Home > Fastening & Joining > Hex Head Cap Screw, Carbon Steel

M21x29mm Carbon Steel Hex Head Cap Screw - High Strength

Expert Overview

This M21x29mm hex head cap screw is engineered from high-grade carbon steel for exceptional strength and durability. Featuring a 23mm head width for superior torque application, it ensures secure and reliable fastening in critical assemblies.

StandardISO 9001
MaterialCarbon Steel
FinishGalvanized
GradeN/A
SizeM21
Length29mm
Head Width23mm

Detailed Engineering Specifications

Precision-manufactured to tight tolerances, this M21x29mm hex head cap screw offers superior performance in demanding environments. Constructed from hardened carbon steel, it exhibits excellent tensile strength and shear resistance, making it ideal for load-bearing applications. The 23mm hexagonal head allows for optimal torque application with standard tooling, ensuring secure seating and preventing loosening under vibration. Its robust design ensures long-term structural integrity in machinery, construction, and heavy-duty equipment.

🧊 Download 3D CAD Model (.STEP)

Verified Global OEM Partners

This component strictly adheres to the tolerances, material specifications, and quality benchmarks set by the world's leading industrial manufacturers.

BossardEst. 1831
Switzerland🇨🇭
"Global leader in fastening technology."
Market Rank
🏆 Top 3 Global Fastener Network
Industry Approvals
🚀 Aerospace & Tesla Approved
Warranty & Support
🛡️ Lifetime Traceability
Green Manufacturing
🌱 Carbon Neutral by 2030
Certified:ISO 9001, RoHS, REACH
Würth GroupEst. 1945
Germany🇩🇪
"Premium assembly and fastening materials."
Market Rank
🏆 #1 Global Assembly Supplier
Industry Approvals
🚀 VW & BMW OEM
Warranty & Support
🛡️ 5-Year Industrial Warranty
Green Manufacturing
🌱 100% Recyclable Packaging
Certified:ISO 9001, DIN EN
Brighton-BestEst. 1925
USA🇺🇸
"Master distributor of industrial fasteners."
Market Rank
🏆 Largest Distributor in NA
Industry Approvals
🚀 Boeing Approved
Warranty & Support
🛡️ Global Replacement Guarantee
Green Manufacturing
🌱 Green Steel Initiative
Certified:ISO 9001, A2LA

Certifications & Compliance

RoHS Compliant:Yes
REACH Compliant:Yes
Material Traceability:Available on Request
DFARS Compliant:Yes

Installation Procedure

1. Select the appropriate wrench or socket for the M21 hex head. 2. Insert the screw into the pre-drilled and tapped hole or mating component. 3. Tighten the screw to the recommended torque specification using a calibrated torque wrench.

Equivalent Standards (Cross-Reference)

Standard SystemDesignation
ISO EquivalentISO 898-1 / ISO 4014
DIN EquivalentDIN 931 / DIN 933
Primary StandardISO 9001

Mechanical Properties

Tensile StrengthStandard Commercial Spec
Yield StrengthStandard Commercial Spec
HardnessVaries by specific batch

Chemical Composition

Carbon (C)0.28 - 0.55%
Manganese (Mn)0.60 - 0.90%
Phosphorus (P)0.04% max
Sulfur (S)0.05% max

Temperature & Environment Rating

Min Operating Temp
-20°F (-29°C)
Max Continuous Temp
400°F (204°C)
Thermal Expansion
Typical for Material Class

Recommended Torque Values

Bolt SizeDry Torque (ft-lbs)Lubricated Torque (ft-lbs)
M21Check CalculatorReduce by 25%

Weight Reference Table

Size / TypeEst. Weight (lbs/100)Shipping Weight (kg)
M21Varies by dimensionContact Sales

Corrosion Resistance Guide

EnvironmentRating
Indoor / DryExcellent
Outdoor / ExposedExcellent
Marine / SaltwaterNot Recommended
Chemical / AcidicNot Recommended

Common Mistakes & How to Avoid Them

❌ Mistake✅ Correct Approach
Using an undersized or worn wrench, leading to cam-out and potential stripping of the hex head.Always use a properly sized, high-quality socket or wrench that fits snugly on the hex head to ensure maximum engagement and prevent damage.
Over-tightening the screw, which can lead to thread stripping, fastener failure, or damage to the mating components.Employ a calibrated torque wrench and adhere to the manufacturer's recommended torque values for the specific thread size and material combination.

Common Applications

  • Heavy machinery assembly
  • Structural steel construction
  • Automotive and aerospace components

⚠️ Engineering Warnings

  • Ensure thread compatibility with the mating component before installation.
  • Use appropriate personal protective equipment (PPE) during installation, including safety glasses and gloves.

Alternative Products to Consider

Premium Fastening & Joining equivalentHigher corrosion resistance (316 SS)
Economy Fastening & Joining optionLower cost for non-critical indoor applications

Frequently Asked Questions

Q: What is the Hex Head Cap Screw, Carbon Steel made from?

A: This Hex Head Cap Screw, Carbon Steel is manufactured from Carbon Steel.

Q: What are the main applications?

A: Heavy machinery assembly, Structural steel construction, Automotive and aerospace components.

Technical Schematic

HEX BOLT DIAGRAMSAE J429 / ASME B18.2.1HEXHEADLENGTH = 29mmAF23mm1/2"-13TIGHTEN →MECHANICAL PROPERTIESTensile Strength: 150,000 psiThread: 1/2"-13 UNCTorque Direction: Clockwise (CW)Head Marking: 6 radial lines (Grade 8)

Torque Specifications

⚡ UNIT CONVERTER

Conversion factor: 1 ft-lb ≈ 1.356 Nm

Verified Compatibility

StatusMating ComponentStandardTorque SpecEngineering Notes
No verified compatibility data found for this component.