MJF vs SLS: A Comparison of 3D Technologies

MJF vs SLS: A Comparison of 3D Technologies
Comparing an MJF and SLS part

MJF vs SLS

A Comparison of Powder Bed Fusion Technologies

Written By: Patrick Wirt, Production Manager - Oct 13, 2020

The term "Powder Bed Fusion" encompasses  both Selective Laser Sintering (SLS) and Multi Jet Fusion 3D printing. Since MJF's launch in 2016,  it has quickly become one of the most popular powder bed fusion technologies with more than 10 million parts produced in MJF in 2018 alone.

 

HP has been successfully propelling the manufacturing industry into a higher adoption of 3D printed parts for end-use production. So what makes Multi Jet Fusion so unique, and why has the manufacturing industry been so quick to adopt it? Is Multi Jet Fusion actually that much better?

 

In short, no.

 

HP's Multi Jet Fusion is not unlike the Makerbot movement of 2012 that popularized 3D printing in the mainstream. The technology has helped generate awareness about 3D printing, however the industry capabilities has stayed relatively similar.

 

Below we provide a side-by-side comparison of Multi Jet Fusion (MJF) & Selective Laser Sintering (SLS)

Print Process

Multi Jet Fusion differs from other powder bed fusion technologies as it uses a inkjet array of fusing agents, engineered to absorb infrared light emitted across the bed of nylon powder.  The infrared light heats the areas with the fusing agent, melting and fusing powder in those areas to form the cross section of a part. After a layer is built, a fresh layer of nylon powder is distributed and the process repeats.

 

In selective laser sintering, the process is similar, however fusion happens via a high power laser that that selectively sinters the parts, fusing each layer together.

Surface Finish

Orientation plays a major factor in surface finish for both processes, and the skill of an operators can greatly determine the finish of a part. Both MJF & SLS go through similar post processing steps which can include both sandblasting and tumbling. This is another major driver of surface finish, rather than the print process itself.

 

Winner: Tie

Surface finish comparison of SLS and MJF parts

MJF on the left, SLS on the right.

Mechanical Properties

The strength of a part is primarily determined by the quality of the powder used. Material blends as well as machine calibration can have a significant impact on part strength and durability between batches. Forge Labs uses a 50/50 blend of PA2200 offers slightly improved mechanical performance over HP's high reusability PA12.

 

Material Property

PA 2200 (SLS)

PA12 (MJF)

Tensile Strength

50 MPa

48 MPa

Elongation at Break

15 -20%

10-20%

Impact Strength (notched)

5.3 kJ/m2

3.5 kJ/m2

Heat Deflection

95 – 175°C

95 – 175°C

 

Winner: Selective Laser Sintering (PA 2200)

Colors

The base color of SLS is almost always white, which allows for a much broader range of color options through dye. Multi Jet Fusion only offers parts in PA 12 in a grey base color, which can be dyed black to improve part aesthetics. However this grey base color makes it much trickier to achieve any other color, especially scratch resistant white parts.

 

Winner: Selective Laser Sintering

Dyed SLS

SLS can be dyed or painted any color quite easily.

Material Availability

Multi Jet Fusion only offers parts in PA 12 & PA 11 whereas SLS has a much wider material availability including Polymers with FR ratings, elastomers as well as alumide.

 

Material

SLS

MJF

PA12

PA 11

PA 12 Glass Filled

Alumide

Polypropylene

TPU

Fiber Reinforced

 

Winner: Selective Laser Sintering

Small Feature Accuracy

SLS and MJF both offer very high dimensional accuracy, however they are both equally susceptible to warping due to the heat required during the 3D printing process. Often larger SLS builds tend to result in looser tolerances, however small print beds can achieve much higher tolerances  due to less variance in heat within the chamber. Accuracy comes down to a number of factors, but ultimately depends on the machinery used.

 

Accuracy

SLS (Forge Labs)

MJF

Dimensional Accuracy

± 0.3% (with lower limit on ± 0.2 mm)

± 0.3% (with lower limit on ± 0.2 mm)

Slice Height

60 – 100 microns

70 microns

 

Winner: Tie

 

If you have any other questions, or would like to get a quote in either process please get in touch!

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