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"Pada pengecoran Besi Tuang Dinding Tipis terjadi fenomena unik, yaitu terbentuknya lapisan kulit. Lapisan tersebut menjadi pusat stress konsentrasi untuk terjadinya retak material. Salah satu cara untuk meminimalisir terbentuknya lapisan kulit adalah menjaga kecepatan pendinginan pada keadaan optimum. Penelitian ini dilakukan untuk mengetahui pengaruh ketebalan isolator glasswool terhadap kecepatan pendinginan dalam pembentukan lapisan kulit. Variasi modifikasi cetakan yang digunakan adalah tanpa isolator (P4M1), isolator glasswool tebal 40mm sebelah kiri benda dan 50mm sebelah kanan benda(P5M1), dan isolator ketebalan 50mm dikedua sisi benda(P7M1). Dilakukan karakterisasi metalografi non etsa dan etsa, uji mekanis berupa uji tarik, dan uji kecepatan pendinginan pada plat urutan ketiga masing-masing benda cor. Hasil menunjukkan bahwa adanya pengaruh ketebalan isolator terhadap kecepatan pendinginan benda cor. Kecepatan pendinginan tertinggi hingga terendah adalah 21,59⁰C/menit, 3,75⁰C/menit, dan 3,61⁰C/menit. Lapisan kulit ketebalan rata-rata yang didapat P7M1 324μm, P4M1 105μm dan P5M1 71μm. Jumlah nodul tertinggi hingga terendah P4M1 1121 nodul/mm2, P7M1 916 nodul/mm2, dan P5M1 801 nodul/mm2. Nodularitas yang didapat P4M1 78%, P5M1 75% dan P7M1 64%. Nilai tensile strength yang didapat dengan nilai 287MPa, 288MPa sampai 383 MPa. Matriks yang didapat adalah full ferit.

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Thin wall ductile iron has unique phenomena in manufacturing called skin effect. Skin effect becomes stress concentration to form crack initiation. One of many methods to decrease skin effect is providing optimum cooling rate. This research used the influence of glasswool isolator thickness leading to different cooling rate as variable. Variation of casting also investigated which are molding without isolator (P4M1), molding using isolator glasswool with thickness 40mm on the left side and 50mm on the left side of plate (P5M1) and the last is molding using isolator glaswool with 50mm on both of sides (P7M1). Samples were characterized using metallograpy technique (etching and non etching), mechanical testing especially tensile test and cooling rate testing.

The result shows that thickness of isolator glasswool has influences on cooling rate. The cooling rate varies from fastest to slowest which are 21,59⁰C/minutes, 3,75⁰C/minutes, and 3,61⁰C/minutes. The skin thickness is produced from the thickest to thinnest on the mold using 50mm thickness glaswool isolator, the mold without glasswool isolator and the mold using 40mm glasswool isolator on left side and 50mm glasswool isolator on the right side. High nodul counting resulted from the mold without isolator, the mold using 50mm glasswool isolator and the mold using 40mm glasswool isolator on left side and 50mm glasswool isolator on the right side. Highest nodularity was produced on the mold without isolator which is 78%, the mold using isolator glasswool 40mm and 50mm thickness produced 75% nodularity dan the mold using glasswool isolator 50mm produced 64% nodularity. Tensile test showed tensile strength alter from 287MPa, 288MPa until 383 MPa. The matrix obtains full ferritic"

"Dewasa ini, dalam menghadapi tantangan krisis energi, berbagai pengembangan teknologi dilakukan sebagai upaya penghematan energi. Salah satu sektor yang paling banyak menggunakan energi yaitu industri otomotif. Berdasarkan hal tersebut, industri otomotif dituntut untuk melakukan inovasi dalam mengatasi masalah energi ini. Teknologi pembuatan material thin wall ductile iron (TWDI) sedang dikembangkan sebagai komponen otomotif pengganti alumunium karena sifat mekanis dan biaya produksinya lebih murah serta proses pembuatannya relatif mudah. Tantangan yang dihadapi dalam proses pembuatan material TWDI yaitu terbentuknya lapisan kulit (skin effect) pada permukaan logam hasil pengecoran yang dapat menurunkan sifat mekanis. Pada penelitian ini, studi pengaruh perbedaan kadar carbon equivalent terhadap sifat mekanis dan struktur mikro, khususnya pembentukan skin effect, pada thin wall ductile iron dilakukan. Metode pengujian yang dilakukan adalah pengujian komposisi kimia, pengamatan makro, pengamatan mikro dan pengujian tarik. Pengamatan struktur mikro dilakukan secara kualitatif dan kuantitatif, dengan menggunakan software NIS Elements Image Analysis sedangkan kecepatan pendinginan dianalisis secara kualitatif. Hasil dari penelitian ini didapat bahwa dengan meningkatnya nilai carbon equivalent ketebalan lapisan kulit yang terbentuk semakin rendah sehingga sifat mekanis yang dihasilkan lebih baik. Sampel P2M1 dengan carbon equivalent 4,66% memiliki tebal lapisan kulit rata ? rata 21,01μm sedangkan P3M2 dengan carbon equivalent 4,32% memiliki tebal 37,47μm dan P4M1 dengan carbon equivalent 4,26% memiliki tebal 105,90μm. Dari karakteristik nodul, P2M1 memiliki nodularitas tertinggi sebesar 80% lalu diikuti P3M2 sebesar 76% dan P4M1 sebesar 72%. P2M1 memiliki 1405 nodul/mm2, P3M2 577 nodul/mm2 dan P4M1 1099 nodul/mm2. Kontras dengan jumlah nodul, diameter nodul P2M1 10,41μm, P3M2 14,94μm, P4M1 12,16μm. Matriks yang didapat dari pengamatan mikro struktur yaitu ferit dan karbida. Tingkat keparahan karbida dari yang rendah sampai yang tinggi yaitu P2M1, P4M1 dan P3M2. Untuk sifat mekanis, Ultimate Tensile Strength (UTS) tertinggi didapat oleh P2M1 dengan 450 MPa lalu P3M2 dengan 392 MPa dan P4M1 dengan 343 Mpa. Sedangkan untuk elongasi, P4M1 3,25%, P2M1 3% dan P3M2 1,5%.

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Nowadays, in challenging the energy crisis issue, an array of advance technology is being developed in order to tackel this problem. The sector spending most energy is automotive industry. Regarding the fact, this industry is forced to solve this problem by inventing new sophisticated material which can reduce the consumption of energy. The process of thin wall ductile iron (TWDI) making is being developed in order to replace the utilization of alumunium. TWDI has better efficiency compared to alumunium, both on mechanical properties and cost production. The obstacle confronted in TWDI is the formation of skin effect on the surface of casting product. This phenomena can lead to the decrease of mechanical properties.

In this research, the effect of different carbon equivalent addition on mechanical properties, microstructure, particularly on skin formation, is conducted. The testing methods perfomed are chemical composition, visual observation, microstructure observation and tensile testing. While, Microstructure observation is carried out qualitatively and quantitatively, Cooling rate analysis is carried out qualitatively. NIS Elements Image Analysis is used to analysis microstructure.

In this research, it is acquired that as the carbon equivalent increases, the thickness of skin decreases, as a result, the mechanical properties improve. P2M1, with carbon equivalent 4,66%, has the biggest skin thickness at 21,01μm. P3M2, with carbon equivalent 4,32%, has the skin thickness at 37,47μm. P4M1, with carbon equivalent 4,26%, has the smallest skin thickness at 105,90μm. For nodule characteristics, P2M1 has the nodularity as high as 80% and then followed by P3M2 with 76% and P4M1 with 72%. While, P2M1 has 1405 nodule/mm2, P3M2 and P4M1 has 577 and 1099 nodul/mm2, respectively. In contrast with nodule count, P3M2 has the biggest nodule diameter with 14,94μm, the next is P4M1 with 12,16μm and then P2M1 with 10,41μm. Ferrite and Carbide is found in the matrix. The severity level of carbide, from the lowest to the highest, is P2M1, P4M1 and P3M2. From mechanical aspects, the highest Ultimate Tensile Strength (UTS) is obtained by P2M1 with 450 Mpa, then followed by P3M2 with 392 MPa and P4M1 with 343 Mpa. Where as, for the elongation, P4M1 is 3,25%, P2M1 is 3% and P3M2 is 1,5%."

"Penggunaan energi yang tidak terbarukan seperti minyak bumi dan batu bara secara perlahan telah membawa dunia ini ke dalam krisis energi, sehingga diperlukan upaya penghematan energi. Isu dunia mengenai penghematan energi tersebut sangat berkaitan erat dengan industri otomotif. Industri otomotif dituntut untuk menghasilkan produk dengan emisi kendaraan yang rendah dan kendaraan yang hemat bahan bakar. Material TWDI (thin wall ductile iron) yang dapat dilakukan pemrosesan lanjut menjadi TWADI (thin wall austempered ductile iron) menjadi kandidat yang paling menarik karena sifat mekanisnya yang baik serta biaya yang lebih murah jika dibandingkan dengan aluminium. Tantangan yang dihadapi pada proses pembuatan material TWDI saat ini yaitu kecenderungan terbentuknya lapisan kulit (skin effect) pada permukaan logam hasil pengecoran yang dapat menurunkan sifat mekanis.Penelitian ini dilakukan untuk mendapatkan pengaruh penggunaan isolator berupa glasswool, kayu, dan rockwool dengan ketebalan 40 mm terhadap kecepatan pendinginan. Pengujian yang dilakukan adalah pengujian komposisi kimia, pengamatan makro, pengamatan struktur mikro, dan pengujian tarik. Pengamatan struktur mikro dilakukan secara kualitatif dan kuantitatif, dengan bantuan program image analysis. Sedangkan analisis kecepatan pendinginan didapatkan secara kualitatif.Hasil dari penelitian ini diketahui bahwa kecepatan pendinginan merupakan fungsi dari jumlah nodul, karbida, nodularitas, dan diameter rata-rata nodul. Kecepatan pendinginan tercepat hingga terlambat yaitu pada penggunaan isolator rockwool (P9M1), kayu (P8M1), dan glasswool (P6M1). Untuk ketebalan lapisan kulit rata-rata terbesar hingga terkecil yaitu P8M1 32,58 μm, P9M1 25,59 μm, dan P6M1 25,45 μm. Dari karakteristik nodul, P8M1 memiliki nodularitas tertinggi sebesar 81% lalu diikuti P6M1 sebesar 79% dan P9M1 sebesar 76%. P6M1 memiliki 1605 nodul/mm2, P9M1 1274 nodul/mm2 dan P8M1 1141 nodul/mm2. Sedangkan, diameter nodul P6M1 10,20 μm, P8M1 9,71 μm, dan P9M1 9,09 μm. Matriks yang didapatkan adalah ferit dan karbida dengan tingkat keparahan karbida tertinggi hingga terendah yaitu P9M1, P8M1, dan P6M1. Nilai kekuatan tarik P6M1 367 MPa, P9M1 329 MPa, dan P8M1 146 MPa. Sedangkan elongasi P6M1 2%, P9M1 1,1%, dan P8M1 1%. Sifat mekanis yang didapatkan masih berada di bawah nilai standar.

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Nowadays, the use of unsustainable energy such as petroleum and coal subsequently has brought us to the energy crisis. So that the effort of saving energy is crucial. World issues regarding energy savings is very closely related to the automotive industry. The automotive industry is required to produce products with lower emissions and fuel-efficient vehicles. TWDI (thin wall ductile iron) which can be processed to TWADI (thin wall austemperd ductile iron) became the best candidate due to good mechanical properties and lower cost comparing to aluminum. The challenge confronted in the process of TWDI making is the tendency of skin formation on the surface of the metal casting reduced its mechanical properties.

This research is conducted to obtain the effect of insulators utilization such as glasswool, wood, and rockwool with the thickness of 40 mm towards the cooling rate. Methods performed are chemical composition, visual observation, microstructure observation, and tensile testing. While, microstructure observation is conducted qualitatively and quantitatively using image analysis program, the analysis of the cooling rate is obtained qualitatively.

The cooling rate, from the fastest to the slowest, is rockwool (P9M1), wood (P8M1), and glasswool (P6M1). Where as, for the average skin thickness, from the biggest to the smallest, is P8M1 32.58 μm, P9M1 25.59 μm, and P6M1 25.45 μm. For nodule characteristics, P8M1 has the 81% nodularity and then followed by P6M1 with 79% and P9M1 with 76%. While, P6M1 has 1605 nodule/mm2, P9M1 and P8M1 has 1274 and 1141 nodul/mm2, respectively. While, the biggest nodule diameter is P6M1 with 10.20 μm, the next is P8M1 with 9.71 μm and then P9M1 with 9.09 μm. Ferrite and carbide is found in the matrix. The severity level of carbide, from the highest to the lowest, is P9M1, P8M1 and P6M1. From mechanical aspects, the highest ultimate tensile strength is obtained by P6M1 with 367 MPa, then followed by P9M1 with 329 MPa and P8M1 with 146 MPa. Where as, for the elongation, P6M1 is 2%, P9M1 is 1.1% and P8M1 is 1%. The mechanical properties obtained don't fulfill the standardfollowed by P6M1 with 79 and P9M1 with 76 While P6M1 has 1605 nodule mm2 P9M1 and P8M1 has 1274 and 1141 nodul mm2 respectively While the biggest nodule diameter is P6M1 with 10 20 m the next is P8M1 with 9 71 m and then P9M1 with 9 09 m Ferrite and carbide is found in the matrix The severity level of carbide from the highest to the lowest is P9M1 P8M1 and P6M1 From mechanical aspects the highest ultimate tensile strength is obtained by P6M1 with 367 MPa then followed by P9M1 with 329 MPa and P8M1 with 146 MPa Where as for the elongation P6M1 is 2 P9M1 is 1 1 and P8M1 is 1 The mechanical properties obtained don rsquo t fulfill the standard."

"Besi Cor Nodular Berdinding tipis (TWDI Thin Walled Ductile Iron) dengan ketebalan 1mm dengan desain vertikal telah banyak dikaji. Namun dengan yield yang masih kecil menjadikan desain dengan mempertimbangkan kenaikan yield, merupakan area yang luas untuk di teliti. Penelitian ini dilaksanakan dengan maksud menaikan yield melalui desain penambah antar pelat spesimen TWDI yang lebih kecil, serta mengkaji pengaruh dari inokulan terhadap desain yang telah diperbarui.Model pengecoran dan desain masih mengikuti sistem yang telah dilaksanakan yaitu bottom fill oleh Stefanescu dan untuk ketebalan 1mm di paparkan oleh Sudarsono & R Ariobimo, dengan riser yang diperkecil mengikuti perbandingan modul (Wlodawer) serta sampel pelat yang terdiri 3 susun.Proses perancangan ulang dibantu dengan program simulasi pengecoran untuk mendapatkan hasil dengan parameter yang berbeda. Pengujian hasil rancangan dilaksanakan dengan menggunakan cairan logam grade FCD 500 dengan variasi pada persentase inokulan dan temperatur penuangan. Sampel pelat kemudian diuji struktur mikro, kekerasan dan pengujian tarik dengan standar spesimen JIS Z 2201 no5.Hasil pengujian menunjukan bahwa masa tuangan diameter yang sudah diperkecil menjadi 10mm berbanding dengan tuangan RD Ariobimo menghasilkan kenaikan yield dimana rancangan sebelumnya masih memiliki yield 5.3 menjadi 28.6%. Hasil pengujian metalografi menunjukan mikrostruktur dengan komposisi perlit yang tinggi mencapai 90% dan hampir semua sampel didominasi oleh struktur perlit. Rata ? rata hasil pengujian tarik ada pada kisaran 600 MPa yang juga dipengaruhi oleh faktor strukturmikronya. Terdapat komposisi ferit yang lebih dari 50% pada kondisi temperatur tuang 1365°C dengan laju pendinginan sekitar 4°C/detik. Dengan penambahan inokulan mempengaruhi jumlah nodul dari pelat juga meningkatkan kekerasan dan mengurangi fasa karbida pada TWDI

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TWDI 1mm thickness with a vertical design has been widely studied. However, the yield is still in low value wich makes the possibility taking into redisign to increase the yield, a large area to be investigate. This research was carried out with the intention to raise the yield by reducing inter-plate design TWDI into smaller riser diameter, as well as the effect of inoculant to the design that has been updated.Foundry models and designs still follow the system that have been implemented are bottom fill by Stefanescu and for 1mm thickness in by J Sudarsono & R Ariobimo, with riser which reduced follow a comparison module (Wlodawer) and the sample plate comprising three parts.Redesign process assisted with casting simulation program to get results with different parameters. Testing the design is implemented using liquid metal grade FCD 500 with variations on the percentage of inoculants and pouring temperatures. Plate samples were then tested microstructure, hardness and tensile test specimens with JIS Z 2201 standard no.5.Mass of casting that has been reduced to a diameter of 10 mm, there is an increase yield where the previous design was 5.3% into 28.6%. Metallographic test results showed pearlite microstructure with a high composition reaches 90% and almost all samples are dominated by the pearlitic structure. Average tensile test results exist in the range of 600 MPa are also influenced by microstructure. There is a ferrite composition which more than 50% on the condition of 1365 °C temperature castings with a cooling rate of about 4 °C/sec. Effect of amount inoculants is increasing the nodule count, increasing hardness and reduced carbide formation."

"Pemakaian peredam panas dan bahan pelapis pada cetakan pasir resin adalah sebagian cara untuk mengendalikan terbentuknya lapisan kulit skin effect pada permukaan produk coran besi tuang nodular dinding tipis atau TWDI Thin Walled Ductile Iron . Peredam panas glasswool dan bahan pelapis MgO, Grafit dan Zr yang memiliki sifat penghantar panas yang berbeda-beda akan berpengaruh terhadap lapisan kulit skin effect yang terbentuk. Penelitian pengecoran TWDI yang menggunakan peredam panas glasswool dan bahan pelapis coating MgO dan Grafit dengan CE= 4.29 secara berurutan menghasilkan jumlah nodul 647 nodul/mm2 dan 452 nodul/mm2, persentase nodularitas 79 dan 76 , dan lapisan kulit 52,27 m dan 87,75 m. Sedangkan pada CE= 4.58 , pemakaian glasswool dan bahan pelapis Zr, Zr-Grafit dan MgO-Grafit memperlihatkan jumlah nodul 679 nodul/mm2, 978 nodul/mm2 dan 702 nodul/mm2, persentase nodularitas 83 , 80 dan 80 , dan lapisan kulit 80,94 m, 54,58 m dan 70,38 m.

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Application of isolator and coating in resin sand casting are some of skin effect controlling in TWDI Thin Walled Ductile Iron production. Glasswool isolator dan MgO, Graphite dan Zr coating with different heat conductivity will affected the formation skin effect. The present study of TWDI casting using glasswool isolator, MgO and Graphite coating with CE 4.29 has produced graphite nodule amount of 647 nodule mm2 and 452 nodule mm2, nodularity percentage 79 and 76 , and 2.83 and skin effect 52,27 m and 87,75 m respectively. In other side with CE 4.58 , the application of glasswool and coating of Zr, Zr Graphite and MgO Graphite show nodule amount of 679 nodule mm2, 978 nodule mm2 and 702 nodul mm2, nodularity percentage 83 , 80 and 80 , and skin effect 80,94 m, 54,58 m and 70,38 m."

"Kebutuhan penghematan energi dunia menuntut untuk melakukan peminimalisasian energi tak terlepas di bidang pengecoran. Penggunaan TWADI (Thin Wall Austempered Ductile Iron) yang didapatkan dari heat treatment TWDI (Thin Wall Ductile Iron) menjadi kandidat yang paling menarik karena ketangguhannya yang sangat tinggi serta biaya lebih murah dan tentunya lebih hemat energi dibandingkan aluminium. Dalam Pemrosesan TWDI menemui masalah yaitu perubahan grafit nodul menjadi flakes atau yang dikenal sebagai skin effect dimana skin akan menurunkan sifat mekanis dari TWDI. Penelitian ini mempelajari pengaruh penambahan kadar nodulizer terhadap terbentuknya skin serta pengaruhnya terhadap sifat mekanis. Skin yang didapat pada penambahan 1,1 % nodulizer dengan tebal 40 µm lebih tipis dibandingkan 1 % nodulizer yang memiliki tebal skin 45 µm. Nilai UTS yang didapat oleh penambahan 1,1% nodulizer yaitu 416,5 MPa, lebih tinggi dibandingkan 1 % nodulizer sebesar 387,54 MPa, dimana hal tersebut sejalan dengan nodularitas yang lebih tinggi dengan penambahan 1,1 % nodulizer. Nilai elongasi kedua sampel tidak mencapai 10 % yang dikarenakan terbentuknya kolumnar karbida yang terbentuk dari berlebihnya kadar mangan pada kedua sampel.

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Recent world energy condition obligates people to reduce quantity of energy useement especially ini casting process. Uses of Thin Wall Austempered Ductile Iron (TWADI), which is a heat treatment material from Thin Wall Ductile Iron (TWDI) , become a best candidate to replace aluminium in industry due to the fact of its high quality toughness and another mechanical properties, with low producing cost and also low energy production. One of the most issue that have been met in processing TWDI is a phenomenon that nodular graphites turn into flakes shape which will decrease large amount of mechanical properties.

This research is studying about the enhacement of content nodulizer for reducing skin thickness and also to increase mechanical properties. The addition of 1,1 % nodulizer that obtained shown an effective result with reducing 11 % thickness of skin compared to the thickness of addition 1 % nodulizer. The thickness of skin with addition 1,1% nodulizer is 40 µm, while with addition 1 % nodulizer is 45 µm. The UTS number that has been reached by 1,1 % nodulizer is 416,5 % MPa, which is bigger than the UTS of 1 % nodulizer in the amount of 387,54 MPa which also as a result of grater nodularity of 1,1 % nodulizer. The elongation of both sample have elongation below 10 %, as result of carbides that have been formed in the microstructure, because of excessive number of manganese."

"In producing Thin Wall Ductile Iron (TWDI) plate, special notice should be taken on the skin effect formation. Skin effect is a rim of flake interdendritic graphite formed in the surface. In a normal ductile iron casting, skin effect can be removed with machining process. Unfortunately this procedure cannot be applied in TWDI due to the thickness. This paper discusses the effect of casting design to the skin effect formation. Vertical casting design is used in this work. Variations are made in the thicknesses of the plate. The T1 model is equipped with 5 plates with thicknesses of 1, 2, 3, 4, and 5 millimeters; while the T1-Mod is equipped also with 5 plates, but with the same thickness, which is 1 mm. Skin thicknesses, nodule count, and nodularity are measured by NIS Element software. The result showed that skin effect formation is determined by magnesium content and cooling rate. Skin effect thicknesses are determined by cooling rate and the interaction area of molten metal with the mould. The presence of the skin effect in similar thickness and position of plate improved nodule count. In the same thickness, without the presence of the skin effect, the nodule count tends to increase as the positions of the plates increase. In the design ranging from 1 to 5 mm plate thickness, the highest nodule count is 1284 nodule/mm2 gained by 1 mm plate thickness in 1st position and the lowest one is 512 nodule/mm2 gained by 5 mm plate thickness in 5th position. As for the design of all 1 mm thickness where skin effect is not formed the highest nodule count is 1689 nodule/mm2 gained by 1 mm plate thickness in the 5th position and the lowest is 1113 nodule/mm2 gained by 1 mm plate thickness in the 1st position (near the in gate). The highest nodule count is 90 and the smallest is 85."