A growth opportunity & technical challenge exists for injection moulders to manufacture micro sized plastic parts for medical industry as m anufacturers increasingly design small devices such as hearing aids, ear canal implant devices, micro pumps, and micromanipulators. The trend toward very small devices means that features on these devices need to become even more refined. Medical device manufacturers are designing products with micro features that require tolerances in microns. Hence the micro moulding process is gaining momentum for producing plastic parts with such micro features.

Precision mold building is key to the micro moulding process. Micro scale features with high aspect ratios require advanced mould building techniques. These techniques include micro machining, micro EDM, micro stereolithography and laser ablation. LIGA - a German acronym for deep-etch lithography, electroforming and molding,- techniques are also used to manufacture molds with high aspect rations.
It is critical to have EDM and milling machines with high positioning resolutions of 0.1 µm and accuracies of 1 µm to build moulds that produce micro parts.

It is commonly assumed that as a mould gets smaller, the cost of material and labour decreases, but micro moulds do not adhere to common pricing models. The equipment and methods required to create micro features and hold micron-level tolerances typically create an inverse relationship between mould cost and part size. Also, as the equipment necessary to hold the expected tolerances is on the leading edge of technology, it is typically much more expensive. The micro moulding process requires machines with precise control over the metering and injection of the plastic melt. Injection capacity increases as the part size becomes smaller. Shot weights of less than a gram are normal in micro moulding.

To meet these requirements, machine manufacturers have recently developed machines with electric servo drives to enable the machines to produce smaller injection units for more precise process control. Downsizing of injection units to minimize the residence time or introduction of an extruder and plunger concept are also among the new developments. The minimized residence time improves quality of plastic melt quality, which is critical to the mechanical properties of the moulded part.
Tight tolerances for plastic parts with micro features require advanced measurement technology. The resolution and accuracy of the measuring equipment should be able to capture the part-to-part variation within a micron.
Statistical process control, with the help of sensor technology, should be employed to minimize inspecting quality into the part. Nano indenting and atomic force microscopy inspection techniques are being evaluated to understand the characteristics of moulded micro parts.
Investment is required in research & development to understand interrelationships that exist between the intricacies of micro sized moulding and cost effective manufacturing methods.