Kuat mekanik sambungan laminasi plat baja untuk Mold Mesin Injeksi Plastik

FEBRIANTOKO, Bambang Waluyo, Ir. Alva Edy Tontowi, M.Sc.,Ph.D

2006 | Tesis | S2 Teknik Mesin

Permasalahan yang dihadapi pada industri injeksi plastik yaitu menyediakan mold yang cepat, murah dan mempunyai sistim pendinginan yang efisien. Tipe pendinginan ini dapat mendinginkan komponen cetakan yang rumit, disebut dengan pendinginan jenis conformal. Pembuatan mold jenis pendinginan conformal dapat dilakukan dengan cara laminasi plat baja. Perekatan antar layer harus kuat menahan tekanan dari cavity, maka kekuatan perekatan mold jenis ini perlu diuji kekuatannya. Perekatan antar layer dilakukan dengan dua cara yaitu metode adhesive bonding dan Brazing. Material perekat adhesive bonding digunakan epoxy merk Devcon plastic steel dengan perlakuan perendaman dalam air suhu 27oC, air suhu 60oC, plastik cair (polyethelyne) suhu 130oC dan kondisi normal tanpa perlakuan. Material perekat brazing digunakan filler Tembaga lokal (Cu 99%) serta filler paduan (Ni-Cr-Si-Fe-B & Cu-Ni-Sn-P) dari Tokai University Jepang dengan metode furnace brazing pada variasi suhu 970oC, 1000oC, 1050oC, dan 1100oC. Pengujian dilakukan dengan standart ASTM D1002 untuk uji geser, ASTM D897 untuk uji tarik dan ASTM D1062 untuk uji pembelahan pada mesin UTM servopulser. Pengamatan struktur mikro dilakukan dengan uji foto optik dan foto SEM. EDAX digunakan untuk mengetahui komposisi kimia sambungan filler dan logam induk. Hasil penelitian menunjukkan bahwa pembuatan mold dengan perekatan adhesive bonding lebih murah 75 % dan lebih sedikit proses pembuatannya dibanding perekatan brazing. Kekuatan tertinggi didapatkan pada metode brazing dengan filler tembaga pada suhu furnace 1100oC.

Nowadays, injection molding industry is facing a huge problem for providing a mold as fast as possible, less expensive and has efficient cooling system in order to provide high quality products. This system has to be able to provide cooling of part with complex shape. The current cooling system is called as a conformal system. Manufacturing of mold conformal cooling can be carried out by laminated steel tooling methods. However, the bonding between the layers of the plate must be strong enough to overcome the pressure of the cavity. The strength of the bonding between layers then needs to be investigate. In this research, two methods of layer bonding have been applied: adhesive bonding and brazing. Test which has been carried out to investigate the strength of the layer bonding were tensile, shear, and cleavage. Whilst, microstructure and chemical composition observation have been done by optic, SEM, and EDAX. The bond material used in adhesive bonding was epoxy, with Devcon Plastic Steel type. Whereas the filler used in brazing was local cooper (Cu 99%) and a kind of metal alloy (Ni-Cr-Si-Fe-B & Cu-Ni-Sn-P) which was imported from Tokay University of Japan. The specimen was soaked in different conditions: in water temperature of 27oC and 60oC, fluidized plastic temperature of 130oC, and without soaking. Furnace brazing was carried out at a variation temperature of 970oC, 1000oC, 1050oC, and 1100oC. The standard of experiment used in shear test was ASTM D1002, while ASTM D897 was used for tensile test and ASTM D1062 was used for cleavage test. The results of experiment show that the highest strength of layer bonding found in the brazing methods which use a filler of cooper, after heated in a furnace at a temperature of 1100oC. However, adhesive bonding methods is cheaper by 75% and more compact than brazing methods.

Kata Kunci : Injeksi Plastik,Mold,Laminasi Plat Baja,laminated steel tooling, rapid tooling, adhesive bonding, brazing