Sains Malaysiana 42(12)(2013): 1787–1791

 

Thermoplastic Natural Rubber (TPNR) As a Backbone Polymer for Metal Injection Molding

( Getah Asli Termoplastik(TPNR) Sebagai Polimer Asas Untuk Pengacuanan Suntikan Logam)

 

NORITA HASSAN¹²*, SAHRIM AHMAD¹,NORHAMIDI MUHAMAD³, MOHD AFIAN OMAR⁴& NOOR AZLINA HASSAN²

 

¹School of Applied Physic, Faculty of Science & Technology, Universiti Kebangsaan Malaysia

43600 Bangi, Selangor, Malaysia

 

²Department of Manufacturing and Materials Engineering, Faculty of Engineering

International Islamic University Malaysia, P.O.Box 10, 50728 Kuala Lumpur, Malaysia

 

³Department of Mechanical and Material Engineering, Faculty of Engineering

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

 

⁴Advance Material Research Centre (AMREC), SIRIM Berhad, Lot 34, Jalan Hi-Tech 2/3,

Kulim Hi-Tech Park, 09000 Kulim, Kedah, Malaysia

 

Received: 23 March 2012/Accepted: 28 May 2012

 

ABSTRACT

 

Moldability of metal injection molding (MIM) is dependent on the outward appearance of the resultant feedstock. Properties of the binders used will influence the properties of the feedstock. Stainless steel powder 316L with mean size 22 μm and the binder system consists of three major fractions of paraffin wax, thermoplastic natural rubber and stearic acid with a powder loading of 65 vol. % was investigated. Comparison was also made with existing palm stearin in the binder system replacing the paraffin wax. Kinetic solvent extractions were done to determine the differences between the binder systems. The feedstock was then injected into tensile bar using vertical injection machine. The results showed that there is a slightly time extension during the solvent extraction as a comparison. The feedstock has been successfully injection molded at 190-200°C. Study of thermal analysis such as DSC and TGA has been done as a preparation for the thermal debinding and sintering process. This study demonstrated that a backbone polymer; thermoplastic natural rubber performs best in term of flow stability and compact quality and also saves in processing time.

 

Keywords: Backbone polymer; metal injection molding (MIM); thermal analysis; thermoplastic natural rubber

 

ABSTRAK

Kebolehan pengacuan suntikan logam (MIM) amat bergantung kepada sifat bahan suapan yang dihasilkan. Sifat bahan pengikat yang digunakan akan mempengaruhi sifat bahan suapan. Serbuk keluli tahan karat 316L dengan purata saiz 22 μm dan sistem bahan pengikat yang terdiri daripada tiga bahagian utama iaitu lilin parafin, getah asli termoplastik dan stearik asid dengan bebanan serbuk logam 65% telah pun dikaji. Pembandingan turut dilakukan dengan kehadiran stearin sawit dalam sistem bahan pengikat menggantikan lilin parafin. Pengekstrakan kinetik larutan dilakukan untuk menentukan perbezaan antara sistem-sistem bahan pengikat tersebut. Bahan suapan kemudian disuntik kepada bentuk bar regangan menggunakan mesin suntikan tegak. Keputusan menunjukkan terdapat perbezaan masa semasa pengekstrakan larutan dilakukan sebagai satu perbandingan. Bahan suapan telah berjaya disuntik pada 190-200°C. Analisis terma iaitu DSC dan TGA telah dilakukan sebagai persediaan untuk penyahikatan terma dan proses pensinteran. Kajian ini telah membuktikan bahawa bahan pengikat iaitu asas (tulang belakang) getah asli termoplastik menunjukkan potensi yang baik daripada segi kestabilan aliran dan kualiti padatan dan menjimatkan masa pemprosesan.

 

Kata kunci: Analisis terma; getah asli termoplastik ; pengacuan suntikan logam (MIM); polimer asas

 

 

REFERENCES

 

Fan, Y-L., Hwang, K-S., Wu, S-H. & Liau, Y-C. 2009. Minimum amount of binder removal required during solvent debinding of powder-injection-molded compacts. Metallurgical and Materials Transactions A 40(4): 768-779.

German, R.M. & Bose, A.1997. Injection Molding of Metals and Ceramics. New Jersey, USA: Metal Powder Industries Federation, Princeton.

Huang, M-S. & Hsu, H-C. 2009. Effect of backbone polymer on properties of 316L stainless steel MIM compact. Journal of Materials Processing Technology 209(15-16): 5527-5535.

Kryachek, V.M. 2004. Injection moulding (Review). Powder Metallurgy and Metal Ceramics 43(7): 336-348.

Li, Y., Li, L. & Khalil, K.A. 2007. Effect of powder loading on metal injection molding stainless steels. Journal of Materials Processing Technology 183(2-3): 432-439.

 

 

*Corresponding author; email: norita.hassan08@gmail.com