33 Fastening Materials
In P&O you will learn many methods of fastening materials together. Some of the most common methods include the use of rivets, screws, and glues. This chapter covers the use of tools and techniques for riveting.
Rules of thumb:
- When fastening parts together, ALWAYS USE THE SAME type of fastener. NEVER combine rivets with bolts and screws in the same joint. In general, a joint composed of similar fasteners is the most efficient because all fasteners reach capacity with the same amount of force.
- Edge distance: make a thru hole two fastener diameters from an edge to prevent pull out failure.
- Spacing: minimum spacing between rivets is three times the nominal rivet diameter
| Fastener Type | How do they resist shear, tensile, flexural and cyclic loading? | Rules of thumb |
| Screws and bolts
|
Create clamp-up, friction, compressive forces
Can support tension loads better than rivets and adhesives |
Need at least three threads for full engagement for strength |
| Rivets: aluminum, steel, cadmium-plated copper rivets, speedy | Create compressive forces inside the radius of the hole
More capable of supporting shear loads (loads perpendicular to the axis of the shaft) |
Edge distance at least two x diameter of rivet |
| Welding, brazing, soldering | Fusion of materials resists tension, compression and shear. | |
| Adhesives | Distribute bond over a large area to reduce shear stresses
Resist shear forces better than tension (opening) forces |
Clean/rough surface to create strong bond |
| Buckles, straps, string ties | Fibers resist tension only in one direction relative to tensile strength of fibers |