A start into an exciting year 2021
This year marks a turning point for our young company, after two years of product development in the field of semi-industrial 3D-printing. Still being industrial design students, we are looking into graduating this spring with a year behind schedule. We invested the pandemic induced time-out into the development of our Badass Pellet Extruder and the Bloft Mk2 large-scale 3D-printer, whose beta testing is about to start soon.
New Technology for New Challenges
We started 2018 building a Hangprinter v3.3 by Torbjørn Ludvigsen. The following year we already printed two massive projects on it, but to be honest, it was pain and highly experimental. The Hangprinter is an unique 3D-printer class, that has the printhead suspended and guided only by cables/lines, where as the traditional 3D-printer works with a rigid frame and linear guides and bearing.
A cable-driven 3D-printer eliminates the need for expensive parts in the motion mechanics. And in case of the Hangprinter, also the need for a rigid frame. The main benefit of a cable-driven 3D-printer lays in the low cost scalability of the system. It makes hardly a difference if your print area is 1 m in diameter or 10 m. As long as you have enough cable you are good to go, at least in theory. And cable happens to be rather cheap.
The flip side of the coin is the complexity of the software and hardware components needed for accurate and reliable print results. But, it is doable. It's only a LOT of work.
Â
We learnt pretty quickly, that FDM-extruders are too slow for cable-driven 3D-printers. This class of printers is playing out its true potential beyond the one cubic meter dimensions. FDM-extruders take weeks, if not months to finish a print that big. So, it was quite obvious, that we needed to have another solution. But that wasn't the only concern when thinking about extrusion technology. There were actually three other things to consider.
Let's think first about the properties of thermoplastic. Plastic has the tendency to degrade during each melt cycle, some plastic types degrade more, others less, but in the great picture there are always polymer chains breaking, causing the plastic to lose some of its mechanical strength. Production of plastic filament for FDM-printing starts with the plastic raw material, the pellets, that are made of virgin resins and which then are extruded for the first time. After exiting the extruder, it is chopped to a more or less standardized granulate size of 3-5 mm.
At the filament factory these pellets are then remolten and extruded again, but this time the plastic is cooled and pulled to either 1.75 or 3 mm diameter filament before wound up onto a spool. A high quality filament requires a tight dimensional tolerance. Something you can only achieve with expensive, high quality, machinery. That of course reflects in the filament price, which is approx. ten fold compared to the raw material.
FDM-filaments are easy to extrude and the required extruders are perfectly suited for desktop 3D-printers. When you think of printing a 50 kg object, other things start to matter. Why to do a detour with filament, when you can extrude directly with pellets? Faster and cheaper, while at the same time saving energy otherwise put into filament production. And you get a better end result in terms of mechanical strength.
And then there is the famous last thing
By now you should be aware of the world drowning in plastic waste, and of the fact that the production of new FDM-filament isn't making the situation any better (with the exception of recycled plastic filament).
Since the dawn of plastic production the world has been pushing out around 8 billion tonnes of the everlasting material. Yeah, that's a pile of plastic with a weight of an average car, for each and every person on this planet. Imagine for a second, if every one of us would drag a nice, molten and one tonne heavy, plastic cube fixed to the leg. Lucky for us that the plastic is dumped in landfills, burned and buried in the oceans. It would be otherwise pretty full in our already over-crowded cities.
Facing a problem this magnitude is overwhelming. After all it is plastic, that made this world possible in first place. But, we can't simply ignore the fact anymore, that plastic is everywhere. Latest research even found it in the placentas of pregnant women.
So, what to do?
Since plastic will be with us for centuries to come, we should put a thought or two into what to do with it in future. Functional recycling systems at industrial scale are at place in the most developed countries. And even if they are far from perfect, they are better than nothing. The western world also excelled at shipping their plastic garbage to South-East Asia up until few years ago, before the receiving countries could not, or did not want to, bear the burden anymore.
The research has already proven, that for instance high-density polyethylene (the stuff your milk bottle is made of) can keep up to 80% of its original strength, even after 100 reprocessing cycles. Empirical research by the Precious Plastic community confirms also the viability of degraded ocean waste plastic for recycling purposes. We took these as starting point for our own material research on post consumer and marine waste plastic. The research is the base for the Bachelor's Thesis by Roni-Pekka Järvi at the Metropolia University of Applied Sciences in spring 2021. The preliminary results are very promising as they show, that waste plastic is far from being just waste.
Injection moulded polypropylene tensile strength test specimens from waste plastic collected from beaches in Helsinki proved to be only 12% weaker compared to virgin plastic. And in comparison to its closest reference, shredded post consumer waste plastic, only marginal 4% weaker. The biggest surprise were the results of the ocean plastic tests. We bought for the testing shredded fibers from a scavenged trawl net, that had been washed ashore in Scotland. We interpreted the heterogenous coloration as a sign of long exposure to UV-radiation of the Sun, one of the main causes for degradation. The specimens were even stronger and tougher, than those made of virgin plastic. We concluded, that the resin used in the net must have been a high quality one, due to the mechanical requirements for a professional trawl net. But, nonetheless it seems, that even degraded ocean plastic can and should be recycled.
Stop looking away
We should instead start looking at waste plastic as a precious raw-material. In many places it literally lays there in front of you, just grab it and it's yours. But the thing is, unless you have the machinery to recycle it, it will be pretty much worthless. The industry won't take it, because it's too dirty, too expensive to collect/process/whatever.
But, what about the people? The communities, that have to live surrounded by the plastic? What if they would gain access to low cost machinery, that enable them to produce new goods from practically free material, in the best case powered by renewable energy? Add value and the problem starts to look just a little bit less grim.
That is the philosophy behind the Precious Plastic movement. With their open source plastic recycling machinery people and communities around the globe make new products from waste plastic. We set to fill the empty gap in the Precious Plastic machine collection, namely a large-scale 3D-printer for semi-industrial production.
Just recently we released the first beta of our pellet extruder, and the accompanying 3D-printer will follow later in near future. Join us on our journey to a just a little bit brighter future.
#pelletextrusion #fgf #3Dprinting #distributedmanufacturing #additivemanufacturing #opensource #preciousplastic #oceanplastic