Among the three common 3D printing technologies, powder printing's features such as movable structure, one-piece molding, and support-free operation always bring amazing results. However, there is actually more than one way to use powder 3D printing , and each material has its own strengths and effects!
Taking HP's MJF (Multi Jet Fusion) technology and Sinterit 's SLS (Selective Laser Sintering) technology as examples, both are powder-based 3D printing , and the main difference is the heating method.
MJF can be described as a combination of SLS and inkjet technology. The following comparison will focus on the 3D printing process, forming effect, material properties, cost, and speed:
I. 3D Printing Process
A thin layer of powder is evenly spread on the printing platform. A laser is used to spot-sinter the printing area and directly sinter the powder. Then, the platform is lowered by one layer, and the powder spreading and laser treatment are repeated until printing is complete. After the printer has cooled down, the compacted powder clumps can be peeled off and the finished product can be removed.
The first layer of powder is laid flat on the printing platform and heated to near the sintering temperature. The inkjet head sprays solvent from above, and a fine agent is sprayed on the non-forming areas to prevent edge sintering. Then, the powder is irradiated with infrared light. The areas sprayed with solvent absorb the heat source and melt into shape. A new layer of powder is then laid on top, and this process is repeated until the 3D printing is completed. After printing, it is necessary to wait for it to cool before it can be removed.
II. Molding effect
Both types of 3D printed products have a matte finish. MJF is usually black because dark solvents can absorb heat more effectively. SLS parts are often white and easier to dye. Gray SLS nylon powder is also very common. These materials have a smoother feel than MJF .
Both MJF and SLS are high-precision industrial technologies that require no support structure and are suitable for one-time 3D printing of complex movable samples. However, MJF has a better overall appearance because the MJF inkjet head sprays solvent at a resolution of 1200 DPI (about 0.022 mm per unit) at the printing area, while the SLS laser spot is about 0.3-0.4 mm.
In addition, the fine agent used in non-molded areas by MJF helps to enhance the features and sharp edges of 3D printing ; however, MJF is more prone to warping compared to SLS technology.
III. Material Properties
The most commonly used powder for both technologies is PA 12 (nylon polymer). Since 3D printed objects will have stress differences due to the printing direction, MJF performs better than SLS in terms of stress uniformity in all directions. However, SLS printers offer more material options, such as elastic TPU, TPE , PA11 , etc., and the technology was developed earlier and is more mature.
HP's MJF currently only offers PA materials, and important engineering properties such as high impact resistance and deformation resistance have not yet been fully developed. With the rapid development of technology, it is believed that more material options will be available in the future.
IV. Cost and Speed
Taking HP, a major manufacturer of MJF, as an example, professional post-processing equipment can significantly accelerate the cooling speed and remove excess powder, and 80-85% of the recycled powder can be reused. In SLS , the ratio of old powder mixed with new powder needs to reach 50%.
In addition, MJF technology can print when the powder is not fully filled, while SLS equipment needs to completely fill the powder space for each print. The printing time depends on the number of powder layers, which is the main reason for the speed difference. Therefore, for SLS , it is the most cost-effective approach to accumulate multiple objects at once and fill the printing space as much as possible.
As shown in the table below, due to MJF's exclusive post-processing and cooling simplification process, the price of 3D printing a single object is lower than that of SLS . However, as the quantity increases, the prices of the two technologies become quite similar, because printing multiple SLS parts at once reduces the average cost.
Key points summarized:
SLS powder sintering involves laser dot deposition, while MJF ( Metal-Jet Fabrication) involves solvent spraying followed by infrared irradiation. Both SLS and MJF technologies can 3D print high-precision, matte-finish, complex moving parts without the need for supports. Currently, SLS has a wider range of usable materials and is a more mature technology, while MJF is slightly faster and produces more even mechanical stress. The production costs for small quantities are similar for both technologies, but MJF is cheaper for single-item production.
Through this sharing, do you have a better understanding of powder 3D printing ? Sandima offers more than just 3D printing contract manufacturing services . Contact us now to get more equipment and application examples of SLS powder sintering and MJF multi-shot fusion technology .
References