BigRep is pushing filament printing technology to new extremes with their Metering Extruder Technology (MXT). MXT enables you to print engineering plastics in half the time compared to traditional filament extrusion processes.
What is MXT? It is a metering system that sits inside their new extruder and helps print faster without the oozing you may experience when printing at high speeds.
The theoretical extrusion rate (max. throughput) is an idealised metric, which generally only applies when all is going well and the print head is moving in a straight line. Most parts do not consist of exclusively straight line filament tracks, and so they struggle to meet this ideal value of maximum throughput.
A lot of these inefficiencies stem from how the filament pushes the melted material out of the nozzle. It is a combined process that combines the melting and extrusion in one step.
This is all fine and good, until certain motions can interfere with the steady deposition of filament and can result in stringy depositions with filament drooling from the nozzle. The proper extrusion of the material is highly dependent on that one process going smoothly over a range of conditions.
MXT does away with these issues by separating the melting and extrusion processes. The filament feeds into a heated chamber, and it pools as a melt, ready to be deposited.
As you can see in the image below, a normal filament deposition extruder is on the left and the MXT is on the right. The MXT extruder shows a little depositing chamber which is absent in FFF.
The MXT eradicates the dropping and oozing caused by fast, angular moments of the print head for faster, repeatable quality parts.
The MXT is controlled by a precision servo motor, allowing consistent deposition, regardless of what sudden motions your toolpath is telling your printer to do.
MXT vs FFF
To demonstrate the apparent awesomeness of MXT technology, BigRep took two of their printers, the MXT-powered BigRep PRO and the power extruder driven BigRep ONE, to see how they compare. You can see that video below.
In the video, two geometrically identical parts were printed using the ONE and the PRO.
It’s hard to tell the dimension of the parts, but for reference the build volume of the PRO is 1020 mm x 970 mm x 980 mm. So it was a fairly big part. In the ONE, the part took over 23 hours to print.
The PRO, with its judder-resilient MXT system managed the job in under 14 hours. That’s a fairly significant time saving.
Add to this a Bosch CNC closed loop motion control system, a humidity controlled filament spool chamber and this PRO unit is looking like a fairly potent tool in terms of speed, quality & repeatability.