4-48 Socket Head Cap Screw & 5/16-18 Flat Head Screw | Buy
4-48 Socket Head Cap Screw & 5/16-18 Flat Head Screw โ Buy Direct from China Factory
๐ฏ Eliminate sourcing pain โ Get ISO-certified socket head cap screws and flat head screws at factory-direct prices. No middlemen. No surprises.
โ 10+ years export expertise | โ 30+ countries served | โ OEM/ODM ready
๐ญ Handan Boen Fastener Mfg. Co., Ltd.๐ค The Real Cost of Cheap Fasteners
You're not just buying a screw โ you're buying reliability, safety, and uptime. Here's what keeps procurement and engineering teams up at night:
Inconsistent Thread Quality
A 4-48 socket head cap screw with poor thread tolerance causes assembly jams and rework. Cost: $2,000+/hr downtime
Hidden Freight & Tariff Costs
Split shipments, delayed customs, and unexpected fees inflate total cost by 18โ30% on average.
Surface Corrosion & Failure
5/16-18 flat head screws with substandard plating fail in humidity or chemical exposure. Warranty claims skyrocket.
Supplier Communication Lag
Waiting 48+ hours for a reply? 56% of buyers say slow response delays their production schedule.
๐ You need a partner who ships on spec, on time, and on budget.
โ Why Boen Fastener Is Your Trusted Source for 4-48 Socket Head Cap Screw & 5/16-18 Flat Head Screw
We turn fastener sourcing into a competitive advantage โ not a headache.
Factory-Direct Power
We control the entire process โ from raw material to heat treatment to packaging. 30-40% cost savings vs. distributors.
Certified Quality
ISO 9001, RoHS, CE, and more. Every 4-48 socket head cap screw and 5/16-18 flat head screw is traceable with batch testing reports.
High-Speed Delivery
Standard lead time: 15-25 days. Express option available. Real-time tracking from factory to your warehouse.
OEM/ODM Flexibility
Need custom head markings, special threads, or unique packaging? Your spec, our production line. Minimum order: flexible.
๐ Technical Specifications โ 4-48 Socket Head Cap Screw & 5/16-18 Flat Head Screw
Data-driven specs for engineering and procurement teams. All values tested per ASTM & ISO standards.
| Parameter | 4-48 Socket Head Cap Screw | 5/16-18 Flat Head Screw |
|---|---|---|
| Thread Size | #4-48 UNF | 5/16โณ-18 UNC |
| Head Type | Socket (hex) head | Flat / countersunk head |
| Drive Style | Hex key (Allen) | Hex socket / Phillips |
| Material Grades | Alloy steel 12.9 / Stainless 304/316 | Carbon steel 8.8 / Stainless 304 |
| Surface Finish | Black oxide, zinc plated, plain | Zinc plated, hot-dip galvanized, plain |
| Tensile Strength | โฅ 1220 MPa (Grade 12.9) | โฅ 800 MPa (Grade 8.8) |
| Certification | ISO 898-1, RoHS, CE | ISO 898-1, RoHS, CE |
| Standard Lengths | 1/8โณ to 1โณ (custom available) | 1/4โณ to 3โณ (custom available) |
| Packaging | Bulk boxes, poly bags, custom labeling | Bulk boxes, poly bags, custom labeling |
๐ง Where These Fasteners Deliver Real Value
Automotive Assembly
4-48 socket head cap screws used in ECU housings, brake components, and interior fixtures.
Agricultural Machinery
5/16-18 flat head screws for tractor panels, harvester guards, and irrigation systems.
Construction & Structural
High-strength fasteners for steel framing, handrails, and heavy equipment attachment.
Industrial Machinery
Precision fasteners for pumps, compressors, conveyor systems, and robotics.
โ Frequently Asked Questions
Q1: What is the difference between a 4-48 socket head cap screw and a 5/16-18 flat head screw?
The 4-48 socket head cap screw is a #4-48 UNF thread with a cylindrical hex socket head, ideal for compact assemblies. The 5/16-18 flat head screw has a 5/16โณ-18 UNC thread with a countersunk flat head, designed for flush-mount applications. Choose based on your clearance, load, and aesthetic requirements.
Q2: What is the minimum order quantity (MOQ) for these fasteners?
MOQ starts at 1,000 pieces per size for standard stock items. For OEM/ODM custom orders, MOQ is typically 5,000 pieces. We also offer sample orders (50-100 pcs) for qualification at a nominal cost.
Q3: Do you provide certificates of compliance (COC) and material test reports?
โ Yes. Every shipment includes a COC and mill test report at no extra charge. Third-party inspection (SGS, TรV) is available upon request.
Q4: How do you handle international shipping and customs?
We ship via sea, air, or express (DHL/FedEx/UPS) based on your urgency. We handle all export documentation, and our logistics team provides HS code guidance to minimize customs delays. DDP terms available for select regions.
Q5: Can you customize the head marking or packaging?
Absolutely. We offer custom head stamps (your logo, grade, or part number) and private-label packaging (boxes, poly bags, barcode labels). Just share your artwork or sample.
Q6: What is the typical lead time for a 4-48 socket head cap screw order?
For standard sizes: 15-20 days from deposit. For custom sizes or finishes: 20-30 days. We also offer express production (10 days) for urgent orders at a 10% surcharge.
Q7: Do you offer free samples for evaluation?
โ Yes. We provide free samples (up to 10 pcs per size) for qualified buyers. Simply pay the shipping cost, and weโll deduct it from your first order.
Q8: What payment methods do you accept?
We accept T/T (bank wire), L/C (letter of credit), PayPal (for samples), and Western Union. For first-time buyers, 30% deposit + 70% against copy of B/L is standard.
โญ Real Reviews from Global Buyers
Verified feedback from procurement and engineering professionals who trust Boen Fastener.
Hans W. โ ๐ฉ๐ช Automotive Tier 1โ5/16-18 flat head screws delivered to our Stuttgart plant. Thread fit was perfect. 100% on-spec across 3 batches.โ
Emily R. โ ๐บ๐ธ Industrial DistributorโBoenโs 4-48 socket head cap screws helped us win a major robotics contract. The uniformity is better than our previous Japanese supplier.โ
Carlos M. โ ๐ง๐ท Construction Sr. BuyerโFast delivery, excellent communication. The 5/16-18 flat head screws arrived in Sรฃo Paulo in 18 days. Saved 28% vs. local suppliers.โ
James Whitfield
Senior Fastener Engineer & Procurement Advisor โ 18+ years in industrial sourcing
James has overseen fastener quality programs for automotive OEMs, agricultural equipment manufacturers, and construction firms across 12 countries. He joined Boen Fastener in 2018 to lead technical sales and supplier quality engineering. His insights are backed by field experience, metallurgical knowledge, and a passion for supply chain efficiency.
๐ Ready to Source with Confidence?
Get your free quote for 4-48 socket head cap screws or 5/16-18 flat head screws within 24 hours.
๐ Free samples for qualified buyers | ๐ Full test reports included | ๐ Secure payment
๐ Call: +86 15630072814 | +86 13293070568 | โ๏ธ mary@fastenboen.com | grace@fastenboen.com | stella@fastenboen.com
๐ Hanguang Industrial Park, Yongnian District, Handan City, Hebei Province, China | ๐ MonโSat 09:00โ17:00
๐ Trusted by Industry Leaders Worldwide
โWe replaced three suppliers with Boen. Their 4-48 socket head cap screws reduced our assembly reject rate from 4.2% to 0.3%. Lead times are consistent.โ
โThe 5/16-18 flat head screws from Boen fit perfectly into our assembly line. Zero defects in the first 50,000 pieces. Fast shipping too.โ
โBoenโs factory-direct pricing saved us 37% on total fastener cost in Q1 2025. Their OEM team designed custom packaging at no extra charge.โ