**4. Conclusions**

This work took a talc-filled PP and used low gas dosing in a microcellular injection moulding setup. The initial research performed was a design of experiments with 5 varying input processing parameters: mould temperature, injection speed, back-pressure, melt temperature and holding time. The physically foamed parts with the best surface finishes from this research were compared to similarly manufactured parts through a chemical foaming agent. The major findings from this research are:


**Author Contributions:** Conceptualisation, G.L., M.J. and C.G.; Formal analysis, G.L.; Investigation, G.L.; Supervision, A.R.; Writing—original draft, G.L.; Writing—review and editing, A.R., C.G. and M.J. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was part funded by the EU's European Funding Office and the Engineering and Physical Sciences Research Council (EPRSC) and the Welsh European Funding Office (WEFO).

**Acknowledgments:** The authors would like to acknowledge the financial support of the Materials and Manufacturing Academy (M2A) and the access of AIM facilities at the College of Engineering.

**Conflicts of Interest:** The authors declare no conflict of interest.
