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Analysis of Metal Pick-Up Formation Process within Automotive Brake Pad

SAE International Journal of Materials and Manufacturing

Ask Technica Corporation, Japan-Hirokazu Noda
University of Yamanashi, Japan-Takahiro Takei
  • Journal Article
  • 05-13-01-0003
Published 2019-11-19 by SAE International in United States
Metal Pick-Up (MPU) is a problematic phenomenon in automotive disc brakes. MPU generally forms as some metal lumps on the surface of the brake pad. If brake pads have MPU, during braking they would cause grooving of the disc rotor, generating brake noise and deteriorating the performance of the brake. The previous literature has so far reported that the source of the MPU is an Fe component from a disc rotor or brake pads. However, only a few of the generation mechanisms of MPU have been proven. We investigate MPU to completely elucidate the mechanism of MPU generation by using different analyses than the previous literature. First, to find out the source of MPU generation, we focus on the chemical reaction of a certain component with wear debris during braking, and some of the verification experiments are conducted under the conditions of simulated friction interface. Second, to clarify the change in the form of the MPU growth process, the crystal structure of MPU is analyzed in detail by using the world’s largest synchrotron radiation facility…
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The Influence of Differential Pad Wear on Low-Frequency and High-Frequency Brake Squeal

SKR Consulting Inc.-Seong K. Rhee
Technische Universitat Braunschweig-Johannes Otto, Georg-Peter Ostermeyer
Published 2019-09-15 by SAE International in United States
The NVH behavior of disc brakes in particular, is in the focus of research since a long time. Measurements at a chassis dynamometer show that brake pad wear has a significant influence on the occurrence of low- and high-frequency squealing [1]. It is suspected that high-frequency squealing is more likely to occur when the wear difference between the inner and outer brake pad is small. In the other case, if the differential wear rate between the inner and outer pads becomes higher, the prevalence of low-frequency squealing increases.In order to examine this hypothesis, this work focuses on a simplified model of a commercial brake system [2]. In a first step, the inner pad’s wear is iteratively increased, while the wear on the outer pad remains unaffected. In a second step, the coefficient of friction at the worn pad is iteratively increased to investigate the influence on the low and high-frequency squealing. With the aid of the Complex Eigenvalue Analysis (CEA), the real part of the eigenvalue is used as a quantification measure in order to…
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The Normal-Load and Sliding-Speed Dependence of the Coefficient of Friction, and Wear Particle Generation Contributing to Friction: High-Copper and Copper-Free Formulations

Compact International (1994) Co., Ltd.-Meechai Sriwiboon, Nipon Tiempan, Kritsana Kaewlob
SKR Consulting Inc.-Seong K. Rhee
Published 2019-09-15 by SAE International in United States
Automotive brakes operate under varying conditions of speed and deceleration. In other words, the friction material is subjected to a wide range of normal loads and sliding speeds. One widely accepted test procedure to evaluate, compare and screen friction materials is the SAE J2522 Brake Effectiveness test, which requires full-size production brakes to be tested on an inertia brake dynamometer. For the current investigation, disc pads of two types of 10 different formulations (5 high-copper and 5 copper-free formulations) were prepared for testing on a front disc brake suitable for a pickup truck of GVW 3,200 kg. Each pad had 2 vertical slots, and one chamfer on the leading edge and also on the trailing edge of the pad. One segment of the test procedure looks at the coefficient of friction (Mu) under different brake line pressures and different sliding speeds to determine its stability or variability. In all cases, the Mu is found to be dependent on the normal load and sliding speed, contrary to the commonly called “Amontons-Coulomb’s Laws of Friction”. According to…
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Inboard Mounted Disc Brake Rotor/Disc Wheel Hub Interface Dimensions - Commercial Vehicles

Truck and Bus Wheel Committee
  • Ground Vehicle Standard
  • J2696_201909
  • Current
Published 2019-09-03 by SAE International in United States
This SAE Recommended Practice establishes dimensions and tolerances for the interface between inboard mounted disc brake rotors and disc wheel hubs. This document is intended for inboard mounted disc brake rotors and disc wheel hubs for Class 5, 6, 7, and 8 commercial vehicles. Special and less-common applications are not covered.
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Inertia Dynamometer Rotor Crack Test Procedure for Air Disc Brakes

Truck and Bus Foundation Brake Committee
  • Ground Vehicle Standard
  • J3080_201905
  • Current
Published 2019-05-17 by SAE International in United States
This Recommended Practice applies to commercial vehicles equipped with air disc brakes and above 4536 kg of Gross Vehicle Weight Rating. Other assessments on the friction material or rotor related to wear, durability, correlation to product life, noise, judder, compliance to specific regulations, etc., are not part of this RP (Recommended Practice).
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ABS Exciter Ring Location Standardization

Truck and Bus Wheel Committee
  • Ground Vehicle Standard
  • J1730_201902
  • Current
Published 2019-02-11 by SAE International in United States
This SAE Recommended Practice establishes the Antilock Brake System [ABS] sensor interface and envelope dimensions for standardizing the location of the ABS rings mounted on the inner end of spoke wheels, hubs and hub-rotor assemblies on the following axle designations. a FF b FL c FC d FH e L f R g U h W j N k P
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Off-Vehicle Brake Testing for Service Brakes Over 10000 Pounds GVW Air, Hydraulic, and Mechanical Actuation

Truck and Bus Brake Systems Committee
  • Ground Vehicle Standard
  • J2806_201901
  • Current
Published 2019-01-14 by SAE International in United States
Subject document is specifically intended for service brakes and service brakes when used for parking and/or emergency brakes (only) that are commonly used for automotive-type, ground-wheeled vehicles exceeding 4536 kg (10000 pounds) gross vehicle weight rating (GVWR). Subject specification provides the off-vehicle procedures, methods, and processes used to objectively determine suitability of tactical and combat ground-wheeled vehicle brake systems and selected secondary-item brake components (aka, aftermarket or spare parts), including brake “block” for commercial applications only, specifically identified within subject document. Subject specification is primarily based on known industry and military test standards utilizing brake inertia dynamometers. Targeted vehicles and components include, but may not be limited to, the following: a Civilian, commercial, military, and militarized-commercial ground-wheeled vehicles such cargo trucks, vocational vehicles, truck tractors, trailers, and specialized support and engineering equipment under the generic heading of ground vehicle “dry” brake systems (GVDBS). b Hydraulic, air, and mechanical “dry” disc brake and drum brake systems, when used as service brakes, including service brakes (only), when used as emergency and/or parking brakes. c Hydraulic, air, and…
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Analysis of Changes in Disc-Brake Squeal Characteristic due to Regenerative Braking Simulation on Brake-Inertia-Dynamometer

HORIBA Europe GmbH-Dieter Weiss
HORIBA India Technical Center-Chaitanya Chilbule
Published 2019-01-09 by SAE International in United States
Brake is very crucial functional part of automobile, therefore need a robust testing for validation in order to ensure its failsafe functionality under harsh circumstances. For performance testing and foundation brake system design optimization purpose Brake-Inertia-Dynamometer (BID) being used extensively since its inception, and from last two decades for optimization of brake Noise, Vibration, and Harshness (NVH) performance too. In brake NVH the major issue is brake squeal or squeak generation, which is very difficult to predict its occurrences and standardized its prerequisite conditions. Since, brake is the only device which is designed for power absorption in automobile and therefore the regenerative braking concept come to the picture for energy conservation. The loss of energy in braking in case of Hybrid Electric Vehicle (HEV) and Electric Vehicle (EV) is more crucial and hence implementation of regenerative-braking is more discernible in HEVs and EVs to enhance the efficiency. Furthermore, the propensity of brake squeal generation plays very important role as its gain more attention by occupants and rise questions against vehicle’s level of sophistication especially in…
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Brake Pads, Lining, Disc, and Drum Wear Measurements

Brake Dynamometer Standards Committee
  • Ground Vehicle Standard
  • J2986_201901
  • Current
Published 2019-01-07 by SAE International in United States
This Recommended Practice provides a common method to measure wear of friction materials (brake pad assemblies and brake shoes) and their mating parts (brake disc or brake drum). These wear measurements apply to brakes fitted on passenger cars and light trucks up to 4536 kg of Gross Vehicle Weight Rating under the Federal Motor Vehicle Safety Standard (FMVSS), or vehicles category M1 (passenger cars up to nine occupants, including the driver) under the European Community’s ECE Regulations.
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FMVSS 105 Inertia Brake Dynamometer Test Procedure for Vehicles Above 4540 kg GVWR

Truck and Bus Hydraulic Brake Committee
  • Ground Vehicle Standard
  • J2684_201812
  • Current
Published 2018-12-05 by SAE International in United States
This Recommended Practice is derived from the FMVSS 105 vehicle test and applies to two-axle multipurpose passenger vehicles, trucks, and buses with a GVWR above 4540 kg (10000 pounds) equipped with hydraulic service brakes. There are two main test sequences: Development Test Sequence for generic test conditions when not all information is available or when an assessment of brake output at different inputs are required, and FMVSS Test Sequence when vehicle parameters for brake pressure as a function of brake pedal input force and vehicle-specific loading and brake distribution are available. The test sequences are derived from the Federal Motor Vehicle Safety Standard 105 (and 121 for optional sections) as single-ended inertia-dynamometer test procedures when using the appropriate brake hardware and test parameters. This recommended practice provides Original Equipment Manufacturers (OEMs), brake and component manufacturers, as well as aftermarket suppliers, results related to brake output, friction material effectiveness, and corner performance in a laboratory-controlled test environment. The test sequences include different dynamic conditions (braking speeds, temperature, and braking history as outlined in the FMVSS 105);…
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