3D printing is widely used, from prototyping to mass production, but the post-processing finish greatly affects product quality and functionality. In particular, surface treatment is essential not only for appearance but also for improving durability and functionality. The optimal treatment method differs depending on the material and printing method, so proper selection is important.
This article introduces optimal coating and surface finishing methods tailored to 3D-printed products’ materials and printing methods.
Selecting the Optimal Coating for 3D-Printed Products
Coating Selection Criteria by Material
A wide range of materials are used in 3D printing, each with different characteristics. When selecting a coating, the first step is to identify the material used for printing. For example, thermoplastics such as nylon are suited to coatings that improve heat and chemical resistance. In contrast, resin materials produced by stereolithography (SLA) benefit from coatings that enhance surface smoothness and add UV or water resistance. If a metallic appearance or strength is desired, metal plating is an option.
Types and Characteristics of Coatings
Representative types of coatings are as follows:
- Ceramic coatings
Provide excellent heat, chemical, and wear resistance. Suitable for high-temperature environments or applications involving chemicals. - Metal plating
Adds metallic gloss and strength while improving corrosion resistance. Nickel and chrome plating are common options. - Polymer coatings
Enhance surface smoothness and gloss, reduce scratches, and are available in many varieties for different applications.
Advantages and Disadvantages of Coatings
- Ceramic coatings
High functionality, but costly and may require specialized knowledge and equipment. - Metal plating
Offers metallic texture and strength, but may raise environmental concerns. - Polymer coatings
Relatively inexpensive and easy to apply, but chemical and heat resistance vary widely depending on the type.
Surface Finishing Methods for 3D-Printed Products
Surface Treatment Procedures by Printing Method
Surface treatment procedures vary depending on the printing method. In stereolithography (SLA), the process begins with cleaning and post-curing, followed by polishing or coating. Cleaning is important to remove uncured resin. Post-curing increases the strength of the printed product and improves surface smoothness.
In selective laser sintering (SLS), excess powder is first removed, followed by blasting. The surface is then smoothed using methods such as barrel polishing or vapor smoothing, with coating or painting applied as needed.
In fused deposition modeling (FDM), layer lines are prominent, making polishing especially important.
Polishing Methods and Key Points
Polishing is an important step to reduce surface roughness and achieve a smooth finish. Abrasives such as sandpaper are used, starting with coarse grit and gradually moving to finer grit. Wet sanding can reduce scratches and produce an even smoother surface. During polishing, it is important to avoid applying excessive force and to work carefully to prevent surface damage. For complex shapes, specialized polishing tools are effective.
Types and Procedures of Coating
Coating is applied to protect the surface and improve functionality. Methods include spraying, dipping, and brushing. Spraying produces a uniform coating but may require facilities such as a spray booth. Dipping can handle complex shapes but may take longer to dry. Brushing is suitable for fine areas, but achieving a uniform finish requires skilled technique. Coating materials are also diverse, so the choice must be made according to the application, material, and required properties.
Summary
The optimal coating and surface finishing for 3D-printed products vary depending on the material used and the printing method. By appropriately combining processes such as cleaning, post-curing, polishing, and coating, product quality and functionality can be improved. It is important to understand the materials, tools, and precautions for each process and to select the most suitable method.
Our offerings include the development of reliable dip coating equipment as well as rental and contract coating solutions. We would be happy to discuss your coating requirements.