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"Surface roughness plays an important role in product quality. In this study effects of cutting speedworkpiece hardness, feed rate and depth of cut on surface roughness in the finish hard turning of DF-3hardened steel were experimentally investigated Cubic boron nitrite inserts and ceramics with through -hardened DF-3 steel bars were used Four factor-two level fractional experiments were conducted andstatistical analysis of variance was performed During hard turning experiments, roughness of themachined surface was measured. This study shows that the effects of workpiece hardness, depth of cut,feed rate and cutting speed on surface roughness are statistically significant. The ejects of two factorinteractions of the cutting speed and the workpiece hardness, the cutting speed and the feed rate, and thecutting speed and depth of cut are also appeared to be important. Especially, CBN suitable for high ortow cutting speed because on the 55.4 to 59.6 HRC hardness range resulted in better surface roughness."

"Penelitian ini bertujuan untuk mengetahui perbedaan nilai kekasaran permukaan lempeng resin akrilik polimerisasi panas dengan serat dan tanpa serat. Penelitian menggunakan 32 spesimen dengan 16 spesimen untuk masing-masing kelompok. Nilai kekasaran permukaan (Ra) diukur dengan menggunakan Surface Roughness Tester pada 5 tempat berbeda dengan masing-masing panjang evaluasi 7,5 mm.Hasil penelitian ini menunjukkan bahwa tidak terdapat perbedaan bermakna antara nilai rata-rata kekasaran permukaan resin akrilik polimerisasi panas dengan serat dan tanpa serat.

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The aim of this study was to determine the difference of surface roughness value of veined and non-veined heat-cured acrylic resin. Thirty two specimens of acrylic resin were used in this study with 16 specimens of each group. Surface roughness value (Ra) was measured using Surface Roughness Tester at 5 different places with each 7,5 mm of evaluation length.

The result of this study showed that there was no significant difference between the mean of surface roughness value of veined and non-veined heat-cured acrylic resin."

"Engineering merupakan ilmu yang mempelajari proses merekayasa pembuatan suatu produk sehingga mempunyai fungsi yang bermanfaat sesuai dengan desain yang dirancang. Dalam pembuatan suatu produk pasti menemukan kendala ? kendala tertentu sehingga harus dilakukan analisa kembali dalam menemukan jalan keluar untuk menyelesaikan kendala ? kendala yang ditemui. Salah satu kendala yang sering ditemui dalam proses pembuatan suatu produk adalah adanya efek secara fisik kepada benda kerja yang dilakukan proses permesinan seperti panas maupun tegangan yang dapat mengakibatkan kerusakan pada benda kerja. Peneliti ? peneliti sebelumnya telah melakukan riset jangka panjang dan menemukan salah satu cara yang dapat dijadikan solusi dalam proses permesinan. Alternatif yang ditemukan adalah penggunaan bakteri yang digunakan sebagai cutting tool dalam proses permesinan. Beberapa keunggulan yang dimiliki oleh proses biomachining adalah ramah lingkungan, tidak terjadi thermal damage pada permukaan benda kerja serta hemat energi. Dalam peneltian sebelumnya telah dilakukan proses kareakterisasi terhadap material nickel dimana terdapat pertambahan kedalaman permesinan seiring dengan bertambahnya waktu proses biomachining, sehingga pada penelitian kali ini peneliti akan melakukan variasi waktu yang lebih lama dan optimalisasi kondisi temperatur lingkungan proses biomachining pada suhu 330C, selain itu bentuk pola yang akan digunakan pada proses biomachining berbentuk lingkaran dengan tujuan untuk melakukan rekayasa dari bentuk microneedle, microneedle merupakakan jarum dalam bentuk micro yang biasa digunakan sebagai alat uji kesehatan dan proses pemberian vaksinasi pada manusia . Proses rekayasa microneedle bermula dari pembuatan pola lingkaran dengan ukuran 3mm hingga kecil 400μm dimana akan dilakukan perbandingan kontur dan sufrace roughness dari setiap hasil lingkaran yang terbentuk pada proses biomachining.

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Engineering is a knowledge that studies about makings a product which has usefull function according to design . In makings a product must find some problem that has to be reviewed back by re-analysis to find a way out or find the solution. One of constraint which often been found when creating product is physicall effect when processing engineering machinery that create hot condition and also tension who can damage the object. Previous researcher have research in long time and they found several ways which can be the solution in engineering process. One of the famous alternative is biomachining which used bacteria that is utilized as cutting tool in machinery process. Some reason which had by biomachining process are environmentally-friendly, there were not happening thermal damage on object surface and energy saving.

In previous the researcher did characterisation process to significant nickel characteristic where the result was the depth of material is increased proporsional to increased condition of biomachining time , so this time the researcher will increased time variation and optimalize the condition of temperature in biomachining process which is 33 0 C, on the other side researcher will make a new pattern form that will be used on biomachining process, that new form is a circle that will be used as a microneedle mask, microneedle is several needle which shaped in micro that is different to the ordinary one, microneedle was being utilized as tool for vaccination application on human .Microneedle enineering started from making several pattern with size 3mm until 400μm, until then researcher will do contour and surface roughness comparison of each model which is the result from biomachining process."

"ABSTRAKPenelitian ini bertujuan untuk menganalisis pengaruh perendaman resin komposit nanohybrid dalam obat kumur mengandung etanol dengan waktu berbeda terhadap kekasaran permukaan. Dua puluh empat spesimen resin komposit nanohybrid dibagi menjadi 4 kelompok perendaman: obat kumur etanol 17 dan 26,9 selama 1,5 jam dan 3 jam. Kekasaran permukaan diukur menggunakan surface roughness tester Mitutoyo SJ301. Berdasarkan analisis statistik uji one-way ANOVA dan uji Tukey.

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ABSTRACTThe aim of this study was to analyze the effect of ethanol containing mouthwash with different concentration and duration of immersion on the surface roughness of nanohybrid composite resin. Twenty four specimens of nanoybrid composite resin were divided into 4 groups of immersion 17 ethanol containing mouthwash, and 26,9 ethanol containing mouthwash for 1,5 hours and 3 hours. Surface roughness was measured using SJ301 Mitutoyo surface roughness tester. Statistical analysis of one way ANOVA and Tukey test."

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Di pekerjaan ini, pembelajaran mengenai efek kekasaran permukaan (Ra) terhadap umur kelelahan perpaduan Aluminum 7075-T6 dilakukan. Berdasarkan pekerjaan sebelumnya,  umur kelelahan adalah fungsi dari kekasaran permukaan material/spesimen. Semakin kasar permukaan spesimen, semakin menurun umur kelelahannya. Sebaliknya, semakin halus permukaan specimen maka umur kelelahannya meningkat. Dalam kasus ini, kekasaran (Ra) hanya didapat dari proses machining. Selanjutnya, dibuatlah suatu faktor koreksi yang merupakan perbandingan dari umur kelelahan specimen dengan nilai Ra tertentu terhadap umur kelelahan specimen ideal. Kemudian, digambarkan sebuah kurva nilai faktor koreksi sebagai fungsi dari Ra. Simulasi keausan dengan menggunakan perangkat lunak komersil telah dilakukan untuk memprediksi umur kelelahan pada kondisi ideal. Kemudian, umur kelelahan untuk spesimen dengen berbagai kondisi kekasaran dapat diestimasi dengan factor koreksi yang didapat dari atas. Dapat disimpulkan bahwa kurva yang menunjukan hubungan Ra dengan faktor koreksi dapat digunakan untuk memprediksi umur kelelahan secara efisien saat simulasi.

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In this work, the effect of surface roughness to the fatigue life of 7075-T6 Aluminum Alloy were studied. The objective is to estimate values of surface factor correction of 7075-T6 Aluminum Alloy and its fatigue life using the obtained correction factors. Based on previous research, a function of fatigue life in terms of surface roughness were obtained. As the surface roughness increases, fatigue life decreases and vice versa. In this case, the Ra value were obtained from machining process only. First, an estimated surface factor correction was obtained as the fatigue limit ratio of specimen with certain Ra value to specimen having ideal surface condition. Then, a function of surface factor correction in terms of Ra were generated. After that, a fatigue simulation was conducted using commercial software to predict fatigue life at the ideal surface condition. Finally, fatigue life for various value of Ra can be estimated using the correction factors obtained. It was concluded that the function of surface factor correction in terms of Ra was applicable to estimate the fatigue life efficiently during simulation.

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"Material Ti6Al4V sangat umum digunakan sebagai Biomaterial karena memiliki karakteristik yang mendukung sebagai Biomaterial. Namun, sejumlah kecil kadar aluminium (Al), vanadium (V), dan Titanium (Ti) dapat terlepas sehingga dapat berdampak bagi tubuh manusia. Penelitian ini bertujuan untuk mengevaluasi stabilitas lapisan oksida pada permukaan implan Ti-6Al-4V yang diberikan pembebanan mekanis berupa bending sesuai dengan kontur wajah manusia. Preparasi Ti-6Al-4V dilakukan hingga permukaan tampak seperti mirror-like dan bersih dari unsur pengotor. Proses pembebanan mekanis menggunakan metode 3-point bending dengan variasi strain 0,01586, 0,016022, 0,015916. Sampel kemudian akan diimersi dalam larutan HBSS selama 21 hari dan 28 hari. Pengaruh strain terhadap kekasaran permukaan pasca imersi diidentifikasi melalui pengujian Surfcom, pengamatan morfologi dan karakterisasi unsur pada permukaan lapisan TiO2 sebelum dan sesudah proses imersi dengan larutan HBSS dengan SEM-EDS dan OM. Hasil penelitian memerlihatkan bahwa semakin tinggi pembebanan yang diberikan akan semakin berpengaruh terhadap ketidakstabilan lapisan pasif titanium oksida. Selain itu, ditemukan microcrack pada lapisan oksida pada tiap variasi strain yang diberikan. Hasil pengujian imersi menunjukkan bahwa microcrack yang terdapat pada lapisan oksida menjadi tempat utama terdepositnya komponen HBSS. Selain itu, terjadi peristiwa stress corrosion cracking pada lapisan oksida di permukaan yang dibuktikan dengan perubahan warna oksida pada permukaan Ti-6Al-4V.

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Ti6Al4V material is commonly used as a biomaterial due to its supportive characteristics for biomedical applications. However, a small amount of aluminum (Al), vanadium (V), and titanium (Ti) can be released, which can have implications for the human body. This study aims to evaluate the stability of the oxide layer on the surface of Ti-6Al-4V implants subjected to mechanical loading in the form of bending according to the contour of the human face. The Ti-6Al-4V specimens were prepared until the surface appeared mirror-like and free from impurities. Mechanical loading was applied using the 3-point bending method with strain variations of 0.01586, 0.016022, and 0.015916. Subsequently, the samples were immersed in HBSS solution for 21 and 28 days. The effect of strain on the surface roughness after immersion was identified through Surfcom testing, morphology observations, and elemental characterization of the TiO2 layer using SEM-EDS and OM. The results showed that higher applied loading had a greater impact on the instability of the titanium oxide passive layer. Additionally, microcracks were found in the oxide layer for each strain variation applied. The immersion test revealed that microcracks served as primary sites for the deposition of HBSS components. Furthermore, stress corrosion cracking occurred in the oxide layer on the Ti-6Al-4V surface, which was evidenced by changes in the oxide coloration on the surface."

"This research was done to investigate influence of the base metal surface roughness on the BAg-8 spreading behavior and to get a proper surface roughness number for large area brazing. The filler metal was melted at 830o C for 15 minutes on a S50C surface for with various roughness levels. After solidified, the spreading area was observed and characterized in macro and micro scale. The results show that physically the filler spreading consists of two kinds of spreading forms: true and apparent filler spreading with composition of the both being almost same; 77% Ag and 23% Cu. For some roughness numbers, irregularities in uniformity of the heating and cooling process on the filler and dissolving of contaminant into the molten filler caused the true spreading that tend to separate became several parts and tend to flow out from initial placement. Increasing of the surface roughness tends to increase the capillarity effect and to decrease imbalance in the surface tension. Optimum surface roughness was obtained at Rz = 0.92. At this number, the ratio, as well as fitness of the true spreading with initial condition, was at the maximum. During the application process, this condition is predicted as being able to prevent or avoid weaknesses in the joint, thereby increasing the joint strength and its appearance quality."

"Pemutihan gigi kini menjadi pilihan untuk mengembalikan warna gigi yang mengalami diskolorasi. Salah satu teknik pemutihan gigi yang menjadi pilihan adalah teknik pemutihan gigi in-office yang dilakukan oleh dokter gigi. Namun pada praktiknya, aplikasi bahan pemutih gigi tidak hanya mengenai jaringan gigi yang sehat tapi juga jaringan gigi yang mengalami tumpatan, contohnya tumpatan sewarna gigi resin komposit. Untuk memaksimalkan kegunaan dari resin komposit, bahan ini haruslah halus, karena permukaan yang kasar dapat menjadi tempat retensi plak, mengiritasi gingiva dan juga mengurangi kenyamanan pasien.Tujuan : Mengetahui adanya pengaruh aplikasi bahan pemutih gigi hidrogen peroksida 38% terhadap kekasaran resin komposit hibrid. Material dan Metode :20 spesimen resin komposit berdiameter 6mm dan tebal 3mm dibuat secara inkremental dan dipolimerasi menggunakan sinar halogen selama 30 detik. Spesimen dibagi menjadi 2 kelompok, yaitu kelompok aplikasi sebanyak 10 spesimen yang diberi aplikasi bahan pemutih gigi hidrogen peroksida 38% selama 30 menit dan dilanjutkan sampai 60 menit. Sedangkan kelompok kontrol hanya direndam dalam aquabides selama 30 menit dan dilanjutkan sampai 60 menit.Hasil : Terjadi peningkatan nilai kekasaran permukaan resin komposit hidrid setelah aplikasi bahan pemutih gigi hidrogen peroksida 38% baik selama 30 menit maupun 60 menit.Kesimpulan : Bahan pemutih gigi hidrogen peroksida 38% dapat meningkatkan nilai kekasaran permukaan resin komposit hibrid. Peningkatan kekasaran ini dapat menyebabkan berkurangnya nilai estetika resin komposit hibrid.

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Bleaching is one of the technique that used to get back the colour of the discolour tooth. One of the bleaching technique than can be use is in-office bleaching that should be applied by the dentist. But, in the fact, bleaching agent not only applied on the healthy tooth but also in a tooth that has been restorated,by resin composite. To optimize the benefit of resin composite, it has to be smooth, because the rough surface of resin composite can increase the plaque retention, irritate the gingiva, and also make the patient uncomfortable.

Objective : To evaluate the effect of 38% hydrogen peroxide ? containing at in-office bleaching agent apllication to the surface roughness of hybrid composite resin. Material and Method: Twenty specimen of hybrid composite resin (6mm diameter & 3mm in thick) were incrementally polimerized by halogen light for 20 seconds. All spesimens were devided into two groups as follow: 10 spesimens were applied with 38% hydrogen peroxide for 30 minutes and continue to 60 minutes. The other group was soak into the aquabidest for 30 minutes and continue to 60 minutes.

Result: The surface roughness (Ra) of hybrid composite resin is increased significantly before and after application of 38% hidrogen peroxide for 30 minutes or 60 minutes.

Conclusions : The in ? office bleaching agent 38% hydrogen peroxide could increase the surface roughness of hybrid composite resin and may be reduce the estetic of hybrid composite resin."

"ABSTRAKFinite Element Method is one of the most power ful methods in numerical analysis techniques. The time consuming tasks and high costs can be reduced by using this method in the early stages of machine component design. The truck chassis is a base component of vehicles and integrates many of the truck component systems such as the axles, suspension, power train, cab and trailer. The truck chassis has been loaded by static, dynamic and also cyclic loading. Static loading comes from the weight of cabin, its contents and passengers. The movement of truck affects a dynamic loading to the chassis. The vibration of engines and the roughness of roads give a cyclic loading. The chassis used in trucks has almost the same appearance since models were developed 20 or 30 years ago, denoting that they are a result of slow and stable evolution of these frames throughout the years. The manufacturers of these chassis, in the past, and some still today, solve their structural problems by trial and error. Conducting experimental tests in the early stage of design are time consuming and expensive. In order to reduce these costs, it is important to conduct simulations using numerical software methods to find the optimum design. Determination of static, dynamic and fatigue characteristics of a truck chassis before manufacturing is important for design improvement. This paper presents the finite elementanalysis (FEA) of road roughness effects on stress distribution of heavy duty truck chassis."