Additive Manufacturing using carbon fiber sheet and thermoplastic resins
3D printing is now called as " Additive manufacturing ".
Today I would like to write about the company of Impossible Objects that is trying to do the new approach of additive manufacturing in FRP industries.
The company seems to have more than 20 years experience about the additive manufacturing. Below is the URL of it.
http://impossible-objects.com/
They use the word of CBAM, and that means;
Composite-based additive manufacturing technology
The video below is the one of the easy ways to understand what technology Impossible Objects has.
https://www.youtube.com/watch?v=6xBxierGRrE
They said the technology is the prototype stage but their concept is interesting for me.
Their approach is;
The Impossible Objects composite-based additive manufacturing process (CBAM) is the first truly new 3D printing process in more than 20 years. Conventional thermal inkjet heads are used to "print" designs on sheets of composites, like carbon fiber, Kevlar or fiberglass. Each sheet is then flooded with a polymer powder, such as nylon or PEEK, causing the powder to stick where inkjet fluid has been deposited on the sheets. Excess powder is vacuumed off and the sheets are stacked, compressed and heated. The polymer powder melts and bonds the sheets together. The uncoated fibers are then mechanically or chemically removed, and what remains is an exceptionally durable, lightweight object that was previously impossible to make so quickly and inexpensively.
(referenced from http://www.prnewswire.com/news-releases/impossible-objects-introduces-3d-printed-peek-polymer-carbon-fiber-composite-parts-300296149.html )
Impossible Objects presented the press release as below.
Impossible Objects Introduces 3D Printed PEEK Polymer Carbon Fiber Composite Parts
Addition of PEEK to revolutionary 3D printing process brings carbon fiber closer to replacing metals in manufacturing
You can see the release the site below.
They applied PEEK (polyetheretherketone ) as the matrix resin system with carbon fiber sheet to make Femoral stem implant part by 3D printing system. The composites demonstrated two-third ultimate strength but 50 % lighter than A6061-T6. PEEK is also well known the very high performance of chemical and heat resistance. The article mentioned that PEEK can be used up to 250 degree C.
If you have some knowledge or experience about the polymer materials, the content regarding heat resistance is strange. PEEK is the super engineering plastics but it is the
crystalline polymer which has about 143 degree C of glass transition temperature. If you try to apply PEEK composite material at elevated temperature condition constantly, it should not be reasonable from the design view point.
The ultimate composite in-plane shear and compression strength should be decreased up to 40 – 50 % compared with room temperature condition, even though you choose the matrix resin system of PEEK or high temperature resistance epoxy resins with more than 200 degree C glass transition temperature.
Of course the cooling temperature profile has the impact on the crystallinity, the balance of amorphous and crystalline area.
We should consider such kind of polymer character before we start the design of the products.
About what shall we need to think from the article?
Reinforced fiber configuration is unwoven
This would be one of the points we need to focus.
Unwoven material demonstrated lower mechanical and physical properties, compared with long fiber configuration. But unwoven material is more isotropic. Fiber alignment is very complex and go into the interlaminar direction as to each layer.
The matrix resin is impregnated into the isotropic fiber configuration. The condition is the ideal because;
" Load on matrix resins could be transferred and dispersed to fibers effectively"
The higher fiber volume is almost same as the harder resin impregnation but the performance above would be very attactive.
Possibility of recycling composites
Unwoven material would be the goal of the composite material recycle systems. As I have already mentioned in this column so far, the composite recycle flow should be must in the near future. It would not be matter whether the recycle could become business or not. Probably Europe would make the regulation regarding material cycle, including composite recycle. If such kind of regulation would be valid, the manufacturers and customers should think also about the recycle the composites when they make or use composites.
The Japanese company like Ai-Carbon has already started carbon fiber recycle business.
Of course, there are many ways to the composite recycle, but nonwoven materials should be the one of the possibilities.
