1/4-28 Socket Head Cap Screw Dimensions & 1/4 Socket Head | Wholesale
1/4-28 Socket Head Cap Screw Dimensions & 1/4 Socket Head | Wholesale
Precision 1/4-28 Socket Head Cap Screw & 1/4 Socket Head Fasteners | Factory-Direct Wholesale
Stop overpaying for inconsistent quality. We deliver exact 1/4-28 socket head cap screw dimensions with full traceability, ISO-certified production, and 40% cost savings for B2B buyers in automotive, agriculture, and construction.
๐ฅ 15,000+ SKUs in stock ย |ย ๐จ๐ณ Direct from Hebei, China ย |ย โฑ 7-15 days delivery
โ๏ธ 100,000 sqm manufacturing base ยท ISO 9001 certified
โ ๏ธ The Hidden Cost of โCheapโ 1/4-28 Socket Head Cap Screws
When a 1/4 socket head cap screw fails on the assembly line, itโs not just a fastener that breaks โ itโs your production schedule, your reputation, and your bottom line.
Cost Overrun Trap
Off-spec 1 4 28 socket head cap screw dimensions cause rework rates up to 12%, wiping out any per-unit savings. (Industry benchmark: 3% acceptable reject rate.)
Delivery Delays
Unreliable suppliers miss promised lead times 34% of the time, forcing costly production stoppages.
Inconsistent Quality
Batch-to-batch variation in hardness and thread fit leads to strip-out, galling, and field failures โ especially in high-vibration applications.
Compliance Headaches
Missing RoHS, REACH, or CE documentation can block your products from entering EU or US markets entirely.
โ Boen Fasteners eliminates these risks with 100% dimensionally verified, fully traceable, and certified 1/4-28 socket head cap screws โ at factory-direct prices.
๐ง Exact 1/4-28 Socket Head Cap Screw Dimensions & Technical Specifications
Every 1/4 socket head cap screw we produce conforms strictly to ANSI/ASME B18.3 and ISO 4762 standards. Below are the full dimensional details you need for procurement and engineering validation.
| Parameter | Specification (1/4-28 UNC) | Tolerance | Standard |
|---|---|---|---|
| Nominal Diameter | 1/4 inch (0.2500 in / 6.35 mm) | ยฑ0.001 in | ASME B18.3 |
| Threads per Inch | 28 TPI (UNC fine thread) | Class 2A / 2B | ASME B1.1 |
| Head Diameter (Max) | 0.375 in (9.53 mm) | -0.010 in | ASME B18.3 |
| Head Height (Max) | 0.250 in (6.35 mm) | ยฑ0.005 in | ASME B18.3 |
| Hex Socket Size | 1/8 in (0.125 in / 3.175 mm) ๐ง Allen key | +0.002 in | ASME B18.3 |
| Overall Length Range | 1/4 in to 4 in (6.35 mm โ 101.6 mm) | ยฑ0.015 in | Custom lengths available |
| Tensile Strength | Grade 12.9: 180,000 psi min | Grade 8.8: 150,000 psi | Per heat lot tested | ISO 898-1 |
| Surface Finish | Black oxide, zinc plated, plain, or HDG (hot-dip galvanized) | Salt spray โฅ 72h | ASTM B633 / ISO 4042 |
๐ All dimensions are verified with digital micrometers and optical comparators. Full material certs (MTC) included with every shipment.
๐ญ Why Boen Fasteners Is Your Trusted Partner for 1/4-28 Socket Head Cap Screws
Powerful Factory, Direct Pricing
100,000 sqm production base with 200+ cold forging, heat treatment, and threading lines. Eliminate middlemen โ pay 30-40% less than distributor prices.
Quality Assurance You Can Trust
Every batch of 1 4 28 socket head cap screw undergoes 3-stage inspection: incoming raw material, in-process dimensional check, and final hardness/tensile testing. โค 0.2% defect rate โ verified by SGS and TรV reports.
OEM/ODM Design Capabilities
Need a custom length, special coating, or unique head marking? Our engineering team (15+ years experience) can develop and produce custom 1/4 socket head cap screw variants in as fast as 10 working days.
High-Speed Global Delivery
Stocked in 15,000+ SKUs ready for same-day dispatch. Air freight: 5-7 days. Sea freight: 15-20 days. 98% on-time delivery rate across 30+ countries.
Full Compliance & Certification
We provide ISO 9001, CE, RoHS, REACH, and PPAP Level 3 documentation. Our fasteners meet ASTM F835, SAE J429, and DIN 912 standards โ no market access barriers.
One-Stop Service, End-to-End
From material selection (carbon steel, alloy steel, stainless steel 304/316) to logistics tracking and after-sales support โ one point of contact saves you time and hassle.
๐ฉ Real-World Applications of 1/4-28 Socket Head Cap Screws
Agricultural Machinery
Used in tractor linkages, harvester blades, and irrigation systems. The 28 TPI fine thread resists loosening under constant vibration.
Automotive & Heavy Truck
Critical for engine brackets, transmission housings, and suspension components. Grade 12.9 ensures high clamp load in confined spaces.
Construction & Structural Steel
Ideal for steel beam connections, handrails, and heavy equipment anchoring. Hot-dip galvanized option provides 50+ years of corrosion resistance.
Industrial Machinery & Robotics
Precision 1 4 28 socket head cap screw dimensions allow secure fastening in compact robot arms, CNC tooling, and conveyor systems.
๐ Trusted by Industry Leaders Worldwide
+ RoHS, REACH, PPAP Level 3, and ASTM F835 compliant
James Mitchell
Procurement Manager, Midwest AgriParts (USA)
โWe switched to Boen for our 1/4-28 socket head cap screws and cut our fastener spend by 37% while improving on-time delivery from 72% to 99%. The dimensional consistency is the best Iโve seen from any Asian supplier.โ
Elena Vogt
Technical Director, BauTech GmbH (Germany)
โThe 1 4 28 socket head cap screw dimensions matched our drawings exactly. Boen provided full PPAP documentation and MTC within 3 days of shipment. We now use them as our primary fastener supplier for all European projects.โ
Raj Patel
Operations Director, Apex Construction (UAE)
โFast delivery, great communication, and the quality is outstanding. We ordered 50,000 pieces of 1/4 socket head cap screws and received them in Dubai in 12 days. Zero defects. Highly recommended.โ
๐ฌ Real Conversations with Our Customers
โ Frequently Asked Questions about 1/4-28 Socket Head Cap Screws
Q1: What are the exact 1/4-28 socket head cap screw dimensions I need to know for procurement?
The key dimensions are: nominal diameter 0.2500 in (6.35 mm), 28 threads per inch (UNC fine), head diameter 0.375 in (9.53 mm), head height 0.250 in (6.35 mm), and hex socket size 1/8 in (3.175 mm). Lengths range from 1/4 in to 4 in. All tolerances conform to ASME B18.3.
Q2: What grade of 1/4 socket head cap screw should I choose for high-stress applications?
For high-stress environments (automotive, heavy machinery), we recommend Grade 12.9 (180,000 psi tensile strength) or Grade 8.8 for medium-duty. Both are available in carbon steel, alloy steel, or stainless steel 304/316. We provide hardness and tensile test reports with every batch.
Q3: Do you offer custom lengths or special coatings for 1/4-28 socket head cap screws?
Yes. We provide OEM/ODM custom lengths (from 0.125 in to 6 in), coatings including zinc plating, black oxide, hot-dip galvanized, Dacromet, and Geomet, plus custom head markings and packaging. Minimum order quantity (MOQ) for custom is usually 5,000 pcs.
Q4: What is the typical lead time and shipping cost for 1/4 socket head cap screws to the USA or Europe?
For standard sizes: production 7-10 days, air freight 5-7 days (USA/EU), sea freight 15-20 days. We offer DDP (Delivered Duty Paid) terms โ no hidden costs. Shipping cost is typically $0.02-$0.08 per piece depending on volume and destination.
Q5: What certifications and quality documentation do you provide with each shipment?
We provide ISO 9001:2015, CE, RoHS, REACH, and PPAP Level 3 documentation. Each shipment includes Mill Test Certificate (MTC) with chemical composition and mechanical properties, plus dimensional inspection reports upon request.
Q6: Can I get a free sample before placing a bulk order?
Absolutely. We offer free samples (up to 10 pieces) of standard 1 4 28 socket head cap screw sizes. You only pay for shipping. Request your free sample here.
Q7: What is the minimum order quantity (MOQ) for wholesale 1/4-28 socket head cap screws?
For standard sizes and finishes, MOQ is 1,000 pcs per size. For custom lengths or special coatings, MOQ is typically 5,000 pcs. We offer tiered pricing โ the more you order, the lower your per-unit cost. Contact us for a volume discount quote.
Q8: How do I ensure the 1/4 socket head cap screw dimensions match my existing assembly?
We recommend sending us a drawing, sample, or reference part number. Our engineering team will verify the 1 4 28 socket head cap screw dimensions against your requirements and provide a dimensional approval drawing before production. We also offer 3D CAD models for integration testing.
โญ What Our Customers Say About Us
Carlos Herrera
Supply Chain Manager, InduParts (Mexico)
โExcellent quality and service. Weโve been buying 1/4-28 socket head cap screws from Boen for 2 years. The dimensions are always spot on, and the pricing is unbeatable. 5/5 stars.โ
Sarah Thompson
Procurement Officer, TractorWorks (UK)
โThe team at Boen is incredibly responsive. They helped us select the right grade and coating for our agricultural equipment. Delivery was 3 days early, and the documentation was perfect. Highly recommended.โ
Andrei Popescu
Technical Manager, EuroConstruct (Romania)
โWe needed a custom length for a special project. Boenโs engineering team delivered prototypes in 5 days and full production in 12 days. The 1 4 28 socket head cap screw dimensions were perfect. Great partner.โ
โ๏ธ About the Author โ David Chen
Senior Fastener Engineer & International Trade Specialist at Handan Boen Fastener Manufacturing Co., Ltd. With 14 years of experience in the fastener industry, David has helped 200+ B2B clients across 30 countries optimize their supply chain for socket head cap screws, bolts, and custom fasteners. He is a certified ISO 9001 internal auditor and a regular contributor to industry standards discussions.
๐ Ready to Secure Your 1/4-28 Socket Head Cap Screws at Factory-Direct Prices?
Get a custom quote within 24 hours โ including free samples, detailed dimensional drawings, and full compliance documentation.
โณ Limited-time offer: Free shipping on first orders over $500 USD
๐ง Or email us: shuan@fastenboen.com ย |ย mary@fastenboen.com
๐ Hanguang Industrial Park, Yongnian District, Handan, Hebei, China ย |ย โฑ MonโFri 09:00โ17:00
