BR(E)AKING NEWS!!! - MTI Instruments - #2

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sales@mtiinstruments.com • www.mtiinstruments.com The Problem No brake rotor is perfect. Inconsistencies in manufacturing processes introduce thickness variation and runout. It is important to identify these conditions prior to installation in a vehicle. In order to accomplish this, dynamic measurements of the rotor are required on the production line. Conventional non-contact capacitance displacement sensors are used to monitor the distance between the probe and the rotor while spinning. Unfortunately, rotating targets frequently have an intermittent, uncertain or nonexistent ground path which causes inaccuracies in typical capacitance sensors. The Solution MTII offers a unique “Push/Pull” Capacitance sensor (see Figure 2) which eliminates the need to electrically ground the rotor. This novel approach uses two sensing elements built into one probe body that work together to complete the measurement circuit. The push/pull probe design provides a clean and consistent electrical path resulting in decreased noise, higher accuracy and signifi cantly more stable and repeatable measurements. The Results Tests were performed to compare the results of a standard capacitance probe to that of MTII’s Push/Pull technology. As the rotor was rotated, the output of each sensor was captured on an oscilloscope and is presented in Figure 3. Clearly it can be seen that the Push Pull technology provides a much cleaner and more accurate output signal. MTII’s newest Multi-Channel brake rotor measurement system, the Accumeasure™ 500 (see Figure 4) provides up to 6 independent measurement channels in a rugged, compact amplifi er package. It provides the manufacturer the ability to measure thickness in 3 separate areas along the brake rotor radius “on the fl y”. The AS-500 can operate on 12 Vdc power for in-vehicle testing and its compact design is ideal for installation into small, confi ned spaces. The amplifi ers are specifi cally designed to be protected from shorts caused by the probe contacting the brake rotor or from contaminants such as water or oil. Based on the push/pull advantages, several major Japanese and Korean vehicle manufacturers have standardized on MTII’s Accumeasure sensors for their testing requirements. In addition to brake testing MTII’s sensors have been used in demanding applications such as spindle and shaft runout, engine vibration, thermal expansion and contraction, suspension travel and fuel injector motion, to name a few. If you have a challenging noncontact measurement application, contact MTII’s experienced Application Engineers for more details on laser, capacitance and fi ber-optic sensors. With over 50 years of product line history MTII will provide a practical, cost effective solution to meet or exceed your requirements. Figure 2 Figure 4 Figure 3 MTII appnote: breakrotors.pdf - Page 2 of 2