The latest talk around 3D Printing industry is the launch of HP’s first ever 3D Printer in India which works on HP’s proprietary Multi Jet Fusion (MJF) technology. MJF is quite similar to Selective Laser Sintering (SLS) (SLS). Both are powder based technologies and there is no support structure generation in either of them. But the fundamental difference between SLS and MJF is that, in SLS the laser acts as a source of energy, whereas in MJF the material is fused together with the help of an infrared light source (lamp). Chizel had the pleasure of being part of HP’s unveiling of its HP Jet Fusion 3D 3200 Printer in Mumbai, and here are our insights on it.
On the onset, the HP printer looks sleek and well designed. The printer consists of:
- A bed of powdered material (Reusability PA 12)
- Recoater (to deposit new layer of powder)
- Incorporates heat lamps on the periphery which maintain the ambient temperature of the build volume just below the fusion temperature
- Houses a print head with two infrared light sources mounted on either sides with an array of nozzles sandwiched between them.
These nozzles deposit the fusing and detailing agents on to the powdered bed. The IR light source then selectively melts the powder where the fusing agent has been deposited. The fusion takes place in both the passes (to and fro movement of the print-head) thereby resulting in faster cycle time as compared to SLS technology. HP claims their MJF technology to be 10x faster than SLS.
There are two kind of additives used in MJF 3D Printer:
- Fusing Agent: The fusing agent is Black in color. It is deposited on the exposed area of the part geometry. The function of the fusing agent is to absorb heat and selectively melt the part. Hence it is black in color, as black absorbs more light (energy).
- Detailing Agent: The detailing agent is Transparent. Detailing agent is deposited on the periphery of the part geometry. Unlike fusing agent, the detailing agent is a heat repellent. Thus, it keeps the energy contained within its periphery and doesn’t allow it to escape its boundary. As a result, it leaves the rest of the power uncontaminated. This detailing agent is responsible for crisp and sharp features on MJF parts.
The printer comes with an interactive User interface that’s highly intuitive. It houses a thermal tracking feature which showcases real-time heat maps of the build so that corrective action, if any, can be taken at the onset of any error.
After the parts are fabricated, the build unit – which is a movable unit – is taken to a post-processing station where the parts are cooled and cleaned, and the used powder is stored in a container using a suction hose. During new build, another hose is commissioned, which automatically mixes the new and old powder in 80:20 ratio and readies the unit.
- Layer thickness: HP’s 3200 3D Printer comes in one standard layer thickness setting of 80µm (0.08 mm)
- Effective Build Volume: 380 x 284 x 380 mm
- Powder Mixing ratio: In powder based technologies, after a build has been completed, the used powder isn’t thrown away; it is stored for reuse during the next successive build. In SLS technology, EOS recommends the powder mixing ratio of 50:50. That is 50% new powder and 50% old powder for good part quality. Whereas in MJF, HP recommends 80:20 ratio. That is 80% old powder and 20% new powder. Since the old powder usage is so high in MJF, it can be reclaimed numerous times resulting in little material wastage. Whereas, in SLS, one has to discard the old powder after 3-4 build cycles as the material begins to lose its property.Both the technologies make use of PA 12 material. However, the properties of both these materials are different. Due to its high reusability rate, HP calls its PA 12 material as Reusability PA12. One crucial point to note is that, in SLS, there is freedom to alter this material mixing ratio. Whereas in MJF, one can only go as low as 85:15.
- Density: HP’s PA12 is denser as compared to EOS’s PA 12 material.
|Density after sintering/fusion||1.01 g/cm^3||0.91 g/cm^3|
- Part Color: HP’s Reusability PA 12 comes in white color, but owing to the black color of the fusing agent, the parts come out greyish-black in color. The parts can later be dyed jet-black, but this limits the coloring options on the final part. Whereas the end-parts in SLS PA 12 come in pure white color which can later be painted or dyed (preferred) to any desired color.
- Machine Price: Starts from INR 2.5 Crore (inclusive of pre and post processing unit, the 3D Printer and initial consumables. The cost is inclusive of three year maintenance and service contract.)
- Installation: Reports suggest that, one has to commission a 44KV three phase line to incorporate this machine.
- Resellers: HP has partnered with Imaginarium (India) and Adroitec as its official 3D Printer resellers in India.
Interesting fact, HP’s MJF is exactly as same as Voxeljet’s HSS (High Speed Sintering) technology. The only difference being the use of detailing agent by HP. Source: engineering.com
Although HP’s MJF looks promising by the looks of it, it’s still primitive to say how it fairs in comparison with EOS’s SLS. It will be interesting to see MJF’s response to:
- Warpage issues
- Strength considerations.
So far the parts that we have seen get manufactured in MJF had considerable(high) thicknesses. We would actually like to see how effectively the minute, detailed features are captured in MJF as compared to SLS. Also its response to Post-processing (dyeing) will be a peculiar characteristic.
We plan to run some experiments in the coming days with an aim to address these aforementioned queries. LEAVE YOUR COMMENTS HERE IF YOU WANT US TO TRY SOMETHING IN SPECIFIC.
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