Brake shoe friction materials are critical elements of every vehicle. The advent of hybrid and electric cars, regenerative braking and modern safety regulations are key motivations to develop brake friction materials. Brake materials are typically evaluated by standard protocols such as SAE J2522 on a full-blown dynamometer. The test involves evaluating behavior of a friction material at varying pressures, speeds, temperatures and deceleration conditions. Designing and manufacturing real components for such tests is often a tedious and expensive process.
Rtec MFT 5000 is a modular tribometer that offers several ASTM/ISO/DIN standard and customized test on the same platform. Specifically, for the brake industry, MFT 5000 offers a cost-effective method for rapid brake materials testing. The versatile platform can test functionality and wear resistance of the brake pad material in conditions simulating dynamometer testing. It can measure inline torque, friction, pressure, temperature and speed. In addition, the patented inline imaging options allows the researcher to characterize wear w.r.t number of cycles. This application note describes the use of MFT 5000 to perform standard tests (SAE J2522) and a custom test to measure wear rate of the brake pad friction materials. Other tests such as pin on disc, linear reciprocating wear, fretting wear etc. can also be performed on the same platform.
Here, we demonstrate use of Rtec MFT 5000 to simulate a subsection of SAE J2522. Different material combinations can be quickly evaluated by testing on coupons. Three cylindrical samples are mounted as representative of brake materials. A cast iron disc is used as the counter surface. A minimum sample size of 12.7 mm X 6.35 mm [0.5”X0.25”] for brake materials and a disc of 50.8 mm radius [2”] for rotor is recommended. Other sample sizes can also be accommodated easily on the platform.
MFT 5000 with patented inline imaging technology offers the unique advantages to characterize wear vs. number of cycles on brake materials. The setup includes a 3D Profilometer designed specifically for tribology that combines spinning disc confocal and white light interferometry. Advanced encoders on the automatic stage allow the sample to alternate between mechanical test area and profilometer.
Rtec MFT 5000 is a fast, reliable and cost-effective tool for screening of brake materials. The high-resolution sensors can characterize even small changes in the composition of material. Using the inline profilometer it is possible to study the change in sample surface with sub nm resolution. The advantages in size and flexibility makes MFT 5000 an ideal tool to compliment full scale dynamometer testing.