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Key Process Points of UV Vacuum Plating

Release time:

2026-05-25 23:18

In the UV vacuum plating process, product quality largely hinges on meticulous control of key process parameters. From substrate cleaning to primer curing, and from vacuum coating to topcoat protection, each step entails specific technical requirements. Mastering these critical process points helps prevent common defects and ensures strong adhesion of the coating layer, a smooth surface finish, and optimal metallic luster.

I. Key Points of Substrate Pre-treatment

Substrate cleanliness is the primary factor determining adhesion. Residual release agents, oil, and dust on the workpiece surface can impede the bond between the primer and the substrate, leading to blistering or delamination of the coating. After cleaning, avoid direct hand contact with the workpiece surface to prevent secondary contamination. For low‑surface‑energy materials, corona or plasma treatment is required to introduce polar functional groups onto the substrate surface; otherwise, the primer will struggle to wet and adhere effectively.

The dust‑removal stage should not be overlooked either. Tiny particles that settle on uncured primer can create raised imperfections, which are then accentuated by the metallic sheen after coating. Prior to spraying, the surface must be thoroughly cleaned of static charge and particulates using an ion‑air gun or an electrostatic dust‑removal device.

II. Key Points for Primer Spraying and Curing

The thickness of the primer coat must be precisely controlled. If the coat is too thin, it will fail to adequately seal substrate defects, potentially resulting in orange‑peel texture or pinholes on the coated surface; if it is too thick, it may lead to sagging, incomplete curing, or excessive internal stresses. The amount of paint drawn into the spray gun should be adjusted so that the output is uniform without dripping, and during spraying, maintain a consistent nozzle‑to‑surface distance and a steady travel speed.

The leveling time must not be skipped. After applying the primer, allow a brief leveling period to enable the coating to spread evenly and eliminate spray marks. Insufficient leveling can lead to premature curing, leaving an orange‑peel texture on the surface and compromising the reflective performance of the coating. The leveling environment should be kept clean to prevent dust from settling on the wet film.

The curing energy must be matched to the primer formulation. Insufficient energy can result in incomplete curing, a tacky primer surface, and reduced adhesion of the coating layer; excessive energy, on the other hand, may cause yellowing or embrittlement of the primer. Regularly monitor the UV lamp’s output energy, and replace aged lamps promptly.

III. Key Points of Vacuum Coating

Vacuum level is a critical parameter for coating quality. When the vacuum is insufficient, residual gas molecules collide with the metal vapor, compromising the density of the deposited film and causing haze or reduced adhesion. Vacuum pumping must meet the process specifications before coating can commence.

The deposition rate influences the microstructure of the coating. At excessively high rates, metal particles deposit in a disordered manner, resulting in a loose coating with significant internal stress; at too low a rate, production efficiency declines and the coating may become overly thin. For aluminum coatings, deposition should be carried out at a stable rate to prevent fluctuations during the process. The coating thickness should be maintained within the range of 0.01 to 0.1 micrometer; exceeding this range does not significantly enhance gloss and may instead increase internal stress.

IV. Key Points for Topcoat Spraying and Curing

The topcoat application thickness should be sufficient to fully cover the coating layer. If too thin, wear resistance will be inadequate and the coating layer may easily become scratched; if too thick, sagging or curing‑induced shrinkage cracks may occur. The leading edge and edges are prone to undercoating, so special attention should be paid to these areas.

The degree of curing of the topcoat directly determines its protective performance. Insufficient curing results in a tacky surface, low hardness, and an easily damaged coating; excessive curing, on the other hand, may lead to yellowing or increased brittleness. For wipe‑off topcoats, the adhesive layer must be thoroughly wiped away after curing; otherwise, residual tackiness can compromise feel and gloss. Wash‑free topcoats demand even greater uniformity in application, requiring consistent coating thickness.

V. Prevention of Common Issues

Sagging typically occurs when the coating is applied too thickly, the paint viscosity is too low, or the spray distance is too close. Controlling the coating thickness, adjusting the paint viscosity, and standardizing spraying procedures can effectively prevent it.

Orange‑peel defects are often caused by insufficient leveling time or poor leveling properties of the coating. Ensure adequate leveling time, select coatings with good leveling performance, and, if necessary, add a leveling agent.

Particulate contamination primarily originates from dust in the construction environment. Maintain a clean spray booth, perform dust removal prior to application, and minimize personnel movement during operations to reduce dust generation.

Fogging of the coating may be caused by insufficient vacuum, improper deposition rate, or an unclean primer surface. Inspect the condition of the vacuum system, optimize the coating parameters, and ensure that the primer surface is clean and smooth.

VI. Conclusion

The key process parameters of UV vacuum plating span the entire production cycle, from substrate pretreatment to topcoat curing. Substrate cleaning and surface activation lay the foundation for adhesion; thin application, leveling, and thorough curing of the primer determine surface smoothness; vacuum deposition conditions—such as vacuum level and deposition rate—affect the quality of metallic luster; and the thickness and degree of cure of the topcoat ensure protective performance. Common defects like sagging, orange peel, particle formation, and haze each have distinct causes and corresponding preventive measures. Effectively implementing these process guidelines and continuously refining them during operation are essential for producing high‑quality UV vacuum‑plated products.

Disclaimer: The above content has been compiled from publicly available sources and is provided for reference only. If any infringement occurs, please contact us, and we will address it promptly.

Bossin Related Product Recommendations – Vacuum Plating
Primer
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA.
B-151	Modified epoxy acrylate	Low halogen, yellowing-resistant, excellent plating performance, and strong adhesion.
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-163	Modified epoxy acrylate	Good flexibility, excellent pigment wetting, and strong adhesion.
B-165	Modified epoxy acrylate	Good flexibility and strong adhesion
B-212A	Aromatic polyurethane acrylate	High cost-performance, excellent plating adhesion, good toughness, and resistant to boiling water.
B-221	Aliphatic polyurethane acrylate	Fast curing, resistant to boiling water
B-268M	Aliphatic polyurethane acrylate	Good flexibility, excellent adhesion, superior plating performance, and strong hiding power.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV.
B-619W	Aliphatic polyurethane acrylate	Fast curing, high hardness, excellent toughness, wear resistance, and chemical resistance.
Intermediate coat
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-374	Aliphatic polyurethane acrylate	Excellent flexibility, good leveling, resistant to abrasion and chemicals, and resistant to yellowing.
B-601	Aromatic polyurethane acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost-effectiveness.
B-6020	Special functional group acrylate	Resistant to boiling water, excellent color development, and strong interlayer adhesion.
Topcoat
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-221	Aliphatic polyurethane acrylate	Fast curing, resistant to boiling water
B-301	Aromatic polyurethane acrylate	Fast curing, excellent toughness, and good sandability.
B-302	Aromatic polyurethane acrylate	Fast curing, high strength, excellent toughness, and good grindability.
B-368	Aliphatic polyurethane acrylate	Good toughness, excellent leveling, excellent bend resistance, and excellent heat resistance.
B-374	Aliphatic polyurethane acrylate	Excellent flexibility, good leveling, resistant to abrasion and chemicals, and resistant to yellowing.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV.
B-601	Aromatic polyurethane acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost-effectiveness.
B-6016C	Special functional group acrylate	Easy to apply, resistant to yellowing and boiling water, and improves the appearance of the paint film.
B-6019	Special functional group acrylate	Good leveling, excellent wettability, resistant to boiling water, and excellent color dispersion.
B-609	Aliphatic polyurethane acrylate	Fast curing, high hardness, scratch resistance, and chemical resistance.
B-615A	Aliphatic polyurethane acrylate	Fast curing, excellent toughness, wear resistance, and chemical resistance.
B-619W	Aliphatic polyurethane acrylate	Fast curing, high hardness, excellent toughness, wear resistance, and chemical resistance.
B-6210	Aliphatic polyurethane acrylate	Low viscosity, chemical resistance, environmental resistance, and dual photothermal curing.
B-6211	Aliphatic polyurethane acrylate	Fast curing, high hardness, scratch-resistant, and free of organotin.
B-919B	Aliphatic polyurethane acrylate	Fast curing, high hardness, excellent toughness, and outstanding chemical and wear resistance.
Monomer Recommendation
Product Model/English Abbreviation	Product Name/Product Type	Product Features
BM2223 (TPGDA)	Dipropylene glycol diacrylate	Good flexibility and low volatility
BM3231 (TMPTA)	Trimethylolpropane triacrylate	High crosslink density, high hardness, high gloss, and excellent wear resistance.
BM3235 (PET3A)	Pentaerythritol triacrylate	Fast curing, high crosslink density, high hardness, and chemical resistance.
BM3380 (3EO-TMPTA)	Pentaerythritol triacrylate	More flexible and less irritating than TMPTA.
BM6261 (DPHA-80)	Dipentaerythritol hexaacrylate	High crosslink density, high hardness, chemical and wear resistance, and water resistance.
BM6263 (DPHA-90)	Dipentaerythritol hexaacrylate	High crosslink density, high hardness, chemical and wear resistance, and water resistance.

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