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Menentukan Regime Pelumasan Pada Ball Bearing Dengan Menggunakan Kurva Stribeck Dedison Gasni; Syahrul Rahmat
Jurnal Mettek: Jurnal Ilmiah Nasional dalam Bidang Ilmu Teknik Mesin Vol 3 No 1 (2017)
Publisher : Program Studi Magister Teknik Mesin Universitas Udayana

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Gesekan yang terjadi pada ball bearing akan menimbulkan keausan yang akan mengakibatkan umur pakai dari ball bearing akan berkurang. Gesekan dapat diminimalisir dengan cara memberi pelumas, untuk menentukan regime pelumasan pada ball bearing sebagai acuan dapat digunakan kurva Stribeck. Untuk mendapatkan kurva Stribeck dari sebuah ball bearing, diperlukan nilai koefisien gesek pada setiap putarannya dengan menggunakan pendekatan mixed lubrication model. Pada model ini, akibat beban yang diberikan pada ball bearing akan mengakibatkan terjadi kontak dengan sebagian dari asperity dengan cairan pelumas dan sebagian lagi berkontak dengan sesama asperity. Kontak yang terjadi pada ball bearing terjadi antara bola dengan inner ring dan outter ring. Pada tulisan ini akan dilihat bagaimana perbedaan kurva Stribeck antara inner ring dan outter ring. Disamping itu, akan dilihat bagaimana pengaruh viskositas, kekasaran permukaan, beban dan ukuran dari bantalan terhadap kurva Stribeck. Dari kurva Stribeck yang telah diperoleh, nantinya akan dapat diketahui regime pelumasan dari ball bearing. Berdasarkan hasil kurva Stribeck yang diperoleh untuk bantalan jenis deep groove ball bearing 6410, maka dapat diketahui bahwa koefisien gesek pada inner ring lebih besar dari koefisien gesek pada outter ring untuk daerah mixed lubrication. Pada daerah mixed lubrication, untuk perubahan viskositas, kekasaran permukaan, dan beban dapat dilihat bahwa : dengan meningkatnya viskositas pelumas, akan menurunkan harga koefisien gesek, dengan naiknya harga kekasaran permukaan, akan meningkatkan harga koefisien gesek dan begitu juga dengan peningkatan beban, akan menurunkan harga koefisien gesek. Namun dari semua parameter tersebut, perubahan harga koefisien gesek tidak terlihat pada daerah elasto hydrodynamic lubrication. Dengan demikian, untuk meminimalisir gesekan yang terjadi, maka ball bearing harus dioperasikan pada daerah elasto hydrodynamic lubrication. Friction on ball bearing will generate heat and wear that resulting service life of the ball bearing will be reduced. Friction can be minimized by giving the lubricant. To determine the lubrication regime in the ball bearing, a Stribeck curve can be used by using a mixed lubrication models. In this model, the total pressure is shared between the asperity contact and the elastohydrodynamic pressure. The contact is occurred on ball bearing between balls with the inner ring and outer ring. In this paper, Stribeck curve between the inner ring and the outer ring as well as the effect of viscosity, surface roughness, load and size of the bearings will be investigated. Based on the results obtained from Stribeck curve of deep groove ball bearing 6410, it is known that the coefficient of friction of the inner ring is greater than the coefficient of friction in the outer ring for mixed lubrication regime. In mixed lubrication regime, an increase of viscosity lubricants and loads will reduce the coefficient of friction and an increase of surface roughness will increase the coefficient of friction. In contrast, for all parameters, the change of coefficient of friction is not seen in the elastohydrodynamic lubrication regime, so the ball bearing must be operated in elastohydrodynamic lubrication regime.

Pengaruh Penambahan Minyak Kelapa dan Sawit Terhadap Sifat Fisik dan Tribologi Pelumas SAE 40 Dedison Gasni; KM Abdul Razak; Ahmad Ridwan; Muhammad Arif
Jurnal Mettek: Jurnal Ilmiah Nasional dalam Bidang Ilmu Teknik Mesin Vol 5 No 1 (2019)
Publisher : Program Studi Magister Teknik Mesin Universitas Udayana

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/METTEK.2019.v05.i01.p01

Penelitian ini bertujuan untuk mengetahui efek dari penambahan minyak kelapa dan sawit terhadap sifat fisik dan tribologi pelumas SAE 40. Vegetabel oil, seperti; minyak kelapa dan sawit, memiliki nilai viskositas indek yang tinggi dan sifat pelumasan yang baik terutama didaerah boundary lubrication jika dibandingkan dengan mineral oil (SAE 40). Hal ini disebabkan karena vegetabel oil memiliki kandungan fatty acids yang tidak dimiliki oleh mineral oil. Keunggulan lain dari minyak kelapa dan sawit adanya sifat yang ramah lingkungan karena mudah terurai di alam dan dapat diperbaharui. Pada penelitian ini sifat yang baik dari minyak kelapa dan sawit ini akan dimanfaatkan sebagai zat aditif pada minyak pelumas SAE 40. Pengujian dilakukan terhadap sifat fisik dan tribology dengan penambahan 5%, 10%, 15%, dan 20% berat dari minyak kelapa dan sawit ke dalam minyak pelumas SAE 40. Pengujian sifat fisik terdiri dari pengukuran viskositas pada temperatur 400C dan 1000C dan viskositas index. Pengujian sifat tribologi untuk menentukan keausan dan koefisien gesek berdasarkan ASTM G99 dengan menggunakan alat uji pin on disk. Dari hasil pengujian diperoleh bahwa dengan penambahan minyak kelapa dan sawit kedalam minyak pelumas SAE 40 terjadi peningkatan viskositas indeks. Peningkatan viskositas indeks sebanyak 17% dengan penambahan 20% minyak sawit. Terjadi perubahan sifat tribologi dengan penambahan minyak sawit, berupa penurunan keausan dan nilai koefisien gesek dibandingkan dengan penambahan minyak kelapa. This study aims to determine the effect of coconut and palm oils as additives to physical and tribological properties of SAE 40 lubricating oil . Vegetable oils, such as; coconut oil and palm oil, have high viscosity index and good lubrication properties, especially in boundary lubrication compared to mineral oil. This is due to vegetable oil having fatty acids that are not owned by mineral oil. The advantages of coconut oil and palm oil are environmentally friendly properties because they are biodegradable and renewable. In this study, the good properties of coconut and palm oils will be used as additives in SAE 40 lubricating oil. Tests are carried out on the physical and tribological properties with the addition of 5%, 10%, 15%, and 20% by weight of coconut and palm oils into SAE 40 lubricating oil. Physical properties testing consists of measuring viscosity at temperatures of 400C and 1000C and viscosity index. The tribological test is to determine wear and coefficient of friction based on ASTM G99 using a pin on disc test equipment. From the test results, it was found that coconut and palm oils as additives into SAE 40 lubricating oil could increase in viscosity index. The increase of the viscosity index was 17% by adding 20% of palm oil. There was a change of tribological properties in the form of decreasing on the wear and the coefficient of friction with the addition of palm oil compare to addition of coconut oil.

PENGEMBANGAN MESIN PENGEPRESS TANDAN KOSONG SAWIT (TKS) CACAHAN DENGAN SISTEM HANTARAN SCREW Junaidi Junaidi; Adriansyah Adriansyah; Dedison Gasni
Prosiding Semnastek PROSIDING SEMNASTEK 2014
Publisher : Universitas Muhammadiyah Jakarta

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Tandan kosong sawit (TKS) kandungan seratnya ±70% dan bisa dimanfaatkan untuk serat berkaret,matres, kasur, keset dan bahan baku produk papan komposit berbasis serat, tetapi sampai sekarangbelum termanfaatkan secara maksimal. Permasalahannya adalah belum tersedianya unit pengolahTKS menghasilkan serat dalam skala usaha kecil, salah satunya adalah mesin pengepress TKScacahan skala kecil.Teknologi pengepress TKS cacahan yang ada saat ini adalah skala besar yanghanya bisa dimiliki oleh industri kelapa sawit dengan kapasitas ± 2 ton/jam.Untuk industri seratskala kecil dibutuhkan mesin pengepres TKS cacahan minimal kapasitas pengepresan ± 200 -300kg/jam, tetapi mesin ini belum tersedia dipasaran. Secara umum tujuan penelitian ini adalahmerekayasa mesin pengepress TKS cacahan skala kecil dengan kapasitas 200 – 300 kg/jam,mengidentifikasi parameter desain dan kondisi operasi optimum untuk setiap komponen denganmelakukan uji teknis terhadap Prototype. Dari hasil rancangan mesin didapatkan kapasitas mesin±250 kg/jam, ukuran mesin yaitu 130 cm x 60 cm x 120 cm, daya motor penggerak 10 HP denganputaran 1450 RPM dengan 3 phase. Beberapa komponen utama dari mesin yaitu unit pengepressterdiri dari ulir screw sebanyak 7 screw sepanjang 80 cm dengan ukuran screw Ø 20, poros screwØ 4,5 cm x 130 cm, cone head Ø 20 cm x 10 cm dengan sudut konis 300, rumah screw Ø 9 inchi x80 cm dan saringan. Unit corong, dan unit rangka Unit penggerak terdiri dari reducer, motor listrik,transmisi sabuk dan pully. Hasil pengujian mesin diperoleh penurunan kadar air TKS cacahansetelah di press adalah 50%, kapasitas mesin press adalah ± 220 kg/jam dengan lebar bukaan conehead antara 2-3 cm. Cairan TKS cacahan dikeluarkan melalui gaya gesekan antar TKS sertagesekan antara TKS cacahan dengan dinding mesin. Gaya gesekan antara TKS cacahan dengandinding mesin akan semakin besar dengan adanya tekanan balik yang disebabkan penyempitan daricone head. Dengan adanya proses pengepressan TKS cacahan ini, untuk proses selanjutnya padaproses penguraian serat TKS cacahan akan lebih mudah untuk pemisahan seratnya.

Kondisi Running-in pada Sliding Contact dengan Variasi Pelumas Berbahan Minyak Kelapa Dedison Gasni; Brento Napitupulu
METAL: Jurnal Sistem Mekanik dan Termal Vol 3, No 2 (2019)
Publisher : Department of Mechanical Engineering, Universitas Andalas

Bathtube curves are often used by reability engineers to describe the life of a product's population. This graphical representation of the bathtube curve can be divided into 3 phases. The first phase of the curve is infant mortality failure which is characterized by decreasing failure rate. The second phase is normal life or useful life which the failure rate is aproximately constant. Finally, the third phase is wearout failures and it is assumed that failure rate increases. To observe the running-in periode, a pin on disc test was conducted based on the ASTM G99 standard, where the disk rotates and the pin is loaded. So that the relative motion occurs between the pin and disk with a point contact. Between the surface of the disk and the pin is lubricated with several types of lubricant. Tests carried out for 30 minutes with a time interval of data collection every 6 minutes. From the results of tests, in the phase of running-in periode shows that the wear rate in the first 6 minutes was very high and it tends to decrease exponentially. Lubricant could influence the wear rate and surface texture of the discs in the running-in periode as well.

Analisis Kegagalan Pada Roda Gigi Miring Intermediate Gear 2 Pada Gear Box Untuk Roller Press Milling Machine Andri Anto; Dedison Gasni
METAL: Jurnal Sistem Mekanik dan Termal Vol 1, No 2 (2017): Jurnal Sistem Mekanik dan Termal (METAL)
Publisher : Department of Mechanical Engineering, Universitas Andalas

This paper reports the result of an investigation of a fatigue failure of a helical gear in a reducer gear box used in roller press milling machine. Standard procedures in stress analysis on helical gear were used in failure analysis of this helical gear. It was found that the gear failed by fatigue fracture. Beach marks on the fracture surfaces were clearly visible. Detail examination of the surface of the gear revealed that extensive surface damage had occurred in the form of pitting and scuffing. Sub-surface damages in the form of spalling were also observed. Such observations indicated that the gear was under excessive contact stress during operation. Stress analysis did, in fact, confirm such hypothesis. Stress analysis has been conducted by using Niemann methods and Lewis equation. Finite element methods also have been conducted by using commercial software where the stress was obtained on the root of gear by modeling with pitting, without pitting, and matting. The results show that the working stresses on the root of gear were lower than strenght of gear material. It was proofed that the gear failure due to dynamic loading but not because of static loading. These surface and sub-surface damages leed to fatigue crack initiation followed by crack growth and eventual fracture excessive contact stress. It is showed that from contact mechanic analysis showed that Hertzian stress and shear stress at surface and at sub surface were excessive. It is concluded that the helical gear failed by fatigue fracture initiated by surface and sub-surface damages resulting from excessive contact stress.

Pengaruh Fraksi Massa Serat Terhadap Kekuatan Fatik Material Komposit Berpenguat Serat Tandan Kosong Kelapa Sawit Devi Chandra; Randha Mulia; Dedison Gasni; Gusriwandi Gusriwandi
METAL: Jurnal Sistem Mekanik dan Termal Vol 2, No 2 (2018)
Publisher : Department of Mechanical Engineering, Universitas Andalas

The present study was investigated the effect of fiber mass fraction on the tensile and fatigue strength of oil palm fiber reinforced composite and resin as the matrix. Fatigue test has been performed by using rotary bending fatigue machine. The specimens were made by press hand lay-up with matrix to fiber mass ratio was 90:10, 80:20 and 70:30 respectively. Fracture surface of fatigue specimens have also been observed by using digital camera to knowing the failure mode. The results showed that the tensile and fatigue strength and fatigue life increased with increasing the fiber mass fraction as seen in the S-N curve. The fatigue limit was found 0.27 MPa, 0.55 MPa, and 0.82 MPa for composites with 90:10, 80:20 and 70:30 of matrix to fiber mass ratio respectively. The observed failure modes were matrix cracking, fiber debonding, and fiber breaking.

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