5/16-18 Socket Cap Screw & 5/16-18 Socket Head Cap Screw | Maker

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Premium 5/16-18 Socket Cap Screw & 5/16-18 Socket Head Cap Screw – Direct From The Maker

Stop overpaying for inconsistent fasteners. Get factory-direct pricing, ISO-certified quality, and same-day dispatch on every 5/16″-18 socket cap screw order. Engineered for automotive, construction & agricultural machinery.

📦 Get Free Quote in 24h 📋 Request Sample

⭐ Trusted by 300+ buyers in 30+ countries | Lead time: 7–15 days

⚠️ The Real Cost of a Bad Fastener

Every 5/16″-18 socket cap screw that fails in the field costs you more than the part itself. Here’s what our customers tell us hurts most:

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Hidden Cost Overruns

“We lost $4,700 in downtime last quarter because a batch of 5/16″-18 socket head cap screws sheared during torque.” — Operations Manager, Midwest machinery

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Inconsistent Quality

Thread pitch that varies ±0.003″ might pass inspection, but it jams your assembly line. 11% rejection rate on a recent shipment from a low-cost supplier.

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Lead Time Nightmares

Waiting 6–8 weeks for a standard 5/16 18 socket cap screw order? That’s 3 weeks of idle labor. 45% of buyers say slow delivery is their #1 frustration.

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Compliance Risk

Non-certified fasteners can void your equipment warranty. 1 in 5 imported fasteners fail ASTM F835 / ISO 898-1 requirements.

✅ You don’t have to settle. Boen Fasteners delivers certified, traceable, and affordable 5/16-18 socket cap screws — every time.

🔧 Engineered for Reliability – The Boen Advantage

Our 5/16-18 socket head cap screw line is built to outperform in demanding environments. Here’s what sets us apart:

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Factory-Direct Power

We own the full production line — from raw material inspection to final packaging. No middlemen, no markups. You save 18–30% compared to distributor prices.

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ISO 9001:2015 Certified

Every 5/16-18 socket cap screw is traceable to its heat lot. 100% dimensional inspection per ASTM F835 / ASME B18.3. Full material certs available.

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High-Speed Delivery

Stock sizes ship within 24–48 hours. Custom orders (OEM/ODM) in 7–15 days. We keep 50+ tons of 5/16-18 stock ready to go.

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OEM/ODM Flexibility

Need a non-standard length, drive depth, or coating? Our engineering team supports custom designs with fast prototyping. Minimum order? Just 500 pcs.

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Global Logistics

We ship via FedEx, DHL, sea freight, or air freight — whatever fits your timeline. Door-to-door tracking, customs-ready docs included.

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Full Material Range

304/316 stainless, alloy steel (Grade 8, Grade 5), carbon steel, and more. 18-8, 316, 410, 12.9, 10.9 — we speak your spec.

📊 Technical Specifications — 5/16″-18 Socket Cap Screw

All data verified per ASTM F835 / ASME B18.3. Custom lengths & drives available on request.

Parameter	Standard Range	Available Options
Thread Size	5/16″-18 UNC	5/16″-24 UNF, 5/16″-18 rolled or cut
Length Range	1/2″ – 6″ (standard)	Up to 12″ custom; increments of 1/8″
Drive Type	Hex socket (Allen) — 5/16″ hex key	Torx, Phillips, hex flange, tamper-proof
Material Grade	Alloy steel 4140, Grade 8	304SS, 316SS, 410SS, 12.9, 10.9, 18-8
Hardness (HRC)	39–45 HRC (Grade 8)	22–32 HRC (stainless), 32–39 (Grade 5)
Tensile Strength	150,000 psi (Grade 8)	70,000–180,000 psi depending on grade
Finish / Coating	Plain / black oxide	Zinc plated, HDG, Dacromet, PTFE, Xylan
Certification	ISO 9001:2015, ASTM F835	CE, RoHS, REACH, DFARS, NACE MR0175

🔍 Need a specific spec? We’ll confirm availability within 2 hours. Send your inquiry →

🏗️ Where Our 5/16-18 Socket Head Cap Screws Are Used

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Agricultural Machinery

Tractor linkages, harvester blades, tiller assemblies — Grade 8 5/16-18 socket cap screws withstand vibration & heavy loads.

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Automotive & Trailer

Engine brackets, suspension components, hitch systems. 18-8 stainless for corrosion resistance in underbody applications.

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Construction & Structural

Steel beam connections, scaffolding clamps, formwork. Hot-dipped galvanized finish for outdoor durability.

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Industrial Equipment

Conveyor systems, pumps, compressors, robotics. 12.9 alloy steel for high-torque precision joints.

💬 Real conversations — real trust

❓ Frequently Asked Questions

What is the difference between a 5/16-18 socket cap screw and a socket head cap screw?

They are the same product. “5/16-18 socket cap screw” and “5/16-18 socket head cap screw” refer to the same fastener — a 5/16″ diameter, 18 threads per inch, with a hex socket drive and a cylindrical head. Both terms are used interchangeably in the industry.

What grade of 5/16-18 socket cap screw do I need for heavy-duty applications?

For high-stress environments (construction, off-road, heavy machinery), we recommend Grade 8 alloy steel (150,000 psi tensile) or 12.9 alloy steel. For corrosive environments, choose 316 stainless steel. Our team can help you select the right grade based on your load and environment.

Do you provide material certificates and traceability?

Yes. Every shipment of 5/16-18 socket head cap screw includes a Mill Test Report (MTR) and full traceability to heat lot. We also provide ASTM F835 compliance documentation, CE declaration, and third-party inspection reports upon request.

What is the minimum order quantity (MOQ) for 5/16-18 socket cap screws?

For standard sizes in stock, MOQ is just 500 pieces. For custom lengths, materials, or coatings, MOQ starts at 1,000 pieces. We also offer sample packs (25–50 pcs) for qualification at a nominal cost — refundable with your first order.

How long does shipping take to the USA / Europe?

We ship from Handan, China. Air freight: 5–7 business days to major US/European hubs. Sea freight: 18–25 days to any port. We also offer express courier (FedEx/DHL) for urgent orders — 3–5 days door-to-door. All shipping costs are transparent — no hidden fees.

Can you provide custom packaging or labeling?

Absolutely. We offer OEM/private labeling, bulk bags, retail-ready clamshells, or custom kits. Just share your label artwork or packaging requirements, and we’ll handle the rest. No additional tooling fees for standard packaging.

What payment methods do you accept?

We accept T/T (bank transfer), L/C, PayPal, and Western Union for international orders. For new customers, a 30% deposit and 70% balance against shipping documents is standard. Long-term credit terms available for qualified buyers.

Do you offer free samples for evaluation?

Yes! We provide free samples (up to 10 pieces) for standard 5/16-18 socket cap screws. You only pay for shipping. Once you place a production order, the sample cost is fully refunded. Request your free sample now →

⭐ What Our Customers Say

Lars Hoffmann

Procurement Manager, Germany

“We switched to Boen for our 5/16-18 socket cap screw supply. The quality is more consistent than our previous US supplier, and we’re saving 27% annually. Their team is responsive and delivery is always on time.”

Sarah Mitchell

Operations Director, UK

“The technical support from the Boen engineering team helped us select the right material for a corrosive environment. We’ve had zero failures since switching to their 316 stainless 5/16-18 socket head cap screws.”

Mike Chen

Supply Chain Manager, Canada

“We needed a custom length 5/16-18 socket cap screw for a new product launch. Boen delivered the prototype in 4 days and full production in 12 days. Unbelievable speed. They’ve earned our ongoing business.”

Ana Rodriguez

Senior Buyer, Spain

“The certification package Boen provides is second to none. Full MTR, ASTM compliance, and CE declaration — all organized and digital. It makes our audit process so much smoother.”

Written by James Liu

Senior Technical Director, Boen Fastener Manufacturing Co., Ltd.

🔧 18+ years in industrial fastener engineering & global supply chain. I personally oversee every batch of 5/16-18 socket cap screws that leaves our factory.