Premier Bolts Factory: Forged, Threaded & Ready for Export
Kbear Metal manufactures hex bolts, carriage bolts, anchor bolts, flange bolts, U-bolts, eye bolts, and structural bolts at scale. Property classes 4.6 through 12.9, sizes M3 to M64, finished and packed for international buyers.
// Bolt Production Spec
Nine bolt categories from our production floor
Each runs on dedicated heading and threading tooling with its own QC checkpoints.
Hex Head Bolts
The workhorse bolt for general assembly. DIN 933 fully threaded, DIN 931 partially threaded, ISO 4014 / 4017 compliant.
Carriage Bolts
Round head with square neck. Designed for wood-to-metal connections — the square neck locks against material when tightened.
Flange Bolts
Integrated washer flange spreads load and resists loosening from vibration. Common in automotive and machinery assembly.
Anchor Bolts
J-bolts, L-bolts, and headed anchors for embedding in concrete foundations. Galvanized or epoxy-coated for outdoor service.
U-Bolts
U-shaped bolts for pipe clamping, suspension systems, and chassis mounting. Round, square, or semi-round bend profiles.
Eye Bolts
Forged shoulder eye bolts and welded eye bolts for lifting, rigging, and tie-down applications. Load-rated and tested.
Structural Bolts
High-strength bolts for steel construction. A325 / A490 heavy hex, TC bolts with tension-control tips, and HSFG sets.
Stud Bolts
Double-end threaded studs for flange connections in oil & gas, refining, and chemical plants. B7, B16, B8 grades.
Plow Bolts
Flat or domed countersunk head with square or fin neck. Used on agricultural equipment, bucket teeth, and wear plates.
Bolt sizing and mechanical properties
Reference table for common metric hex bolt grades produced in our factory.
| Property Class | Tensile Strength (MPa) | Yield Strength (MPa) | Typical Material | Common Application |
|---|---|---|---|---|
| 4.6 | 400 min | 240 min | Low carbon steel (Q235) | General assembly, light duty |
| 5.8 | 500 min | 400 min | Medium carbon steel | Furniture, light machinery |
| 8.8 | 800 min | 640 min | Medium carbon, Q&T (C45 / 35K) | Automotive, construction |
| 10.9 | 1040 min | 940 min | Alloy steel, Q&T (SCM435 / 40Cr) | Wind energy, heavy equipment |
| 12.9 | 1220 min | 1100 min | Alloy steel, Q&T (SCM435 / 42CrMo) | Aerospace, motorsport, dies |
| A2-70 (SS 304) | 700 min | 450 min | Stainless steel 304 | Food, marine, chemical |
| A4-80 (SS 316) | 800 min | 600 min | Stainless steel 316 | Offshore, saltwater service |
From commodity carbon steel to specialty alloys
Match the alloy to the load, environment, and service life of your application.
Q235 · C45 · 10B21
Standard bolts up to Class 8.8
SCM435 · 40Cr · 42CrMo
Class 10.9 and 12.9 high-strength
304 · 316 · 316L · 410
A2-70 and A4-80 grades
Silicon Bronze C65500
Marine and decorative hardware
H62 · H65
Electrical, plumbing applications
6061 · 7075
Lightweight, aerospace assemblies
Gr 2 · Gr 5 (Ti-6Al-4V)
Severe-service, weight-critical
Inconel 718 · Monel 400
High-temp, corrosion-resistant
How a bolt becomes a finished part
Six stages from coiled wire rod to packed export carton.
Wire Drawing
Coiled rod drawn to target diameter and surface finish.
Cold Heading
Multi-station presses form bolt head and shank in one pass.
Thread Rolling
Cold-rolled threads work-harden the surface for fatigue strength.
Heat Treatment
Quench and temper achieves target property class.
Surface Coating
Plating, galvanizing, or organic finish applied to spec.
QC & Pack
AQL sampling, mechanical testing, packaging for export.
Tested bolts. Documented batches.
Every production batch ships with material certificates, dimensional inspection reports, and mechanical test results. Standard third-party verification through SGS or BV is available on request.
Tensile Testing
Proof load and ultimate tensile strength tested per ISO 898-1 on samples from every batch.
Hardness Testing
Rockwell (HRC) and Vickers (HV) hardness verified across heat-treated bolt heads and threads.
Salt Spray Testing
Coated bolts run through 96 / 240 / 500-hour neutral salt-spray cycles per ASTM B117.
Thread Gauging
Go / no-go ring and plug gauges verify 6g / 2A thread class conformance on every shift.
Industries that source bolts from our Professional factory
Each market has its own standards, finishes, and documentation requirements — we adjust per buyer.
Construction
Structural bolts, anchor bolts, threaded rod for buildings, bridges, and steel frameworks.
Automotive
Engine, chassis, and suspension bolts. IATF 16949 process with PPAP documentation.
Wind Energy
Tower flange bolts, foundation bolts, blade bolts in HDG and Geomet finishes.
Oil & Gas
B7, B16, B8 stud bolts for flange connections in refining and petrochemical plants.
Marine
316L stainless and silicon bronze bolts resist saltwater corrosion in offshore service.
Heavy Machinery
High-strength bolts for cranes, presses, agricultural equipment, and mining machinery.
Railway
Track bolts, fishplate bolts, and rail clamp assemblies meeting AREMA and EN standards.
HVAC & Plumbing
U-bolts, hanger bolts, and pipe-support hardware in zinc-plated and stainless finishes.
Why distributors choose Kbear for bolts
Six factory-direct advantages that show up on the procurement P&L.
Direct Top factory pricing
No trading-house markup. Volume tier pricing kicks in at 500 kg, 1,000 kg, and full container loads.
In-house heat treatment
Continuous mesh-belt furnaces let us hit Class 10.9 and 12.9 without outsourcing — protecting quality and lead time.
Custom tooling in 7–10 days
Our die shop builds new heading and thread-rolling dies in-house for non-standard bolt designs.
Mixed-SKU containers
Combine bolts, nuts, washers, and screws on one pallet to hit container utilization targets.
Engineering DFM support
Our engineers review drawings and propose cost-down adjustments before tooling is cut.
Documentation bundle
Material certs, inspection reports, packing lists, and shipping docs delivered as a single PDF package.
Inside our bolt production lines
Heading presses, thread rolling machines, heat-treatment furnaces, and inspection stations dedicated to bolt manufacturing.
Watch bolts being made
Three short videos showing the steps from wire rod to finished, packed bolts.
Cold Heading to Thread Rolling
Bolt blanks formed on cold-heading presses, then thread-rolled to DIN 933 or DIN 931 specification.
Inspection & Testing Process
Tensile testing, proof-load checks, and salt-spray verification on every production batch.
Packing to Container Loading
Finished bolts sorted, bulk-packed or boxed, and loaded into export containers.
Free Samples
Standard fastener samples shipped free for evaluation. You only cover express courier cost.
First-Order Inspection
Third-party SGS or BV inspection on your first order at our cost — verify before paying balance.
30% Deposit Only
T/T 30% deposit gets your order into production. 70% balance after pre-shipment inspection.
Quality Replacement
Any defect outside agreed AQL gets replaced free on the next shipment, no questions asked.
Common questions from procurement teams
Quick answers on standards, tolerances, finishing, and shipping.
What sizes and lengths do you produce?
What is the difference between Class 8.8 and Class 10.9?
Can you produce bolts to ASTM A325 or A490 structural standards?
What surface finishes are available for bolts?
Can you supply bolts with mill certificates?
What is the lead time for bolt orders?
Contacts
Kbear Metal Factory
Zhanggezhuang Industrial Pack, Pingdu, China
Head Office
Support
+86 18562662895