3D printed parts finishing

Understanding the Various Options for Finishing 3D-Printed Parts

3D Printing, also called additive manufacturing, is one of the fastest growing technologies in the world. The process turns a digital model into a physical three-dimensional object by adding a single material layer at a time. As the object is manufactured layer-by-layer directly on a platform, you don’t need to use molds or cutting tools to create the desired shape. As a result, you can produce objects relatively quickly with less investment and more flexibility.

However, the 3D-printed parts still need to undergo finishing. Finishing is required to smooth the surface of the product, improve its life-cycle, adjust its size and shape, and provide a sleek appearance. Although several finishing processes are available, not all are suitable for 3D parts.

Here are seven options for finishing 3D-printed parts post-processing.

Here are seven options for finishing 3D-printed parts post-processing.


1. Vapor Smoothing

Vapor smoothing is one of the best techniques for improving the surface finish of 3D-printed parts. You can use acetone vapor to smooth the surfaces of 3D-printed parts, especially the ones made from ABS (Acrylonitrile Butadiene Styrene). It results in a uniform and shiny finish in just a few minutes or hours, depending on the size and shape of the parts.

Usually, a solvent such as acetone is used to melt the surface of the 3D-printed part in a vapor chamber. Acetone acts quickly. So, you need to place the object into the cooling chamber immediately following the vaporization to prevent any damage to its original shape. However, you can’t use this process for 3D-printed objects made from materials such as polycarbonate, polyphenylsulfone (PPSF), ULTEM 1010 or ULTEM 9085 as the solvent will chemically react with them.


2. Solvent Dipping

Solvent dipping is a cost-effective alternative to vapor smoothing method. Instead of using a vapor chamber, you can directly dip the 3D-printed object into the solvent. This method comes in handy if the object is larger than the vapor chamber.

However, as the solvent such as acetone usually acts quickly, this process is time-sensitive. It’s game over if you keep the 3D-printed object too long in the solvent. So, you have to time the process, depending on the size, shape, and the type of material used for the 3D-printed part. Still, you are less likely to get a smooth finish like the vapor smoothing process.

3. Sanding

The sanding process is similar to using sandpaper for finishing wooden objects. Sanding removes imperfections, making objects ready for painting. If you are using sandpaper, start with 100-200 grit sandpaper gradually working your way up to a higher grit (up to 1500) to achieve a smooth finish without sanding lines.


3D printed parts model ship
3D printed parts model ship (Source wikipedia)


You can also use a handheld electric sander, if required. Unfortunately, sanding is a time-consuming process, especially if you are using manual means. It can also be challenging to polish hard-to-reach areas with sanding. Still, it is a cost-effective alternative for medium and large-sized 3D-printed parts with simple geometry.


4. Bead Blasting

The bead blasting process involves using a spray gun to shoot fine media in the form of a bead or sphere to smoothen the 3D-printed objects. The process works just like sanding or abrasive blasting. However, it is more efficient in finishing the hard-to-reach spots, and it is also less time-consuming.

Although it can create a smooth uniform finish, you must maintain the right pressure throughout the process and also avoid lingering too long on a particular area. Excessive time duration or blasting pressure can wear out the surface, resulting in small divots. You can use a variety of media including fine glass particles, aluminum oxide, silica carbide, and garnet, among others.


5. Shot Peening

The shot peening process may work just like the bead blasting process. However, it is usually carried out to modify the mechanical properties of metals instead of removing surface imperfections. Shot peening prevents failures resulting from fatigue, cracking, wear-and-tear, and stress corrosion, and prolongs the life of the 3D-printed part.

In this process, you can hit the surface of 3D-printed parts with round metallic, glass, or ceramic particles having enough force to produce plastic deformation rather than abrasion. Make sure the pressurized air shoots the tiny metal or glass beads with the correct intensity and repeatability. This process usually comprises steel, ceramics, and glass media.


6. Tumbling (Mass Finishing)

Tumbling is ideal for small 3D-printed parts post-processing. As you can polish multiple small and rough plastic or metal parts in a single batch. The process is also called mass tumbling. It may take anywhere from a few minutes to a few hours to complete the process, depending on the size, shape, and type of the 3D-printed parts and the media.


3D printed ceramic parts
3D printed ceramic parts (Source: wikimedia)


Usually, a horizontal barrel filled with the parts, media, water or any other lubricant is rotated gently with a vibrator. You can also use high-energy tumbling process. But, it is suitable for parts made from metals. You can use various combinations of media and lubricants to get different levels of finishing quality. Running a process for too long or using an unbalanced media-lubricant combination can damage the parts.


7.  Vibratory Finishing

Just like tumbling, you can also use the vibratory finishing process to polish multiple 3D-printed objects in a single batch. The vibratory finishing machine causes the parts and media to grind against each other in a circular motion. You can use this process for large and small 3D-printed objects.


3D printed brass parts
3D printed brass parts (source: flicker)


It is a cost-effective and non-labor-intensive process. It also produces an accurate uniform pattern of finish without causing excess surface wear, resulting in higher durability. That’s why it is popular. However, it is often applied to objects with round edges as it can damage uneven edges and corners.


8. Conclusion

Whether you are just enjoying 3D printing as a hobby or using it commercially, you will need to provide 3D-printed products with a smooth polish. Hopefully, understanding these seven finishing methods will help you give the necessary aesthetic appeal to your products. What means do you use to polish your 3D products? Tell us in your comments.