Multi Jet Fusion is additive manufacturing technology invented by Hewlett-Packard (HP). It uses a multi-agent printing process printing a plastic part layer by layer.
Multi Jet Fusion uses Nylon 12 (PA 12) as materials and it is, a strong thermoplastic material that is great for high-volume functional prototyping and low-volume production applications.PA 12 Black is a type of nylon that offers high tensile strength and the final 3d printed parts are normally dyed in black with more isotropic mechanical properties when compared to SLS. Comparing SLS with HP MJF printer, it can achieve a smaller minimum feature resolution (0.02 in) as compared to SLS materials (0.03 in). The benefit of PA 12 is that it exhibits isotropic mechanical properties and is an economical material choice. PA 12 40% Glass-Filled Black is another type of HP MJF printer material, it consists of 40% glass-filled nylon. It provides heat deflection at 347°F and economical as well.
The Multi Jet Fusion process is ideal for building in batches to achieve lower unit pricing while adding increased functional design complexity. Material costs are associated with part volumes, not part extents volumes, saving costs when compared to Laser Sintering or CNC Machining. The Multi Jet Fusion process starts with a layer of material applied to the work area. In the opposite direction, in one continuous pass, the machine prints fusing and detailing agents across the full working area.
This pass combines the printing with the fusing energy, and the process is completed.
The innovative technology prints quickly along the bed width, enabling extreme precision and dimensional accuracy.
Manufacturing cycle-time for Multi Jet Fusion is driven by the height of the particular batch of parts being printed. Nesting parts together in a single batch is the way to reduce the average cycle-time per unit.
Multi Jet Fusion printing is applicable in a hidden area like complex thin-wall ductwork, connectors, non-cosmetic housings, brackets, covers, wiring clips, guides and grommets. Transportation industries also utilize this technology for pre-production and spare parts. The technology also can be used for mechanical such as the production of prototypes, articulated objects, geared systems and mould. Moreover its also employed in the field of electrical, medical, ornamental, automotive and educational purposes to produce low-volume production of complex end-use parts.
Material jetting is technology-free from issues with the printing process such as warping and shrinkage as there is no heat involved and it produces the most accurate result. Material jetting has a dimensional tolerance of ± 0.1% and a lower limit of ± 0.05 mm. However, some inaccuracy comes from the features and the walls being printed below the printer’s specification as thin walls and extremely detailed features might not be printed correctly. Normally MJF consists of prints a solid support structure from soft secondary material that is removed after the print is done. The surfaces of the print are stuck onto the support due to its solid nature hence there shall be careful handling of the parts produced as they can easily warp and even change dimensionally due to the exposure of sunlight, ambient heat and humidity hence, not very durable. the deposition of material by an MJF printer is 1200 DPI (or approximately 1 dot every 0.022 mm) while an SLS system is 0.3 – 0.4 mm in diameter and details such as small features and sharp edges can be printed with an aid of a detailing agent. Large flat areas have to be avoided to prevent warping. Although MJF is more accurate it is likely to warp more than the SLS part.
A thin layer of powder deposited over the build platform is heated to a near-sintering temperature. the inkjet nozzle then passes over the bed spreading the fusing agent on the powder layer, while simultaneously depositing the detailing agent near the edge of the printing part. Over the build platform, a high-power IR energy source passes and sintering the areas where the fusing agents were dropped with the rest of the powder area unchanged. this process continues until the print completes. The prints then like SLS have powder that needs to be removed after it cools down. HP MJF printer has a dedicated post-processing station that assists in the speeds up the cooling rate of the printed bin and helps with powder removal HP offers a dedicated post-processing station that speeds up the cooling rate of the printed bin and does powder removal. The recovered powder is re-used and recycled by 80-85% compared to SLS the powder is only 50% recyclable.MJF cool and operate faster than SLS because it operates with faster cooling rates and is recyclable.
MJF is more cost-effective by approximately 15% to 30% compared to SLS. For larger quantities, the price difference is smaller due to the streamlined post-processing workflow such as cooling, powder removal etc with MJF and this enables service providers working with these systems to drop their prices.