1. Introduction: Need to Modernize Industrial Bearing Systems
Operational efficiency and regulatory compliance are critical imperatives for the aerospace and energy industries. Outdated bearing systems, while functional, often represent a weak point in terms of energy consumption, maintenance needs and overall reliability. Upgrading these components is not just about increased performance; it is essential to meet environmental requirements, such as European Directive 2009/125/EC on ecodesign, and current productivity expectations.
Proactively replacing conventional bearings with sealed-for-life solutions, such as the ABB EV1141 bearing, helps reduce life cycle costs and minimize the carbon footprint of operations.
2. Assessment of Legacy Systems: Pre-Renovation Criteria
Before embarking on a renovation strategy, a rigorous assessment of existing bearings is essential. This analysis must cover several technical and operational dimensions in order to identify the components whose replacement would bring the most significant benefit.
| Evaluation Criteria | Description | Impact on the Replacement Decision |
|---|---|---|
| Re-lubrication frequency | Maintenance interval (e.g. every 500 hours). | Labor costs and contamination risks. |
| Energy Consumption | Power dissipation due to friction (eg: +1 kW per bearing compared to a modern solution). | High operational costs, non-compliance with energy audits (EN 16247). |
| MTBF (Mean Time Between Failures) | Average duration between two failures (e.g.: 5,000 hours). | High risk of unplanned production shutdowns. |
| Vibration Levels and Temperature | Measurements according to ISO 10816 (eg: Class C or D). | Advanced degradation indicators, risk of catastrophic failure. |
| Operational Environment | Presence of contaminants (dust, humidity, chemicals). | Accelerated wear of unprotected bearings. |
| Cost of Failure | Cost of repair, spare parts, loss of production. | Economic justification for preventive replacement. |
An in-depth analysis of these parameters makes it possible to quantify the modernization opportunity.
3. Modern Alternatives: Comparison and Advantages of Lifetime Sealed Bearings
Bearing technologies have evolved considerably. Sealed-for-Life (SFL) bearings offer significant advantages over traditional open or shielded designs. These bearings are factory pre-lubricated with a high quality grease and permanently sealed, eliminating the need for on-site re-lubrication.
| Feature | Conventional bearing (ex: 6205 open) | Sealed for Life bearing (e.g. ABB EV1141) |
|---|---|---|
| Maintenance (Lubrication) | Requires regular re-lubrication (eg: every 500-1000 hours). | Maintenance free (lubricated for life). |
| Protection Against Contaminants | Low or none. Sensitive to dust, humidity. | Excellent protection (e.g. type 2RS seals), ATEX compliance possible. |
| Lifespan (MTBF) | Limited by grease degradation and contamination (e.g.: 5,000 – 10,000 h). | Extended thanks to optimized grease and sealing (eg: 25,000 – 50,000 h). |
| Energy Consumption | Higher friction, up to 20% more energy loss. | Optimized friction, significant reduction in losses (e.g.: 0.5 kW per bearing). |
| Initial Cost | Generally lower. | Typically 15-30% higher. |
| Total Cost of Ownership (TCO) | High due to maintenance, energy and failures. | Lower due to maintenance and energy savings. |
The ABB EV1141, designed for demanding applications, exemplifies the capabilities of SFL bearings. It incorporates advanced materials and optimized geometry to minimize friction and maximize service life, even in hostile conditions such as those encountered in aerospace or energy.
4. Calculation of Return on Investment (ROI)
Replacing bearings is a strategic investment. A detailed financial analysis is crucial to justify this transition. Consider a typical case for an industrial pump operating 8,000 hours/year.
Cost Assumptions
- Energy cost: €0.15/kWh
- Hourly labor rate: €60/hour
- Cost of production shutdown: €500/hour
- Initial cost of conventional bearing: €50
- Initial cost ABB EV1141 bearing: €75
Current Scenario (Obsolete Bearing)
- MTBF: 5,000 hours.
- Re-lubrication frequency: every 500 hours (1 hour of work per operation, 1 kg of grease at €10/kg).
- Additional energy consumption due to friction: 1 kW per bearing.
- Average downtime for replacement: 8 hours.
- Number of bearings to replace per year: 8,000h / 5,000h = 1.6 bearings/year (rounded to 2 for analysis).
Annual Rolling Costs Obsolete
- Energy cost (8000h * 1kW * 0.15€/kWh): €1,200
- Re-lubrication cost (8000h / 500h * 1h * 60€/h + 8000h / 500h * 1kg * 10€/kg): €960 + €160 = €1,120
- Failure cost (1.6 * 8h * €500/h): €6,400
- Cost of spare parts (2 * 50€): 100 €
- Total annual cost: €8,820
Modernized Scenario (ABB EV1141)
- MTBF: 25,000 hours.
- No re-lubrication.
- Reduced power consumption: 0.5 kW per bearing (saving 0.5 kW).
- Average downtime for replacement: 4 hours (less complex, better planning).
- Number of bearings to replace per year: 8,000h / 25,000h = 0.32 bearings/year (rounded to 1 every 3 years).
ABB EV1141 Annual Costs
- Energy cost (8000h * 0.5kW * 0.15€/kWh): €600
- Re-lubrication cost: €0
- Failure cost (0.32 * 4h * 500€/h): 640 €
- Cost of spare parts (1/3 * €75): €25
- Total annual cost: €1,265
ROI Analysis
- Annual savings: €8,820 - €1,265 = €7,555
- Initial investment cost (difference in bearing cost): €75 - €50 = €25 (for a single bearing replaced, which is underestimated because the renovation would apply to the entire fleet).
For a fleet of 100 bearings to be modernized, the initial investment is €2,500. The annual savings amount to €755,500. The return on investment is almost immediate, with a return on investment (ROI) time of only a few months.
5. Staged Implementation Roadmap
The implementation of a renovation program must be planned precisely to minimize production interruptions.
- Audit and Prioritization of Assets: Identify critical equipment and bearings presenting the highest risks or the most significant maintenance costs. Use condition monitoring data (vibration, temperature) compliant with ISO 10816 to prioritize.
- Selection and Procurement: Collaborate with qualified suppliers such as UNITEC-D to select suitable SFL bearings (e.g. ABB EV1141) and ensure the availability of compatible spare parts.
- Production Shutdown Planning: Integrate bearing replacements into planned maintenance shutdowns, or group them together to optimize intervention time. Minimizing downtime is essential.
- Installation and Alignment: Implement strict installation procedures. Accurate shaft alignment (according to ISO 1940-1) is crucial to bearing life. Use appropriate assembly and disassembly tools.
- Commissioning and Monitoring: After installation, perform performance tests and establish a condition monitoring program for the retrofitted bearings. Monitor vibration, temperature and power consumption to validate gains.
6. Technical Challenges and Associated Solutions
Renovating bearing systems can present technical challenges.
- Housing Compatibility: SFL bearings have standardized dimensions (EN ISO 15). However, minor adaptations to housings or bearings may be necessary for some older equipment. Fixing sleeves or reducing rings supplied by UNITEC-D can solve this problem.
- Vibration Analysis: Modification of friction and mass characteristics can influence vibration signatures. A post-installation vibration analysis is imperative to confirm system integrity and compliance with ISO 10816. standards
- Thermal Management: Although SFL bearings generate less heat, the thermal design of the housing must be reviewed, especially for high speed or high temperature applications, to ensure adequate heat dissipation and prevent overheating.
- Installation Procedures: Correct installation is critical. Improper installation can significantly reduce bearing life. Technicians must be trained in hot (induction) and cold assembly techniques, respecting the tolerances defined by EN standards.
7. Case Study: Retrofit of an Industrial Air Compressor
A manufacturing plant in the energy sector was experiencing recurring bearing failures on a critical air compressor, operating 24/7. The open, manually lubricated ball bearings had an MTBF of only 6,000 hours and required re-lubrication every 750 hours.
Before the Renovation
- MTBF observed: 6,000 hours.
- Re-lubrication frequency: Every 750 hours (1.5 labor hours per bearing).
- Annual failures: 1.3 shifts/year (8,760 hours / 6,000 hours).
- Annual maintenance cost (lubrication + replacement): €2,500 per bearing.
- Energy consumption due to friction: 1.2 kW additional.
After Renovation with ABB EV1141
The compressor bearings have been replaced with ABB EV1141 sealed for life. The renovation was carried out during a planned 48-hour plant shutdown, minimizing the impact on production.
- MTBF observed: > 20,000 hours (extension of more than 230%).
- Re-lubrication: Eliminated.
- Annual failures: 0.4 turnover/year (8,760 hours / 20,000 hours).
- Annual maintenance cost: Reduced to €800 per bearing (mainly replacement).
- Energy consumption: Reduction of 0.7 kW per shift (saving of 6,132 kWh/year, or €919.8/year at €0.15/kWh).
The annual savings per rotation amounted to (2500€ - 800€) + 919.8€ = 2619.8€. The initial investment cost, including the part and installation, was amortized in less than a year.
8. Commissioning and Validation: Ensuring Performance
The commissioning phase after a bearing replacement is fundamental to guarantee that the expected performance is achieved.
Validation procedures:
- Visual Inspection: Verification of the integrity of the installation, the absence of visible damage and the correct positioning of the joints.
- Initial Vibration Analysis: Acquisition of a new vibration baseline (according to ISO 10816-1 and ISO 10816-3 for industrial machines) for ABB EV1141 bearings. Comparison with manufacturer's specifications.
- Thermal Monitoring: Control of operating temperatures (in accordance with ISO 15242-1) during the first hours of operation. Stable temperatures and within acceptable limits are indicative of correct installation and adequate lubrication.
- Functional Tests: Running the equipment at different loads and speeds to confirm general proper operation and integration of the new bearing into the dynamic system.
Acceptance criteria include vibration levels below Class B (ISO 10816), a stable operating temperature not exceeding 80°C, and an absence of abnormal noises.
9. Conclusion: The Lifetime Sealed Bearing Strategy
Replacing obsolete bearings with sealed-for-life solutions represents a modernization strategy with high added value. The gains are manifested by a drastic reduction in maintenance costs, optimization of energy consumption, an increase in equipment reliability and reinforced compliance with environmental regulations.
The initial investment is quickly offset by substantial operational savings, making this approach essential for plant engineers, maintenance managers and investment decision-makers. For precise technical selection and sourcing of performance bearings, including life-sealed alternatives like ABB EV1141, see the UNITEC-D E-Catalog.
10. References
- Directive 2009/125/EC of the European Parliament and of the Council of 21 October 2009 establishing a framework for setting ecodesign requirements for energy-related products.
- EN 16247: Energy audits – Part 1: General requirements.
- ISO 281: Bearings – Dynamic bearings – Rated loads and rated lifespans.
- ISO 10816-1: Mechanical vibrations – Assessment of machine vibrations by measurements on non-rotating parts – Part 1: General guidelines.
- ISO 15242-1: Bearings – Methods of measuring temperature characteristics – Part 1: General principles.
- SKF Bearing Migration Guide for Specific Applications (Technical Reference Document).
- AFNOR NF E 22-251: Bearings – Graphic symbols for pneumatic and hydraulic diagrams (indirect applicability for surrounding systems).
