When a bearing fails, the obvious culprits often get blamed first:
- poor lubrication
- contamination
- improper installation
But lurking underneath many of these surface-level issues is a deeper problem – excessive stress. This internal force is what ultimately pushes components beyond their limits and causes otherwise preventable breakdowns.
Whether you’re running industrial compressors, agricultural machinery, or plant-wide conveyor systems, understanding bearing stress is critical to improving your equipment’s structural integrity and long-term reliability.
In this guide, we’ll explain how bearing stress is calculated, what causes it to spike, and what strategies engineers use to reduce it – all in clear, practical terms tailored to maintenance pros and sourcing teams alike.
Ignoring bearing stress doesn’t just lead to part failure – it drives up repair costs, strains production schedules, and often leaves you scrambling to source replacements under pressure. Fatigue cracks, elongated holes, and warped bearing seats are often symptoms of stress that went unchecked for too long.
But with the right understanding and sourcing support, you can avoid these downstream issues and keep your operation running smoothly with properly sized, properly installed components.
How Do You Measure the Pressure on Your Bearing Components?
In mechanical engineering, bearing stress refers to the pressure between two contacting surfaces, typically between a pin and a hole, or a shaft and its housing. It is defined by the formula:
Bearing Stress (σ) = Force Applied (F) / Bearing Area (A)
While the equation is simple on paper, its real-world application depends on several factors: the exact shape of the contact area, whether the force is evenly distributed, and the material properties of both components in contact.
For instance, if you’re mounting a bearing into a steel structure and applying a known radial load through the shaft, the actual contact surface – or bearing area – must be carefully calculated based on the width and diameter of the mating parts. Even small deviations in measurement or fit can result in a load exceeding safe levels, triggering fatigue, deformation, or outright failure.
Let’s take a real-world example: imagine a conveyor belt motor with a drive shaft supported by a standard ball bearing. If the shaft diameter is 50 mm and the width is 20 mm, that gives you a bearing area of roughly 1,000 mm². If that system applies a radial force of 10,000 N, the bearing stress would be 10 MPa.
However, if the load suddenly spikes due to a jam, or the shaft fit is too tight causing reduced contact area, the pressure could easily double – and that’s enough to cause deformation in many standard housings.
It’s also important to note that these values vary depending on whether the load is static or dynamic, and whether it’s applied in a shear (parallel) direction or purely compressive (perpendicular).
Calculations should always factor in safety margins and the yield strength of the materials involved. When in doubt, consult a stress table or standardized engineering chart – or better yet, bring in a bearing supplier (like us) who knows exactly how to guide you to the right specs.
Of course, calculations are just one part of the picture; understanding the real-world signs of excessive load is equally important for preventing costly failures.
6 Ways to Tell if Your Bearing is Under Too Much Stress
Spotting early signs of bearing stress is critical to avoiding catastrophic failure. While some symptoms mimic general wear or misalignment, others point directly to excessive contact pressure between parts. Here are some of the most common indicators:
- Uneven wear on the bearing raceways – May suggest misalignment or excessive localized force.
- Discoloration or heat marks – High operating temperatures due to stress overload can cause bluing or dark patches.
- Vibration or noise during operation – Can indicate excessive radial or axial force, internal clearance issues, or distortion of the housing.
- False brinelling patterns – Circular dents from stationary vibration, often caused by poor storage or external environmental stress.
- Loosening of fasteners or mounting bolts – Suggests excessive dynamic load transfer through bolted joints, causing shifting or elongation.
- Lubricant leakage or breakdown – Excess pressure or heat degrades grease more rapidly, resulting in thin film failure or dry spots.
These symptoms are more than minor annoyances – they’re red flags for structural stress. If you spot any of these issues, it’s time to either reassess the application conditions or consider a properly sized, properly rated replacement.
Where Does Bearing Stress Come From? 6 Primary Causes
Even with proper calculations, bearing stress problems can arise when hidden variables stack up with 6 leading causes:
1. Overloading
Exceeding the load rating of your bearing causes stress to rise beyond the material’s capacity, leading to early fatigue and cracks around the contact point. This is especially risky in dynamic systems where the applied force fluctuates or spikes during operation.
2. Misalignment
When shafts and housings aren’t aligned properly, the force is no longer distributed across the full bearing area. This uneven loading increases pressure on localized areas, eventually creating deformation or edge fractures.
3. Contamination
Dirt, metal shavings, or moisture between contact surfaces reduce effective bearing area and introduce abrasive stress points that can deform or pit the metal. Over time, these micro-defects compromise surface area contact and raise stress well above safe limits.
4. Clearance Problems
If internal clearances are too tight, especially at high temperatures, thermal expansion reduces the bearing area and causes contact pressure to spike. On the flip side, too much clearance allows excessive play, which introduces impact loads and stress fluctuations.
5. Improper Installation
Forcing a bearing into a housing, or using fasteners with too much preload, introduces unwanted shear forces. Misalignment during mounting can also skew contact pressure, turning what should be a flat, uniform load into an uneven and damaging force.
6. Material Incompatibility
Using structural members or joints with mismatched material properties (e.g., soft aluminum housing with a hardened steel shaft) can lead to uneven compression stress and plastic deformation over time. The difference in how each material handles stress and strain can create long-term fatigue issues.
Even a small oversight in one of these areas can cause bearing stress to exceed safe tolerances. That’s why selecting the right parts – with the correct clearances, load capacity, and material properties – is so critical to long-term performance.
Need New Parts? Our Team Helps You Source Exactly the Right Bearing for Your Load
When bearing stress exceeds design limits, the best course of action is often replacement – but not just any replacement. You need the right part: one that matches the load, material requirements, area, and fit for your specific application.
Whether you’re working with bolted connections, rotating shafts, or heavy structural members, the wrong choice can quickly lead to repeat failures.
At Central Surplus, we make sourcing stress-resistant components fast and straightforward. If you know the part number, we’ll help you match it. If not, just send us the basic specs – like load applied, type, full dimensions (IDxODxWidth) or application – and our team will guide you through the options.
We stock thousands of new industrial components, all competitively priced and available for same-day shipping.
Don’t guess when it comes to contact pressure, yield strength, or the right bearing stress calculation. Reach out today and let our experts help you find a precise solution that protects your equipment and preserves your peace of mind.
8 Effective, Expert-Approved Strategies to Manage Bearing Stress
Keeping your systems running optimally necessitates thoughtful design, proper installation, and consistent maintenance. Below are 8 proven strategies used by maintenance teams and engineers to reduce stress, prevent failures, and maximize equipment life.
1. Choose the Right Bearing Type for the Load
Select industrial-grade bearings specifically designed for the direction, magnitude, and duration of the applied force. For example, tapered roller bearings handle combined loads better than ball bearings and can significantly reduce localized stress.
2. Optimize Shaft & Housing Fits
Ensure tolerances and mounting surfaces are precise to avoid misalignment and uneven stress distribution. Using precision locknuts and inspecting for roundness or taper can prevent distortion of the inner ring.
3. Use Bearings with Appropriate Clearance
Internal clearance affects how the bearing responds under thermal expansion and operational load. Too tight, and stress spikes; too loose, and vibration increases – both shorten lifespan.
4. Avoid Overloading Beyond Bearing Rating
Respect the manufacturer’s rated dynamic and static load limits to avoid plastic deformation or early fatigue failure. Implementing load monitoring can also help detect unexpected spikes before damage occurs.
5. Control Operating Temperatures
Install temperature sensors or thermal cutoffs to avoid excess heat that causes lubricant breakdown and material expansion. High heat reduces hardness and changes internal clearances – both elevate stress.
6. Improve Lubrication Practices
Consistently apply the correct type and quantity of lubricant, and avoid mixing incompatible greases. Lubricants not only reduce friction but act as a cushion that absorbs stress between contact points.
7. Align Equipment Precisely During Installation (and Periodically Check It)
Improper alignment leads to uneven loading and accelerates surface fatigue. Use laser alignment tools or dial indicators during setup to ensure concentricity and perpendicularity.
8. Prevent Vibration During Storage or Idle Periods
Even stationary bearings can suffer damage from ambient vibrations that cause false brinelling. Rotate stored bearings occasionally and isolate them from high-vibration areas to preserve surface integrity.
Together, these strategies form the foundation of a stress-conscious maintenance plan. Now, let’s tackle some of the most frequently asked questions about bearing stress so you can troubleshoot issues with greater speed and confidence.
5 Bearing Stress FAQs to Help You Prevent Damage Faster
Even with the right practices in place, questions still come up–especially when diagnosing unusual wear or selecting replacement parts. Below are some of the most frequently asked questions about bearing stress and how to manage it effectively.
1. What’s the difference between bearing stress and normal stress?
Normal stress is force per area applied perpendicular to a surface. Bearing stress, however, occurs between contacting bodies – like a pin pressing against a hole – and is directional, often compressive.
2. How do I reduce stress without changing the load?
You can increase the bearing area (e.g., wider components or more bolts), use stronger materials, or improve fit and finish to reduce contact pressure.
3. Can using lubricants help reduce bearing stress?
Yes – lubricants reduce friction, which helps distribute force more evenly across surfaces and reduces peak stress concentrations.
4. What’s the failure mode for excessive bearing stress?
Typical stress failures include cracking, plastic deformation, edge shearing, and hole elongation. All reduce structural integrity and must be addressed immediately.
5. Do fasteners affect bearing stress?
Absolutely. The size, placement, and torque of bolts can all influence bearing area and applied pressure. Use washers or backing plates to reduce stress concentrations.
Reduce Your Stress: Bearing Experts to Help You Seamlessly Find & Replace Parts
When bearing stress causes damage, downtime isn’t your only problem. You also need to find a replacement – fast – and make sure it won’t fail again under the same conditions.
That’s where we come in.
At Central Surplus, we specialize in hard-to-find, industrial-grade bearings for every type of load, pressure, and contact surface. Whether you’re replacing a precision-fit joint or redesigning a high-load bolted connection, our team can help you identify the right dimensions, materials, and ratings to prevent repeat failures.
If you don’t see the bearing part number you need in our vast inventory, we can help you source it fast. Send us a message and let us reduce your stress by finding the right part for your next job.
