We’ve seen FDM printers lay down layers by extruding plastic in a line. We’ve seen printers use sintering and lithography to melt or cure one layer at a time before more print medium moves into place for the next layer. What we’ve never seen before is a printer like this that builds parts from distinct layers of substrate.
At the International Manufacturing Technology Show last week I spoke with Eric Povitz of Impossible Objects. The company is using a “sheet lamination process” that first prints each layer on carbon fiber or fiberglass, then uses a hydraulic press and an oven to bake the part into existence before bead-blasting the excess substrate away. Check out my interview with Eric and join me below for more pictures and details.
It’s incredible to see a process that prints the layers individually, using holes to align all of the layers on rods before fusing them together. I’m told the accuracy and resolution is quite good but don’t have a metric to back that up. The accuracy is best running parallel to the layers, so wide flat parts will yield consistent results. Very tall parts that require many layers will eventually see variations in accuracy.
Update: We made an inquiry with Impossible Objects about the accuracy and layer height limits of this process and received the following explanation:
The process does not recommend a layer limit. The Z height is currently limited to the size of the heated press we can find. We could theoretically have a much higher Z, but it would A) need to be large enough to fit the loose stack of sheets, and B) provide enough energy to still melt the thermoplastic powder at the center of the part.
When the Z height of the geometry is entered into the press, the press will stop at the desired height. We factor in any expansion / shrink, and it adjusts accordingly. But the long answer to the short question is that the accuracy still falls within the 50-200 micron range.
The substrate used in this process is quite thin and wispy. The printer itself moves the substrate through a process that uses inkjet printing to deposit a binder. Powdered thermoplastic is then applied where it sticks to the binder and the excess is reclaimed. The layers are automatically stacked in order at the end of the machine.
The second half of the process compresses the layers in a press, and bakes them to melt the thermoplastic into a solid. Bead blasting is then used to remove the excess substrate. Depending on your application, the part is now ready to used, or can be further processed through machining, adding threaded inserts, or other processes common to working with composites.
There’s a range of materials available for use with this technique. They depend on what substrate and thermoplastic is chosen. One of the more interesting examples they had on hand is made of carbon fiber reinforced polyether ether ketone (PEEK). This material has excellent heat resistance, and feels like metal when held in your hand. This particular demo is a jig for holding PCBs during wave soldering.
What you end up with are composite parts that have very different properties from those printed in powder or resin processes. These parts are reinforced by the fibers of the substrate and will certainly find eager customers in the manufacturing industry for applications that aren’t being met by other additive technologies.
If you loved this, make sure you also check out the direct metal printing equipment we saw at IMTS.