In the field of CNC machining, the surface quality of parts directly influences the market competitiveness of products. However, the common orange peel phenomenon during the painting process often poses a significant challenge to many engineers. This article delves deep into the causes of the orange peel phenomenon and provides a series of practical solutions. By implementing these strategies, you can enhance product quality, reduce rework costs, and meet customers’ high expectations for appearance.
This article details five key control points for avoiding the orange peel phenomenon on CNC machined parts after painting. These include precise formulation of the coating system, a matrix of spraying process parameters, a three – stage verification method for substrate pretreatment, intelligent compensation of the baking curve, and a dual – closed – loop environmental monitoring system. Through these systematic solutions, you can effectively control and prevent the orange peel phenomenon, improving the appearance texture and coating adhesion of products.
The causes of the orange peel phenomenon are complex, involving multiple aspects such as coatings, spraying processes, and substrate pretreatment. To address this issue systematically, we need to approach it from multiple angles and tackle each aspect one by one. Let’s now explore each key control point in detail.
## Subtitle 1: Precise Formulation of the Coating System
The precise formulation of the coating system is crucial for avoiding the orange peel phenomenon. By controlling the volatile gradient of the thinner, the dynamic balance of viscosity, and the resin modification plan, we can effectively improve the leveling property of the coating and reduce the occurrence of the orange peel phenomenon.
For the volatile gradient of the thinner, different solvents have different evaporation rates. A proper combination ensures that the solvent evaporates evenly during the drying process, preventing uneven surface tension that could lead to orange peel. Regarding viscosity, maintaining a dynamic balance during application is essential. High – viscosity coatings may not flow smoothly, while low – viscosity coatings may cause sagging. Resin modification can enhance the compatibility of the coating components and improve the overall performance, including flowability.
## Subtitle 2: Matrix of Spraying Process Parameters
Precise control of spraying process parameters is of utmost importance in avoiding the orange peel phenomenon. By establishing a matrix of spraying process parameters, we can digitally control the spraying distance, gun travel speed, fan pressure, and overlap rate, ensuring consistency and stability during the spraying process.
The spraying distance affects the pattern and thickness of the coating deposition. An inappropriate distance can result in uneven coating thickness and potentially lead to orange peel. The gun travel speed determines the amount of coating applied per unit area. A consistent travel speed is necessary to achieve a uniform coating. Fan pressure influences the atomization of the coating material, and proper atomization is crucial for a smooth finish. The overlap rate ensures that there are no gaps or thick spots in the coating.
## Subtitle 3: Three – Stage Verification Method for Substrate Pretreatment
Substrate pretreatment is the foundation of painting quality. Through surface energy testing, closed – loop roughness control, and electrostatic dust removal blind testing, we can ensure that the substrate surface is in the optimal state, providing a good adhesion basis for painting.
Surface energy testing helps determine the wettability of the substrate. A substrate with low surface energy may not allow the coating to adhere properly, increasing the risk of orange peel. Closed – loop roughness control ensures that the surface has an appropriate roughness level. Too smooth a surface may not provide enough mechanical interlocking for the coating, while too rough a surface can cause uneven coating application. Electrostatic dust removal blind testing verifies the effectiveness of dust removal, as dust particles on the substrate surface can disrupt the coating’s smoothness.
## Subtitle 4: Intelligent Compensation of the Baking Curve
Temperature control during the baking process is crucial for coating quality. By developing a temperature compensation algorithm based on machine learning, we can adjust the heating rate in real – time to ensure uniform curing of the coating.
During baking, different stages require specific temperature profiles. If the heating rate is too fast or too slow, it can cause uneven curing, leading to problems such as orange peel. The machine – learning – based algorithm analyzes data from sensors during the baking process and makes real – time adjustments to the heating system, ensuring that the coating cures evenly and consistently.
## Subtitle 5: Dual – Closed – Loop Environmental Monitoring System
Environmental factors have a significant impact on painting quality. By establishing a dual – closed – loop environmental monitoring system, we can automatically control humidity, maintain positive pressure cleanliness, and recycle waste gas, providing an ideal environment for painting.
Humidity can affect the drying rate and quality of the coating. High humidity may cause the coating to dry slowly and potentially lead to orange peel. Maintaining positive pressure cleanliness prevents dust and contaminants from entering the painting area. Waste gas recycling not only helps protect the environment but also ensures a stable painting environment.
## Frequently Asked Questions
Q: How to quickly diagnose and solve mild orange peel problems?
A: When mild orange peel occurs, wet – sand with 600# water sandpaper and then adopt a “two – spray – one – bake” remedial process. Additionally, establish an SPC control chart with 18 key parameters to achieve continuous quality control.
Q: How to update the operation instruction manual to adapt to process improvements?
A: After process improvements, promptly update the operation instruction manual and use an AR visualization system to guide operations, reducing human errors.
Q: How to regularly detect coating quality?
A: It is recommended to use a 3D surface profilometer to detect the coating waviness every quarter, ensuring that Wt ≤ 0.15μm to maintain coating quality.
By implementing the systematic solutions for the five key control points described above, you can effectively avoid the orange peel phenomenon on CNC machined parts after painting, enhancing the appearance texture and market competitiveness of products. Remember, continuous process optimization and quality control are the keys to ensuring product quality. As a professional in the CNC machining industry, ly – machining is committed to providing high – quality services and solutions to meet your manufacturing needs and ensure the best possible surface finish for your products.