The team of Stanford researchers behind the rapid CLIP (continuous liquid interface production) resin printer technology have unveiled a multi-material version of the technology referred to as iCLIP.
iCLIP, or “injection continuous liquid interface production” utilizes the same process as traditional CLIP printing, but instead uses a number of pump syringes to inject the different resins into the printer.
Recall that CLIP is a resin-based technology that is capable of printing incredibly fast thanks to the use of a “dead zone”, which is where a layer of oxygen prevents curing at the bottom of the resin vat. As the printed piece rises in the printer, the liquid resin fills behind it, allowing for rapid printing…or at least that’s the idea. In practice, this is not always the case, especially if the print is moving too quickly in the z-axis or if the resin is too viscous. In these cases, bubbles can form, resulting in voids in the print, particularly at the centre of the print, where the negative pressure is the highest.
By adding syringe pumps to the machine, the process can print faster by injecting the resins at key points of the print. You can see an example of a part printed with the multi-coloured iCLIP print process below.
“The resin flow in CLIP is a very passive process – you’re just pulling the object up and hoping that suction can bring material to the area where it’s needed,” says mechanical engineer Gabriel Lipkowitz, lead author on the paper.
“With this new technology, we actively inject resin onto the areas of the printer where it’s needed.”
What is particularly interesting about this process is how the resin is delivered from the syringes to the part itself. The part is printed, and the fluid conduits are printed alongside with the part to deliver the fluid where it needs to go. They can be removed afterwards, or they can be incorporated into the design and left intact. This is indicated in the image below as a viaduct.
In a nutshell, iCLIP works by injecting resin into the dead zone, thus alleviating suction forces and speeding up the traditional CLIP process (which was already fast by any standard).
“This new technology will help to fully realize the potential of 3D printing,” says Joseph DeSimone, the Sanjiv Sam Gambhir Professor in Translational Medicine and professor of radiology and of chemical engineering at Stanford.
“It will allow us to print much faster, helping to usher in a new era of digital manufacturing, as well as to enable the fabrication of complex, multi-material objects in a single step.”
If you think that adding the viaducts is going to be another DfAM headache for you to worry about, then do not fret- the researchers are working on that.
“We’re trying to create efficient software that can take a part that a designer wants to print and automatically generate not only the distribution network, but also determine the flow rates to administer different resins to achieve a multi-material goal,” said Lipkowitz.
So, how fast is the new iCLIP process exactly? According to the paper, iCLIP can accelerate printing speeds to 5- to 10-fold over current resin methods, including traditional CLIP
The paper, titled “Injection continuous liquid interface production of 3D objects“, can be found in the journal Science Advances can be found at this link.