The microcellular injection moulding process utilizes physical blowing agents – mainly N2 or CO2. These gases are used as supercritical fluid to produce microcells. There are a lot of challenges in working with microcellular injection moulding process because of the dynamic nature of the procedure. Most of the time it becomes difficult to get the desired cell morphology (i.e. high cell density and small average cell size) and often large and non-uniform cell size results due to the lack of control on the process