Penerapan Metode Six Sigma Dalam Perbaikan Kualitas Kampas (Lining) Produk Brake Shoe Pada PT X

Salah satu tujuan jangka pendek PT X adalah mampu meminimalkan defect pada produk brake shoe. Selama berjalannya proses produksi, part brake shoe yang menghasilkan kecacatan terbesar adalah kampas (lining). Padahal kualitas kampas berpengaruh langsung terhadap kualitas pengereman mobil. Penelitian ini menggunakan metode Six Sigma dengan tahapan DMAIC, untuk mengidentifikasi defect pada kampas serta mengurangi variansi dalam proses. Dua CTQ terbesar kecacatan kampas adalah kampas miring dan kampas keropos. Persentase muncul cacat tersebut sebesar 70,41% dari total kampas cacat. Kedua jenis kecacatan ini muncul secara signifikan disebabkan karena terdapat kerak pada permukaan matras cetakan (krom) yang digunakan pada proses hidrolis. Analisis improvement yang diterapkan adalah melakukan upaya preventive maintenance, yaitu membersihkan permukaan matras secara berkala dengan periode waktu setiap 5 kali cetak kampas. Setelah diterapkannya usulan perbaikan, diperoleh peningkatan level sigma dari 3,629 sigma menjadi 3,976 sigma. Usulan perbaikan ini juga terbukti efektif mampu mengurangi 2 jenis cacat terbanyak pada kampas yaitu kampas miring dan keropos. Pencapaian peningkatan level sigma ini dipertahankan dengan menerapkan pemberian insentif kepada operator hidrolis apabila mampu menghasilkan kampas cacat di bawah standar yang telah dibuat. Kata kunci: DMAIC; DPMO; preventive maintenance; Six Sigma

Analysis on mechanical characteristics of brake wheel and brake shoe of elevator traction machine

This paper analyzes the change of brake torque during normal stop and emergency braking of elevator. Taking the permanent magnet synchronous elevator traction machine as an example, the mechanical characteristics of the brake wheel and brake shoe on the brake under emergency braking are analyzed. According to the finite element analysis and calculation results, the impact and stress of the elevator are the largest at the moment of emergency braking, reaching 270.3MPa, and the strain increases gradually. The analysis results can provide reference for the design and verification of brake wheel and brake shoe of elevator traction machine.

Explosive atmosphere ignition source identification during mining plant suspended monorail braking unit operation

Coal dust and methane explosions are some of the most common causes of mining disasters in hard coal mines all over the world, and research continues to be conducted with the purpose of understanding the mechanisms of an explosion, explosion prevention and risk reduction. This article presents the test methodology as well as virtual and bench test results for a braking unit, which constitutes one of the main components of a suspended monorail transport system. The design work and virtual and bench testing were performed as part of a European research programme. The tests were conducted in a dedicated specialist test facility. The tests were based on Polish standard PN-G-46860:2011, concerning braking trolleys employed in mining plant suspended railway systems. The tests also factored in the requirements for non-electrical devices intended for use in explosive atmospheres, including braking systems, as defined in standard PN-EN ISO 80079-36:2016, harmonised with the ATEX directive. The test scope encompassed braking unit operational component temperature measurements using thermal imaging and the contact method, as well as braking distance measurements. Further tests involved virtual simulations of brake pad heating. The tests employed the finite element method (time-varying calculations). Results obtained over the course of numerical calculations indicate that brief brake pad friction face heating, even up to a temperature exceeding 200C, does not result in inward heat propagation towards the brake pad material. This is also confirmed by the measurement results. However, under real conditions, the braking unit would be engaged only during an emergency situation, which would not lead to exceeding the permissible brake shoe material temperature values.

Effect of Vibration on Emergency Braking Tribological Behaviors of Brake Shoe of Deep Coal Mine Hoist

The effects of vibration on the emergency braking tribological behaviors of the brake shoe of a deep coal mine hoist were investigated in this study. The thermal, frictional and mechanical parameters of the brake shoe were obtained. The vibration characteristics of the brake shoe during emergency braking were investigated, employing multibody dynamics analysis. The effect of vibration on the emergency braking tribological behaviors (temperature and stress distributions) of brake interfaces was explored using the finite element method. The self-made tribo-brake test rig of a brake shoe was employed to reveal the friction deterioration behaviors of the brake shoe during emergency braking. The results show obvious vibrations of all brake shoes along the direction of positive braking pressure during emergency braking. The vibration causes increases in the equivalent Von Mises stress and temperature at the contact interfaces between the brake disc and the brake shoe as compared to the case of ignoring the vibration. Along the rotation direction of the brake disc, the equivalent stress and temperature of the brake disc surface present three overall rapid increases, as well as two slight decreases during emergency braking. As compared to cyclic emergency braking, continuous emergency braking exhibits more obvious tribological degradation of the brake shoe, attributed to enhanced vibration. The wear loss of the brake shoe increases with increasing emergency braking cycles and continuous emergency braking time.

THE PRINCIPLE OF CONSTRUCTING A MICROSYSTEM INDICATOR OF THE STATE OF THE BRAKE PAD OF A ROBOTIC CAR

Проблема и цель. С развитием и широким применением колесной наземной транспортной техники выдвигаются повышенные требования к устройству машин, их управляемости с одновременным упрощением требований к водителю по управлению машиной и обеспечению ее функционирования в широком диапазоне технических возможностей. Целью исследований явилось теоретическое обоснование и практическая реализация способа непрерывного мониторинга состояния накладок тормозных колодок автомобиля КамАЗ. Методология. Разработано микросистемное устройство для контроля состояния тормозной колодки, отвечающее требованиям автоматизации и роботизации. Электрическая схема устройства построена по аналоговой форме с непрерывной регистрацией неэлектрического сигнала о состоянии (толщине износа) накладки в преобразованной электрической форме. Принцип действия сигнализатора состояния тормозной колодки автомобиля построен на использовании явления изменения электрической емкости конденсатора с изолирующей прокладкой между электродами при изменении толщины этого изолятора. Если встроить в керамическую (изолирующую) накладку тормозной колодки металлический электрод, то он образует электрическую емкость с поверхностью тормозимого металлического тела. Это позволяет в качестве изолирующей прокладки использовать изнашивающийся слой фрикционной накладки тормозной колодки. В таком датчике первичным источником информации будет являться непосредственно контролируемый параметр – остаточный рабочий слой фрикционной накладки тормозной колодки Результаты. Разработано индикаторное устройство, позволяющее водителю, находящемуся в кабине автомобиля, не отрываясь от управления осуществлять непрерывный мониторинг состояния тормозных накладок (толщины рабочего слоя) вплоть до критического, при котором дальнейшая эксплуатация транспортного средства становится небезопасной. Заключение. Применение разработанного индикаторного устройства для визуального функционального контроля водителем состояния тормозных колодок автомобиля делает возможным предотвращение нештатных ситуаций, которые могут возникнуть из-за невозможности эффективного использования рабочей тормозной системы автомобиля по причине предельно допустимого или неравномерного износа фрикционных накладок тормозных колодок. Problem and purpose. With the development and widespread use of wheeled ground transport equipment, increased requirements are put forward for the device of machines, their controllability, while simplifying the requirements for the driver to control the machine and ensure its functioning in a wide range of technical capabilities. The aim of the research was the theoretical substantiation and practical implementation of the method for continuous monitoring of the state of the brake pads of the KamAZ car. Methodology. Microsystem device for monitoring the condition of the brake pad, which meets the requirements of automation and robotization. The electrical circuit of the device is built in an analog form with continuous registration of a non-electrical signal about the state (wear thickness) of the pad in a converted electrical form. The principle of operation of the signaling device of the state of the brake shoe of a car is based on the use of the phenomenon of change in the electrical capacitance of a capacitor C with an insulating gasket between the electrodes when the thickness of this insulator changes. If a metal electrode is embedded in the ceramic (insulating) lining of the brake shoe, then it forms an electric capacitance C with the surface of the braking metal body. This allows the wear layer of the brake pad friction lining to be used as an insulating pad. In such a sensor, the primary source of information will be the directly monitored parameter - the residual working layer of the friction lining of the brake shoe Results. Development of an indicator device that allows the driver, who is in the cab of the car, without interrupting control, to continuously monitor the state of the brake linings (thickness of the working layer) up to the critical state, at which the further operation of the vehicle becomes unsafe. Conclusion. The development of an indicator device for visual functional control by the driver of the state of the brake pads of a car makes it possible to prevent abnormal situations that may arise due to the impossibility of effective use of the working brake system of the car, due to the maximum permissible or uneven wear of the friction linings of brake pads.

An analytical thermal model of a railway vehicle brake shoe

Estimation of temperature distribution in brake shoes is very important in order to prevent thermal damages such as cracks, fading etc. In this research, the thermal model of brake shoe in a train is introduced considering time-dependent frictional heat load in two modes of emergency and continuous braking. The governing heat conduction equation is solved in polar coordinate by using the method of separation of variables combined with Duhamel integral and a closed-form solution is introduced. Results show the good ability of analytical solution to estimate exact temperature profile in composite and cast iron brake shoes. The ability of the solution for estimation of braking situation to prevent from melting criteria is demonstrated. The composite brake shoe will reach to the melting point of 590 °C in continuous braking at the speed of about 120 km/h and the fading limit in cast iron shoe is occurred after 8 sec in emergency braking mode. The introduced thermal model can be applied as a verification branch of other works and can reduced the huge costs of experimental tests of brake shoes.

Investigation of the effect of addition of boron nitride on microstructure and mechanical properties of cast iron brake materials used in railway vehicles

In this study, characterization of cast iron break shoes used in locomotives and the effect of BN addition and BN addition on microstructure and mechanical properties by using powder metallurgy (PM) method by adhering to the chemical composition of cast iron break shoes were investigated. In this context, cast iron sabers were chemically analyzed and all elements were supplied in powder form, and then BN added powder compositions were produced by cold and hot pressing technique. A total of 4 different compositions were created without BN, with 0.25, 0.5 and 1 % BN addition. Cold pressing was made in a steel mold with a diameter of 10 mm under 700 MPa pressure under room conditions. Hot pressing was carried out in a graphite mold with a diameter of 15 mm in an argon atmosphere under a pressure of 45 MPa at a temperature of 900 °C. Then the cold and hot pressed samples were sintered at 1 200 °C for 2 hours in argon atmosphere. Density measurement of the produced compositions, microstructure examination, micro hardness measurement were made. Generally, in density measurements, the densities of the samples subjected to hot pressing were higher than the cold pressing process. The hardness value decreased in parallel with the addition of BN. Keywords: Brake shoe; powder metallurgy; microstructure; mechanical properties