645 was a result of the feedback from the industrial community that had started using nylon 618 as 618 was released about 6 months earlier. The industrial community made requests for a higher strength nylon, as well as a polymer that was easier to evaluate in the final part/print. taulman3D worked with industry to develop nylon 645. Nylon 645 is a nylon 6/9, or a variant of nylon 6 and nylon 6T with a crystallinity optimization process. This provides a high degree of transparency. The transparency allows the industrial quality control groups to evaluate printed parts without destructive evaluation. They can easily look through the perimeters and make a determination as to the adhesion of inner fills.
645 is a 50% transparent white colour. It has a higher strength than 618 and is about 20% less pliable. 645 will dye with acid based dyes. Even though the polymer is less pliable, it maintains the slippery surface feature of nylons. Also as a nylon 6T variant, clumping is almost non-existent. 645 is a preffered polymer when parts to be printed will be subject to high stresses. As an extremely durable polymer, it handles stress at elevated temperatures. Depending on use, as high as 160C. 645 has the same chemical resistance as 618, but has 20% more resistance to chlorides.