A Mold Surface Treatment for Improving Surface Finish of Injection Molded Microcellular Parts

Abstract

Micro-cellular foaming technology draws attention due to the enhancement of mechanical strength, which has been considered as a weak point of current plastic foaming technology. Foam materials produced by this technology offer improved consistency and homogeneity of cell structure, which can result in products with superior properties and uniformity⁽¹⁾. Thus it is widely used for commercial purposes and its market is now growing significantly. However, since the foamed injection parts have swirl marks on its surface, this technology has limited uses such as interior products, in spite of its diverse merits. In this paper, we propose surface treatment of the mold as a way to remove the swirl mark. We injected simple shape specimens with PP and PC/ABS materials and measured the surface quality values such as roughness and gloss. Also we researched the foaming characteristics of both treated and untreated surface using SEM analysis.

Get full access to this article

View all access options for this article.

References

Kelvin

T. Okamoto

2003, “Microcellular Processing,” Hanser Gardner Publications, Inc. Cincinnati.

Martini

J.E.

, Waldman

F.A.

, and Suh

N.P.

1982, “The Production and Analysis of Microcellular Thermoplastic Foam,” Society of Plastic Engineers Technical Papers, Vol. 28, pp. 674–676.

Waldman

F.A.

1982, “The Processing of Microcellular Foam,” S.M. Thesis, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA.

Kumar

, and Vander Wel

M.M.

1991, “Microcellular Polycarbonate – Part II: Characterization of Tensile Modulus,” Society of Plastics Engineers Technical Papers, Vol. 39, pp. 1401–1405.

Weller

J.E.

, and Kumar

1992, “Application of Effective Medium Theories for Predicting the Tensile Modulus of Microcellular Foams,” Cellular Polymers, MD-Vol. 38, ASME, pp. 55–67.

Collias

D.I.

, and Baird

D.G.

1992, “Does a Microcellular Structure Improve the Modulus of Toughness of a Polymer Matrix?” Society of Plastics Engineers Technical Papers, Vol. 38, pp. 1532–1535.

Seeler

K.A.

, and Kumar

1992, “Fatigue of Notched Microcellular Polycarbonate: Initial Results,” Cellular Polymers, MD-Vol. 38, ASME, pp. 93–108.

Shimbo

, Baldwin

D.F.

, and Suh

N.P.

“Viscoelastic Studies of Microcellular Plastics,” Polymeric Materials Science and Engineering, Vol. 67, Proceedings of the ACS Conference, August, pp. 512–513.

Park

C.B.

, and Suh

N.P.

1992, “Extrusion of Microcellular Filament: A case of Axiomatic Design,” Cellular Polymers, MD-Vol. 38, ASME, pp. 69–91.

10.

http://www.trexel.com

11.

Kim

D.H.

, Kang

M.H.

, Chun

Y.H.

“Development of a Notebook PC Housing by Using MMSH Process,” ANTEC2001, pp3353-3356.

12.

http://www.akchem.com/emt/EG00511.html

13.

Doi

2001, “Introduction to polymer physics,” Clarendon press, Oxford.

14.

Satoshi

Abe

, Yasuhiko

Murata

, Hidetoshi

Yokoi

2003, “Measurement of Melt Temperature Distribution along the Cavity Thickness Direction by Using Integrated Thermocouple Sensor,” SEIKEI-KAKOU Vol. 12 No. 2, pp. 140–147

15.

Kennedy

Peter

1995, “Flow analysis of Injection Molds,” Hanser Gardner Publications, Inc. Cincinnati.