- Ningbo Zhongli bolts manufacturing Co., Ltd. +86-574-86587617
- tan@nbzyl.com
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High-tensile Grade 8.8, 10.9, and Grade B7 fasteners designed to eliminate dynamic loosening, counter shear forces, and provide reliable clamping force for heavy industrial mountings.
Discover how state-of-the-art metallurgical treatments, fine-pitch geometry, and calibrated preload dynamics secure modern heavy machinery, robotic cells, and structural chassis under extreme cyclic stress.
Engineered thread flank angles and fine pitches provide higher clamping torque conversion and resist vibration-induced loosening.
Cold-forged alloy steel meeting ISO 898-1 standards (Grade 8.8, 10.9, 12.9) ensures minimum tensile strength up to 1220 MPa.
Hot-dip galvanizing, mechanical zinc, and yellow passivation withstand harsh industrial environments, coolants, and moisture.
Continuous unbroken grain flow achieved through advanced cold heading and rolled threads eliminates stress concentrations.
In modern mechanical engineering and plant construction, the structural integrity of equipment mounting systems depends heavily on the mechanical fastener bridging heavy equipment bases with structural frames, steel skids, and concrete footings. A Frame Bolt For Equipment Mounting is not simply a standard threaded rod; it is a high-precision structural fastener designed to maintain permanent clamping forces under dynamic vibration, thermal expansions, variable shear stresses, and high static deadweight loads.
With the acceleration of automated manufacturing, high-speed stamping presses, wind turbine installations, heavy CNC machine centers, and electric vehicle assembly fixtures, industrial operating environments have become significantly more demanding. Loose bolts or fastener shear failure during operational cycles lead to catastrophic machine misalignment, micro-fretting corrosion, hydraulic line rupture, and unplanned factory downtime costing tens of thousands of dollars per hour. Consequently, original equipment manufacturers (OEMs) and structural engineering contractors globally require specialized high-tensile fasteners such as structural hex bolts, DIN960 fine-pitch fasteners, and ASTM A325 structural assemblies.
When anchoring machinery to supporting chassis and frames, mounting bolts experience three concurrent load vectors: direct axial tensile tension from preload and overturning moments, transverse shear across the mounting interface, and cyclic bending fatigue.
To prevent interface slip between the equipment foot and the mounting beam, the bolt must generate sufficient axial preload. The frictional grip force ($F_f = \mu \cdot F_p$, where $\mu$ is the friction coefficient and $F_p$ is bolt preload) prevents transverse sliding without relying solely on the bolt shank bearing against the hole wall. Fine-pitch metric bolts like the DIN960 Grade 10.9 feature a smaller lead angle ($\lambda$), which fundamentally increases self-locking friction within the mated threads and allows more granular torque calibration during pneumatic or hydraulic torque tensioning.
| Fastener Standard & Grade | Material Specification | Nominal Tensile Strength (MPa) | Yield Strength / Proof Load (MPa) | Primary Equipment Mounting Application |
|---|---|---|---|---|
| ISO 898-1 / DIN 931 Gr 8.8 | Medium Carbon / Quenched Steel | 800 MPa | 640 MPa | Standard machine beds, conveyor framing, pump skids |
| DIN 960 / DIN 933 Gr 10.9 | Alloy Steel (40Cr / 10B21 / 35CrMo) | 1,040 MPa | 940 MPa | Heavy stamping presses, CNC machining centers, automotive chassis |
| DIN 912 / ISO 4762 Gr 12.9 | High-Alloy Quenched & Tempered | 1,220 MPa | 1,100 MPa | High-shock robotic mounts, hydraulic clamp frames, turbine mounts |
| ASTM A325 / EN 14399-4 | Quenched Boron / Medium Carbon | 830 MPa (120 ksi) | 660 MPa (92 ksi) | Structural steel frame mounting, offshore skids, civil infrastructure |
| ASTM A193 Grade B7 | AISI 4140/4142 Chromium-Moly | 860 MPa (125 ksi) | 720 MPa (105 ksi) | High-pressure vessels, petrochemical pump mountings, continuous studs |
Heavy Machine Tool and CNC Gantry Mounting: Precision machine tools require sub-millimeter level stability. Frame bolts used in gantry mountings and lathe beds must resist dynamic resonance frequencies generated during high-speed cutting. Flanged bolts with serrated underside bearing faces, such as DIN6921 Hex Flange bolts, spread clamping pressure evenly across cast iron beds without requiring secondary loose washers, preventing localized deformation.
Automotive Frame and Chassis Assembly: Commercial vehicles, off-highway construction rigs, and agricultural tractors utilize specialized fine-thread frame bolts to assemble chassis side rails, suspension hangers, and powertrain cradles. The fine thread pitch ensures vibration resistance over hundreds of thousands of duty cycles across rugged terrain.
Energy, Wind Power & Heavy Compressor Bases: Wind turbine nacelle frames and industrial gas compressors generate substantial torsional moments. High-tensile continuous stud bolts paired with 2H heavy hex nuts provide uniform double-ended tensioning, allowing hydraulic torque wrenches to apply exact elongation targets.
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. The company has set up several sales branches in different provinces in China. Meanwhile, the company's products are exported to Europe, USA, Middle East, Africa, Southeast Asia and other regions. The company has strong technical ability, complete testing equipments and a variety of fully automatic multi-station cold and hot heading machines, so as to provide you with reliable and high quality products.
Our main products ZYL brand fasteners include structural hex bolts ASTM A325 type 1, A490, hex head bolts DIN931, DIN933, EN14399, DIN6914, ISO4014, ISO4017 Gr8.8 Gr10.9 Gr12.9, ANSI B18.2.1 UNC and UNF Gr5, Gr8, fine pitch hex bolts DIN960, DIN961 Gr8.8 Gr10.9 Gr12.9, hex socket cap screws DIN912, ISO4762 Gr8.8 Gr10.9 Gr12.9 with surface Black, Zinc plated, Hot dip galvanized. Diameters from M10 to M48, length no limited. Hex Flange bolts DIN6921 Gr8.8 Gr10.9 with serration, thread rod A193 B7 long sizes and short sizes with 2H nuts, stud bolts. We also can supply hex nuts DIN934, DIN6915, plain washers DIN125, DIN126, DIN6916, spring washers DIN127 with Black, Zinc plated and Hot dip galvanized surface.
Our physical and mechanical test results can reach to ISO898-1 for bolts and ISO898-2 for nuts. Through scientific management, Ningbo Zhongli Bolts Manufacturing Co., Ltd. obtained ISO9001 certificate of Quality Management System. Quality is the most important for us. We have strict production and inspection equipments to support this point. We hope to establish business relationship with all over the world, and our business can bring in mutual benefits for both parties.
From incoming raw wire rod spheroidization to multi-station cold heading and continuous atmosphere heat treatment, our manufacturing pipeline delivers reliable fastener performance.
Equipped with multi-station cold heading machinery, high-tonnage hot forging presses, and precision thread-rolling centers covering 10,000 m² of specialized production space.
High-strength bolts, socket caps, threaded rods, and hardware engineered to international dimensional standards.
Over 20 years of dedication to high-strength mechanical engineering, proprietary laboratories, and integrated forging capabilities.
A Professional Sales and Technical Team with More Than 20 Years History.
We Have Our Own Testing Equipment and Laboratory, Our Products Have Initial Inspection, Patrol Inspection, And Final Inspection.
Our Factory Has Its Own Cold Forged, Hot Forged, And Heat Treatment Equipment.
Standard Fasteners in Stock, Non-standard Fasteners Can Be Customized.
We Have Passed Iso 9001, En 15048, En 14399, Ad2000 and Ce Certificates.
Our advanced metallurgical laboratory performs comprehensive non-destructive and destructive testing on every production batch to ensure zero defect rates under dynamic equipment mounting conditions.
We hope to establish business relationship with all over the world, and our business can bring in mutual benefits for both parties.
EN 15048 CE Certification, EN14399 CE Certification, ISO9001 Certificate, AD2000 Conformity
Grasp first-hand information from worldwide engineers, equipment manufacturers, and structural contractors.
Browse our standard and custom high-tensile fasteners, DIN960 fine-pitch hex bolts, ASTM A193 B7 stud bolts, and yellow zinc flange assemblies.
Fine-pitch threads provide a smaller helix angle, creating higher thread contact friction that substantially resists counter-rotation under transverse cyclic vibration. Furthermore, because the thread depth is shallower, the effective tensile stress area of the core bolt is larger than that of coarse-thread bolts of the same nominal diameter, resulting in increased tensile yield resistance.
For indoor industrial environments with mild humidity and machine oil mist, black oxide with anti-rust oil or yellow zinc electroplating (Cr3+ passivation) provides optimal dimensional accuracy and clean torque-tension conversion ($K$-factor of approximately 0.18–0.22). For outdoor equipment, skids, and coastal facilities, hot-dip galvanizing (HDG) or specialized zinc flake coatings conform to ASTM A153/ISO 10684 standards, preventing red rust across 1,000+ hours of salt spray testing.
We implement end-to-end quality control across all 8 manufacturing phases: incoming raw material chemical composition spectroscopy, controlled spheroidizing annealing, multi-die cold forging, thread rolling with continuous metal grain lines, continuous protective-atmosphere mesh belt furnace heat quenching and tempering, and full 100% optical sorting alongside destruct-pull tensile proof testing in accordance with ISO 898-1 standards.
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