Hot press fabrication of hemisphere shell product made of bamboo fibers extracted with a machining center

In our research work, we are focusing on bamboo due to its advantages of fast growth, renewability, flexibility, low cost, and high specific strength and stiffness which can be frequently compared with glass fiber. We have proposed a novel hot press fabrication method of binder-free green composite products made of bamboo fibers extracted by end-milling with a machining center. Lignin could serve as a bonding material to make the bamboo fiber self-bonded itself by hot press forming to fabricate our green composite from pure 100% bamboo fiber without any binder materials because its extracted fibers are hardly damaged with a machining center. In our previous studies, we have developed a hot press forming method to fabricate two-dimensional small and simple shape products based on bamboo fiber self-bonded technology. In the present report, we propose a novel two-step hot press forming method based on two kinds of dies to fabricate three-dimensional shape products. Especially, we focus on hemisphere shell shape products because a hemispherical conical cup press forming test is frequently used to estimate the press forming performance of a kind of complex plate products. As a result, the proposed two-step concept of hot press forming is found to be effective to fabricate the three-dimensional shell shape product made of pure 100% bamboo fibers. It can be also seen that a suitable treatment between first and second step is considered important because it aids effective action due to liquid flow performance and the plastic zone of molding material.