PLB v2 is a patent-protected, mass-producible mechanical-locking fastening system that achieved the highest rating in ISO 16130-compliant Junker transverse vibration testing, one of the most severe standardized tests for evaluating self-loosening in threaded fasteners, while remaining removable with standard tools.

Problem and Benefits

In severe-duty equipment, fasteners must combine easy installation, clamp-force retention, and removability. Self-loosening causes retightening, inspection labor, downtime, failure, and safety risk. Existing countermeasures often trade one problem for another: extra steps, friction dependence, difficult removal, limited reuse, special machining, or higher cost. By reducing repetitive inspection and retightening, PLB v2 lowers routine maintenance burden and lets workers focus on predictive maintenance, reliability improvement, and safety-critical work.

How It Works and Innovation

The innovation is not simply using two nuts. PLB v2 creates a mechanical lock from the thread-lead difference between a dual-thread bolt, a larger-lead inner nut, and a smaller-lead outer nut. Thread lead means how far a nut moves axially per rotation.

During tightening, rotating the outer nut drives the larger-lead inner nut forward. Both nuts are secured in one action without special tools.

During loosening, the function reverses. Vibration-induced loosening makes the larger-lead inner nut tend to move faster, but the smaller-lead outer nut cannot follow at the same rate. The outer nut mechanically blocks the inner nut’s progression. 

This mismatch converts loosening motion into internal mechanical locking while preserving removability.

In short, PLB v2 follows during tightening and locks during loosening.

Validation

PLB v2 has been validated by:

• achieving the highest rating in third-party ISO 16130-compliant Junker testing, while maintaining residual clamp force above the ISO 85% reference threshold throughout testing;
• demonstrating 166× longer resistance to loosening than a standard bolt-and-nut assembly and 2.75× longer resistance than the nearest competing locking fastener in controlled Junker testing under identical loosening-threshold criteria;
• confirming strength equivalent to a standard bolt through third-party tensile testing;
• establishing technical credibility through peer-reviewed Elsevier/ASME publications, FEM-based loosening analysis, and Simufact Forming thread-rolling simulation supporting reliability and manufacturability.

Manufacturability and Cost

PLB v2 is designed for cost-effective mass production by:

• using existing bolt-and-nut manufacturing infrastructure;
• dedicating only function-critical tools: rolling dies and an inner-nut tap;
• requiring no new machinery, special process, exotic material, or special installation method;
• being backed by 18 granted patents and 62 design registrations while protecting the locking structure, not a specific manufacturing method, enabling adaptation to typical fastener materials and sizes;
• demonstrating production of more than 40,000 bolts under production conditions.

Because PLB v2 uses conventional high-volume production routes, it can reduce the cost barrier normally associated with high-performance locking fasteners.

Marketability and Future

PLB v2 expands adoption in maintenance-critical industrial and infrastructure applications by:

• targeting mining, heavy construction, chemical, power-generation, environmental, and steelmaking facilities, civil engineering, and public infrastructure;
• being listed in NETIS, Japan’s national public-works technology database;
• building on development work recognized by the Ministry of Economy, Trade and Industry Minister’s Award, and Fastener Innovation Award;
• acting as a reliability infrastructure component that supports automation, labor-saving operation, higher uptime, and improved productivity for industrial operators.