Through-thickness embossing process for fabrication of three-dimensional thermoplastic parts

The standard embossing process is limited to the fabrication of surface structures on relatively large polymer substrates. To overcome this limitation, a hybrid punching and embossing process was investigated for through-thickness embossing of three-dimensional parts. The embossing tool included a punching head and to-be-replicated features in the socket behind the punching head. The built-in punching head facilitated a through-thickness action and provided a closed-die environment for embossing pressure buildup. The method was used to emboss multichannel millimeter waveguides which requires uniform edges and accurate dimensions. With a tool temperature of 140°C, an embossing time of 3 min and a total cycle time of 7 min, discrete 4-channel waveguides were successfully embossed from a room-temperature ABS substrate. A computer model was established to study the flow behavior during through-thickness embossing. It was found that nonisothermal embossing conditions help confine the polymer in the cavity and reduce the outflow into the surrounding region, thus achieving complete fill of the cavity. POLYM. ENG. SCI., 47:2075-2084, 2007. © 2007 Society of Plastics Engineers
INTRODUCTION The standard hot embossing process is designed for imprinting surface features onto polymer substrates [1, 2]. The substrate is relatively thick as compared with the feature size. During the [...]