1. Introduction: Screw Loosening Challenges in Industrial Vibration Working Conditions
In automated equipment, new energy machinery, vehicle equipment and heavy-duty machinery, long-term vibration, temperature alternation and mechanical impact will cause torque attenuation and gap loosening of ordinary standard fasteners, leading to equipment abnormal noise, structural offset and even potential safety hazards. To solve the problem of thread failure under alternating vibration, Prevailing Torque Fasteners are widely adopted as standardized anti-loosening solutions in European and American industries.
Many foreign trade purchasers and engineers confuse prevailing torque fasteners with ordinary fasteners and simple washer combination fasteners, resulting in incorrect selection and unqualified anti-loosening effect. As a professional anti-loosening system, prevailing torque fasteners mainly include two categories: nylon locking fasteners and pre-coated nylock anti-loosening fasteners, covering most industrial anti-loosening scenarios.
2. Definition and Classification of Prevailing Torque Fasteners
2.1 Industry Definition
A prevailing torque fastener refers to a special threaded fastener that generates stable and continuous locking damping torque through structural optimization or special coating technology. It does not require auxiliary accessories such as spring washers or stop washers, and can independently offset loosening force caused by vibration and external impact to maintain long-term thread locking stability.
2.2 Main Product Categories
The prevailing torque fastener system is divided into two core types. The first is structural physical anti-loosening fasteners, represented by nylon insert lock nuts, which rely on nylon elastic extrusion to generate friction damping. The second is coating chemical anti-loosening fasteners, represented by pre-coated nylock screws and nuts, which realize thread locking through anaerobic glue curing reaction.
3. Anti-loosening Working Principle
3.1 Working Principle of Nylon Locking Fasteners
Nylon lock nuts adopt pure physical anti-loosening structure. The built-in high-temperature resistant nylon ring has a slightly smaller inner diameter than the thread outer diameter. When the bolt is screwed in, the nylon ring is elastically deformed and tightly wraps the thread, generating stable damping torque. The elastic holding force can effectively offset the loosening trend caused by long-term equipment vibration, maintain continuous thread pre-tightening force, and avoid torque attenuation and structural loosening.
3.2 Working Principle of Pre-coated Nylock Fasteners
Pre-coated nylock fasteners apply professional anaerobic resin coating on the thread surface. The coating remains flexible and uncured when exposed to air, enabling long-term storage without pre-locking failure. After the thread is fully tightened, the air in the thread gap is completely isolated. With the catalytic effect of the metal thread, the anaerobic coating cures rapidly, fills all tiny thread gaps, and integrates the occluded thread structure to form reliable locking torque, realizing anti-loosening, sealing and anti-seize effects.
Comparison Item | Nylon Locking Fastener (Physical Anti-loosening) | Pre-coated Nylock Fastener (Chemical Anti-loosening) |
Anti-loosening Principle | Elastic extrusion of nylon ring produces physical damping torque | Anaerobic coating cures and fills thread gaps for locking |
Anti-loosening Characteristic | Flexible locking, buffers vibration impact, protects threads | Rigid locking, thorough anti-loosening, excellent fatigue resistance |
Disassembly Performance | Reusable and easy to maintain | Blue grade detachable; red high-strength grade requires heating for disassembly |
Sealing Performance | Only anti-loosening function, no sealing and anti-rust effect | Integrates anti-loosening, thread sealing and anti-corrosion functions |
Temperature Resistance | Suitable for conventional room temperature working conditions | Adaptable to normal and high-temperature special scenarios |
Application Scenarios | Light-duty electromechanical equipment, maintainable structures | Heavy-load vibration, outdoor corrosive and high-precision structures |
5. Application Scenarios and Selection Rules
5.1 Applicable Scenarios for Nylon Locking Fasteners
Nylon locking fasteners are the preferred choice for general electromechanical equipment, small household appliances and light automated structures requiring regular inspection, debugging and replacement. They are suitable for working conditions with moderate vibration, normal temperature and non-corrosive environment, featuring convenient assembly and maintenance and high comprehensive cost performance.
5.2 Applicable Scenarios for Pre-coated Nylock Fasteners
Pre-coated nylock fasteners are applicable to new energy equipment, vehicle chassis, heavy machinery, fan equipment and other heavy-load high-frequency vibration scenarios. They are also ideal for outdoor humid and corrosive environments requiring thread sealing and rust prevention, as well as permanent fixed structures and high-temperature precision limit assembly scenarios. Different color coatings can match diverse working condition requirements.
6. Common Foreign Trade Procurement Mistakes & Solutions
6.1 Confusing Ordinary Fasteners with Prevailing Torque Fasteners
Many purchasers mistakenly believe that ordinary bolts matched with spring washers can achieve reliable anti-loosening effect. In fact, simple elastic extrusion locking is prone to failure under long-term vibration. Solution: Adopt standard prevailing torque fasteners for all vibration-prone working conditions.
6.2 Blind Interchange of Two Anti-loosening Products
Using nylon fasteners for heavy-load sealing structures will cause loosening and corrosion failure; using high-strength permanent nylock fasteners for maintainable equipment will lead to difficult disassembly and workpiece damage. Solution: Select physical locking for light-duty maintainable scenarios and chemical locking for heavy-load sealed structures.
6.3 Ignoring Product Process Quality
Inferior nylon rings are prone to aging and elastic failure, and low-quality nylock coatings may peel off or cure incompletely, resulting in anti-loosening failure. Solution: Adopt fasteners with stable technology and qualified materials to ensure long-term service stability.
7. Conclusion & Manufacturer Advantages
Prevailing torque fasteners are core anti-loosening solutions for industrial vibration working conditions, including physical nylon locking and chemical nylock locking systems. Nylon fasteners focus on convenient maintenance and reusability, while nylock fasteners focus on high-strength locking, sealing and multi-scene adaptation. Our factory supplies full-series standard prevailing torque fasteners with stable performance and compliant technology, providing one-stop reliable supporting solutions for global foreign trade procurement and engineering projects.
8. Frequently Asked Questions (FAQ)
Q1: What is a prevailing torque fastener and how is it different from ordinary fasteners? A: Prevailing torque fasteners are professional anti-loosening threaded parts with self-locking properties. They generate stable damping torque through their own structure or coating without auxiliary washers, providing far more reliable anti-loosening performance than ordinary fastener combinations under vibration conditions.
Q2: Which is better, nylon locking or nylock locking? A: They apply to different working conditions. Nylon locking is suitable for light-duty and maintainable equipment, while nylock locking features higher strength, sealing and anti-corrosion performance, ideal for heavy-load, vibrating and harsh environments.
Q3: Can prevailing torque fasteners be reused after disassembly? A: Nylon lock nuts can be disassembled and reused many times. Blue nylock screws support routine maintenance and disassembly, while red high-strength nylock fasteners are not suitable for repeated use and are only for permanent fixation.
Q4: Are prevailing torque fasteners mandatory for vibration equipment? A: Yes. Ordinary fasteners with simple anti-loosening accessories cannot resist long-term high-frequency vibration and are prone to loosening failure. Standard prevailing torque fasteners are essential to ensure equipment operation safety.
