Meaning
Specialized tooling assemblies featuring micrometer channels define the flow geometry for lab on a chip devices and biomedical cartridges. A micro fluidic mould integrates ultra precise channel cores with rigid support plates to replicate narrow fluid channels in polymers such as cyclic olefin copolymer. The tool governs dimensional tolerances, channel surface finish and bonding interface flatness required for microfluidic device performance.
The scope of this tooling design applies strictly to high precision micro channel replication, excluding conventional structural moulding practices.
Channel Geometry
Microscopic channels demanding submicron depth tolerances require specialized steel inserts produced via photo etching or high speed micro milling. Thermal expansion discrepancies between mould components alter channel dimensions during hot runner heating cycles. Cavity layout must account for extreme aspect ratios to prevent channel collapse or flash formation during resin injection.
High flow amorphous polymers like polycarbonate or poly-methyl methacrylate fill micro channels under elevated injection velocities. Precise venting along channel terminations prevents air entrapment and incomplete filling of micro features. Tooling alignment pins must maintain micron level registry across mould halves to ensure mating channel alignment during device assembly.
Viscous Resistance
High shear rates generated inside submillimeter channels dramatically increase melt viscosity resistance during cavity filling. Polymer cooling rates accelerate rapidly in narrow channels, requiring high mould temperatures to prevent premature freezing. Process engineers utilize variotherm mould temperature control to maintain resin fluidity during filling before rapid cooling.
Tool Deflection
Injection pressures exceeding one thousand bar cause microscopic tool deflection along parting lines. Cavity plate breathing creates micro flash along channel edges, disrupting fluid flow in final diagnostic chips. Rigid mould base designs with clamped backing plates maintain channel cross section integrity throughout production runs.
