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.
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