Monday, June 11, 2012

3D Printer Raw Materials

3D printers utilize different types of raw materials. Following are my personal thoughts on two different raw material types.

Filament ABS, PLA:
- Mainly used in RepRap derivate printers.
Relative low cost printer design. Utilizes low cost extruders. Printed objects have continuous layers, improving rigidity and smooth look.  Depending on the nozzle width, the build speed can be considerable increased in trade off lowering the detail of final object.

Uniform and perfect circle filaments are required for high quality results.
Difficult to align layers. Difficult to control the extruded plastics thickness. Bubbling may occur.
Supporting the design is not that easy, either another extruder is required with a water soluble plastic is used or the gap can be filled with loosely build plastic.  Stringing is also another problem.
The object printed would deform while being printed due to temperature differences. The bottom platform can be heated and the extruded plastic is hot, however the plastic in between is exposed to the ambient temperature. Due to these temperature differences warping is inevitable depending on the shape of the object. Heated platform is required for larger ABS prints.

Powder Plastic (I don’t know the exact plastic composition):
- Mainly used in high end 3D printers.
Plastic powders unlike filaments can have higher tolerances in manufacturing. No support material is needed while the powder serves as the support. No heated platform is required. Less warping occurs due to less temperature deviation. Consistent printed unit volume results in consistently high quality prints. Parallel processing can be easier to implement compared to filament based printers.

Higher cost of printer design. Laser sintering, thermal print heads or inkjet technologies are utilized in these printers making them difficult to develop for low budget startups.
Unless multiple lasers are used printing object with laser sintering is slower compared to large nozzle filament printers. Because focused laser beam can only melt small regions compared to large size of nozzle. It is expensive to manufacture very fine plastic powder (2-3 micron).

Monday, June 4, 2012

Suggestions on Future 3D Printer Design

Current printers utilize circular extruders. These extruders have a fix width. If you would like fine details on your print you should use extruders with small nozzle size (I use the term nozzle size for the nozzle opening diameter). The downside of this is it takes a longer time to print the object while only small amount of plastic can be extruded at a given time. If you would like to shorten the print times and do not require detail on your print you can use extruders with larger nozzles.
One possible question comes to mind, “Is it possible to have an extruder with variable nozzle size?”.
A continues variable nozzle is complicated and therefore not feasible at the moment. However it is possible to have an extruder with two nozzle sizes. While printing, the printer can alter the nozzle size, either fine (0.25 mm) or bold (1.00 mm). For further detail on this subject you can read the paper   “Variable fused deposition modeling - concept design and tool path generation”.

Here are my suggestions on the extruder design:
The plastic extruder opening can be rectangular instead of being circular. One side of the rectangle can be controlled to adjust the size of the opening. With this method it is more feasible to achieve variable fused deposition system. Additionally it is possible to add channels on the nozzle to color the extruded  plastic. Special ink should be used to color the hot plastics outer surface. The ink should stay intact with the plastic even after it is cooled down and shouldn’t peel off or wash out with water. Most probably the ink used will make the surface of the plastic dull instead of shiny. However it is just a guess.

Another major change I propose, is on the plastic feeding system. The printer should use raw ABS or PLA as a granule. There will be two stage plastic feeder. First one will move raw plastic to the melting chamber. The second one will push the melted plastic from the chamber to the nozzle at a variable speed.  The trick is how to design the second stage. Most probably if it were easy it would have been implemented.
The main advantage of using granular plastic is that they are widely available and cheaper than the filament plastics used at current 3D printers. Additionally the quality of printers would be independent of the plastics shape. On the other hand filament plastics should be perfectly round and consistent in size in order to get high quality prints.

Friday, June 1, 2012

Thoughts on The Future of Personal Manufacturing Systems

Internet and smartphones are the two most popular subjects of the decade.  Web2.0 and smart phone revolutions are quite new.  Therefore people are still amazed with what they can do with them.  There is a new generation growing up with internet and smart phones.  They take these two things as granted not something new like we grownups do.  By the time this new generation grows up. They would be quite fed up with internet and smart phones. They would be looking for more…

Internet by the help of smart phones help people get whatever information they want immediately.
Internet era children will be therefore eager to get what they want.  They will not like to wait a week for internet purchase delivery. Additionally they will want to have something which is unique to them.

Next generation manufacturing systems need to keep up with the demand characteristics of the future.  Even the big industrial companies will not have the luxury of having manufacturing facilities focusing only on one product. The facilities will be small and scattered all around the world.  The supply will be there where the demand is.

Personal Manufacturing Systems and Local Manufacturing Systems will be the future of production.  My objective is to contribute on the development of these systems and I will be sharing my work on this blog.