Multi jet modeling
The term Multi-Jet Modeling (MJM) describes a process of rapid prototyping in which a model is built up in layers using a printhead with several linearly arranged nozzles, which works similarly to the printhead of an inkjet printer . Machines used for multi-jet modeling belong to the machine class of 3D printers .
Due to the small size of the droplets generated with these systems, even fine details can be displayed. A print resolution of 450 dpi and better is technically possible.
In order to be able to produce overhangs, support structures are necessary. These are - depending on the manufacturer - built up from a low-melting wax or in the form of needle-like supports from the model material.
Hard waxes or special wax-like thermoplastics were first used as the starting material . The first systems in this group of processes only had these meltable plastics and only one print head. The further development of the system technology led to two-head systems. The use of a model material and a special support wax is possible. The support geometry (also referred to as support) required during production can be removed with little effort due to the use of meltable materials by heating.
UV-sensitive photopolymers are often used as model material . These raw materials in the form of monomers are polymerized by means of UV light immediately after they have been “printed” onto the existing layers and, in the process, transferred from the initial liquid state to the final solid state. The chemical process here is similar to stereolithography (SL). The essential properties of the generated objects largely correspond to the parts manufactured using SL. The machines are very compact and can be operated in an office environment.
Printing in powdery substrate
Another variant of Multi Jet Modeling is to apply an adhesive to a powdery substrate using an inkjet process.
For this purpose, the substrate is applied to the floor layer by layer in a tub with a lowerable floor. After each applied layer, the adhesive is then sprayed onto the areas that belong to the finished model. Additional support structures can thus be omitted, as the model is completely enclosed by the substrate until completion.
The model material is also no longer limited to liquid materials that are hardened after application. Printing in any powder, this can also be a metal or glass powder, creates a bond of adhesive and substrate. In the case of metal and glass powders, the model can then be sintered to create a solid metal or glass model. The glue is burned away.
Since the density of the material after sintering is only approx. 60% due to the former adhesive inclusions, an additional step, infiltration, is possible to increase the density of metal models. Additional material, usually bronze, is introduced into the gaps.
Infiltration is currently (2014) not possible with glass models.
Individual evidence
- ↑ ExOne: Archived copy ( Memento of the original from July 13, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
