Pannysylvania Magazine

Ningbo, Zhejiang, China – September 6, 2026 – Main Applications of 10.9‑Grade Fine‑Thread Bolts: 10.9‑grade fine‑thread bolts feature smaller thread pitch, higher thread engagement and better anti‑loosening performance compared with coarse‑thread bolts. They are widely used for high‑strength connection scenarios requiring vibration resistance, high pre‑tension and compact installation space.

They are commonly applied in automotive chassis, engine assemblies, heavy‑duty machinery, construction steel structures, hydraulic equipment and transmission systems. These fasteners are also preferred for thin‑wall components and parts subject to strong shock and alternating vibration. Fine‑thread 10.9 bolts can maintain stable clamping force under heavy‑load working conditions, effectively preventing loosening caused by vibration. Besides, they are suitable for occasions with limited assembly space where coarse‑thread fasteners cannot fit.

2. Quality Requirements

10.9‑grade fine‑thread bolts shall comply with relevant fastener standards. The core mechanical properties include minimum tensile strength of 1040 MPa and yield strength of 940 MPa. Full hardness inspection is required to avoid over‑tempering or brittleness.

Fine thread tolerance must be strictly controlled to guarantee smooth thread fit. Surface defects such as cracks, burrs and scratches are prohibited. For anti‑loosening performance, thread profile shall be precise to sustain stable preload under vibration and alternating load.

If surface treatment like hot‑dip galvanizing or Dacromet is applied, coating thickness shall be uniform. Hydrogen embrittlement relief baking is mandatory after plating to prevent delayed fracture. Dimension sampling inspection, torque test and salt‑spray corrosion test shall be carried out for batch validation.

3. Production Process

Raw high‑strength alloy steel bars are first cut to required length. Then cold heading forms bolt head and blank body. Fine thread is produced by thread rolling instead of cutting, which improves thread‑fiber continuity and mechanical performance.

Subsequently, heat treatment including quenching and tempering is performed to achieve 10.9 grade mechanical properties. After heat‑treatment, surface descaling is done, followed by surface anti‑corrosion treatment. Hydrogen baking shall be arranged right after electroplating.

Final procedures cover dimensional checking, thread gauge inspection, hardness testing, visual defect screening. Qualified products are sorted and packed for delivery.

About Us

Ningbo Zhongli Bolts Manufacturing Co., Ltd. founded in 2003, is a professional manufacturer of high-strength fasteners in different specifications for various models, which is covering an area of about 10,000 square meters, registered capital of 1500,000 RMB, with the total annual productivity of 8,000 tons per year.

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Company Name: Ningbo Zhongli bolts manufacturing Co., Ltd.
Contact Person: Media Relations
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Country: China
Website: https://www.cnzyl.com/