Konsep Proses Pemesinan Berkelanjutan

Metal industrial machining usually strongth pressure from all sectors, ether raw material industries or user metal industries. Manufacturint process which offered to all sectors industries or companies that sustainable manufakturing consist of three main factor are efective cost, enviroment and social performance

Pengaruh Pemesinan Kering Terhadap Kekasaran Dan Kekerasan Permukaan Paduan Titanium

Komponen-komponen mesin pesawat terbang yang dibuat daripada bahan paduan titanium memerlukan tingkat kelayakan dan Kenyamanan terhadap kondisi permukaan yang dimesin. Integritas permukaan yang dimesin menjadi salah satu indikator penting terhadap kualitas komponen mesin yang diproduksi. Bagaimanapun juga, pada waktu pemesinan, permukaan paduan titanium yang dimesin mudah mengalami kerusakan karena bahan ini bersifat mampu-mesin yang tidak baik. Penelitian ini bertujuan untuk menginvestigasi pengaruh model pemesinan kering terhadap integritas permukaan bahan Ti-6%Al-4%V ELI yang dimesin. Hasil penelitian menunjukan bahwa nilai kekasaran permukaan yang diperoleh sangat ditentukan oleh kadar pemakanan dan jari-jari ujung pahat. Pada tingkat awal proses pemesinan, nilai kekasaran permukaan yang dihasilkan ada pada level yang tinggi dan kemudian menurun seiring dengan aus yang berlaku pada ujung mata pahat. Pada jara beberapa mikron di bawah permukaan bahan yang dimesin, didapati efek pengerasan sehingga nilai kekerasan yang dihasilkan lebih tinggi dibandingkan pada permukaan paling atas. Bahkan, lapisan putih yang keras dijumpai setebal lebih kurang 2 m pada kondisi operasi pemesinan; kecepatan potong 95 m/min, feed rate of 0.35 mm/rev and depth of cut of 0.10 mm. Kondisi ini diperoleh pada akhir pemotongan atau pada kondisi aus telah mencapai maksimum. Kata kunci: pemesinan kering, titanium, kekasaran permukaan, kekerasan permukaa

Prestasi Pahat Karbida Berlapis TiN-Al2O3-TiCN Pada Saat Pembubut Baja Perkakas AISI D2

Kajian terhadap pahat karbida dilakukan untuk menginvestigasi umur pahat sifat ausnya pada berbagai kondisi proses pemesinan. Pahat karbida yang dilapisi (KC 125) dan tidak dilapisi (K 313) digunakan untuk membubut baha perkakas AISI D2 yang berbentuk bulat dengan nilai kekerasan 25 HRC. Pengujian dilakukan dalam keadaan kering atau tanpa menggunakan pelumas pada berbagai jenis keceptan potong dan pemakanan, sedangkan kedalaman potong konstan. Disain penelitian Metode Tagcuhi diimplementasikan untuk mengakomodir parameter pemesinan pada beberapa jenis kecepatan potong dan pemakanan. Hasil penelitian menunjukan bahwa progress haus untuk kedua jenis pahat karbida terdiri dari tiga tahap yaitu mekanisme haus awal, pertengahan (teratur) dan akhir pemesinan. Mekanisme aus perlahan dan seragam terjadi pada kadar pemakanan rendah, 0,05 mm/rev. secara umum, pahat karbida yang dilapisi menunjukkan prestasi yang lebih baik berbanding dengan pahat karbida yang tidak dilapisi. Umur pahat yang panjang dan keadaan permukaan yang baik diperoleh bila mengunakan pahat karbida yang dilapisi

Thermal degradation and estimation of dietary intakes of vitamin C from fruits and vegetables

Thermal degradation of vitamin C in eight different vegetables were determined. These comprised Onion, Tomato, Red Pepper, Spinach, Okra, Green Beans, Cauliflower, and Cabbage. Maximum degradation was observed in Tomato with 83% loss while minimum loss of 37% was in Red Pepper. An estimate of adult dietary intake of Vitamin C was carried out with an increased number of samples, the mean dietary intake of 147mg/day was found. Application of t-test indicates significant difference existed between the two classes of peoples studied ( tcal = 6.443, and P=0.05 )and standard deviation was found to be ±101.Key words: Thermal degradation, dietary intake and Vitamin

Identifikasi Nilai Kekasaran Permukaan Pada Pemesinan Paduan Magnesium

The using of magnesium alloy, as alternative to iron and steel, is becoming more popular in the manufacturing industries. Magnesium and its alloys were classified as lighter material and also available in a quite large quantity in this world. Some of machined componens, included automotive and aerospace componens were produced by cutting, which is known as machining process. The machining process done in several conditions doe to the pharamater or factor in machining process. The main factors in machining process are feed rate, cutting speed, machining condition and deep of cutting. The purpose of this research is to investigate the influence of cutting pharameter to the surface roughness of magnesium, when machined using milling process and supplied with cooling air from vortex tube cooler. Cutting pharameters used in this research are feed rate and cutting speed. Feed rate used was three levels, those are 0,15 mm/rev, 0,20 mm/rev, and 0,25 mm/rev. Cutting speed used also three levels, those are 23,18 m/min, 32,15 m/min and 42,7 m/min. Cooling air is released from vortex tube cooler with 15 oC of temperature. The result of this research is found that feed rate affected signicantly on surface roughness value. The surface roughness value increased with increasing of the feed rate level. An other han, the surface roughness value is also affected wear on the edge of the cutting tool. The wear on the cutting tool contributed to the changes of nose radius (become bigger), so increase the surface roughness value

The Life-cycle of biosteres persulcatus with reference to adults' reproductive capacity on eggs of Carambola fruit-fly

A study of the life-cycle of Biosteres persulcatus Silvestri, a larval parasitoid of (Bactrocera (B) sp. near Bactrocera dorsalis A), was conducted in the laboratory (26.50C± 1.50 C). There are 4 larval stages as indicated by the sizes of the mouthhooks. The first larval moult occurred in the newly{ormed puparium of the host. The entire developmental period from egg to adult emergence for male and female was 16.3± 0.80 days and 1 7.1 ± 0.80 days respectively. The average reproductive capacity during the life span was 67 ± 3.5 eggs

Determination of Optimum Frame Rates for Observation of Construction Operations from Time-Lapse Movies

Construction professionals have been using time-lapse movies in monitoring construction operations. However, some amount of detail is always lost in the interval between two consecutive frames in a time-lapse movie. This poses the question: By how much can the frame rate be lowered from the standard 30fps (frames per second) to allow for the accurate observation of construction operations from a time-lapse movie? This paper addresses the problem by establishing the optimum frame rates for observation of activities related to mortar mixing and block handling. The activities were first recorded at the standard rate of 30fps. Using the Adobe Premier Pro video editing software, the records were then segregated into still images from which 15 different time-lapse movies of various time intervals were generated. The movies were then shown to 25 Construction Managers. A structured questionnaire was employed to capture the level of accuracy with which Construction Managers could interpret the job site situation from each movie. The results suggest that 1fpm (frame per minute) is sufficient for the accurate tracking of labourers involved in mortar mixing while 1 frame in every 20 seconds is sufficient for accurate identification of number of cement bags used. However, for tracking number of blocks off-loaded, and those damaged, 1 frame in every 2 seconds is required

Probing scalar-pseudoscalar mixing in the CP violating MSSM at high-energy e+e−e^+e^- colliders

We study the production processes $e^+e^-\to H^0_iZ$, $H^0_iH^0_j$ and $H^0_i\nu_e\overline \nu_e$ in the context of the CP violating MSSM. In a given channel we show that the cross-section for all i (=1,2,3) can be above 0.1 fb provided M_{H_{2,3}}\la 300 GeV. This should be detectable at a Next Linear Collider and would provide evidence for scalar-pseudoscalar mixing.Comment: 17 pages, RevTex, 4 ps figures, figure 4 changed, minor modifications to text, version to appear in PR

Experimental behavior of full-scale exterior beam-column space joints retrofitted by ferrocement layers under cyclic loading

A majority of the traditional reinforced concrete frame buildings, existing across the Middle East, lack adequate confinement in beam-column joints, or in other words, are shear deficient because they were constructed before the introduction of seismic codes for construction. This research studies the experimental behavior of full-scale beam-column space (three-dimensional) joints under displacement-controlled cyclic loading. Eleven joint specimens, included a traditionally reinforced one (without adequate shear reinforcement), a reference one with sufficient shear reinforcement according to ACI 318, and nine specimens retrofitted by ferrocement layers, were experimentally tested to evaluate a retrofit technique for strengthening shear deficient beam column joints. The studied variables were the number of layers, orientation angle of expanded wire mesh per layer, and presence of steel angles in the corners of joint specimen prior to wrapping with ferrocement layers. The experimental results showed that proper shear reinforcement for the test joints, according to ACI 318, enhanced the behavior of the specimen over that of the traditionally reinforced specimens without adequate shear reinforcement. The joints retrofitted by ferrocement layers showed higher ultimate capacity, higher ultimate displacement prior to failure (better ductility), and they did not suffer heavily damage as observed for the traditionally reinforced one. Increasing the number of ferrocement layers for retrofitted specimens led to improving performance for such specimens compared to the traditionally reinforced ones in terms of enhancing the ultimate capacity and ultimate displacement. Specimens retrofitted by ferrocement layers reinforced by expanded wire mesh of 60° orientation angle showed slightly better performance than those of 45° orientation angles. Retrofitting using steel angles in addition to ferrocement layers improves the seismic performance of the specimens, achieves better stability for stiffness degradation, attains higher capacity of the dissipated energy, and reduces the vulnerability of joints to excessive damage. Based on the experimental work in this study, it is recommended to retrofit beam-column joint specimens by two ferrocement layers in addition to steel angles as stiffeners taking the orientation angle of expanded wire mesh into consideration. Keywords: Retrofitting, Beam-column space joints, Ferrocement layers, Orientation of expanded wire mesh, Ultimate capacity, Stiffness degradation, Cyclic loading, Shear deficient, Traditionally reinforced building