Sensor Placement Matters: Are They Telling You What You Need to Know?
The promise of wireless vibration monitoring is powerful: real-time insights, early warnings, and fewer unexpected failures. But that promise is only as strong as the quality of the data your sensors provide. Poorly placed vibration sensors don’t just weaken your monitoring. They feed your team bad data, which leads to bad decisions.
That leads to the critical question every reliability leader should ask: Are your sensors actually telling you what you need to know?
At Waites, we’ve seen how subtle details—a sensor mounted on one bearing cap versus another or inside the load zone rather than just nearby—make the difference between catching a problem early and missing it until it’s too late. Correct placement, reliable mounting, and the right sensor selection aren’t small details. They’re the foundation of safer operations, lower maintenance costs, and meaningful insights you can act on.
How Placement Can Make or Break Your Sensor Data
When it comes to vibration monitoring, where you place the sensor is just as important as the sensor itself. A well-engineered device installed in the wrong spot will still deliver faulty or incomplete information.
Take bearing caps as a simple example. Some caps are designed so that they make direct contact with the bearing’s outer race. Mounting a sensor here gives you a solid transmission path and reliable vibration data. Other caps, however, act more like protective covers. They don’t connect structurally to the bearing race at all, which means a sensor mounted there will pick up weak or misleading signals.
The lesson is straightforward but critical: the physical contact path to the vibration source determines signal quality. If the sensor isn’t directly “listening” to the component under stress, it can’t give you the early warning data you’re counting on.
Case Study: Proving the Value of Placement
The placement principle becomes even clearer in high-speed, high-risk applications. In one case study, we examined centrifuges with spindle assemblies running at over 4,000 RPM. The factory-installed sensors were mounted on the outer housing, which was isolated with vibration absorbers to reduce imbalance. On paper, that sounds fine—but in practice, the isolators dampened the very signals that would have revealed developing bearing defects.
When Waites placed sensors directly on the spindle bearing housing (two radial and one axial), the results changed dramatically. Suddenly, defects could be detected up to 10 times earlier in their development. That difference allowed operators to:
- Eliminate unnecessary time-based rebuilds by switching to condition-based maintenance.
- Reduce repair costs by addressing bearing issues earlier.
- Improve safety by catching imbalance before it reached catastrophic levels, which is a critical concern with heavy centrifuge bowls spinning at extreme speeds.
The Key Factors of Getting Vibration Sensor Placement Right
Once you understand that placement determines data quality, the key question becomes: where, and how, should sensors be installed to capture the clearest signal? There are three key factors that make the difference between reliable data and misleading noise.
The Load Zone Advantage
Vibration data is always strongest in the bearing load zone, which is the area where force transfers through the bearing. Sensors mounted here pick up the earliest, most accurate signs of trouble.
Side-by-side readings show just how big the difference can be. A sensor mounted on the non-load side might show nothing unusual, while a sensor just a few inches away in the load zone will clearly reveal developing defects. Too often, sensors are placed on the non-load side for convenience, but this simple mistake delays detection and leaves operators blind to early warning signs.
The data makes it clear: placement matters. These charts from our motor bearing study show how a few inches can change what your sensors pick up and what they miss.
Fan Motor Shaft Sensor Placement
Top reading on outside of motor: 1st reading non load side; 2nd reading loaded side.
Fan Bearing Sensor Placement
Fan bearing: 1st reading non loaded side; 2nd reading loaded side.
Mounting Methods
How a sensor is attached is equally important. The mounting method directly affects the frequency response (and therefore, the accuracy) of your vibration data.
- Magnetic mounts are quick and convenient, but they don’t provide the solid contact needed for high-frequency accuracy. They can shift or get knocked loose, compromising repeatability and data reliability.
- Epoxy or stud mounts, on the other hand, create permanent, stable contact. That’s why Waites uses epoxy mounting as our standard practice for all sensors. Doing so promotes consistent, trustworthy data over the long term.
Single Axis vs. Tri-Axial Vibration Sensors
Tri-axial sensors have transformed vibration monitoring. Instead of needing multiple single-axis sensors and setups, a tri-axial unit captures three directions of vibration at once. That means faster installation, more complete data at every point, and the ability to uncover issues that might otherwise go unnoticed. Many reliability programs find they can cut route collection time nearly in half by using tri-axial sensors.
Of course, getting the most from tri-axial sensors still comes down to placement and interpretation. Only one axis will be perfectly aligned with the shaft, while the others may be slightly offset. That doesn’t reduce their value—it just means non-aligned axes should be treated as supplementary data points, especially useful for tracking rate of change rather than absolute amplitude.
Best practices make all the difference:
- Use permanent, near-bearing placements to secure a strong and consistent signal.
- Rely on aligned axes for amplitude, and trend the others for early fault indicators.
- Don’t underestimate distance: even a one-inch relocation can dramatically change the readings you capture.
How Waites Vibration Analysts Validate Data Integrity
Getting vibration monitoring right extends beyond installing sensors to analyzing and consistently capturing meaningful data. That’s why Waites uses tri-axial, epoxy-mounted sensors as a standard, creating a permanent and reliable connection for accurate, repeatable results.
Reliability is built on three equally powerful strengths at Waites: hardware, AI, and people. Our sensors deliver industry-leading performance, with 11.2 kHz sensing (detecting issues beyond 30 kHz), unmatched radio range and density (over 25,000 sensors in a single site), and rugged durability that thrives from -40ºC to +85ºC—even in caustic or underwater conditions. That data feeds into advanced AI models trained on more than 8 trillion historical readings and 10 billion new ones every day, allowing us to separate true faults from background noise. And behind it all, our certified analysts and reliability engineers partner directly with customers to interpret signals and recommend the right actions.
Together, the result is simple: with Waites, you’re not just getting vibration sensors, you’re getting a reliability partner that turns raw data into actionable solutions.
Make Every Sensor Reading Count
The difference between early detection and catastrophic failure often comes down to just a few inches of sensor placement. Put a sensor on the wrong surface, outside the load zone, or mounted with the wrong method, and you risk being blind to the signals that matter most. Get it right, and those same sensors can uncover defects months earlier, giving your team time to plan, repair, and keep operations running smoothly.
Waites places, mounts, and monitors your facility’s sensors the right way, so you can rest easy knowing your equipment health is our number one priority. With an average of 1,500 sensors per site, our clients benefit from the highest sensor density in the industry. That level of coverage means no critical asset gets overlooked and no early warning goes undetected.
Don’t settle for condition monitoring that simply “checks the box.” Get the clarity, confidence, and early warnings your team needs to stay ahead of failure.
