Vapor Smoothing 3D Printed Parts

3D printing is one of the best ways to get low-volume production goods. However, plastic 3D printing tends to have one significant trade-off: parts with coarse surface finishes. Powder bed fusion processes like selective laser sintering (SLS) and HP Multi Jet Fusion (MJF) leave a matte, sugar cube-like surface finish. Fused deposition modeling (FDM) shows distinct layer lines. For the last 30 years, post-process surface finishing like abrasive media tumbling, hand finishing, or coatings have minorly improved the surface finishes of 3D printed parts. If cosmetics are a priority, engineers may choose other processes entirely like injection molding, machining, or urethane cast parts.

With the introduction of chemical vapor smoothing, a technology that smooths the surface of 3D prints and enhances mechanical performance via vaporized solvents, 3D printed plastics are now more suitable than ever for low-volume production. This process works on most 3D printed polymers and elastomers, including over twenty 3D printing materials available through Xometry. Read on to learn more about chemical vapor smoothing, its benefits, and its applications.

Xometry has adopted AMT’s PostPro3D chemical vapor smoothing technology. Unlike physical smoothing processes such as sanding or media tumbling, vapor smoothing does not remove material on the workpiece. Instead, a vapor finishing agent (FA 326) is introduced into a sealed processing chamber with the parts. Although the finishing agent is the same, different processing parameters are used for different materials and geometric features. Parts are racked, or hung, in a 600 x 400 x 400 mm chamber to maximize the surface exposure to the vapor. The vapor clings to the part surface where it creates a controlled chemical melt. This melt reduces the surface peaks and valleys by liquifying and redistributing material and evening the surface. The melt also has the effect of enhancing shine.

Once the parts are finished, the chamber is heated to evacuate the finishing agent to a collection vat. No residue is left on the parts. Smoothed parts are then ready for shipping or another secondary process such as dyeing.

You can get instant pricing and lead times on vapor smoothing in the Xometry Instant Quoting Engine℠ based on the process, material, quantity, and part geometry for the most popular HP MJF and SLS materials. Because the process is batch-based, costs are relatively low per part and will decrease with increased order volumes. Xometry typically adds between 1-5 business days to lead times for vapor smoothing. 

Xometry will manually review vapor smoothing orders for fused deposition modeling and specialty materials like SLS high-performance blends, Nylon 11 EX, Nylon 12 AF, Nylon 12 HST, and Nylon 12 CF. Please select "Custom" as your finish option and submit the quote for an expert review.

Vapor smoothed parts have improved cosmetics and are comparable to injection molding surface finishes. Standard SLS parts typically have a surface roughness greater than 250uin Ra, but with chemical vapor polishing can improve to below 125uin Ra and as low as 40uin Ra. In some studies, chemical vapor smoothing improved material surfaces by 800%-1000%. It is important to note that chemical vapor smoothing re-distributes surface material to provide a sealed, smooth surface but it does not create a polished surface. There will still be visible surface topology and minimal layer lines.

Chemical vapor smoothing can significantly increase the viability of 3D prints in food processing, medical devices, and consumer products, and is recommended for end-use applications in these industries. Notably, vapor-smoothed nylon 12 3D prints effectively reduce bacterial attachment and growth compared to standard nylon 12 3D prints. Studies have shown that vapor-smoothed SLS and HP MJF parts conform to and pass multiple biocompatibility and safety tests.

Other benefits of chemical vapor smoothing include: