MANFAAT METODE INQUIRY TERHADAP PENGAMATAN HASIL PRAKTIKUM LAS LISTRIK DI LABORATORIUM MANUFAKTUR POLITEKNIK META INDUSTRI CIKARANG

ABSTRACTThe purpose of this study was to determine student achievement in the manufacturing process subject before giving treatment, to determine student achievement in the manufacturing process course after treatment, to determine whether there was an effect of the inquiry method on student achievement in the manufacturing process course and to find out whether there is a difference in learning achievement after treatment on the use of the inquiry method and the demonstration method. The type of research conducted by the researcher is Quasi Experiment. The research design used is Non Equivalent Control Group Design. The subjects of this study were third semester students (Industrial Engineering) at the Cikarang Industrial META Polytechnic. Data collection techniques were carried out through objective tests, observations of the welding process and assessment of welding results with performance. The results showed that the learning achievement of electric arc welding subjects before being given treatment in the control group and the experimental group had the same initial ability and the data results showed that there were still many students who had not finished. Learning achievement after being given treatment increased in both the control group and the experimental group. After learning with the inquiry method there is an influence on student learning achievement. Besides the effect, there are also differences in learning achievement after being given treatment, namely by comparing the results of the pretest and post-test, after the application of the demonstration method the test results have a significant percentage difference. Keywords: Inquiry Method, Learning Achievement, Electric Arc Welding ABSTRAKTujuan dari penelitian ini adalah untuk mengetahui prestasi belajar mahasiswa pada mata kuliah proses manufaktur sebelum pemberian perlakuan, mengetahui prestasi belajar mahasiswa pada mata kuliah proses manufaktur setelah pemberian perlakuan, mengetahui ada tidaknya pengaruh metode inquiry terhadap prestasi belajar mahasiswa pada mata mata kulaih proses manufaktur dan mengetahui ada tidaknya perbedaan prestasi belajar setelah perlakuan pada penggunaan metode inquiry dan metode demonstrasi. Jenis penelitian yang dilakukan oleh peneliti adalah Quasi Eksperimen. Desain penelitian yang digunakan adalah Non Equivalent Control Group Design. Subjek penelitian ini adalah mahasiswa semester III (Teknik Industri) di Politeknik META Industri Cikarang. Teknik pengumpulan data dilakukan melalui tes objektif, observasi terhadap proses pengelasan dan penilaian hasil las dengan unjuk kerja. Hasil penelitian menunjukkan bahwa prestasi belajar mata pelajaran las busur listrik sebelum diberikan perlakuan pada kelompok kontrol dan kelompok eksperimen memiliki kemampuan awal yang setara dan hasil data menunjukkan masih banyak mahasiswa yang belum tuntas. Prestasi belajar setelah diberikan perlakuan mengalami kenaikan baik pada kelompok kontrol maupun kelompok eksperimen. Setelah pembelajaran dengan metode inquiry terdapat pengaruh pada prestasi belajar mahasiswa. Selain pengaruh terdapat juga perbedaan prestasi belajar setelah diberikan perlakuan yaitu dengan membandingkan hasil pretest dan post-test, setelah penerapan metode demonstrasi hasil tes memiliki persentase perbedaan yang cukup berarti .Kata kunci: Metode Inquiry, Prestasi Belajar, Las Busur Listrik

Critical Assessment of the Electric Effect in Electric Arc Welding

This work provides a critical assessment of electric effects on the microstructure evolution at the heat-affected zone in electric arc welding. Electric effects are the interactions between electromagnetic fields and materials’ microstructures. They differ from the arc effect and the Joule heating effect by providing an alternative contribution to nucleation, grain growth, recrystallisation and tempering. The influence of the electric effect on grain size, defects, anisotropic properties, precipitates and residual stress has been examined kinetically and thermodynamically. The use of adaptable electric current densities, pulse durations, pulse frequencies and electrode movements is suggested to achieve desirable microstructures and mechanical properties for the weldments.

Determining the dynamics of carbon monoxide formation during gas welding processes

This paper reports a study of the air medium where welding processes take place, with special attention paid to the evolution of carbon monoxide (CO) in the working medium in the process of gas welding. Plots were constructed and polynomial dependences were obtained to show a change in the concentration of carbon monoxide in the air of the working area during gas welding. It was confirmed experimentally that the concentration of carbon monoxide exceeds the permissible sanitary and hygienic indicators MPC (20 mg/m3) during gas welding. As a result of the experiment, the effectiveness of the use of an additional device was proven, namely an umbrella gas concentrator, in order to capture welding gases that are formed during gas welding. It was established that the MPC is exceeded under certain working conditions and welding wire. The carbon monoxide formation during gas welding was analyzed; these processes were compared with electric arc welding. The mathematical dependences derived make it possible to assess the risks of the welders’ work and conclude that the electric arc welding is characterized by a much higher rate of CO evolution from the beginning of the welding process (8.5 mg/s), that speed then decreases over 20 s by 2 times (to 4.5 mg/s). In 90 s, the speed becomes constant, to 2 mg/s. In comparison, gas welding has almost the same rate of CO formation, namely 0.3–0.9 mg/s. By changing the types of welding wires used in gas welding and taking into consideration the type of material that needs to be welded (including the period of its use), it is possible to influence the volume of CO emissions entering the working area and an employee’s respiratory area

Corrosion Rate of Stainless Steel 304 in HNO3 Solution

This literature review was aims to describe corrosion rate stainless steel 304 in sulfuric acid. Immerse process do in 700C temperature for 6 hours and than in 29oC temperature for 18 hours every day. This condition aim to get closer to the actual use in the manufacture of tubes of reactor SAMOP (sub critical assembly for Mo99Prad action). Specimen after TIG welding and electric arc welding cleaned from crust and than measured, drawing, balanced, and record the first weight. The survey findings show heavy shrinkage sample, it is well visible on the corrosion pH 0.5 in electric arc welding of 0.105 gram/dm2/month for corrosion 0.026 gram/dm2/month without welding and pH 0.2, arc welding of 0.045 gram/dm2/month, pH 0.2 no Las 0.02 gram/dm2/month. Specimen that has been welded have significant differences in corrosion rate compare to specimen that have not weld.

Simulation of an Electric Arc in Metal Welding

This paper describes the proces of electric arc welding in the zone of protective gas, with an emphasis on transmitting metal dropelts via a short ciruit.Parameters of the welding proces and of an electric arc are described, and a mathemacal model for the MIG system is sugessted. Model simulation is completed used Matlab/Simulink package. The proces is simulated using real parameters in order for the output values of the process to corespond to real values obtained by the means of mesasurement.

SUBMERGED ARC WELDING TECHNOLOGY

В данной статье раскрываются особенности применения флюса в технологии электродуговой сварки и влияние на характеристики и работоспособность сварных соединений. This article describes the features of the use of flux in the technology of electric arc welding and the impact on the characteristics and performance of welded joints.

Intelligent robotic systems implementation in the shipbuilding enterprise processes production

Работа посвящена автоматизации технологического процесса сварки судокорпусных конструкций. В настоящее время большинство технологических процессов в судостроении сопряжено с использованием ручного труда и имеют низкую степень автоматизации. Авторами был проведен структурный и функциональный анализ типового технологического процесса сварки узлов корпуса судна, на основе которых был сделан вывод о необходимости повышения эффективности функционирования технологического процесса. Для этих целей был разработан роботизированный технологический комплекс электродуговой сварки узлов корпуса судна с применением интеллектуальных алгоритмов управления. Чтобы подтвердить эффективность предлагаемого решения, приведены результаты практической работы авторов по проектированию технологического процесса сварки судокорпусных конструкций в лабораторных условиях. The work is devoted to the automation of the technological process of welding ship hull structures. Currently, most of the technological processes in shipbuilding involve manual labor and have a low degree of automation. The authors carried out a structural and functional analysis of a typical technological process of welding ship hull units, on the basis of which it was concluded that it is necessary to increase the efficiency of the technological process. For these purposes, a robotic technological complex for electric arc welding of ship hull assemblies was developed using intelligent control algorithms. To confirm the effectiveness of the proposed solution, the results of the author's practical work on the design of the technological process of welding ship hull structures in laboratory conditions are presented.

ABOUT THE CLUSTER MECHANISM OF WELDS CRYSTALLIZATION IN ARC WELDING OF METALS AND ALLOYS

In this work, the task was set to analyze the literature data on the cluster mechanism of crystallization of alloys in the field of foundry and metallurgical production and the possibility of its application for the process of crystallization of metal in a weld pool during arc welding and surfacing of metals and alloys. Literature data have shown that the cluster mechanism of their crystallization is widely used to explain many properties of castings and ingots in metallurgical production. It is shown that the previously used diffusion mechanism of crystallization of melts of steels and alloys, that is, the mechanism of crystal growth as the attachment of atoms of a substance from the melt to the solid phase (substrate), does not stand up to criticism. However, this old approach is used in all work on weld solidification in electric arc welding and surfacing. The same approach has always been used in works devoted to the study of the effect of magnetic fields (MF) during arc welding on the refinement of the weld structure. In modern research in the field of foundry and metallurgical industries, it is assumed that there are already clusters in the molten metal. Clusters are centers of crystallization. The process of crystallization of melts is represented as the attachment to larger crystals (clusters) of smaller ones. Earlier it was found that the refinement of the structural components of the weld metal during welding under the influence of MF occurs at the stage of their primary crystallization. Surfacing was performed without and with the influence of a control alternating transverse magnetic field with a frequency of 6 Hz. At the same time, in the structure of the bead deposited with the action of the field, a 2-fold grain refinement was observed. This refinement of the structure of the deposited metal occurred during its primary crystallization. It was assumed that this happened by the cluster crystallization mechanism.