JOIN‑fasteners® offers a comprehensive range of Hex Cap Screws in Grades 2, 5, and 8, manufactured to SAE J429 and ASME B18.2.1 standards. With over 18 years of experience, three factories covering 200 acres, and a monthly production capacity exceeding 8,000 tons, JOIN delivers premium quality, competitive pricing, and on‑time delivery for construction, machinery, automotive, and infrastructure projects worldwide. This article details the technical specifications, head marking identification, material options, and service advantages that make JOIN a trusted one‑stop fastener partner for global buyers.
Hex cap screws are the workhorses of mechanical assembly, engineered for easy installation into tapped holes with a washer face under the head and a chamfered point for smooth engagement. JOIN‑fasteners® supplies these screws in three primary grades—Grade 2 for general applications, Grade 5 for moderate‑strength assemblies (the most common in manufacturing), and Grade 8 for high‑strength, critical joints. All products feature zinc plating per ASTM F1941 to retard corrosion in normal atmospheres, with optional finishes available upon request. Whether you need standard UNC/UNF threads or custom dimensions, JOIN's rigorous quality control—from raw material to final packaging—ensures every screw meets or exceeds SAE specifications.
JOIN's hex cap screws are produced with precise dimensional and mechanical properties, fully traceable via Material Test Reports (MTR) that include lot traceability, dimensional results, and full chemical/mechanical test data. Key attributes include:
• Dimensions – ASME B18.2.1, with body diameters from 1/4" to 1‑1/2" and standard thread classes 2A for UNC, UNF, and UNS.
• Material & Mechanical – SAE J429 specifications; Grade 2 (low carbon steel), Grade 5 (medium carbon steel, quenched and tempered), and Grade 8 (medium carbon alloy steel, quenched and tempered).
• Head Markings for Instant Grade Identification – Grade 2: manufacturer's ID only; Grade 5: manufacturer's ID plus 3 radial lines 120° apart; Grade 8: manufacturer's ID plus 6 radial lines 60° apart. This visual system simplifies field inspection and quality assurance.
• Finish – Fe/Zn 3AN per ASTM F1941/F1941M (zinc plating), with other finishes (e.g., hot‑dip galvanized, zinc‑aluminum, or plain) available for specific environmental requirements.
The table below provides key dimensions for Grades 2, 5, and 8 hex cap screws per ASME B18.2.1. Full length and thread length data are available upon request.
| Nominal Size | Body Diameter (Max/Min) | Width Across Flats (Max/Min) | Head Height (Max/Min) |
| 1/4 | 0.2500 / 0.2450 | 0.438 / 0.428 | 0.163 / 0.150 |
| 5/16 | 0.3125 / 0.3065 | 0.500 / 0.489 | 0.211 / 0.195 |
| 3/8 | 0.3750 / 0.3690 | 0.562 / 0.551 | 0.243 / 0.226 |
| 1/2 | 0.5000 / 0.4930 | 0.750 / 0.736 | 0.323 / 0.302 |
| 5/8 | 0.6250 / 0.6170 | 0.938 / 0.922 | 0.403 / 0.378 |
| 3/4 | 0.7500 / 0.7410 | 1.125 / 1.100 | 0.483 / 0.455 |
| 1 | 1.0000 / 0.9900 | 1.500 / 1.469 | 0.627 / 0.591 |
| 1‑1/2 | 1.5000 / 1.4880 | 2.250 / 2.175 | 0.974 / 0.902 |
JOIN's hex cap screws serve a wide array of demanding sectors:
• Architectural Construction & Bridges – Grade 5 and 8 screws provide the high tensile strength needed for structural steel connections, bridge trusses, and building frameworks.
• Railway & Oil Pipeline Infrastructure – Corrosion‑resistant finishes and reliable mechanical properties ensure long‑term performance in rail fastenings and pipeline supports.
• Machinery Equipment & Shipbuilding – Heavy‑duty assemblies rely on Grade 8 screws for critical rotating parts and marine environments where vibration resistance is paramount.
• Furniture & Industrial Racking – Grade 2 and 5 screws offer cost‑effective, dependable fastening for mass‑production assembly lines.
With a global export footprint spanning North and South America, Europe, Australia, Africa, Southeast Asia, and the Middle East, JOIN's products are trusted by engineers and procurement professionals worldwide.
Jiaxing Join Fasteners Co., Ltd. (JOIN‑fasteners®) was founded in 2007 and has grown into a leading large‑scale fastener manufacturer in eastern China. The company operates three main factories covering approximately 200 acres in Jiaxing, Zhejiang province — strategically located near Shanghai and Ningbo ports for convenient, low‑cost multimodal transport.
The group comprises four specialised entities: JOIN FASTENERS (trading since 2007, exporting to global markets), ZHONGXUAN INDUSTRIAL (founded 2019, focusing on high‑quality standard bolts and threaded rods with over 8,000 tons monthly capacity), CENZE (founded 2008, manufacturing carbon/stainless steel screws with DIY packing capabilities), and CENLON (founded 2012, producing carbon steel and stainless steel nuts and washers). This integrated structure enables a true one‑stop buy solution — from screws and bolts to nuts and washers — simplifying procurement and reducing supply chain complexity.
JOIN‑fasteners® offers flexible and transparent commercial terms to accommodate diverse customer needs:
• Price Terms – FOB, CIF, CFR, EXW, DDP, DDU – we tailor to your logistics preferences.
• Lead Time – Normal production 45‑60 days; expedited options available for urgent orders.
• Packing Options – Warehouse packing (bulk in master cartons, small boxes) or DIY retail packing (tubs, cards, kits, pouches) to suit distribution channels.
• Payment Terms – TT, LC, and flexible financial solutions for regular clients.
All products are accompanied by Material Test Reports (MTR) with documented lot traceability, dimensional results, and full chemical/mechanical test results per SAE J429. JOIN's commitment to quality is backed by rigorous in‑process inspections and a dedicated quality team that monitors every production step.
A: Grade 2 is general‑purpose low‑carbon steel; Grade 5 is medium‑carbon steel, quenched and tempered for higher strength; Grade 8 is alloy steel, quenched and tempered for maximum tensile strength (150,000 psi minimum).
A: Grade 2 has no radial lines; Grade 5 has 3 lines spaced 120° apart; Grade 8 has 6 lines spaced 60° apart — all accompanied by the manufacturer's ID.
A: Yes. JOIN supports custom dimensions and threading per ASME B1.1, including UNC, UNF, and UNS, with Class 2A fit. Please provide your specifications for a tailored quote.
A: We offer hot‑dip galvanizing, zinc‑aluminum coating, plain (oil‑coated), and other corrosion‑protective finishes to meet specific environmental demands.
A: Absolutely. As a one‑stop group with dedicated nut/washer factories, we can consolidate your entire fastener order and ship as a single package, saving you time and freight costs.
A: There is no strict MOQ for standard sizes; we accommodate both small‑batch and large‑volume orders. Larger quantities help reduce unit costs.
To wrap up, JOIN‑fasteners® Hex Cap Screws in Grades 2, 5, and 8 provide a dependable, traceable, and cost‑effective fastening solution for industries ranging from construction to heavy machinery. With 18 years of export expertise, three integrated factories, and flexible commercial terms, JOIN is equipped to be your long‑term partner for all fastener needs. For technical data sheets, samples, or a personalised quotation, please contact our sales team at +86‑573‑83772218 or email bob@jjbfasteners.com. We look forward to delivering quality and value for your next project.
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