In additive manufacturing, SLS and MJF are advanced 3D printing technologies that can produce parts with advanced functionality. However, it all starts with the first print, the first step in completing the product. Finishing is an integral part of the 3D printing technology, significantly improving the mechanical, visual, and functional properties of the fast prototyped parts. This guide covers the most important and widely used post-processing methods for the SLS or MJF 3d printed parts. From powder extraction to surface treatment and dyeing, we will examine those processes and their adequate performance to achieve the desired outcome. This guide will enhance your understanding of each step in producing 3D-printed parts for a simple beginner and an experienced user.
What are the Common Post-Processing Techniques for SLS and MJF Parts?
How is Media Blasting Used for SLS and MJF 3D Printed Parts?
Media blasting, often called blasting, is a finishing operation that aims to clean and finalize SLS and MJF 3D-printed elements. In this procedure, the printed parts are subjected to a jet of abrasive material propelled by a turbine or other mechanical means, such as aluminum oxide, glass beads, or plastic media. The key function of the media blast is to eliminate the remaining powder and the roughness of the surface’s imperfect areas. To this purpose, special blasting media (microbeads, etc.) may be strategically used to create a clean and uniform surface well-prepared for future painting procedures. Media blasting is very efficient in creating the desired texture of the surface, and therefore, it is a very important process in the post-processing steps of SLS and MJF parts.
What are the Benefits of Vapor Smoothing for 3D Printed Parts?
Vapor smoothing is a post-treatment where parts created using 3& printing technologies are placed in vapors of selected solvents that operate by melting and redistributing the facia of the ports, thereby refining it. Among the advantages of vapor smoothing is the improved surface characteristics of the parts whereby visible layer lines are no longer present; hence, the surfaces are smooth and glossy, as is common with high-end 3D printing services. Besides, the tensile strength of 3D printed parts can also improve due to stress concentrators being made less or removed altogether by vapor smoothing. By this technique, the water and chemical barrier properties of the parts are improved in that the surface of the parts is covered, enhancing their functional and decorative properties. Vapor smoothing is generally beneficial in parts that need to be finished and yet are expected to be durable.
Can Dyeing be Applied to SLS and MJF Parts?
Yes, dyeing can also be effectively utilized on Selective Laser Sintering (SLS) and Multi Jet Fusion (MJF) parts. This post-processing technique consists of plunging the parts in a dye solution to give homogeneous coloration to the parts as the dye permeates the material. SLS and MJF parts are known to be porous, and therefore, they can take in more of the dye, making dyeing easier and faster. The process makes the parts look more presentable but does not alter their functionality, which is why it is a good method to obtain interesting colored details. Problems associated with the need to engage paint after making such parts are also easily dealt with. The inefficiency of the method can be eliminated in masterbatching. In addition, the dyes boast other properties such as UV protection from the sun, which prolongs the part’s life and widens the part’s use in MJF and SLS 3D printing to great reference.
How can you achieve a smooth surface finish for SLS and MJF parts?
What Polishing Techniques are Effective for SLS and MJF Parts?
Among the available techniques to enhance the surface quality of SLS and MJF parts, mechanical polishing, chemical smoothing, and media tumbling are best suited. Mechanical polishing is a process that can be done manually or using machines that utilize abrasive materials to eliminate the rough edges and the layer lines and smoothen the surface to a shiny finish. Chemical smoothing is a process that uses vapors or fluids that come into contact with the material’s surface, melt it, and solidify it again to smoothen the surface. Media tumbling, also known as abrasive tumbling or mass finishing, is a process that requires the parts to be placed in a tumbler or vibratory bowl containing an abrasive medium where the parts get polished by the medium through constant movement. All these methods have their merits, though both mechanical and media polishing are cost-efficient and precise. At the same time, chemical smoothing gives better consistency in the surface quality and performance of the component.
How Does Bead Blasting Improve the Surface Finish?
Bead blasting is the second most common post-process for enhancing the surface quality of Selective Laser Sintering (SLS) and Multi Jet Fusion (MJF) parts. Rough areas on the surface are smoothed down, and fillers are made features, too. The information available from the top sources claims that bead blasting helps improve the exterior of the parts and prepare for the next operation in the part-making process, such as painting or coating in 3D printing solutions. This technique is especially beneficial in performing functional and decorative coating on various surface types, including complex geometries and fragile configurations.
What is the Role of Coating in Smoothing 3D Printed Parts?
The coating makes it possible to achieve an improved surface finish of 3D printed parts as additional finishing. After the first post-processing steps, such as sanding or bead blasting, other epoxy, polyurethane, or any specialized paints can be used for coating to smooth out the surface irregularities and layer lines; this gives rise to a more consistent surface that is visually appealing. Additional advantages of the coatings are improved wear, sunlight radiation, and chemical resistance. Thus, because of the numerous enhancement features, the scope of which cut beyond appearance, the coating should be considered more than just aesthetics and one of the necessary steps in post-processing 3D printed parts.
What are the Best Post-Processing Methods for SLS 3D Printed Parts?
How to Remove Excess Powder from SLS 3D Printed Parts?
Removing the excess powder from SLS 3D printed parts is vital to achieving the best quality and usability for the components. It is normally composed of multiple stages, such as surface cleaning and the application of aid material.
- Initial Cleanup After the print is created, there comes a point of cooling of the powder bed and careful extraction of the part which is very important in MJF and SLS 3D printing processes. Quite a huge amount of the excess powder can be eliminated with a brush or a blast of air.
- Media Blasting: At this stage, a media blasting cabinet is employed, where abrasive media like glass beads are used at a controlled air pressure to clear out the residual powder in complex geometries or features. However, excessive mass is cleaned off the surface of the part attachment without causing further damage to the surface of the part.
- Ultrasonic Cleaning: An ultrasonic cleaning bath is helpful where smaller components need to be cleaned. This entails putting the part in a liquid that is stirred by ultrasound until every last bit of dust is removed from the surface.
- Manual Cleaning: Any stubborn powder left behind may require manual cleaning with small brushes, picks, and other dental tools. This is particularly the way forward for delicate sections or very fine detailing.
- Vacuuming and Final Inspection: Once all other cleaning steps, including the antechamber cleaning, have been performed, conduct the final cleaning with a vacuum cleaner for very fine particles. Finally, examine the part carefully to ensure it is free from residue.
You are now adept at performing the necessary steps to finish the excess powder from SLS 3D-printed parts, making them clean and ready for further processing or uninterrupted usage.
What are the Options for Surface Finishing SLS Parts?
Removing the excess powder from SLS 3D-printed parts is vital to achieving the best quality and usability for the components. This process is normally composed of multiple stages, such as surface cleaning and the application of aid material.
- Initial Cleanup After the print is created, there comes a point of cooling of the powder bed and careful extraction of the part which is very important in MJF and SLS 3D printing processes. Quite a huge amount of the excess powder can be eliminated with a brush or a blast of air.
- Media Blasting: At this stage, a media blasting cabinet is employed, where abrasive media like glass beads are used at a controlled air pressure to clear out the residual powder in complex geometries or features. However, excessive mass is cleaned off the surface of the part attachment without causing further damage to the surface of the part.
- Ultrasonic Cleaning: An ultrasonic cleaning bath is helpful when smaller components need to be cleaned. The part is placed in a liquid that is stirred by ultrasound until every last bit of dust is removed from the surface.
- Manual Cleaning: Any stubborn powder left behind may require manual cleaning with the help of small brushes, picks, and other dental tools. This is particularly the way forward for the delicate section or very fine detailing of the part.
- Vacuuming and Final Inspection: Once all other cleaning steps, including the antechamber cleaning, are completed, conduct the final cleaning with a vacuum cleaner for very fine particles. Finally, scrutinize the part to ensure it is free from residue.
You are now adept at performing the necessary steps to finish the excess powder from SLS 3D-printed parts, making them clean and ready for further processing or uninterrupted usage.
How do you apply a metal coating to SLS parts?
To coat metal parts obtained by SLS (Selective Laser Sintering), several steps should be followed accurately to obtain a high-quality and hard coating. The process generally consists of the following steps:
- Surface Preparation: The first step is to prepare the SLS part’s surface. This might involve cleaning the part to remove any remaining powder and impurities and/or smoothing out the surface with tools such as bead blasters or sanders.
- Priming: A primer is applied to the prepared surface to smooth out and enhance the metal adherent on the upgraded coating. Primers used in this case include the epoxy maleic acid type for use during the zinc coating process.
- Electroplating or Electroless Plating:
- In electroplating, a part is placed in an electrolytic bath, and a current is passed, which causes the deposition of a metal layer on the part’s surface. Metal coating processes that employ this method are nickel plating, copper plating, or gold plating. This is ideal for applications where the metal layers required are of uniform thickness and good quality.
- Electroless plating/ Metallizing processes do not involve the application of any current while depositing the metal on the part. This is very helpful because it is able to cover intricate shapes and has controlled metal deposition and coating thickness, even in the case of powder coating methods.
- Post-Coating Finishing: After the metal coating is applied, a sequence of supplementary post-coating operations, such as polishing, heat treatment, or sealing, can be performed to improve the quality, durability, and performance of the coated part.
These steps ensure that the metal coating will act appropriately, not only enhancing the part’s appearance but also giving it other properties like hardness and conductivity, invulnerability to corrosion, and many others.
What are the Post-Processing Options Available for MJF 3D Printing?
How can the surface finish of MJF parts be improved?
There are various ways to tone your surface finish of Multi Jet Fusion (MJF) parts, including considering post-processing techniques:
- Bead blasting In the bead blasting method, fine media is propelled under high velocity to minimize surface defects and achieve a uniform dull end.
- Chemical Smoothing: A smoothing remover is used on the surface, breaking the scab layer and leaving a shiny, even coat.
- Tumbling is one of the common techniques used to enhance part surface quality in 3D printing post-processing. The components are put in a vibratory or rotational tumbler with abrasive media to wear down the sharp edges and give them a more rounded shape.
- Painting: Coatings or paints may be useful not only for improving the surface properties for aesthetic purposes but also for other purposes.
- InfiltrationFor 3D printing post-processing, it is important to introduce any element into the porous surface of an MJF part to improve its aesthetic and mechanical strength.
- Heat Treatment: Thermally controlled processes can mitigate surface roughness and increase optimal characteristics.
These post-processing techniques are crucial in improving the aesthetic quality and functionality of the MJF 3D printed parts.
What are the Color Options for MJF 3D Printed Parts?
The MJF 3D Printed Parts can only take natural gray as the primary color as most of the parts are made of Nylon PA12 powder. However, additional components can be colored to provide various look enhancements. More often than not, parts are colored black, but the code green, blue, red, and even yellow can also be attained by coloring the respective parts. The parts are immersed in the dye bath for maximum efficiency and to eliminate any shade variations that may be evident in the parts.
How do you apply spray paint to MJF parts?
The following instruction explains how spray painting is done to the parts of MJF.:
- Proper part maintenance is necessary to accomplish the 3D printing post-processing effectively. It is mandatory to ensure that the MJF part is clean and free of dust, grease, or any other contaminants. Otherwise, a mild soap or isopropyl alcohol should be used to ensure that the surface is cleaned well.
- Prepare the Area: Prepare an outside space where solvent fumes are vented out, probably using a spray booth. Ensure that surfaces that are not to be painted are covered so that they are not painted by side spray.
- Apply Primer: Where necessary, it is helpful to apply thin, uniform coats of primer intended for attaching the plastic parts to the FDM model. A coarse surface will make it easier for the paint to adhere. Do not use the paint until the primer is completely dry; this should be done as the primer manufacturer prescribes.
- Spray Paint: Before using the can, shake it uniformly to distribute the varnish paint evenly inside it. Only apply several layers of paint very sparingly and relatively evenly to the moderate distance of 6-8in above the model. To avoid drippings, it is better to apply various thin coats of paint than a single thick coat.
Dry and Cure: Follow the manufacturer’s recommendations for the interval between the application of two coats of paint. After the last coat dries, the part should be allowed to undergo a thorough curing or drying process to achieve full strength.
How to Optimize Post-Processing for Additive Manufacturing?
What are the Cost-Effective Post-Processing Techniques?
Affordable post-processing operations, depending on the nature of the parts, include mechanical finishing, tumbling, and chemical smoothing.
Mechanical Finishing:
This particular method involves using sandpaper, grinding wheels, or a bead blaster to remove the last surface layers of the printed parts. It is a manual process that is rather cheap and has qualitatively enhanced the surface quality and overall look of the part.
Tumbling:
Here, parts to be polished are placed in a vibrating tumbler machine along with abrasive media. This is highly efficient for metal parts removes surface roughness and cleans them inexpensively. It is usually done electronically, which makes it more scalable for mass production.
Chemical Smoothing:
Requires the components to be dipped into a chemical solution that attacks the exposed areas of the component to remove excess material. For instance, acetone vapour smoothing of ABS. This method is more economical when used for plastics and can create very smooth and nice-looking, albeit effective, components.
These various methods of surface finishing components have been seen as ideal post-processing methods for most industries in regard to quality improvement and affordability.
How to Integrate Post-Processing in the Workflow?
In order to achieve efficient integration of post-processing activities within the workflow possessed, consider the following steps:
Identify Requirements:
Understand the expected finish, mechanical properties, and functional requirements of the final product. This will determine the post-processing methods to be used.
Plan the Workflow:
Include post-processing activities on the production calendar. For instance, depending on the methods selected, include time for drying, curing, or polishing.
Standard Operating Procedures (SOPs):
Create and archive SOPs for each of the post-processing methods to ensure uniformity and quality. Educate the employees on the performance of these procedures.
Quality Control:
Perform inspections at the different levels of the post-processing stage to verify that the items meet the specific criteria required to proceed further within the workflow.
Automation and Scalability:
Find ways to automate uninteresting post-handling activities. Assess measures to deal with changes in quantity and quality of production.
Following the above sequential steps within the manufacturing work process, post-processing can improve the quality and functionality of additively manufactured parts without sacrificing efficiency and cost.
What are the Considerations for Post-Processing Complex Parts?
Many complex parts require post-processing to achieve quality and functionality.
Geometric Complexity:
Evaluate the description and details of the part’s shape. A complex geometry may require the use of specialized tools and techniques to access and finish all its surfaces.
Material Properties:
Different materials respond to different post-processing methods. It is important to pick methods appropriate for the part’s material so as not to damage it or change the desired shape.
Tolerance and Fit:
Pay close attention to tolerances when post-processing the part, as excessive removal or deformity may interfere with the part’s functional fit in the intended application.
Assembly Requirements:
Consider how post-processing will affect the methods of joining the parts, such as welding bonding or mechanical bonding, on parts that will be assembled. Examine surfaces for proper surface preparation.
Surface Finish:
Understand the post processed surface finish specifications required and how they can be achieved through the use of post-processing such as polishing or coating for design and functionality purposes.
Mechanical Properties:
Process the part without compromising its strength, flexibility, and other properties. Methods should be selected to achieve or preserve such properties.
Considering such considerations, the post-processing of complex parts can be controlled so that the end products are of good quality and reasonably functional.
Reference Sources
Kingsun’s 3D Printing Service for Custom Parts
Frequently Asked Questions (FAQs)
Q: What are the main differences between SLS and MJF 3D printing technologies?
A: SLS—Selective Laser Sintering, SLS, and MJF—Multi Jet Fusion, MJF, are both known as powder bed fusion 3D printing technologies; however, their approaches to the process differ. SLS employs laser sintering of the powder; MJF employs fusing agents and infrared heat. MJF usually offers good print speed and excellent uniformity of the parts, while SLS is able to offer more printable materials and colors.
Q: How do morpho-functional characteristics and morphology of Tendon Shield SLS and MJF 3D printed parts differ?
A: For both SLS and MJF parts, common post-processing processes include powder removal, cleaning, polishing, dyeing or coloring, and finishing, such as painting or coating. The purpose of these post-processing operations is to enhance the surface quality, appearance, and performance of the end parts.
Q: What is the ideal procedure for stripping powder off SLS and MJF parts, and what are the necessary tools?
A: Powder removal is one of the crucial post-processing steps after SLS and MJF printing. It is generally accomplished by using high-pressure air, brushes, and powder removal workstations. In the case of complicated geometrical designs with internal cavity parts, more complex post-processing, such as vibration and/or ultrasonic cleaning, may be required.
Q: What alternatives are there to improve the surface quality of SLS and MJF parts?
A: An epoxy finishing system can be employed to improve the surface finish of the SLS and MJF parts through manual sanding, media blasting, tumbling, and chemical smoothing. To achieve a more professional finish, vapor smoothing and coating over the old one can be utilized.
Q: Can printed parts of the SLS and MJF be painted or stained?
A: It is indeed possible. SLS and MJF parts can be printed and subsequently stained. In the case of SLS parts, usually white or light in color, dyeing has thus emerged as a solution for color application. MJF parts, on the other hand, are usually grey or black but can be powder-coated or painted for color. Both technologies also provide an option for color matching to certain colors utilizing specialized finishing processes.
Q: What do you do about support structures, if any, in SLS and MJF 3D printing?
A: The major difference between FDM (Fused Deposition Modeling) and SLS and MJF techniques is the lack of any need for support structures. The unsintered powder serves as a build material enhancement during the production of the part. Therefore, components may be more kris-shaped and have more movable parts without the restriction of having to remove the supports after the post-processing procedure.
Q: What are the recommended SLS and MJF printing practices for obtaining functional moving parts?
A: To create functional movable objects using SLS and MJF printing, it is fundamental to incorporate facilitating structural clearances relative to the interfaces of different components, considering the size of the powder particles and the degree of bonding. Steps after printing, like cleaning by blowing off excess powder and general washing, are also necessary. In some cases, lubricants will be applied to the moving elements in the parts after they are assembled.
Q: What are the relevant aspects regarding post-processing MJF or SLS parts meant for short-term applications?
A: This would be the case for parts intended for use in end-use applications. Such steps might involve sealing operations to cover the porous surface and improve its waterproofing, applying dust or wear-resistant coatings, or treating the parts to satisfy particular specifications. Therefore, studying the applicable 3D printing post-processing regulations for the final end-use application is vital.
