Provides state-of-the-art physical vapor deposition (PVD) coatings for die casting. It includes initial hardening of the surface by plasma/ion nitriding followed by applying a single layer PVD coating that reduces or eliminates the effects of welding, corrosion, and wears on the tool steel surface. Adhesion during the die-casting process can lead to defects on the part’s surface, shortening tool life, and downtime. In this regard, PVD (physical vapor deposition) coatings on tools appear to be interested in reducing adhesion and abrasive wear and extending tool life. In the following article, PVD coatings for die casting are described.
Table of Contents
What is PVD?
PVD (Physical Vapor Deposition) means physical vapor deposition, divided into vacuum evaporation coating, vacuum sputtering coating, and vacuum ion coating. When we say PVD coating, we mean vacuum ion coating and sputtering coating; when we say NCVM coating, we mean vacuum evaporation coating.
Vacuum vapor deposition basic principle: under vacuum conditions, make the metal, metal alloy, etc. evaporate, and then deposit on the substrate surface; evaporation method commonly used resistance heating, electron beam bombardment coating material, so that evaporation into the gas phase, and then deposited on the substrate surface, historically, vacuum vapor deposition is the earliest technology used in PVD method.
The basic principle of sputter coating: under the vacuum condition of argon (Ar) gas filling, argon gas is made to glow discharge when argon (Ar) atoms are ionized into argon ions (Ar), and the argon ions are accelerated to bombard the cathode target made of plating material under the action of electric field force, and the target will be sputtered out and deposited on the surface of the workpiece. The incident ions in the sputtering coating, generally obtained by glow discharge, are in the range of l0-2Pa to 10Pa, so the sputtered particles are easy to collide with the gas molecules in the vacuum chamber in the process of flying to the substrate so that the direction of motion is random. The deposited film is easy to be uniform.
Ion plating basic principle: Under vacuum conditions, some plasma ionization technology is used to ionize the plating material atoms into ions partially, and at the same time, many high-energy neutral atoms are generated, and negative bias pressure is applied to the plated substrate. The ions are thus deposited on the surface of the substrate under deep negative bias to form a thin film.
Four process steps of PVD technology
Four process steps of PVD technology
1. Cleaning the workpiece: when DC power is connected, argon gas is glow discharged into argon ions, which bombard the surface of the workpiece, and the bombardment throws out the surface particles and dirt.
2. Vaporization of the plating material: After the alternating current is applied, the plating material is evaporated and vaporized.
3. Migration of plating ions: atoms, molecules, or ions supplied by the vaporization source are rushed to the workpiece at high speed after the collision and high voltage electric field.
4. Deposition of plating material atoms, molecules, or ions on the substrate: When the number of evaporated material ions on the surface of the workpiece exceeds the number of sputtered ions, they gradually accumulate to form a layer firmly adhered to the workpiece surface.
When ion plating, evaporation material particles ionized with three thousand to five thousand electron volts of kinetic energy, the high-speed bombardment of the workpiece, not only deposition speed, and can penetrate the surface of the workpiece, forming a kind of injection into the substrate very deep diffusion layer, ion plating interface diffusion depth of up to four to five microns, that is, the depth of diffusion than the ordinary vacuum coating dozens of times deeper, or even hundreds of times, and therefore adhere to each other particularly firmly.
The application of PVD coating technology
The application of PVD coating technology is divided into decorative plating and tool plating.
1. Decorative plating
The purpose of decorative plating is to improve the appearance and color of the workpiece and to make the workpiece more wear-resistant and corrosion-resistant to prolong its service life; this is mainly used in various fields of the hardware industry, such as door and window hardware, locks, bathroom hardware, and other industries.
2. Tool plating
The purpose of tool plating: is mainly to improve the surface hardness and wear resistance of the workpiece, reduce the friction coefficient of the surface, and improve the service life of the workpiece; this aspect is mainly used in various knives and shears, turning tools (such as turning tools, planning tools, milling tools, drills, etc.) and other products.
PVD Coating Benefits
You can run your tooling faster, resulting in shorter cycle times so that you can produce components faster. Because the coating reduces the stickiness of the object, the melt inside flows faster and fills the mold more easily.
Improved end product
This lack of adhesion also makes it easier to release the mold. It reduces the likelihood of distortion of the final product while improving the final surface finish and increasing the product’s elasticity for longer life.
The coating also greatly increases the life of the mold, so there is no need for frequent replacement. Moving parts are also protected against wear and tear.
Easy to clean
Molds are easier to clean because there are fewer deposits at the end of the process.
No need for costly lubricants
Increased fluidity means that expensive lubricants are not needed.
PVD coating vs Conventional chemical plating
The similarity between:
PVD coating and traditional chemical plating is that both of them belong to the surface treatment category, and both cover the surface of one material with another material in a certain way.
The differences between:
①PVD coating layer has a greater bonding force with the surface of the workpiece, the hardness of the film layer is higher, the wear resistance and corrosion resistance are better, and the performance of the film layer is more stable
②PVD coating can be applied to a wider range of film layers, and the colors of various film layers can be more beautiful.
③PVD coating does not produce toxic or polluting substances.
The use of PVD coating in die casting
The production standard of die casting is Z harsh. In the high-temperature metal material aqueous solution, according to the high working pressure injection, the mold shell surface constantly heats up and cold shrinkage, resulting in the short service life of die casting, in the production must constantly repair the mold, maintenance. Relatively poor. Plating companies for this difficult product developed PVD coating before applying new technology to solve, in the improvement of liquid metal sticky mold and thermal cracking level to obtain certain achievements.
PVD coating technology can be widely used in tools, molds, mechanical parts, medical devices, etc., that fail due to wear, galling, corrosion, adhesion, and fusion.
Among them, the lifetime of products failing due to abrasion (e.g., punching, cold heading, powder molding, etc.) can be improved by more than 2-20 times after coating; it can solve the strain problem of products or molds caused by occlusion fundamentally after coating.
PVD coating color series
PVD can be coated on stainless steel, titanium alloy copper, and other metals in heptachlor, blue, fuchsia, black, coffee, gold, champagne gold, brass, rose gold, silver white, smoky gray, brown, purple, burgundy, bronze, and other colors, and can provide the desired color and quality according to your requirements.
PVD coating Manufacturer
V1Diecast can provide PVD Coating service according to your requirements to customize your die casting products.