High-performance polymers are viewed as key materials of the future. They are well-suited for numerous applications including aviation and medical because of a combination of properties such as flame retardance, light weight, high tensile strength, and biocompatibility. One of the first materials from this group is the EOS PEEK HP3. It belongs to the group known as polyaryletherketones. EOS developed the EOSINT P 800 high-temperature system for laser-sintering these polymers. The new system was introduced at EuroMold 2008.
Apart from aggressive acids, PEEK is resistant to other chemicals. In applications such as aerospace – where lightness and flame retardance are important – PEEK has developed into a popular alternative to metals. In medical applications, properties such as biocompatibility, sterilisability, high tensile strength and conductivity make this material an ideal substitute for stainless steel and titanium. PEEK is considered to be one of the highest performing thermoplastic polymers and as such is seen as a promising material for the future.
“Laser-sintering is ideally suited for complex applications that are often based on high-performance polymers” says Dr. Hans Langer, founder and CEO of EOS. “However, the development of such a system initially was considered to be hardly feasible in technical terms due to the high temperatures involved.”
Until now, these polymers could not be used in the laser-sintering process due to their melting point, which is between 220° C (428° F) and 380° C (716° F). The EOSINT P 800, however, includes redesigned components, such as the processing chamber and a removable frame to handle high-temperature processes.
The machine converts the raw PEEK HP3 polymer into a powder. Laser-sintered products reach a tensile strength up to 95 MPa and a Young’s Modulus of 4,400 MPa. These values are up to 100% higher than for the materials PA12 and PA11 that currently dominate the market. The continuous operating temperature is – depending on individual cases – between 260° C/500° F (electrical), 240° C/464° F (mechanical static) and 180° C/356° F degrees (mechanical dynamic).
Within the laser sintering system, the high melting temperature presented challenges in long-term stability, thermal expansion, and temperature distribution. One change EOS engineers made was the patented deployment of glass ceramics for the removable frame. The new machine design not only fulfills the process requirements of temperature distribution but also the mechanical accuracy requirements, taking into account the thermal expansion.
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