Custom Fasteners Manufacturer | Special Fasteners & Large Diameter Bolts - Zhejiang Zhengna Technology

We manufacture a comprehensive range of custom fasteners including: Bolts - hex cap screws, carriage bolts, structural bolts, tap bolts; Nuts - hex nuts, flange nuts, coupling nuts, slotted nuts; Screws - socket head cap screws, flat head screws, machine screws; Special Fasteners - 12-point fasteners, square head bolts, metric fasteners, and custom-designed fasteners for specific applications. We work with diameters from 1/4" to 4" (M6 to M100) and lengths up to 72" (1800mm).

We work with various materials including: Carbon Steels - low and medium carbon for general applications; Alloy Steels - 4140, 4340, 8740 for high-strength requirements; Stainless Steels - 304, 316, 410 for corrosion resistance; Special Alloys - Inconel, Monel, Titanium for extreme conditions; Heat-Treated Steels - quenched and tempered to specific hardness levels. Material selection depends on your application requirements for strength, corrosion resistance, temperature tolerance, and cost.

Our MOQ varies based on complexity: Standard fasteners - minimum 500kg; Custom designs with new tooling - typically 1000-2000kg to amortize tooling costs; Prototype quantities - as low as 50-100kg using existing tooling; High-volume production - no upper limit, we've handled orders exceeding 100 tons. For new customers or complex designs, we may require minimum orders to cover tooling costs. Contact us with your specifications for a customized quotation.

Lead times depend on complexity: Standard items from stock - 1-2 weeks; Custom fasteners with existing tooling - 2-4 weeks; New designs requiring tooling - 4-6 weeks (includes 2-3 weeks for tool design and manufacturing); Prototype samples - 2-3 weeks; Large volume orders - 6-8 weeks for production scheduling. We offer expedited services for urgent requirements - contact us with your timeline needs.

We are ISO 9001:2000 certified and A2LA registered. Our quality system ensures compliance with international standards including: ASTM Standards - A194, A307, A354, A449, A490, A563; SAE Standards - J429 Grade 1, 2, 5, 8; ISO Standards - 898, 4014, 4017; Military Specifications - where applicable. We provide material certifications, test reports, and inspection documentation with every shipment.

Yes, we specialize in extra-large and extra-long fasteners. Our capabilities include: Diameter range - from 1/4" to 4" (M6 to M100); Length capacity - up to 72" (1800mm); Large diameter bolts - for mining, construction, and heavy machinery applications; Special features - drilled holes, extra threads, special body diameters, unique head patterns. We maintain blanks in various head styles that can be modified to your specifications.

We offer multiple surface treatment options: Plating - zinc, cadmium, nickel, chrome plating for corrosion protection; Coating - phosphate, black oxide, hot-dip galvanizing; Special Finishes - Dacromet, Geomet, mechanical plating for enhanced corrosion resistance; Passivation - for stainless steel components; Custom Marking - head marking according to your specifications. All treatments comply with industry standards for thickness and adhesion.

Yes, comprehensive testing includes: Mechanical Testing - tensile strength, yield strength, elongation, hardness (Rockwell B & C); Chemical Analysis - material composition verification; Dimensional Inspection - 100% inspection of critical dimensions; Surface Treatment Verification - coating thickness, adhesion tests; Non-Destructive Testing - as required. We use state-of-the-art computerized hydraulic universal testing machines that produce digitally certified test reports according to ASTM requirements.

We serve multiple demanding industries: Mining - haul truck fasteners, excavator components; Heavy Machinery - locomotive, construction equipment fasteners; Military & Defense - vehicle and weapon system components; Railroad Construction - track and bridge fasteners; Agricultural Equipment - tillage systems, harvester components; Power Generation - turbine and generator fasteners; Industrial Manufacturing - machinery and equipment fasteners. Our fasteners meet industry-specific standards for each application.

We accept multiple file formats: 2D Drawings - PDF, DXF, DWG; 3D Models - STEP, IGES, SAT, Parasolid; CAD Files - Solidworks, AutoCAD, Inventor, Creo; Image Files - JPEG, PNG, TIFF for reference; Specification Sheets - Excel, Word documents. Our engineering team can work from sketches, samples, or detailed specifications. We also provide design for manufacturability (DFM) feedback to optimize your design for production efficiency and cost-effectiveness.