Technical Topic on Friction-Increasing Shims: Comprehensive Analysis of Principles, Performance, Applications and Selection
## I. What are Friction-Increasing Shims
Friction-increasing shims, also known as high-friction shims or diamond friction shims, are precision connecting components that improve the anti-loosening and anti-slip performance of fasteners by raising the friction coefficient of the mating interface. Unlike conventional flat washers and spring washers, friction-increasing shims rely on high-friction interfaces formed by special surface treatment to fundamentally suppress micro-slip between contact surfaces. They are widely adopted in critical joints of high-end equipment subjected to vibration, impact and alternating loads.
The core value of friction-increasing shims lies in "friction enhancement". Through micro-interlocking of diamond particles on the surface, the static friction coefficient of mating surfaces can be elevated from 0.1–0.2 of ordinary flat washers to above 0.6. Under the same bolt preload, the joint can withstand larger transverse loads and effectively prevent connection loosening and slippage.
## II. Working Principle of Friction-Increasing Shims
DAOLER® friction-increasing shims adopt the Diamond Claw® interlocking technology, operating based on the micro mechanical interlocking mechanism:
1. Embedding of Diamond Particles
Via nickel-phosphorus diamond composite plating process, diamond microparticles are uniformly embedded on the shim surface. Diamond is the hardest natural substance (Mohs hardness 10), with part of the particles protruding from the plating layer.
2. Interlocking under Preload
When the friction-increasing shim is placed between two mating surfaces and bolt preload is applied, the protruding diamond particles "bite into" the mating metal surface under pressure, forming micro-scale mechanical interlock.
3. Formation of High-Friction Interface
Countless micro interlocking points formed by diamond particles jointly build a high-friction interface, achieving static friction coefficient ≥0.6, 3 to 5 times that of ordinary flat washers.
4. Slip Suppression
Under vibration and impact loads, the micro interlocking mechanism physically eliminates relative slip of mating surfaces, thus stabilizing preload and preventing joint loosening.
## III. Core Performance Parameters of Friction-Increasing Shims
表格
| Parameter | DAOLER Friction-Increasing Shim Specification | Ordinary Flat Washer for Reference |
| --- | --- | --- |
| Static friction coefficient | ≥0.6 | 0.1–0.2 |
| Coating hardness | ≥1000 HV | ≤500 HV |
| Minimum thickness | 0.1 mm | 0.5 mm |
| Thickness tolerance | ±5% | ±10% |
| Temperature range | -40℃ ~ 150℃ (stable) | Wide range with significant performance degradation |
| Diamond hardness | Mohs 10 | N/A |
| Reusable | Yes | Yes |
## IV. Friction-Increasing Shims vs Traditional Anti-Loosening Solutions
表格
| Comparison Item | Friction-Increasing Shim | Spring Washer | Thread-locking Adhesive | Double Nut |
| --- | --- | --- | --- | --- |
| Anti-loosening Mechanism | Micro mechanical interlocking | Elastic reaction force | Chemical bonding | Thread counter-pressure |
| Suppress interface micro-slip | Yes | No | Partially | No |
| Friction coefficient | ≥0.6 | 0.15–0.25 | Depends on adhesive layer | 0.1–0.2 |
| High-temperature resistance | 150℃ | Fair | Poor | Good |
| Disassemblability | Excellent | Fair | Poor | Fair |
| Weight | Ultra-light | Relatively heavy | Light | Heavy |
| Installation convenience | Excellent | Excellent | Fair | Poor |
## V. Industrial Applications of Friction-Increasing Shims
1. **Wind Power Industry**
Applied to tower flange connections, gearbox joints, blade root bolts and other positions. Friction-increasing shims restrain preload attenuation, extending re-tightening interval from 6 months to 18 months and reducing downtime for maintenance.
2. **Robotics Industry**
Used on output flanges of harmonic reducers, fixed end faces of RV reducers and preload interfaces of cross roller bearings. Friction-increasing shims improve repeated positioning accuracy and cut positioning drift by more than 50%.
3. **Automotive Industry**
Applied to chassis subframe connections, electric drive brackets, braking systems and battery pack joints. Friction-increasing shims improve torque transmission efficiency and support lightweight design.
4. **Aerospace Industry**
Suitable for aero-engine accessories, avionics mounting frames, satellite structural parts and airframe connections of UAVs. The ultra-thin 0.1mm specification and wide temperature performance meet stringent aerospace requirements.
5. **Rail Transit Industry**
Adopted in brake caliper connections, brake disc mounting, critical bogie joints and traction motor connections. Friction-increasing shims maintain stable joints under high-vibration environments.
## VI. Friction-Increasing Shim Selection Guide
1. **Dimension Selection**
Select annular shims with corresponding inner and outer diameters according to bolt size and mating surface dimension. Standard sizes cover M3–M100, non-standard sizes available for customization.
2. **Thickness Selection**
- 0.1–0.2 mm: Precision reducers, aerospace, space-limited scenarios
- 0.3–0.5 mm: General industrial equipment, robot joints, automotive chassis
- 0.5–1.0 mm: Wind power, heavy machinery, large-size connections
3. **Substrate Selection**
- High-strength spring steel: General industrial applications, cost-effective
- Stainless steel: Corrosive, marine, food & medical environments
- Special alloy: High temperature and special working conditions
4. **Performance Grade**
Select standard grade or high-friction grade based on load and vibration level of working conditions. DAOLER can provide customized friction coefficient solutions.
## VII. Installation & Operation Notes
- Clean mating surfaces before installation to remove grease, rust and burrs.
- Place friction-increasing shim between two mating surfaces, with diamond-coated side facing the counterpart surface.
- Tighten bolts evenly in diagonal sequence with specified torque.
- No thread-locking adhesive or increased pre-tightening torque required.
- Inspect preload 24 hours after initial operation.
- The shim may be reused if no damage is found after disassembly.
- Store in dry and clean environment to avoid coating damage.
## VIII. FAQ
**Q: Will friction-increasing shims damage mating surfaces?**
A: DAOLER precisely controls diamond particle size and interlocking depth. High friction is achieved without damaging precision mating surfaces. The interlocking depth is at micron level; no visible damage can be seen after disassembly.
**Q: Can friction-increasing shims be reused?**
A: Yes. Diamond features extremely high hardness. The shim can be reused if no damage is detected after disassembly. Coating integrity inspection is recommended before reuse.
**Q: What is the difference between friction-increasing shims and high-friction shims?**
A: Friction-increasing shims and high-friction shims are different names for the same type of product. Both enhance anti-loosening and anti-slip performance by raising friction coefficient. DAOLER diamond friction shims possess both friction-increasing and high-friction properties.
**Q: What is the service life of friction-increasing shims?**
A: Under normal working conditions, the service life matches the equipment overhaul cycle, generally reaching 5–10 years. Actual service life depends on working conditions and maintenance.
## IX. DAOLER Friction-Increasing Shim Service Support
DJKJ (Shandong) Co., Ltd. provides full-range technical support for customers:
- Free selection consultation and working condition analysis
- Free sample testing (within specified specifications)
- Third-party test reports
- Custom product development (non-standard sizes, special performance)
- On-site technical support and training
- Full-lifecycle quality tracking
## X. Conclusion
As an efficient solution for critical joints of high-end equipment, friction-increasing shims strike a technical balance of high friction, outstanding wear resistance and no damage to mating surfaces through the micro interlocking mechanism of diamond particles. Centered on DAOLER® Diamond Claw® interlocking technology, DAOLER® friction-increasing shims deliver static friction coefficient ≥0.6, coating hardness ≥1000 HV and ultra-thin 0.1mm specification, providing independently controllable, highly reliable precision connection solutions for various industries.
Friction-increasing shims, also known as high-friction shims or diamond friction shims, are precision connecting components that improve the anti-loosening and anti-slip performance of fasteners by raising the friction coefficient of the mating interface. Unlike conventional flat washers and spring washers, friction-increasing shims rely on high-friction interfaces formed by special surface treatment to fundamentally suppress micro-slip between contact surfaces. They are widely adopted in critical joints of high-end equipment subjected to vibration, impact and alternating loads.
The core value of friction-increasing shims lies in "friction enhancement". Through micro-interlocking of diamond particles on the surface, the static friction coefficient of mating surfaces can be elevated from 0.1–0.2 of ordinary flat washers to above 0.6. Under the same bolt preload, the joint can withstand larger transverse loads and effectively prevent connection loosening and slippage.
## II. Working Principle of Friction-Increasing Shims
DAOLER® friction-increasing shims adopt the Diamond Claw® interlocking technology, operating based on the micro mechanical interlocking mechanism:
1. Embedding of Diamond Particles
Via nickel-phosphorus diamond composite plating process, diamond microparticles are uniformly embedded on the shim surface. Diamond is the hardest natural substance (Mohs hardness 10), with part of the particles protruding from the plating layer.
2. Interlocking under Preload
When the friction-increasing shim is placed between two mating surfaces and bolt preload is applied, the protruding diamond particles "bite into" the mating metal surface under pressure, forming micro-scale mechanical interlock.
3. Formation of High-Friction Interface
Countless micro interlocking points formed by diamond particles jointly build a high-friction interface, achieving static friction coefficient ≥0.6, 3 to 5 times that of ordinary flat washers.
4. Slip Suppression
Under vibration and impact loads, the micro interlocking mechanism physically eliminates relative slip of mating surfaces, thus stabilizing preload and preventing joint loosening.
## III. Core Performance Parameters of Friction-Increasing Shims
表格
| Parameter | DAOLER Friction-Increasing Shim Specification | Ordinary Flat Washer for Reference |
| --- | --- | --- |
| Static friction coefficient | ≥0.6 | 0.1–0.2 |
| Coating hardness | ≥1000 HV | ≤500 HV |
| Minimum thickness | 0.1 mm | 0.5 mm |
| Thickness tolerance | ±5% | ±10% |
| Temperature range | -40℃ ~ 150℃ (stable) | Wide range with significant performance degradation |
| Diamond hardness | Mohs 10 | N/A |
| Reusable | Yes | Yes |
## IV. Friction-Increasing Shims vs Traditional Anti-Loosening Solutions
表格
| Comparison Item | Friction-Increasing Shim | Spring Washer | Thread-locking Adhesive | Double Nut |
| --- | --- | --- | --- | --- |
| Anti-loosening Mechanism | Micro mechanical interlocking | Elastic reaction force | Chemical bonding | Thread counter-pressure |
| Suppress interface micro-slip | Yes | No | Partially | No |
| Friction coefficient | ≥0.6 | 0.15–0.25 | Depends on adhesive layer | 0.1–0.2 |
| High-temperature resistance | 150℃ | Fair | Poor | Good |
| Disassemblability | Excellent | Fair | Poor | Fair |
| Weight | Ultra-light | Relatively heavy | Light | Heavy |
| Installation convenience | Excellent | Excellent | Fair | Poor |
## V. Industrial Applications of Friction-Increasing Shims
1. **Wind Power Industry**
Applied to tower flange connections, gearbox joints, blade root bolts and other positions. Friction-increasing shims restrain preload attenuation, extending re-tightening interval from 6 months to 18 months and reducing downtime for maintenance.
2. **Robotics Industry**
Used on output flanges of harmonic reducers, fixed end faces of RV reducers and preload interfaces of cross roller bearings. Friction-increasing shims improve repeated positioning accuracy and cut positioning drift by more than 50%.
3. **Automotive Industry**
Applied to chassis subframe connections, electric drive brackets, braking systems and battery pack joints. Friction-increasing shims improve torque transmission efficiency and support lightweight design.
4. **Aerospace Industry**
Suitable for aero-engine accessories, avionics mounting frames, satellite structural parts and airframe connections of UAVs. The ultra-thin 0.1mm specification and wide temperature performance meet stringent aerospace requirements.
5. **Rail Transit Industry**
Adopted in brake caliper connections, brake disc mounting, critical bogie joints and traction motor connections. Friction-increasing shims maintain stable joints under high-vibration environments.
## VI. Friction-Increasing Shim Selection Guide
1. **Dimension Selection**
Select annular shims with corresponding inner and outer diameters according to bolt size and mating surface dimension. Standard sizes cover M3–M100, non-standard sizes available for customization.
2. **Thickness Selection**
- 0.1–0.2 mm: Precision reducers, aerospace, space-limited scenarios
- 0.3–0.5 mm: General industrial equipment, robot joints, automotive chassis
- 0.5–1.0 mm: Wind power, heavy machinery, large-size connections
3. **Substrate Selection**
- High-strength spring steel: General industrial applications, cost-effective
- Stainless steel: Corrosive, marine, food & medical environments
- Special alloy: High temperature and special working conditions
4. **Performance Grade**
Select standard grade or high-friction grade based on load and vibration level of working conditions. DAOLER can provide customized friction coefficient solutions.
## VII. Installation & Operation Notes
- Clean mating surfaces before installation to remove grease, rust and burrs.
- Place friction-increasing shim between two mating surfaces, with diamond-coated side facing the counterpart surface.
- Tighten bolts evenly in diagonal sequence with specified torque.
- No thread-locking adhesive or increased pre-tightening torque required.
- Inspect preload 24 hours after initial operation.
- The shim may be reused if no damage is found after disassembly.
- Store in dry and clean environment to avoid coating damage.
## VIII. FAQ
**Q: Will friction-increasing shims damage mating surfaces?**
A: DAOLER precisely controls diamond particle size and interlocking depth. High friction is achieved without damaging precision mating surfaces. The interlocking depth is at micron level; no visible damage can be seen after disassembly.
**Q: Can friction-increasing shims be reused?**
A: Yes. Diamond features extremely high hardness. The shim can be reused if no damage is detected after disassembly. Coating integrity inspection is recommended before reuse.
**Q: What is the difference between friction-increasing shims and high-friction shims?**
A: Friction-increasing shims and high-friction shims are different names for the same type of product. Both enhance anti-loosening and anti-slip performance by raising friction coefficient. DAOLER diamond friction shims possess both friction-increasing and high-friction properties.
**Q: What is the service life of friction-increasing shims?**
A: Under normal working conditions, the service life matches the equipment overhaul cycle, generally reaching 5–10 years. Actual service life depends on working conditions and maintenance.
## IX. DAOLER Friction-Increasing Shim Service Support
DJKJ (Shandong) Co., Ltd. provides full-range technical support for customers:
- Free selection consultation and working condition analysis
- Free sample testing (within specified specifications)
- Third-party test reports
- Custom product development (non-standard sizes, special performance)
- On-site technical support and training
- Full-lifecycle quality tracking
## X. Conclusion
As an efficient solution for critical joints of high-end equipment, friction-increasing shims strike a technical balance of high friction, outstanding wear resistance and no damage to mating surfaces through the micro interlocking mechanism of diamond particles. Centered on DAOLER® Diamond Claw® interlocking technology, DAOLER® friction-increasing shims deliver static friction coefficient ≥0.6, coating hardness ≥1000 HV and ultra-thin 0.1mm specification, providing independently controllable, highly reliable precision connection solutions for various industries.
