NVH Gear Analysis & Testing

When gears mesh together they invariably create noise. Tightening gear tolerances and increasing sensitivity to NVH (noise, vibration, and harshness) levels have made this a critical issue. With more hybrid and electric vehicles hitting the roads every year, the demand for “ultra quiet” transmissions, gearboxes, and electrified powertrain systems can only grow. Systrand is here to help you meet that demand.

Systrand has steadily invested in proven production quality systems that proactively identify failure modes on single gears or in gear systems. We can track down transmission errors and NVH issues that previously could not be detected prior to assembly. Our component-level testing simulates the NVH levels that an individual helical gears and spur gears will experience at the system level. Simulated loads are used to mimic the stresses placed on an individual gear, and a noise signature is created for that gear. By evaluating and tracking anomalies in this noise signature, we can isolate an issue before a part is shipped to the customer.

Furthermore, this noise signature data is stored in a database linked to a unique laser-marked serial number. If a disruption later arises due to a known noise signature, we can trace which serial numbers share that same noise signature. OEMs can then rapidly diagnose and contain any potential issues.

The reality is that traditional approaches to gear inspection and control of gear manufacturing are no longer a reliable path toward reduced gear noise. This is especially the case with so-called “ghost order” noise. Ghost noise arises from vibrations that are not related to the bearing frequencies or meshing frequency of helical gears or spur gears and pinions (typically the sources of gear noise). It’s much more complex to analyze and track down than mesh harmonic noise.

A good gear design, produced to spec in a reliable process, can still produce ghost noise. The issue is the “micro-geometry” of the surface of the gear teeth, undulations, modulations, or ripples created in the gear surfaces during the manufacturing and finishing process. These ripples create and amplify vibration energy, leading to ghost order noise.

Importantly, these are often variations well within the acceptable range for surface finish deviations and inherent to the preferred high-production methods for grinding the flanks of the helical gears (for example). Were it not for the ultra quiet transmissions of EVs, their ability to contribute to ghost noise would probably not be detectable.

Since 1982, Systrand has specialized in precision machining. During that period, high-performance gears and gear testing became increasingly important to the automotive industry—and to us. Today, we live and breathe the NVH standards and requirements. We were among the first U.S. manufacturers to supply high-precision hybrid and electric (HEV/EV) gears, and now have millions of our hybrid and electric vehicle components in the field. More importantly, we have proven tools, processes, and procedures in place to ensure that every gear we manufacture performs to ever higher standards.

“Quality” isn’t just something for the Quality Department to worry about. It’s a commitment threaded through every office and workstation. At Systrand, we are a tier 1 supplier with IATF 16949 and ISO 14001 certifications. Our quality systems, processes, and entire organization are committed to ensuring quality for our customers.

Over four decades, we’ve invested and reinvested in the tools and talent that are vital to our customers’ success. That includes a world class operating system of monitored performance and a structured approach to problem solving proven to ensure reliable manufacturing.

These are metrics/results driven systems, built on Lean Manufacturing principles and Six Sigma methodology, and take into account activity-based costing and overall equipment effectiveness (OEE) while maintaining low- to zero PPM. Those systems form a foundation from which we can pursue continuous improvements and cost savings for our customers.