Last years HP (Hewlett Packard) , known from their laptops, 2D-printers, etc entered the 3D-printing market with a fairly new technology, called Multi Jet Fusion, or MJF. The technology was completely new for the 3D-printing industry and is gaining traction in mass manufacturing parts. In this article we compare the materials available for Multi Jet Fusion printers and compare it with their SLS and resin counterparts. All data is obtained from the manufacturers datasheets.
How does HP Multi Jet Fusion (MJF) work?
If you have to compare HP MJF with another 3D-printing technology, it would come closest to SLS, but is still different in many aspects. The MJF printer spreads a thin layer of powder (often PA, PP or TPU) over the build plate. The printer heats this layer to a near-sintering temperature. A set of jetting nozzles passes over the powder bed and deposits a fusing agent. Additionally, the machine prints a detailing agent that stops sintering near the edge of the part to get a higher accuracy. AN IR energy source then passes over the build bed and sinters the areas where the fusing agent was deposited. The rest of the powder remains unaltered. The process repeats until all parts are complete.
Image by Gagat studio: Cleaning a build 3D-printed with HP MJF 3D-printer.
Comparing materials and properties from HP MJF with resin and injection molding.
HP MJF is compatible with a couple materials, currently available are PA12, PA11, PP and TPU. Most of these materials are developed with manufacturers that also develop SLS powders.
PA12 properties for HP MJF technology
Earlier we already compared properties of SLS 3D-printing with injection molding and resin. Now we have added the PA12 properties according to the HP datasheet to the table below.
Table: Comparing properties of 3D-printed PA12 to photopolymer resins.
|Properties||PA12 (SLS in XY direction)||PA12 (Injection molded)||PA12 for HP MJF||Liqcreate Clear Impact|
|Tensile modulus||1,85 GPa||1,1 GPa||1,9 GPa||1,4 GPa|
|Tensile strength||50 MPa||50 MPa||50 MPa||47 MPa|
|Elongation at break||6 – 11%||>50 %||9 – 17 %||15 – 25%|
|IZOD Impact strength (notched)||32 J/m||~144 J/m (different source)||–||31 J/m|
|Impact strength (notched)||–||–||3,8 – 4,2 kJ/m2||–|
|Flexural strength||66 MPa||58 MPa||–||58 MPa|
|Flexural modulus||1,6 GPa||1,8 GPa||–||1,7 GPa|
Although some properties are not available, it seems like the properties of the MJF printer are quite similar to SLS 3D-printed parts.
PA11 properties for HP MJF technology
A similar comparison is made with the PA12 MJF vs SLS vs photopolymer resin. Formlabs Nylon 11 / PA11 is taken as comparison. All data is obtained from the manufacturers datasheets.
Table: Comparing properties of 3D-printed PA11 to photopolymer resins.
|Properties||PA11 (SLS in XY direction)||PA11 for HP MJF||Liqcreate Clear Impact|
|Tensile modulus||1,6 GPa||1,8 GPa||1,4 GPa|
|Tensile strength||49 MPa||54 MPa||47 MPa|
|Elongation at break||40 %||25 – 40 %||15 – 25%|
|IZOD Impact strength (notched)||71 J/m||–||31 J/m|
|Impact strength (notched)||–||3,8 – 4,2 kJ/m2||–|
|Flexural strength||55 MPa||–||58 MPa|
|Flexural modulus||1,4 GPa||–||1,7 GPa|
Again some properties are not available. Similar to the PA12 comparison, it seems like the properties of the MJF printer are quite similar to SLS 3D-printed parts.
PP properties for HP MJF technology compared to SLS and photopolymer resin
The Sinterit PP was taken as reference for the SLS 3D-printing properties. PP is a quite challenging material to copy in SLS, MJF powder printing and also in photopolymer resins.
Table: Comparing properties of 3D-printed PP to photopolymer resins.
|Properties||PP (SLS 3D-printed)||PP (injection molded)||PP for HP MJF||Liqcreate Tough-X|
|Tensile modulus||0,824 GPa||~1 – 1.4 GPa||1.6 GPa||~0.3 GPa|
|Tensile strength||19.3 MPa||33 MPa||29 MPa||15 MPa|
|Elongation at break||44.4 %||150 %||14 – 20 %||100 – 150 %|
|IZOD Impact strength (notched)||–||0,07 kJ/m||–||72 J/m|
|Charpy unnotched impact strength||30 kJ/m2||–||3,5 kJ/m2|
|Flexural strength||25.6 MPa||~40 MPa||—||11.4|
|Flexural modulus||0,66 GPa||~1,0 – 1.4 GPa||–||~0.3 GPa|
It should be noted that general injection molded PP properties are difficult to compile. This is because there is a wide range of properties available for thermoplastic materials. The differences between each technology and choice of PP can be seen in the table above.
TPU / Elastomer properties for HP MJF technology compared to SLS and photopolymer resin
One thermoplastic polyurethane (TPU) material is available for the MJF jetting technology. Properties vary in XY and Z orientation as seen in the deviation in the properties below. Compared to 3D-Systems DuraForm Flex and DuraForm Elastomer SLS powders.
Table: Comparing properties of 3D-printed TPU to photopolymer resins.
|Properties||DuraForm Flex (SLS TPE)||DuraForm Elastomer (SLS TPE)||TPU for HP MJF||Liqcreate Tough-X||Liqcreate Flexible-X|
|Tensile modulus||0,007 GPa||0,005 GPa||0,085 GPa||~0.3 GPa||< 0.05 GPa|
|Tensile strength||1,8 MPa||2,1 MPa||8 – 10 MPa||15 MPa||2,4 MPa|
|Elongation at break||110 %||200 %||137 – 291 %||100 – 150 %||120 – 160 %|
|Tear Strength||15,1 J/m||15,4 J/m||50 – 61 kN/m||67.9 kN/m||14.9 kN/m|
|Shore A||45 – 75||59||–||95||55|
Comparing all properties, each technology and material has its own benefit. Unfortunately some measurements are different or are not available in the official datasheets. This makes it nearly impossible to give a 1-on-1 comparison.