The use of variotherm systems for microinjection molding

Abstract

Microinjection molding (lIM) is a fast-developing technology which is used to produce polymeric microcomponents or components with micro/nanoscale features, such as are used in many fields including microfluidic diagnostics, microneedle drug delivery devices, microgears, and microswitches. The capabilities and performance of the microinjection molding process can be improved by incorporating a variotherm system. This leads to improved component quality, especially for high aspect ratio features. It can also help to increase the polymer flow path, improve feature replication, reduce residual stresses and molecular orientations, and also can eliminate weld lines. This article reviews the use of different variotherm systems in lIM, and describes how simulation of its use can provide insight when designing a mold cavity or a component with challenging microfeatures. The article highlights important problems, challenges and areas for further research. An increased understanding of these issues will provide opportunities to enhance further developments in the lIM process.

Micro-nanostructured polymer surfaces using injection molding: A review

“…The variotherm process employs numerous heating methods including heating by various types of heat transfer phenomena e.g. convection, radiation, conduction, and induction 92 .…”

“…The advantages of using this system include improving component quality, processing control and feature replication, increasing the polymer flow path and fluidity of the polymer, decreasing residual stresses, molecular orientation and flow resistance, and eliminating the formation of weld lines, short shots and material degradation 57,[92][93][94] .…”

Sequencing Metrics of Human Genomes Extracted from Single Cancer Cells Individually Isolated in a Valveless Microfluidic Device

“…It also creates for each hole, a female LUER connector on the side opposite the microfluidics side. The temperature of the mould is regulated such that injection moulding is performed using a variotherm process (26) allowing the polymer part to be moulded and removed from the mould at different temperatures. The shim is replicated using a mould temperature of 115 • C, a shim temperature of 155 • C, a holding pressure of 1150 bar and a cooling time of 14 seconds so the demoulding temperature is below 126…”

Numerical and experimental investigations on polymer melt flow phenomenon in a vario‐thermal mold cavity

“…Elevating the cavity temperature in melt filling process is one of the most efficient methods to eliminate these defects . The elevated mold temperature is essential to improve the capability and performance of the microinjection molding process . Moreover, the heated mold cavity should be cooled down rapidly to the ejection temperature in order to solidify the injected polymer melt.…”