Guide
Friction Materials and Brake Pads Testing
How impulse excitation testing enables brake pad quality control by measuring resonance frequencies and damping per SAE J2598 standards.
Author: Flowzy
Overview
Brake noise reduction depends on tuning resonance frequencies of brake system components—disc, caliper, bracket, and pad—to create harmonization. Impulse excitation testing provides the measurement capability to achieve this tuning in production.
The Challenge: Production Variability
Brake pads exhibit significant frequency spread due to variations in:
- Friction material mixtures
- Compacting pressure
- Oven placement during curing
- Baking parameters
These process variations directly affect acoustic behavior and performance.
Standards Compliance
SAE J2598 standardizes natural frequency and damping measurement for disc brake pads, focusing on the first three frequencies as quality indicators. Compliance ensures consistent acoustic performance across production.
Testing Capabilities
The technology evaluates four frequencies and their damping characteristics, functioning as a universal quality control instrument:
| Capability | Benefit |
|---|---|
| Complete spectral inspection | Full frequency profile visualization |
| GO/NOGO discrimination | Sorting per OEM specifications |
| Damping quantification | Microcrack identification |
| Performance indicators | Spectral analysis development |
Material Fingerprinting
The system measures the mechanico-elastic behavior of brake pads at production line end:
- Lower frequencies: Indicate porosity and hardness
- Damping values: Reveal microcrack presence
- Frequency ratios: Show material consistency
Process Optimization
Manual operation allows manufacturers to evaluate how parameter adjustments impact production output:
Measurable Properties
- E-modulus (Young’s modulus)
- G-modulus (shear modulus)
- Poisson’s ratio
- Internal damping
Applicable Geometries
The system automatically calculates material characteristics across various object shapes, accommodating the diverse forms of brake pad designs.
Production Integration
Testing at end-of-line provides:
- 100% inspection capability
- Immediate feedback for process adjustment
- Objective sorting criteria
- Quality documentation for customers
This replaces subjective assessment with quantitative, traceable measurements.
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