ANALISIS UNJUK KERJA KOLEKTOR SURYA PELAT DATAR DENGAN PENAMBAHAN SIRIP BERLUBANG BERDIAMETER BEDA SEBAGAI NOSEL YANG DISUSUN SECARA STAGGERED

The solar collector is a device that collects solar radiation and converts it into useful heatenergy. Several types of solar collectors include the parallel flow flat plate solar collector and theperpendicular flow absorber plate solar collector. Previous design of flat plate solar collectorperpendicular flow absorber plate usually uses plates with the same hole diameter. To improve theperformance of this solar collector, modifications have been made by adding perforated fins withdifferent diameters which are arranged staggeredly as an air flow channel or nozzle. The intendedmodification of nozzle diameter is to make the nozzle diameter size different from the large diameter nearthe inlet to the small diameter near the oulet and compared to the reverse nozzle position. Making thediameter of the nozzle near the inlet is larger than the diameter of the hole near the outlet aims to makethe mass flow of air passing through the hole near the inlet larger, so that the flow of air massesexperiences more heat transfer while the diameter of the hole near the outlet is made small is to reducethe mass flow of air which is wasted faster through the outlet channel. With the variation of the holediameter from large to small, it is expected that the heat transfer that occurs in the solar collector will bemore optimal, but it should also be seen in the reverse position. The research was carried outexperimentally. The results of his research show that the useful energy and efficiency of solar collectorswith large to small diameter slotted fins are higher than those with small to large diameter slotted fins.

PENENTUAN KECEPATAN PEMOTONGAN EFEKTIF BERDASARKAN NILAI KEKASARAN PERMUKAAN MATERIAL AA-7075 PADA PROSES FACE MILLING

During face milling machining, several machining parameters such as feed rate and cuttingspeed determine the surface quality of the workpiece produced by the process. The selection of the rightparameters will lead to the surface quality as planned. Therefore, to improve machining effectiveness, amethod is needed to determine the appropriate machining parameters to produce the desired surfacequality. This research was conducted using a milling machine, five variations of cutting speed and fivevariations of feed rate were used to cut the workpiece aluminum alloy 7075. After machining, the surfaceroughness was measured using a surface test. The surface roughness value is then substituted into thefeed rate equation and effective cutting speed. By finding effective cutting parameters, the machiningprocess will be more efficient and effective without using unnecessary resources. From the results of thestudy note that the development equation to determine the feed rate based on the value of surfaceroughness is ???? = 0,6????√???? ????????0.443mm/tooth. Development equation to determine the effective cutting speedbased on Surface roughness value is ???????? = 3.0686????????0.124 mm/min

KARAKTERISTIK ENGINE MOUNTING PADA TEMPERATUR AUSTENISASI TERHADAP SIFAT MEKANIS DAN STRUKTUR MIKRO

Engine mounting is one of the car component which is has optimize function to obtain thesystem in the car is extremely perfect. The engine mounting has to be have behavior ductile by strongestenough to support the car engine whether in rest and moving position. To obtain car engine mountingwhich has these function it has to be treated by treatment. The method was used by using Heat TreatmentSystem which we were Hardening and Tempering. Heat treatment of engine mounting is needed toanalyze the microstructure and mechanical properties of low carbon steel used. Tests carried out attemperatures of 800oC, 850oC, 900oC and normal conditions without heat treatment. Then continued withimpact charpy testing, vickers hardness testing, microstructure observation using microscope and SEM.The tests are carried out in accordance with ASTM E23, ASTM E92, ASTM A370 standards. The Vickerstest results provide the lowest HV value of 118.7Hv at 900oC, while the normal condition is at 137.409Hv.The charpy impact test results give the lowest value of 0.06 j / mm2 under normal conditions, while at900oC at 0.0962 j / mm2. The results with microscopy and SEM, the greater the temperature given to heattreatment, the less pearlite will be, while the amount of ferrite and austenite increases which makes theengine mounting more toughness.

Dewan Penyunting

Jurnal Poros Vol 17 No 1 Mei 2021

VARIASI KECEPATAN PEMOTONGAN PROSES PEMBUBUTAN BAJA AISI 4140 TERHADAP KEAUSAN DAN UMUR MATA PAHAT KARBIDA

In the machining process, increased production can be done by increasing the use of cuttingparameters. However, the use of high cutting parameters has an effect on the wear of the cutting toolused. The aim of this research is to analyze the wear and tear that occurs on cutting tools and tool lifewhen cutting AISI 4140 steel by using variations in cutting speed. The machining process uses a CNClathe by turning the surface of the AISI 4140 steel workpiece. The wear criteria are determined when thecutting tool has reached the edge wear limit (VB) of 0.3 mm. Observation and measurement of carbidecutting tools are carried out every 5 minutes the machining process is carried out. If the cutting tool hasnot shown the specified wear value, then the cutting tool then cuts, so that the wear value is obtained.From the research conducted it was found that at a cutting speed of 160 m / min the cutting tool iscapable of cutting for 39 minutes, 13 seconds. At a cutting speed of 180 m / min the cutting tool is capableof cutting for 38 minutes, 14 seconds. At a cutting speed of 200 m / min the cutting tool is capable ofcutting for 33 minutes, 8 seconds. At a cutting speed of 240 m / min the cutting tool is capable of cuttingfor 26 minutes, 3 seconds. Taylor's advanced tool life for the coated carbide cutting tool in turning AISI4140 steel material is: Vc. Tl.0.073 = 8203.

RANCANG BANGUN PROTOTYPE HYDRO TURBINE JENIS CROSS-FLOW UNTUK PERKOTAAN

The problem of fossil fuel crisis, both petroleum and coal, and the phenomenon of climatechange due to global warming, trigger the use of renewable energy that can overcome these problems.Cross-flow water turbine is one of the machine that can be used to produce small scale electric energy insmall scope. This turbine can be used in urban areas to assist industrial activities and their usefulness indaily life. The use of the right materials and strong construction can produce a good shape so that thiswater turbine is not only make efficient energy but also efficient and ergonomic in its use. This study isconducted theoretically to a cross-flow turbine which assumed to operate at 10m water height with 1.4L/s, outer diameter 150mm and 75mm thickness. The turbine consist of 15 blades with angle of attack ofthe blades is 30o. The results show that the turbine generate 119 Watt

OPTIMALISASI PARAMATER RESISTANCE SPOT WELDING UNTUK PENGELASAN TIGA TUMPUK LEMBAR BAJA SPCC

In the automotive industry, the latest breakthroughs and innovations are strongly influenced bymaintaining and increasing production results so that the use and application of technology is anabsolute must, as is welding technology. Thin sheet-shaped components are found in many car bodies.One of the methods used in joining plate sheets is to use the resistance spot welding method, which is awelding process that is only carried out at a certain point using copper electrodes. In the welding method,maintaining quality in order to produce products and services that can meet the needs and expectationsof consumers related to the product's life time or service. SPCC steel (Cold Roller Stell Sheet) is one ofthe most widely used materials in car body welding applications. The characteristics and mechanicalproperties of SPCC steel from the results of the three-sheet welding were examined using the parametersof welding current, welding time, welding distance. The results showed that the increase in current wouldaffect the diameter of the electrode traces and the nuggets that were formed. The greater the current used,the larger the diameter of the trail, so that the optimum pull-shear load is at a current of 6.5 kA at adistance of 20mm with a value of 365.53 MPa, also the highest hardness value is in the nugget area witha hardness value of 595, 14 HVN at a current of 6.5 kA and from the results of measuring grain diameterin microstructural testing for the HAZ area the best at a welding current of 6.5 kA. Because the smallerthe weld grain diameter, the greater the strength of the weld joint. Then the data from the results of theshear-shear test are analyzed using the Taguchi method, and the most effective parameters in the tensilesheartest with a combination of A (6.5) B (1.5) C (15) and from the experimental results for tensile loads.slide obtained 397 MPa.

SIFAT TARIK DAN SIFAT LENTUR PADA BODY MOTOR KOMPOSIT LAMINA DENGAN PERLAKUAN ALKALI

Composite is a combination of two or more materials that have different mechanical propertiesand characteristics. One of the reinforcement materials or reinforcement that is widely used is naturalmaterials. One of Indonesia's natural materials and a very large source of bamboo is widely used inbuilding construction as an alternative to wood because it has high flexibility and strength. To balancethe strength of bamboo with high tensile strength while low flexural strength, a solution is needed tomaximize the strength of bamboo by combining it with a bamboo composite system. In this study, bamboothat has been processed into woven sheets manually with plain weave type is then given a certain amountof epoxy resin and then a Tensile Strength Test is carried out using ASTM D3039 / D3039M and aflexural test using ASTM D7264 / 7264M to obtain maximum composite and flexural strength. After thetest was carried out, it was continued by observing the microstructure of the specimen using SEM(Scanning Electron Microscope). The results showed the tensile test value with a value of 50 Mpacompared to the ABS tensile strength value of 53 Mpa, the Modulus of Elasticity with a value of 0.38 GPacompared to the ABS modulus of elasticity of 0.41 Gpa. The results of the flexural test obtained flexuralstrength with a value of 47.06 Mpa compared to the value of ABS flexural strength of 49.6 Mpa, flexuralmodulus with a value of 0.52 Gpa compared to the value of ABS flexural modulus of 0.55 Gpa.

PENGUJIAN PERFORMA REAKTOR DOWNDRAFT BIOMASSA KOTORAN SAPI

Biomass power plants are electricity generators with alternative energy that utilize organicmaterials, in this case cow dung. The cow dung is then processed to produce syngas. Syngas is used as fuelto turn turbines. In previous studies, a cow manure gasification reactor was designed and manufactured.This reactor is part of a biomass power plant system (PLTBm) which is made separately. The power outputtarget of this PLTBm is 370 kW. The purpose of this study was to examine the performance of the downdraftreactor of cow dung biomass, namely discharge, temperature, and analyze the gas content released by thereactor so that the power that can be generated by the reactor can be obtained. The test results obtained acombustion chamber temperature of 580°C and a discharge of 0.285 m3/s. The composition of the outputgas is acetylene 58.16%, hexane 27.66%, butane 6.38%, and methane 7.8%. From the calculation results,the power generated by the reactor is 342 kW.

PROSES PEMBUATAN ARANG BATOK KELAPA DAN TULANG SAPI MENGGUNAKAN METODE PIROLISIS SEBAGAI MEDIA CARBURIZING

Fueled by a rise in food needs as beef and oil into basic commodities has been consumed by thepublic, has lead the increasing of waste the cows and coconut shell. The main ingredient used in thisresearch is a waste product from cow bones and from the remains of the coconut shells from which no orhousehold wastes, that can be processed into charcoal. The purpose of this research which is to enhanceeconomic value of waste from cow bones and coconut shells using combustion pyrolysis system beingcharred (fixed carbon) to produce good quality charcoal, to find out the extent of the temperature used andthe composition of charcoal. The process used in this research is pack carburizing with cow bones andcoconut shell as the media at the temperature 950oC, time detention three hours with variations compositioncharcoal. It can be concluded that charcoal bone across his cattle and charcoal coconut can be used as asource of carbon that might improve the force and hardness in the material carbon steel low (low carbonsteel). The process of pack carburizing can increase the value of % C, against low carbon steel material.