Hex Head Cap Screws / Hex Bolts (ASTM A307 / SAE J429) – Grade 2 / 5 / 8 – Manufacturer Direct

Premium US Standard Hex Cap Screws & Hex Bolts (UNC/UNF)

At Handan Bolt, we are a specialized manufacturer of Hex Head Cap Screws and Hex Bolts tailored for the North American market. Produced in our export-focused facility in Yongnian, China, these fasteners are manufactured strictly according to ASME B18.2.1 dimensional standards. Whether you need low-carbon Grade A bolts for construction or high-strength Grade 8 alloy steel bolts for heavy machinery, we deliver quality that meets ASTM and SAE specifications.

Hex Cap Screw vs. Hex Bolt: What’s the Difference?

While often used interchangeably, there is a technical difference which we cater to:

• Hex Cap Screws: These feature a “Washer Face” (a raised circular boss) under the head and a chamfered point. They are manufactured to tighter tolerances and are designed to be used in precise machinery applications.
• Hex Bolts (Machine Bolts): These typically have a flat underside without a washer face and looser tolerances. They are commonly used in construction (ASTM A307) where precision is less critical.
• Tap Bolts: A “Tap Bolt” refers to a hex bolt that is threaded all the way to the head (Full Thread), allowing it to be inserted into a tapped hole without bottoming out on the shank.

Material Grades (SAE J429 & ASTM Standards)

Choosing the right grade is critical for safety. We supply the full range of US grades:

1. Grade 2 / ASTM A307 Grade A

Low carbon steel.

• Marking: No head markings.
• Application: General construction, non-critical joints, and consumer products. This is the most cost-effective option for basic fastening.

2. Grade 5 (SAE J429)

Medium carbon steel, quenched and tempered.

• Marking: 3 radial lines on the head.
• Strength: 120,000 psi (tensile).
• Application: Automotive parts, structural steel, and industrial equipment. This is the “workhorse” grade for most machinery.

3. Grade 8 (SAE J429)

Medium carbon alloy steel, quenched and tempered.

• Marking: 6 radial lines on the head.
• Strength: 150,000 psi (tensile).
• Application: High-stress applications like earthmoving equipment, aerospace ground support, and heavy suspension systems. Equivalent to Metric Class 10.9.

Surface Treatments for Every Environment

We offer finishes to match your corrosion resistance requirements:

• Zinc Plated (Clear/Blue or Yellow): The standard commercial finish. Yellow Zinc (Zinc Dichromate) is particularly popular in the US automotive aftermarket for Grade 8 bolts.
• Hot Dip Galvanized (HDG): A thick zinc coating essential for ASTM A307 construction bolts used in outdoor bridges and timber framing.
• Black Phosphate / Oil: Common for Grade 8 bolts to prevent hydrogen embrittlement and retain lubrication.

Thread Types: UNC vs. UNF

Since these are inch-series Screws (Read more on Wikipedia), we supply both thread pitches:

• UNC (Unified National Coarse): The most common thread type (e.g., 1/2″-13). Best for rapid assembly and general use.
• UNF (Unified National Fine): Finer threads (e.g., 1/2″-20) offering higher tensile strength and better vibration resistance.

Why Source US Standard Bolts from Handan Bolt?

Imperial Inventory: Unlike many factories that only stock Metric, we carry wire stock for Inch sizes from 1/4″ up to 1-1/2″.
Head Markings: We can manufacture bolts with your custom head marking (logo) for brand recognition (MOQ applies).
Packaging: We offer 1/4 keg boxes (approx. 10-15 lbs) or standard 50 lbs cartons typical for the US market.

Get a Direct Factory Quote

Are you a fastener distributor in the USA, Canada, or Mexico? Buying direct from us eliminates the trading company markup.

Need a price list for Grade 5 or Grade 8 bolts?

Please click here to Contact Our Sales Team for a Free Quote. We specialize in FCL orders.