Post Processing 3D Prints for FFF (Fused Filament Fabrication)
The 3D printing industry is growing faster than ever, with constantly changing upgrades and improvements to print quality and speeds. According to Canalys, the size of the 3D printing market, including 3D printer sales, materials and associated services, has reached US$2.5 billion globally in 2013, and is predicted to reach US$16.2 billion by 2018. As a result of this rapid growth, there has been a lot of hype and misconceptions about 3D printing. One of the most common misconceptions is the as printed look and feel of a 3D printed object. Many expect a 3D printed part to look completely smooth and finished when it is done printing. While in reality, almost all of the 3D printing technologies to date, including Fused Filament Fabrication (FFF or FDM), Stereolithography (SLA), Multijet Modeling, and Inkjet Head Printing require some levels of post processing after the parts done printing. Have you ever seen a huge bowl of 3D printed plastic fruit, a giant Frankenstein monster’s head, or a 1:1 scale 3D printed rim at a 3D Platform trade show booth or on the web? Those who have seen the large 3D prints by 3D Platform, either in person or on the website, are all amazed by its enormous scale, precise print accuracy and realistic surface finishes. These fascinating half raw and half post processed 3D prints have raised a lot of questions among 3D printing enthusiasts: What is the point of leaving half of the 3D print raw and the other finished?
3D Platform Shares Insights on Post Processing 3D Prints
We intentionally have chosen to go ahead and print objects and have half finished and other half raw, 3D Platform Vice President, John Good explained. The reason we’ve done that is to help connect the dots and paint the possibilities. Earlier this month, 3D Platform, together with a 3D printing service bureau the CIDEAS, shared some insights on post processing 3D prints with the TCT Magazine. The original article Great Expectations is seen in the TCT Magazine, February 2015 Issue https://www.tctmagazine.com/3d-printing-services-bureaux-news/great-expectations-connecting-the-dots/
It’s all about managing great expectations and being transparent about the 3D printing process.
Before You Start a 3D PrintPost processing can significantly improve the surface finish of 3D prints. Depending on the 3D print design and final application, different 3D prints might require different amount of post processing efforts. To reduce the amount of post processing required after a 3D print is done, there are three things your can do before starting a 3D print to get the best surface finish possible. 1. Determine the best nozzle diameter and layer resolution for your project. Keep in mind the relationship between layer resolution and print time. A large diameter nozzle with a thick layer resolution will print much faster than a small diameter nozzle with fine layer resolution. 2. Once the layer resolution is determined, the speed settings for the printer have a direct effect on the quality and surface finish of the printed part. 3. If the part you are printing requires supports, the choice made regarding support material has a direct impact on the surface finish of a printed part.
Whether to post processing the 3D prints or not, determining the end-use of any object prior to printing is the key. It is also important to understand that while there are many post processing techniques that can be applied to your 3D printed parts in order to make it show room quality, you have to have the tool and know how to accomplish this. This video reveals some common misconceptions in large format 3D printing, and brings to light the reality of fused filament fabrication (FFF). These topics include surface finish, print quality, object strength, and some of the post processing techniques that are commonly applied to fill the gap between fresh-off-the-printer and amazing. As the 3D printing industry grows, so does the hype surrounding it. One common misconception is the expectation that a part will look completely finished when right off the printer. In reality, the post-processing involved to get the part looking this way may have taken several days or even longer. Example 1: The vehicle rim was 3D printed using a commonly used plastic called PLA (polylactic acid). The part was relatively inexpensive to print costing only about $250 in material. The model modifiers were set prior to printing to ensure a strong part with enough infill and wall thickness to enable post processing. The part also needed a considerable amount of support structures due to the steep overhangs in the model. When the print was complete the breakaway support structures needed to be removed. Post processing techniques were applied, resulting in a dramatic difference between the raw, fresh-off-the-printer look and the finished piece. Example 2: In this example, Frankenstein was printed on a gigantic scale measuring 695 mm tall. The material cost of this printed part was only $220. After some commonly used post processing techniques were applied, the result was a printed piece with museum quality aesthetics. Typical PLA finishing procedures for Frankenstein included:
- Deburring – which removes all the sharp edges of plastic that may be remnant of the support structures.
- Priming – with a high build automotive primer
- Sanding – ranging from coarse to fine grit
- Airbrushing – adding the final artistic details.
- Acetone vapor treatment for ABS printed parts.
- Ultrasonic cleaning tanks, where water and ultrasonic waves combine to remove support structures.
- A variety of other chemical and sealant treatments to smooth the outside surface finish.
- Breakaway supports – tend to print relatively quickly because they are not printed solid but can leave scarring on the object. Parameters are set in the software to aid in the removal of the supports.
- Wash away supports – are printed nearly solid and can be removed using water or certain chemicals. PVA is soluble in water, and Hipps is soluble in limonene. Wash away support structures provide a high-quality surface finish for the printed part. However, the support material requires a high fill density which means longer print times.
- Optical comparator – Surface finish and overall print quality are often tested by simply feeling the part once it is printed. But when a more scientific approach is needed, the use of an optical comparator can provide a closer look.