A Brief Overview of Post-Processing Techniques in Additive Manufacturing

Remember that fresh-off-the-printer feeling? Excitement buzzing, creation complete... wait, hold on.

As an AM enthusiast, I know the real journey often begins after the print itself: the world of post-processing. Don't get me wrong, the first layer is thrilling, but it's the meticulous finishing touches that transform raw potential into stunning, functional reality. The whirring of the printer fades, the final layer solidifies, and a sense of accomplishment washes over you. Your creation, born from digital dreams, sits before you, tangible and real. But wait, this isn't the end of the story. As an ardent advocate for additive manufacturing (AM), I know the true journey, the meticulous dance of post-processing, has just begun.

Let’s understand it with an example: -

From Rough Diamond to Masterpiece:

Think about it like sculpting. Imagine Michelangelo starting with a raw block of marble and calling it David. It wouldn't quite inspire awe, would it? The same goes for AM parts. Support removal, sanding, polishing, and infiltration - these are the chisel and hammer of our digital age, revealing the hidden beauty and functionality within. Think of it as the final stroke of the brush on a masterpiece. While the 3D printer brings your design to life, post-processing techniques transform it from a rough draft into a functional, aesthetically pleasing reality.

1. Why Post-Processing Matters:

(I) Enhancing Beauty and Functionality But why is post-processing so crucial in additive manufacturing?

Imagine presenting a rough sketch instead of a fully realized painting – it lacks the wow factor and fails to convey the artist's vision. Similarly, post-processing enhances the aesthetics, surface quality, and functionality of our printed parts, ensuring they meet or exceed expectations. From improving visual appeal to optimizing performance, post-processing adds value and versatility to our creations. It's the alchemy that unlocks the full potential of AM, pushing beyond the limitations of raw prints.

(ii) The Magic of Post-Processing:

Adding Depth and Detail Now, let's fast forward to the post-processing stage, where the true magic happens. Just as an artist adds color, shading, and texture to bring their sketch to life, post-processing techniques breathe depth and detail into our additive manufacturing parts. Whether it's smoothing rough surfaces, removing imperfections, or adding decorative finishes, post-processing transforms our raw prints into works of art.

2. Data Dive: The Importance of Post-Processing

Don't underestimate its impact. A 2023 study by Wohlers Associates revealed that post-processing accounts for a staggering 30–50% of the total AM production time. This isn't just time spent; it's an investment in enhancing part quality, functionality, and, ultimately, your success.

But the benefits extend far beyond aesthetics. Imagine:

• Strength and Precision:?

Rough,?layered surfaces hold weaknesses.?Post-processing techniques like sanding, polishing, and CNC machining smooth surfaces improve dimensional accuracy and enhance mechanical properties, making parts stronger and more precise.

• Unlocking Material Potential:?

Think metallic implants infused with polymers for biocompatibility or porous structures infiltrated with resins for enhanced strength.?Post-processing opens doors to?tailored material properties?beyond the inherent limitations of printed materials.

?

• Crossing the Finish Line:

• Not all 3D-printed parts are functional right off the build plate.?Support removal,?cleaning,?and finishing are crucial for unlocking?functionality and performance?in areas like fluid flow,?heat transfer,?and electrical conductivity.

3.1 From Pixels to Perfection: AM Post-Processing Example

I remember the time my friend was working on a 3D-printed prosthetic hand. The printed fingers looked promising, but the surface roughness was a major concern. Skin contact needed to be smooth and comfortable. Using meticulous sanding and polishing techniques, we achieved the biocompatible smoothness required, transforming the prototype into a life-changing device. That's when I truly understood the power of post-processing – it's not just an afterthought; it's a crucial step in bringing AM creations to life.

3.2 A Spectrum of Techniques: Choosing the Right Tool for the Job

Our toolbox for post-processing is filled with diverse techniques, each with its own strengths and weaknesses. Choosing the right one depends on your material, part geometry, and desired outcome. Let's explore some popular options:

• Manual Methods:?

• Sanding,?polishing,?and filing offer?precise control?and are ideal for small parts or intricate details.?However,?they can be time-consuming and labor-intensive for larger projects.
• Thermal Techniques:?

• Vapor smoothing is a chemical process that involves exposing the surface of an SLS 3D-printed part to a solvent vapor. During the process, a combination of heat and solvent vapor selectively melts the surface, creating a smoother, sealed surface.?Vapor smoothing uses solvents to melt and smooth surfaces,?while thermal annealing improves mechanical properties.?These offer?efficiency and repeatability?but require specialized equipment and may alter part dimensions.
• Chemical Methods:?

• Chemical baths can remove support structures or alter surface properties.?They are?versatile and cost-effective,?but require careful handling and proper disposal of chemicals.
• Advanced Techniques:?
• Laser melting,?electroplating,?and CNC machining provide high precision and advanced functionalities?but come with?increased complexity and cost.

?

4. Unveiling the Hidden Magic: A Deep Dive into Post-Processing for All 7 AM Categories

The whirring of the printer fades, the final layer solidifies, and a sense of accomplishment washes over you. But hold your horses, fellow AM enthusiasts! As an ardent advocate for this transformative technology, I know the real journey, the meticulous dance of post-processing, has just begun.

A Spectrum of Techniques Tailored to Each AM Category:

Our toolbox overflows with diverse techniques, each specific to the different AM categories as defined by ASTM F42. Let's explore some popular options, with specific examples:

4.1 Powder Bed Fusion (PBF):

4.1.1 Support Removal:

Manual chiseling or water jetting and electrical discharge machining (EDM) are common for PBF metals due to their strength and potential for laser damage.

Support structures are both a necessity and a challenge in metal additive manufacturing (AM). While they ensure part stability during printing, they also increase post-processing efforts and impact surface quality. But fear not! Here are 5 easy tips to streamline metal support removal and minimize post-processing hassles.

1. Angle Your Supports: Opt for angled support structures to minimize contact with the part's surface, reducing post-processing areas. By connecting supports to the build platform at an angle, you limit the affected surface quality while maintaining part stability.
2. Utilize Fine Tooth Structure: Combine strong supports with fine teeth for easy removal without compromising part integrity. Fine teeth ensure a secure connection while minimizing damage to delicate features like thin walls or lightweight structures.
3. Rescale Support Structures: Adjust the width of support structures based on platform connection requirements. Scaling down support width reduces post-processing areas while scaling up reinforces support for tall and thin geometries.
4. Fragment Block Supports: Opt for fragmented block supports to facilitate support removal. Fragmentation creates channels between support structures, making manual removal easier and minimizing damage to supported areas.
5. Milling Off Additional Material: Consider adding extra material to supported areas and milling it off post-printing. This method maintains part quality without requiring additional post-processing steps, ensuring a smooth surface finish.

Credit: Materialise. For more information, click on https://www.materialise.com/en/inspiration/articles/5-ways-to-remove-metal-support-structures

4.1.2 Heat Treatment:

Stress relieving or annealing improves ductility and reduces residual stresses, especially for large PBF parts.

Heat treatment is a standard practice for nearly all 3D-printed metal components. This process serves to alleviate internal stresses that occur during printing and to tailor the microstructure of the part according to specific requirements. In industrial applications, adjustments to the microstructure are often made to enhance various properties such as hardness, strength, toughness, and resistance to wear.

Credit:- Delva, for more information, click on https://delva.fi/en/heat-treatment-of-3d-printed-metal-components-has-a-big-impact/

4.1.3 Surface Finishing:

Shot peening strengthens surfaces and improves fatigue life, while electrochemical polishing achieves a mirror finish for aesthetic or medical applications.

Shot peening utilizes small metal or ceramic spheres propelled by high-velocity compressed air to bombard the surface of a component. This process induces controlled plastic deformation in the surface layer, leading to enhanced fatigue strength and a decreased likelihood of cracks and fractures. Additionally, shot peening has the potential to improve corrosion resistance and promote better adhesion of subsequent coatings.

Credit: 3Dnatives, for more information click on https://www.3dnatives.com/en/different-methods-for-surface-finishing-in-3d-printing-060920234/

4.2???? Binder Jetting (BJ):

• Infiltration: Resin or metal infiltration enhances the strength and functionality of porous BJ parts.

?Infiltration, whether through resin or metal, serves to augment the strength and functionality of porous Binder Jetting (BJ) parts. This process involves impregnating the pores of the printed part with either resin or metal, thereby reinforcing its structure and enhancing its mechanical properties. Resin infiltration can improve the part's durability and resistance to wear, while metal infiltration offers increased strength and thermal conductivity, making the part suitable for a wider range of applications.

For more information, you can refer to the article. https://doi.org/10.1016/j.addma.2022.103162

• Finishing: Sanding, blasting, tumbling or coating can improve aesthetics and surface properties.

Vibratory finishing and tumbling, also referred to as tumbling or rumbling, are two methods employed for finishing 3D-printed parts. Both techniques involve placing the parts in a drum or tumbler alongside abrasive material. The tumbling or vibrating motion of the drum facilitates friction, leading to the desired surface finish. However, the selection between these methods depends on the specific needs of the part and the desired outcome.

Credit: 3Dnatives, for more information click on https://www.3dnatives.com/en/different-methods-for-surface-finishing-in-3d-printing-060920234/

4.3 Material Extrusion (MEX):

• Support Removal: Manual removal is common for soluble supports. For other materials, chemical baths or mechanical tools might be needed.

• Surface Finishing: Sanding, vapor smoothing, or polishing improve surface quality and appearance.

• Coating: Painting, plating, or other coatings enhance functionality and aesthetics.

• Vapor Smoothing:- Much like polishing and sanding, vapor smoothing can be used to help eliminate layer lines and smooth deformities in a print.

4.?4??? Material Jetting (MJ) and SLA:

• Support Removal: Chemical baths are common for MJ/SLA materials.

?In Material Jetting (MJ) technology, the removal of supports is typically achieved through methods such as water jetting or the use of chemical baths. Waterjetting involves the application of a high-pressure stream of water to dislodge and remove the support structures from the MJ-printed part. Alternatively, chemical baths utilize specific solutions to dissolve and eliminate the supports, leaving behind a clean and finished part. These techniques are commonly employed to ensure the smooth and precise removal of supports without causing damage to the intricate details of the MJ-printed components.

• Curing: UV post-curing improves mechanical properties and dimensional stability.

Curing, particularly through UV post-curing, serves to enhance the mechanical properties and dimensional stability of 3D-printed parts. UV post-curing involves exposing the printed part to ultraviolet (UV) light, which initiates a chemical reaction in the photopolymer resin, resulting in cross-linking and polymerization. This process strengthens the bonds within the resin, leading to improved mechanical strength, durability, and resistance to deformation. Additionally, UV post-curing helps to minimize dimensional changes that may occur during the printing process, ensuring the part maintains its intended shape and size.

?For more info, refer:- https://formlabs.com/blog/how-to-post-cure-3d-prints/

4.5 Sheet Lamination (SL):

• Bonding Optimization: Heat or pressure treatment strengthens bonds between layers.

?In Sheet Lamination (SL) technology, bonding optimization is achieved through heat or pressure treatment, which serves to strengthen the bonds between layers of material. This process involves subjecting the printed part to controlled heat or pressure, facilitating the fusion of adjacent layers and promoting adhesion. By optimizing the bonding between layers, SL-printed parts exhibit improved mechanical properties, such as enhanced strength and durability. Additionally, this treatment ensures the integrity and reliability of the part, making it suitable for a wide range of applications in various industries.

• Surface Finishing: Sanding, machining, or coating improve surface quality and functionality.
• Edge Finishing: Sealing or trimming ensures smooth and accurate edges.

?In Sheet Lamination (SL) technology, edge finishing is crucial to ensuring the smoothness and accuracy of the part's edges. This process typically involves sealing or trimming the edges to achieve the desired finish. Sealing the edges helps to prevent delamination and enhance the part's structural integrity by sealing any gaps or imperfections between layers. Trimming, on the other hand, involves cutting away excess material to refine the edges and achieve precise dimensional accuracy. By implementing edge finishing techniques, SL-printed parts exhibit smooth, uniform edges, enhancing their aesthetic appeal and functionality for various applications.

?

4.6???? Directed Energy Deposition (DED):

• Support Removal: Waterjetting, EDM, robotic cutting, or manual removal are common for DED materials.

?(Note:- The above picture is not DED part)

In Directed Energy Deposition (DED) technology, the removal of supports is typically carried out using methods such as water jetting, robotic cutting, or manual removal. Waterjetting involves the use of a high-pressure stream of water to dislodge and remove support structures from the DED-printed part. Robotic cutting utilizes automated cutting tools to remove supports while minimizing damage to the part precisely. Additionally, manual removal may involve the use of hand tools to detach supports from the printed component carefully. These common support removal techniques ensure the efficient and precise post-processing of DED materials, resulting in high-quality finished parts suitable for various industrial applications.

• Machining: CNC machining offers precise post-processing for complex geometries and tight tolerances.

5. ?Conclusion

As we conclude our deep dive into the captivating world of post-processing techniques in additive manufacturing, one thing becomes abundantly clear: this is where the true magic happens. From rough diamonds to masterpieces, from pixels to perfection, post-processing techniques breathe life into our digital creations, elevating them to new heights of functionality, aesthetics, and value. But beyond the surface-level transformations lie deeper implications. Post-processing isn't just about making parts look pretty – it's about unlocking their full potential. Whether it's enhancing mechanical properties, unlocking material potential, or ensuring functional performance, each post-processing step adds layers of value and versatility to our additive manufacturing endeavors.

So, fellow AM enthusiasts, let's embrace the journey of post-processing with enthusiasm and curiosity. Let's explore the diverse techniques, experiment with new methods, and celebrate the transformative power they bring to our creations. Together, let's continue to push the boundaries of innovation, one layer at a time.

Join the conversation: #AdditiveManufacturing #PostProcessing #Innovation #3DPrinting #LinkedInArticle

Here's to the beauty of post-processing, the final flourish in our additive manufacturing odyssey! Let's make magic happen, one print at a time. ???

?

?