MJF vs SLS Comparison

MultiJet Fusion (MJF) and Selective Laser Sintering (SLS) are two industrial 3D printing technologies, both of them belong to polymers powder bed fusion. In these two printing process, all parts are produced by thermal fusing or sintering polymer powder particles layer-by-layer. The raw materials in both MJF and SLS are thermoplastic polymers with granular form, the most common type is Nylon.

The main difference between MJF and SLS is the thermal heat source. SLS apply a laser system to scan and sinter every cross-section layer. While in MJF, a UV light system passes over platform and fuse the inked areas. MJF is a combination of SLS and Binder jetting technology. As MJF and SLS parts are very similar, we need to understand the slight difference. We will compare these technology in fabrication process, accuracy, materials, cost and leading time.

Fabrication Process

We summarize these two fabrication process as following:

Selective Laser Sintering

The thin layer of polymer powder is spread on build platform, then laser system will scan and sinter power on cross-section. The platform will move down with one layer height, and repeat the scanning and sintering process until final parts are finished. Finally, remove the finished parts once the whole bin are cooling down. You can find the detail process of SLS here.

Multi Jet Fusion

The thin layer of polymer powder is spread on build platform and heated to near-sintering temperature. Then the print head will deposit fusing agent on desired location, a high-powder UV light system will also sinter the area with fusing agent. Repeat this process until final parts are complete. Finally, remove the finished parts once cool down. You can find the detail process of MJF here.

In SLS process, every cross section is sintered point-by-point, while MJF fusing is in a line-wise fashion. However, there is no significant change in printing time for these two process, as the total number of parts layers determine the total printing time.

MJF has an faster cooling process than SLS. In MJF, the recovered powder is 80-85% recyclable, while in SLS, this only reach to 50%. Faster cooling time and higher recyclability determine that MJF operators can start a new printing process one powder bin is partial full, while SLS operators should wart for the power bin to fill. These key difference in fabrication process result in MJF has shorter leading time than SLS.

Dimensional Accuracy

Both MJF and SLS technologies has high dimensional accuracy. However, MJF can print a smaller edge than SLS. This is because MJF print-heads deposit materials at the size of approximate 0.022 mm a dot, while SLS laser spot size is 0.3-0.4 mm in diameter. In addition, MJF technology is more suitable for small features and sharp edges printing than SLS.

We also should notice that once these two technologies create free-form models without any support structures, these parts are susceptible to warping. So large flat are must be avoided in both technologies. In actual testing, MJF parts are more prone to warping than SLS parts.

MJFSLS
Dimensional accuracy±0.3% or ±0.2mm±0.3% or ±0.3mm
Typical size350×250×250 mm300 x 300 x 300 mm
Layer thickness30-60 microns100-120 microns
Minimum wall thickness0.6 mm0.7 mm
Minimum detail0.25 mm0.30 mm

Appearance & Surface Quality

Normally, the fusing agent in MJF is black color, because dark materials can absorb radiation effectively. So MJF parts appearance is light grey. Dyeing can achieve an uniform black finish for post-processed parts. SLS parts are normal withe color, while dyeing also can add any color to parts surface. SLS parts have similar appearance to MJF parts, but more smooth. Both SLS and MJF parts can be post-processed to high standard, dying is the most perfect option.

Material Properties

PA 12 (nylon) is a common material applied in both SLS and MJF. When printing with this materials, MJF parts have superior strength and flexibility, more homogeneous mechanical properties than SLS parts, SLS parts have weaker mechanical properties on the printing direction.

SLS technology has more material options, such as flexible TPU, carbon filled PA and aluminium filled PA (Alumide). As it’s a well-established and well-studied technology, SLS materials properties are documented by both manufacturers and researchers. However, PA is the only available materials for MJF with important engineering properties. MJF has an open material platform, which allow more material development.

Cost & Leading Time

Comparing SLS, MJF is more cost-effective with approximately 15% to 30%, the price difference will be smaller with high volume quantities. The main reason of price different is streamlined post-processing work-flow in MJF. However, SLS provide larger material options like TUP, PP, carbon filled nylon and glass filled nylon.

Conclusion

SLS is only able to produce parts with one single material. However, MJF can produce parts with multi-material and multi-color, in addition, MJF can achieve different material properties by different fusing agent type or concentration. Form more detail information about MJF and SLS, contact our engineering team now.