My journey in the 3D Printing World (a.k.a. how to design industrial FFF 3D printer)

Start of the journey

I first encountered 3D printing technology back in 2010 watching Discovery Chanell. They were airing a series of short videos focused on application of new technologies. One of them showed a group of artists, using an augmented reality to draw a 3D shape of furniture in the air, and then using an SLS machine to realize the design. I was truly amazed by the concept of materializing such complex designs so fast.

Three years later, in 2013, I saw first FFF 3D printer, and that changed the course of my life. A group of enthusiasts from my city started a first Venture capital backed company OMNI3D Industrial 3D printing focused on producing desktop 3D printers. The overall design was of course an offspring of a RepRap project, but everybody in the company had a gut feeling of making something cool and significant. I spend next years servicing those printers, dealing with many of the limitations of the technology back then. I remember how often we struggled to print something more than a figure downloaded from Thingiverse.

When we got a part form an industrial client, very often we had to pass, because of the limitations of the filaments, which was mostly PLA, or the fact that the parts had to had supports. Because of the single design, those were very hard to remove. When I put our current situation into that perspective, I see how big of a leap we made.

Today my position is Chief Technologist at Omni3D, and I manage print on demand, application engineering, trainings, filament testing and certification. Now the type of issues we are encountering changed dramatically. It is not the matter of if I will be able to print a part in decent quality. It’s often a case of reaching 50-micron accuracy. Or printing a benchmark part with ABS, PA-CF, TPU and PEKK part on the same 3D printer. Or meeting a one-week deadline for a project requiring 200h of printing. The issues we are dealing with really changed. The project I would see as impossible eight years ago, today we are printing with ease.

What are the things that changed and enabled us to push the limits of the technology?

Change the construction,

Back in a day we were producing printers with open construction. It had it benefits, for example assembly and maintenance was easier. The fact, that the bed was moving in Y axis, made the construction very easy. But as the customers pushed us to offer printers with bigger print area, soon we realized that this construction had to be changed. We sat down to the drawing board and produced idea of cartesian system with spindle drives. This system was still a reasonably compact solution because it enabled to construct a 50x50x50 cm build area machine that would weigh less than 200 kg and fit on a Euro-palette. This is an important factor in you take logistics into account. But most importantly we decided to use special drive screws instead of a belts. This solution requires much less maintenance and ensures high accuracy and repeatability of printing over longer period. Specially designed system components adapt and compensate for backlash as they wear out.

The Z axis movement also had to be addressed. Single rail system we were used to was not enough. We were also aware of the complexity of correct leveling such a big platform. Decision was made to use three independently driven axes, giving the bed two degrees of freedom. Printer equipped with such system was able to automatically tilt and physically level the bed, shortening and simplifying the calibration.

Cheated chamber,

Once we had a printer with big build area and stable construction it was for the first time really possible to print big models. The cartesian construction also enabled us to install full housing of the printer and insulate a build chamber. We started to print a bigger models with a filament we were used to – PLA, but with such a printer you do not really want to print with a hobbyist’s material. If you have a industrially sized machine, you need to use industrial materials, not something that would melt down left in a car on a sunny day. ABS was the next obvious solutions. Some say ABS is hard to print. I would phrase it differently. ABS is very easy and nice filament, but only when your printer provides right conditions for it. The condition you have to fulfill is a chamber temperature. ABS is a material that expands with the rise of temperature and shrink down when it is cooled. The key is to print in ABS in an expanded state. For that the temperature of air surrounding printed model has to be elevated to around 70 0C.?

As previously mentioned, we had a printer with insulated chamber, so all was left was to put heater inside and we should be ready to go. But it was not that easy. Once you heat up the chamber the conditions are right for ABS, but such elevated temperature is destructive for several other components of the printer. As we soon realized, most important of them was extrusion system.

Dual extruders with liquid cooling,

From the start we wanted our printer to utilize two heads, one to print model material and one for support filament. Such configuration makes possible to print with soluble or breakaway supports. The fact, that the materials of support and model differs, enables to print without a gap between a support and a part. If you work with a single extruder printer, you always need to have a gap sizing at least one layer height. Such clearance is necessary to be able to detach the support later.

But having two extruders, you are able to print filament which do not create a very strong chemical bond one deposited on top of another. Such a pair is for example Acrylonitrile Butadiene Styrene (ABS) and High Impact Polystyrene (HIPS). Styrene is responsible for the bonding between them, but the other ingredients differ, so that the bond in easy to crack while support removal.?

Other important factors in dimensional accuracy and visual quality. With dual head printing it’s easy to obtain the same high quality of both top and bottom layers. Taking accuracy into account, printing in single-head mode always adds 0,1 - 0,3mm to the size of a part in Z direction (depending on a layer height), which is not a case when printing in dual-head mode.

So now we know the benefits of using two heads. From the start we were a big fan on ABS and HIPS duet. It gave us beautiful print with easy to remove supports. But at start, the process was not reliable. As it turned out, the temperature inside extruder body was too high to provide a necessary thermal difference between cold and hot zone in the extruders. The chamber temperature was above 70 0C, which was only increased by the heating up of extruder stepper motor. All those factors resulted in HIPS filament often blocking in the extruder. New solution had to be applied.

Omni3D constructors designed a sophisticated innovative system of liquid cooling of the extruder body. Application of this system decreased the temperature from 90C to around 40C. In such temperature the filament feeding was very reliable, and few days printing jobs started to be achievable. Other positive outcome was lack of the radiator between feeding system and heat block, shortening the distance the filament has from extruder gear to the nozzle tip. Such solution is key in printing elastic filaments. The system we developed was later on patented.

Industrial filaments,

At this point of our journey, we have industrial printer with stable construction, cheated chamber and dual liquid cooled extruders. A lot of firmware programming, testing and developing had to be done, to make such sophisticated system easy to use. Constantly working together with technology users, we were able to prepare the LCD interface and calibration procedures which are easy to use and reliable. Only remaining component was to test and certificate variety of industrial grade filaments.

Within Technology department in Omni3D we benchmarked many different grades of filaments such ABS and PA, picking the best available. We prepared pre-defined profiles to make printing easier for non-expert users.

The work on filaments is never complete, as we are testing newly developed grades, as well as matches between model and supports filaments, such as CF-PA-12 and ODS-20.

The way

Looking back on our journey, I am very proud of what we have achieved. The ambitious minds of our team members were able to come up with solutions that are now becoming industry standards. But most of all, I am excited about what people equipped with our solutions achieve in their fields. Companies like Volkswagen, Samsung and Bosch are using Omni3D printers to push the boundaries of technology. Now I am full of faith in the future of 3D printing, but also Omni3D’s.