4 Bolt & 4 U Bolt 4.8 Bolt 5/16-18 Bolt 5/16-20 Bolt | Maker
⚙️ Premium 4 Bolt & 4 U Bolt · 4.8 Bolt · 5/16-18 Bolt · 5/16-20 Bolt — Direct from the Maker
Tired of unreliable fastener suppliers driving up your total cost of ownership? Handan Boen Fastener delivers factory-priced, certified bolts that meet your exact specs — with 24/7 support and on-time delivery guaranteed.
✅ 10+ years export expertise · ✅ Shipped to 30+ countries · ✅ ISO 9001 · CE · RoHS
📑 Contents
⚠️ The Real Cost of Cheap Fasteners — What Every Buyer Should Know
Every procurement manager knows the pain: you source a 4 bolt or 4 u bolt at a tempting price, only to face field failures, shipment delays, and compliance headaches. Here are the top 6 pain points our customers shared before switching to Boen:
Hidden Cost Overruns
Low-grade 4.8 bolt stock leads to rework — costing up to 37% more in total installed cost.
Inconsistent Thread Fit
A 5/16-18 bolt from one supplier may not torque correctly with a nut from another — safety risk.
Shipping Nightmares
Split shipments, wrong grades, and high freight costs eat 15-20% of your margin.
Compliance Gaps
Missing CE, RoHS, or ISO 9001 certs can block your shipment at customs — costly delays.
Poor Technical Support
Suppliers who can't answer your 5/16-20 bolt tensile strength questions — frustrating.
Lead Time Uncertainty
8-12 week promises that slip to 16 weeks — your production line stops.
🔍 Research shows that 62% of industrial buyers have experienced at least one fastener-related quality incident in the past 12 months. Don't let it be you.
✅ Our Solution — Precision Bolts Engineered for Performance
At Handan Boen Fastener, we don't just make bolts — we engineer peace of mind. Every 4 bolt, 4 u bolt, 4.8 bolt, 5/16-18 bolt, and 5/16-20 bolt is manufactured under strict quality controls and backed by factory-direct pricing.
Powerful Factory
15,000 m² facility with 200+ sets of advanced cold-forging, heat-treating, and threading lines. 10 million+ pieces monthly capacity.
Quality Assurance
In-house lab with tensile testing, hardness testing, salt spray, and metallographic analysis. Every batch traceable.
High-Speed Delivery
Standard lead time 15-25 days for bulk orders. Express shipping available for urgent needs.
OEM/ODM Design
Custom dimensions, head markings, coatings, and packaging. Your brand, our quality.
Factory-Direct Pricing
No middlemen. 15-30% lower than distributor prices. Volume discounts available.
Global Logistics
Partnered with DHL, FedEx, Maersk, and COSCO. Door-to-door service to USA, Europe, and Southeast Asia.
📊 Technical Specifications — 4 Bolt · 4 U Bolt · 4.8 Bolt · 5/16-18 Bolt · 5/16-20 Bolt
All data verified by our in-house lab. Download full spec sheet with your quote.
| Parameter | 4 Bolt | 4 U Bolt | 4.8 Bolt | 5/16-18 Bolt | 5/16-20 Bolt |
|---|---|---|---|---|---|
| Grade / Class | Grade 4.8 / 8.8 | Grade 4.8 / 8.8 | Property Class 4.8 | Grade 2 / 5 / 8 | Grade 2 / 5 / 8 |
| Thread Specification | UNC / UNF / Metric | UNC / UNF / Metric | M6 – M20 | 5/16-18 UNC | 5/16-20 UNF |
| Tensile Strength (min) | 420 MPa / 830 MPa | 420 MPa / 830 MPa | 420 MPa | 74,000 psi (Grade 5) | 74,000 psi (Grade 5) |
| Yield Strength (min) | 340 MPa / 660 MPa | 340 MPa / 660 MPa | 340 MPa | 57,000 psi (Grade 5) | 57,000 psi (Grade 5) |
| Material | Carbon Steel / Alloy Steel | Carbon Steel / Stainless Steel | Carbon Steel | Carbon Steel / Alloy Steel | Carbon Steel / Alloy Steel |
| Coating / Finish | Plain / Zinc / HDG / Dacromet | Plain / Zinc / HDG | Plain / Zinc / Black Oxide | Zinc / Phosphate / Plain | Zinc / Phosphate / Plain |
| Standards | DIN / ISO / ASME / GB | DIN / ISO / ASME / GB | ISO 898-1 | ASME B18.2.1 / SAE J429 | ASME B18.2.1 / SAE J429 |
📌 Custom dimensions, grades, and coatings available on request. Minimum order quantity: 500 pcs per size.
🏗️ Real-World Applications — Where Our Bolts Deliver
Agricultural Machinery
A German tractor OEM switched to our 4.8 bolt and 5/16-18 bolt for their harvester line. Result: 22% cost savings and zero field failures in 18 months.
Construction & Structural Steel
Our 4 u bolt and 4 bolt assemblies are used in bridge railing systems across the UK. CE marked and tested to 150% of design load.
Automotive & Trailer Manufacturing
A Polish trailer builder uses our 5/16-20 bolt for axle mounting. 10,000+ units delivered — zero complaints.
Energy & Power Generation
Our 4.8 bolt in hot-dip galvanized finish is specified for solar tracker structures in the US market. 25-year corrosion resistance.
💬 Real Conversations with Our Customers
📸 Direct messages from our procurement partners — names blurred for privacy.
❓ Frequently Asked Questions
What is the difference between a 5/16-18 bolt and a 5/16-20 bolt?
The 5/16-18 bolt has 18 threads per inch (UNC — Unified Coarse), while the 5/16-20 bolt has 20 threads per inch (UNF — Unified Fine). Use the 5/16-18 bolt for general fastening where quick assembly is needed, and the 5/16-20 bolt for applications requiring higher tensile strength and vibration resistance.
What does "4.8 bolt" mean in terms of strength?
The 4.8 bolt is a metric property class. The "4" indicates a tensile strength of 400 MPa, and the "0.8" means the yield strength is 80% of the tensile strength (320 MPa). It's a common grade for general industrial applications. For higher strength, we also offer 8.8 and 10.9 bolts.
Can you customize a 4 u bolt for my specific application?
Absolutely. Our OEM/ODM service allows us to produce 4 u bolt in custom diameters, thread lengths, bend radii, and coatings. Just send us your drawing or sample — we'll provide a free design review and quote within 48 hours.
What is the minimum order quantity (MOQ) for 4 bolt and 4 u bolt?
Our standard MOQ is 500 pieces per size for stock items. For custom 4 bolt or 4 u bolt orders, the MOQ is 2,000 pieces. We also offer sample orders (50-100 pcs) for qualification at sample price + shipping.
How do you ensure the quality of your 4.8 bolt and other fasteners?
Every batch undergoes three-stage inspection: incoming raw material testing, in-process dimensional and hardness checks, and final tensile, yield, and salt spray testing in our lab. We provide mill test certificates with every shipment. Our facility is ISO 9001 certified.
What shipping options do you offer for USA and Europe?
We ship via sea freight (FCL/LCL), air freight, and express courier. Typical delivery times: Sea to USA West Coast: 18-25 days, Sea to Europe: 22-30 days. Air/express options available in 5-7 days. We handle all customs clearance documentation.
What payment methods do you accept?
We accept T/T (bank transfer), L/C (Letter of Credit), PayPal, and Western Union. For first-time orders, we typically require 30% deposit + 70% balance against BL copy. Long-term partners may qualify for net 30 terms.
Do you provide free samples for testing?
Yes! We offer free samples (up to 10 pieces) for qualified buyers. You only pay the shipping cost. Contact us with your required 4 bolt, 4 u bolt, 4.8 bolt, 5/16-18 bolt, or 5/16-20 bolt specs and we'll prepare samples within 3 working days.
⭐ What Our Customers Say
Michael S.
Procurement Manager, Germany
"We switched from a local supplier to Boen for our 4.8 bolt needs. The cost savings were 28%, and the quality is consistently excellent. Their CE certification made customs clearance a breeze."
Sarah L.
Supply Chain Director, USA
"Boen's 5/16-18 bolt and 5/16-20 bolt are now our standard for trailer assembly. Zero defects in 6 months, and their logistics team is incredibly responsive. Highly recommended!"
James R.
Operations Manager, UK
"We needed a custom 4 u bolt for a bridge project. Boen's engineering team designed it in 2 days and delivered on time. The quality exceeded our expectations."
Alessandro F.
Technical Director, Italy
"Their 4 bolt assemblies are used in our agricultural equipment. The ISO 9001 certification and complete traceability give us full confidence. Lead times are consistently 15-20 days."
David K.
Purchasing Supervisor, Poland
"We've been buying 5/16-18 bolt and 5/16-20 bolt from Boen for over a year. The price-quality ratio is unmatched. Their customer service team responds within 2 hours."
Hiroshi T.
Project Manager, Japan
"The 4 u bolt we ordered for our solar farm project was perfect. Hot-dip galvanized finish passed 1,000-hour salt spray test. Boen's quality is world-class."
🚀 Ready to Source Premium Bolts at Factory Prices?
Stop overpaying for inconsistent quality. Get certified 4 bolt, 4 u bolt, 4.8 bolt, 5/16-18 bolt, and 5/16-20 bolt — direct from the maker.
📧 Email us: shuan@fastenboen.com · mary@fastenboen.com · grace@fastenboen.com · stella@fastenboen.com
📞 Call / WhatsApp: +86 15630072814 | +86 13293070568 | 🕐 Daily 09:00 – 17:00 (GMT+8)
📍 Hanguang Industrial Park, Yongnian District, Handan City, Hebei Province, China
✍️ About the Author — David Chen
David is a senior fastener engineer with 14 years of experience in industrial fastening solutions. He has overseen quality systems at Handan Boen Fastener since 2015, and has personally consulted on bolt specifications for 50+ export projects to the USA, Europe, and Southeast Asia. He writes to help buyers make informed, cost-effective procurement decisions.
🤝 Trusted by Industry Leaders Worldwide
Our bolts are used by 200+ companies across 30+ countries. Here are some of our valued partners:
✅ ISO 9001 · CE · RoHS · UL · FCC — full compliance documentation provided with every shipment.