapped in pores, and defects continue to erupt.
5、 Differences between Low Pressure Casting and MIM Applications
Low pressure casting has weak erosion and is rarely used for thermal spraying; The ceramic coating on the riser belongs to the special branch of thermal spraying and is classified separately. Metal injection mold rarely undergoes thermal spraying, with priority given to DLC PVD for small cavities. Google's "thermal spray coating die casting mold" is suitable for channel and splitter cone maintenance searches.
FAQ
Can thermal spraying create a mirror finish?
It's difficult. Spraying comes with pores, and even after polishing, it's still easy to leave micro pores.
Why is the thickness of thermal spraying much thicker than PVD?
The process mechanism is different, PVD is vapor deposition, while thermal spraying is the accumulation of molten particles.
3. Can I directly re spray if it falls off during thermal spraying?
It is necessary to polish and remove the old coating, sandblasting to roughen the substrate, otherwise it is prone to peeling.
What is the temperature resistance of tungsten carbide spray coating?
Conventional 500-600 ℃, lower than AlTiN's 850 ℃.
5. Should the splitter cone be prioritized for thermal spraying or AlTiN?
ADC12 silicon slag erosion is severe, and many diversion cones use WC thermal spraying.
6. Will the pores of thermal spraying absorb aluminum?
Yes, pores are the main cause of aluminum storage.
Can a set of molds be simultaneously hot sprayed and PVD coated?
Partition treatment: channel thermal spraying, cavity PVD AlTiN.
8. Does the size change significantly after thermal spray repair?
The spraying thickness is large, and machining allowance must be reserved before precision machining after spraying.

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