There is no clear line between conventional injection molding and micro injection molding.
However, it is common to use the therm micro injection molding when parts being produced starting from 0,001g ( 1 Microgram) up to 0,4g per cavity.
The dimensions of the parts ranging mostly between a few millimeter and one micrometer.
The demand on the part precision is very high.
If cold runner molds are used for micro injection molding the shot weight is defined up to 97% by the cold runner itself.
From the production side machines with screw diameters down to 12mm are available as well as machines using a piston in order to inject the melt.
Cycle times in micro injection molding are obviously very short.