Fasteners
Reference data and engineering information about fasteners for mechanics applications.
fasteners
Overview
Engineering reference data for Fasteners in mechanics.
Key Formulas
Newton's Second Law
Force = mass × acceleration.
Work
Work = force × displacement × cos(angle).
Kinetic Energy
Energy of motion.
Potential Energy
Gravitational potential energy.
Variables
| Symbol | Description | Unit |
|---|---|---|
| Force | N | |
| Mass | kg | |
| Acceleration | m/s² | |
| Velocity | m/s |
Common Fastener Types and Applications
This section provides a quick reference to the various fastener categories and their typical uses, as referenced in the related documents.
Bolts and Screws
- Metric Steel Bolts: Classified by Property Classes (e.g., 8.8, 10.9) defining proof load and tensile strength. Used with metric nuts.
- SAE & ASTM Steel Bolts: Classified by Grade (SAE) or Grade (ASTM), defining proof and tensile strength for imperial unit assemblies.
- U.S. Hex Bolts: Standardized dimensions per ANSI/ASME B18.2.1 (Imperial) and B18.2.3M (Metric).
- Machine Screws: Typically smaller than bolts, used with tapped holes or nuts. Dimensions specified for U.S. standards.
- Wood Screws: Feature coarse threads for wood. Dimensions (nominal size, diameter) and pilot hole specifications differ for hard and soft woods.
- Sheet Metal Screws & Self-Drilling SMS: Designed for thin metal applications.
- Lag Bolts: Heavy-duty fasteners for wood.
Nuts and Washers
- Metric Nuts: Proof loads specified for coarse and fine thread series.
- T-Nuts: Standardized metric sizes for T-slot tracks.
Threaded Rods
- Continuous rods used for hanging and anchoring. Load ratings provided for both Imperial and Metric units.
Thread Standards
- Unified Thread Standard (UNC/UNF): Defines coarse (UNC) and fine (UNF) series for inch-based fasteners.
- Metric Threads: Defined by ISO standards, with clearance and tapping drill size charts.
Specialty Fasteners
- Nails and Spikes: Available in metric and U.S. standard dimensions. Withdrawal force (load capacity) is a key design parameter.
- Improvised Torque Wrench: A method using a luggage scale for approximating torque when a calibrated wrench is unavailable.
Important Properties & Considerations
- Torque vs. Tension: Applied torque creates bolt tension (preload). Lubrication significantly affects this relationship, often requiring reduced torque to achieve the same load.
- Stress Area: The tensile stress area of a threaded bolt is critical for calculating its load-bearing capacity, distinct from its nominal cross-sectional area.
- Proof Load: The maximum tensile load a fastener can withstand without permanent deformation. This is a fundamental rating for bolts, nuts, and threaded rods.
- Wrench Sizes: Proper engagement between wrench/socket and bolt head is essential. Conversion between metric (mm) and SAE (inch) sizes is often necessary.