It is an industrial 3D printing technology created by HP. It was first introduced to the market in 2014. Together with the SLS technologies it replaces, it represents 3D printing using the powder sintering method.
This 3D printing technology brings a unique opportunity to reduce the cost of 3D printing to the level of traditional production of plastic parts. It can be advantageously used for serial production of invisible parts. It offers the possibility to print parts that are more durable and should handle some stress.
How it works
3D prints are created by sintering (fusing, sintering) polymer powder layer by layer. Unlike the SLS technology, which uses lasers to sinter the powder, the multi jet fusion technology uses sprayed ink as a binder. This helps the absorption of infrared radiation by the powder.
A fine layer of powder is spread over the entire printing surface and heated to a temperature close to its sintering temperature. When moving over the print surface, the print head sprays tiny droplets of ink - sintering substances in the desired shape of each layer. Subsequently, a highly efficient infrared lamp hardens the places that have been sprayed with the sintering agent. The print surface is moved down one layer and the whole process is repeated.
In order to start post processing, it is still necessary to wait for the prints to cool down. This process is significantly shorter with MJF printers than with SLS printers. The HP company offers special devices for post processing, which cools the powder and then removes the excess.
The aspirated excess powder can be reused. With the MJF technology, 80-85% of the powder is used in this way, while with the SLS technology it is only 50%.
History
Only HP develops industrial 3D printers based on this technology. It is based on its own expertise in 2D printing technology on paper.
HP originally partnered with another 3D printing pioneer (Stratasys) to manufacture its 3D printers. After two years, in 2012, however, the collaboration ended, and since then HP has been developing its patented technology on its own.
She managed to develop print heads that spray the bonding material in droplets with a size of 1200 DPI (so one dot represents 0.022 mm). For SLS, the droplets have a diameter of 0.3-0.4 mm. However, the disadvantage is the deformation of large flat surfaces, which is more pronounced with MJF than with SLS.
Trends
Since this technology is not accessible to other 3D printer manufacturers (it is protected by patents), an influx of new MJF printer manufacturers is not expected. Even after 7 years since its launch, HP remains the only manufacturer of MJF printers.
Global chemical corporations such as Evonik, BASF, Arkema, Henkel were interested in developing special materials for this type of 3D printers as well. In the end, the collaboration with HP was completed only at BASF, where they developed BASF Ultrasint® TPU01 and Evonik - TPA material.
The range of materials for MJF printers remained very limited, more limited than for SLS technology. The most frequently used material is PA 12 - nylon, polyamide with high density and low porosity, or TPU - thermoplastic polyurethane, which is flexible. It is always a black material because it absorbs infrared radiation better.
Since there is zero competition in this technology and the number of printers sold is not very high even worldwide, the several million prices of these printers will remain for a long time at an unprofitable level for many companies and unattainable for smaller companies.
However, if you are interested in this 3D printing technology, we will be happy to supply you with prints from MJF printers.
Advantages
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Ideal for serial production of a large number of complex parts
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Ability to print parts with high resolution and fine details
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Up to 66% material savings compared to the SLS method
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5 times faster than the SLS method
Disdvantages
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Price - these are 3D printers with a higher price tag for professional production
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The surface of the prints is porous and not suitable for visual parts
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Only black materials can be printed
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Patented technology developed by only one company
If you are interested in this (or other) 3D printing technology, please contact us. We will be happy to show you different prints in our showroom and choose the most suitable one for your 3D print.