Finite element analysis (FEA) was conducted to investigate the cutting process of a single-layer PET film during rotary die cutting. In a roll-to-roll system, cutting blades formed on rollers were modeled as rigid bodies, while the PET film was modeled as an elastoplastic material using a two-dimensional approach. Stress-strain behavior of the film was measured through experimental tensile testing and used as input data for FEA. Force-displacement data from vertical cutting experiments of PET film were collected to validate the FE model and compared with simulation results. Stress distribution of the film and cutting force per unit thickness during the rotary cutting process were analyzed. The cutting force and range of effective cutting angles were proportional to tip angle of the blade within a range of 25 to 60 degrees, showing a noticeable change in proportionality slope at a tip angle of 40 degrees. As the film tension increased, the cutting force in thickness direction decreased, while that in longitudinal direction remained almost constant. Errors in film feed velocity significantly affected the cutting force. When the film moved slightly slower than the reference velocity, the cutting force was minimized due to reduced contact between the film and blade surface.

Fabrication of a durable and strong nanopatterned mold insert using metal sheet and plate is important for molding of thermoplastic materials. Conventionally, the nickel stamper replicating a master pattern by electroforming process has been used for injection molding of nanotextured products such as Blu-ray media. However, a more facile and cheaper mold fabrication process is highly required for manufacturing of functional products based on nanostructured surface. In this study, zirconia nanoparticles were blended with UV curing polymer to fabricate a polymer nanocompositebased nanopattern mold. Compared to the cured pure Ormostamp, the modulus of elasticity of the nanocomposite filled with approximately 54 vol% of zirconia nanoparticles increased by 160 times. Additionally, the modulus of elasticity reached 197 ㎬ by thermal decomposition of the UV-Cured polymer and post-annealing at 800°C of the nanoparticle layer. The nanopatterns were formed on stainless steel sheet and block, and applied to hot embossing of the PMMA films and injection molding of the COC materials, respectively. No deterioration of the mold occurred during the hot embossing 30 times and the injection molding 600 shots. Nanoparticle-enhanced UV curing nanocomposites or post-heat treatment methods are cost-efficient and easy, because many molds can be manufactured from one master pattern.

As a deterministic finishing process for the optical parts having complex surface, machining performance of the magnetorheological(MR) fluid jet polishing of optical glass are studied and compared with a general water jet polishing. First, design of the jet polishing system which has the special electromagnet-nozzle unit for stabilizing the slurry jet based on MR fluid and the change of jet shape as magnetic field is applied are explained. Second, for the BK7 glass, machining spot and its cross section profile are analyzed and the unique effect of MR fluid jet polishing is shown. Third, both material removal depth and surface roughness are explored in order to investigate the polishing performance of MR fluid jet. With the same ceria abrasives and amount in the polishing slurries, MR fluid jet shows superior machining performance compared to water jet and the difference of material removal mechanism and its resulting performance are described.