Every Primary 3D Printing Process Explained

When it comes to 3d printing, there are typically 3 primary printing processes that come to mind; FDM, Resin Based, and Powder Jetting. In this blog post, we will go over the strengths and weaknesses of each of these processes.

FDM (Fused Deposition Modeling)

The first process is known as Fused Deposition Modeling, or FDM. Do you remember back in kindergarten when you would roll some play dough into a snake and then coil it up to make a dome like shape? That is essentially how FDM 3d printing works. An FDM printer functions by extruding a plastic filament through a hot nozzle and slowly building the model up layer by layer. This is a very cost-effective way to do 3d printing, especially mass production 3d printing, which is why we use this process here at Slant 3D. FDM printing is also relatively quick as it requires little to no post-processing, which again, is great for mass production. 

The biggest downside of FDM, is that it can produce parts with a somewhat rough surface finish. ​Because the material must be extruded in layers, and has a certain thickness predefined by the nozzle, high detail prints can be hard to achieve. However, in most cases, this roughness is so minute that it has no effect on the function of whatever you are printing. All in all, the FDM printing process remains as the most commonly used process in 3d printing, and for good reason. There aren't many 3d printing processes that are as quick, versatile, or cost-effective. 

Resin Based (DLP/SLA)

Any type of resin based 3​d printing, whether it be DLP (Digital Light Processing) or SLA (Stereolithography), typically all function under the same principle, using a light source to cure a liquid resin into a hardened plastic. In SLA 3d printing, a build platform is lowered into a thin layer of resin where a laser is used to draw out the first layer of the object. The laser hardens the resin and the build platform is then raised back up so a new layer of resin can be added. This process repeats until, layer by layer, the object is finished.

​Resin based parts offer the highest accuracy and best resolution, in terms of surface finish. These parts will be the most similar in quality to traditional injection molded parts. The drawback of resin based printing is that it requires a lot of post-processing. Once the parts are printed they must be washed in isopropyl alcohol to remove any uncured resin from their surface. Then, the parts must go through a post-curing process to help them reach their maximum amount of strength and stability. Finally, supports must be snipped away and the remaining support marks must be sanded down to the desired surface finish. To sum up, resin based parts are great for small scale projects that require a high quality, smooth surface finish. However, it is not very conducive to mass production due to the high amount of post-processing required.

Powder Jetting

Much like resin based printing, powder jetting has many different types of processes that fall underneath it but they all work under the same basic concept. An industrial printhead selectively deposits a liquid binding agent onto a thin layer of powder. This powder then hardens and a new layer of powder is added so the printhead can deposit more binding agent and process repeats layer by layer until the object you are printing is finished. When its all said and done, your part is embedded in the powder like a fossil in the dirt. Then, you dig out your finished product, wash off the excess powder, and then put the parts through a ​post-curing process to strengthen them. 

The biggest advantage that powder jetting has over almost all other printing processes, is its ability to print full color options. By mixing plaster-based powders with colored liquid binding agents, the printhead can seamlessly switch between different colors, thus giving you near full control of the color of your product. Another big advantage is that powder jetting doesn't require any supports. This means less post-processing time and less material wasted on supports. On the other hand, the biggest disadvantage is part strength. Even with post-curing processes, parts created with powder jetting are not as strong as parts created through other printing processes.

Conclusion

In conclusion, each of these printing processes have their fair share of advantages and disadvantages. Some, like FDM, are better suited for large scale production. Whereas others, like resin based, are more suited for small scale, high quality parts. Selecting the right printing process comes down to accessing the advantages and limitations of each technology to your products most important requirements. Although there is no one size fits all solution, properly utilizing 3D printing technology throughout your product's development will reduce design risk and, ultimately, result in better products.

​Happy printing.