AMT Vapor Smoothing: an effective surface treatment process in 3D printing

2023-08-22 17:53 admin

AMT Vapor Smoothing: an effective surface treatment process in 3D printing

Vapor smoothing, which can transform a rough layered surface into a smooth surface, has become an important post-processing technology in the field of 3D printing. As the demand for 3D printed parts grows, achieving a high-quality surface finish is critical. Post-processing technology for 3D printed objects can play a role in enhancing aesthetics and improving mechanical properties. By solving the common problems of visible layer lines and rough surfaces in 3D printing, steam smoothing is an effective option for achieving professional-quality results. So what is steam smoothing in 3D printing?

What is steam smoothing in 3D printing?

Steam smoothing is a finishing technique for 3D printing, also known as "chemical steam smoothing," "steam polishing," or "steam fusion," in which printed parts are exposed to evaporating solvents that help eliminate surface layer lines of 3D printed parts.

The chemical vapor used in this process reacts with the surface of the material, which melts and partially dissolves, resulting in a smoother surface. By using this technique, 3D printed parts can obtain a smooth and glossy surface. Steam smoothing can be seen as an excellent finishing option that can add significant value to 3D printing. The technology is widely used in the automotive and aerospace industries, where parts must be as smooth and perfect as possible for optimal function and beauty.

MJF PA 12 3D printing comparison: Print state (left) and steam melting (right)

How does steam smoothing work?

Steam smoothing is an efficient way to achieve a smooth surface finish on a variety of materials without removing any material. It uses a finishing agent and controlled chemical melting to achieve the desired result, during which the proper temperature and pressure are maintained to obtain the desired effect and avoid damage to the workpiece.

3D printing steam smoothing process illustration

Here is a step-by-step guide to how the fully automated smoothing process works:

Step 1 - Place the workpiece into a sealed treatment chamber with finishing agent (usually FA 326). The finishing agent is commonly used for a variety of plastic materials, but depending on the material being treated, different finishing agents can be used.

Step 2 - Place the workpiece in the smoothing chamber and heat the reagent to a specific temperature to create steam around the part. Maintaining temperature and pressure control is essential to ensure that steam is evenly distributed on the surface.

Step 3 - Steam adheres to the surface of the part to form a controlled chemical melt. This melting reduces peaks and valleys on the surface by liquefying and redistributing the material, resulting in a smoother surface.

Step 4 - Chemical melting also enhances the shine and gloss of the material. The degree of gloss enhancement depends on the processing parameters and finishing agent.

Step 5 - Once the reagent has done its job, the smoothing chamber is heated to remove the steam and finishing agent, which is then collected in a barrel. The workpiece does not have any residue, and no material is removed during the process.

Step 6 - After smoothing is completed, the workpiece can undergo secondary treatment such as dyeing, painting or any other surface treatment.

Types of technologies and materials available

Steam smoothing is widely used in a variety of 3D printing materials, including polymers and elastomers, the most commonly used being PA 12 and PA 11. Steam fusion post-treatment technology can be combined with dyeing to obtain a smooth and colorful component surface.

Steam smooth color SLS and MJF parts
Steam smoothing benefits

3D printing has revolutionized manufacturing, enabling the production of complex parts with complex geometrics. However, with the development of technology, improving the surface finish of printed parts remains a challenge. This is where this post-processing technology significantly enhances the surface effect of 3D printed parts. The main advantages are as follows.
●   Improve surface finish
In contrast to standard SLS parts, where surface roughness is typically greater than 8 μm Ra, chemical vapor smoothing can achieve a surface finish below the 3 μm Ra threshold.
  Enhanced performance

The improved surface finish greatly affects the mechanical properties of the printed part. In additive manufacturing, surface roughness directly affects the tensile strength, elongation at break and bending properties of parts. Poor surface finish can create stress concentration and shorten the fatigue life of parts, leading to premature part failure.

● Moisture resistance

This surface finish significantly reduces the moisture absorption of the part surface. Moisture can cause parts to degrade and affect their mechanical properties. By sealing the surface of the part, steam smoothing prevents moisture absorption, making the printed part more durable.

● Non-line-of-sight function

One of the most significant advantages of this process is its ability to polish non-line-of-sight features that can reach deep recesses and internal cavities that cannot be reached by traditional polishing or sanding methods. As a result, a part with a complex geometry can still obtain a high-quality surface finish.

● Dimensional accuracy

Steam smoothing preserves the geometry and dimensional accuracy of printed parts while improving their surface finish. Unlike traditional machining or sanding processes, which can cause printed parts to deform or change dimensions, steam polishing does not cause wear and maintains the original shape of the part. This is especially important for high-precision parts that require tight dimensional tolerances.

△ Stained PA 12 parts in steam melt black printed by SLS

Steam smooth 3D parts should follow design tips

When designing CAD files for parts that will steam smooth after printing, you can use the following design tips to ensure that the part becomes beautiful:

Includes rounded corners, curves, edges or straight lines connecting two surfaces to create rounded edges, which makes the smoothing process more efficient and even.

Avoid using geometric shapes with sharp edges or sharp interior angles, as these parts can accumulate chemicals and hinder the effectiveness of the smoothing process.

Ensure proper surface treatment, including sandblasting and cleaning prior to steam smoothing, so that steam is uniformly deposited on the surface.

● Keep the wall thickness even, allowing steam to permeate the parts more evenly, thus ensuring a smooth surface texture.

• Design parts with sufficient quality to allow longer exposure to steam. Thin slices may have difficulty retaining heat.

Use support structures in areas with complex features to ensure they do not deform during smoothing.

Steam smoothing applications

Steam polishing is a powerful finishing process that can significantly improve the performance and aesthetics of 3D printing. Some applications where this technology can be used to create quality end-use parts are as follows:

Medical devices: Customized medical devices require high precision, durability and biocompatibility. Steam smoothing makes smooth, non-porous, easy-to-clean medical parts that are comfortable to wear and sweat resistant.

Wearable devices: Wearable technology is a growing market that requires lightweight, durable and comfortable components. Steam smooth 3D printing can provide high quality aesthetics and wear resistance. With soft to the touch finishes, easy-to-clean surfaces and integrated features, custom wear parts with these finishes can meet the stringent requirements of the industry.

Fluid flow components: Fluid transfer and handling components require high precision, leak-proof operation and easy maintenance. Steam smoothing creates liquid storage and storage tanks, fluid transfer lines and manifolding, and pipes with smooth and sealed surfaces to prevent bacterial growth, making it ideal for skin and food contact environments.

Automotive and industrial machinery: Steam smoothing is an ideal finishing process for valve caps, oil pans and other critical components that must be leak-proof and corrosion-resistant. The smooth, tactile and durable surfaces of these components improve their aesthetics and provide more functionality.

△HP MJF 3D printed parts assembled into spheres. Both are dyed black, with one hemisphere treated with steam smoothing (right) and the other with a standard finish (left)

Industry proto-mold ltd can provide you the 3D printing plastic and metal parts .

Industry Proto-mold Limited
Tel: +86 13662571826 Email: Add: Room 611, JiaYu building, Hong xing Area,songgang Street, Baoan district, Shenzhen 518105