Injection Moulding of A Bimodal Size Distribution 316L Stainless Steel Powders

Abstract

Bagi mengurangkan kos bahan mentah untuk proses pangacuan suntikan logam (MIM), bahan teracu yang diperbuat daripada serbuk logam keluli tahan karat dengan nisbah serbuk logam kasar dan halus yang berlainan telah diselidiki. Bahan suapan tersebut disediakan dengan menggunakan sistem bahan pengikat komposit yang terdiri sebahagian besarnya polietilina glikol (PEG) yang berlainan berat molekulnya dan emulsi polimetil metakrilat (PMMA) yang seterusnya disuntik ke dalam bentuk segiempat tepat dengan suhu muncung suntikan logam pada 140°C. Hasil ujikaji menunjukkan kekuatan bahan teracu meningkat secara linear dengan peningkatan nisbah serbuk halus di dalam campuran dan optimum pada 30 wt.% dan seterusnya berlaku penurunan dengan peningkatan nisbah serbuk halus. Peningkatan serbuk logam halus di dalam campuran juga dapat meningkatkan ketumpatan akhir dan kekerasan bahan tersinter. Kadar penyingkiran polietilina glikol semasa proses pengurasan air meningkat dengan penurunan nisbah serbuk logam halus yang mana menunjukkan bahawa serbuk logam kasar memberi kesan ketara ke atas proses penyingkiran bahan pengikat. Kata kunci: pengacuan suntikan logam; polietilina glikol; polimetil metakrilat; pengurusan air; pengsinteran In an effort to lower the cost of raw materials of metal injection moulding (MIM), a moulded part made of a different ratio of coarse and fine stainless steel powder mixtures, ranging from 10 to 50 wt.% of fine powder were investigated. The feedstocks were prepared using a composite binder system which consist of a major fraction of polyethylene glycol (PEG) with different molecular weight and a minor fraction of polymethyl methacrylate (PMMA) emulsion and subsequently moulded into a rectangular shape at the nozzle temperature of 140°C. The results show that the green strength of the moulded part increased linearly with the increased of the ratio of fine powder to an optimum of 30 wt.% and decreased slightly with the increased of coarse/fine ratio. An increase in the fine powder in the mixture, improved the final densification and hardness of the sintered parts. The rate of PEGs removed during water leaching substantially increased with the lower ratio of fine powder, which suggest that the coarse powder has significant influence on the removal of the binder. Key words: metal injection moulding; polyethylene glycol; polymethyl methacrylate; water leaching; sintering