## Common ground
All options are threaded shanks made from different metallic materials.
## Options at a glance
**7318.15 – Iron or steel**
- **Defining trait:** High strength and cost-effectiveness; commonly used in general mechanical applications.
- **Typical examples:** Machine bolts, structural fasteners, automotive hardware.
- **Best fit when:** Durability and load-bearing capacity are key, and cost is a concern.
**7415.33 – Copper**
- **Defining trait:** Excellent electrical conductivity and corrosion resistance; used where thermal or electrical performance matters.
- **Typical examples:** Electrical connectors, heat exchangers, specialized fasteners in electronics.
- **Best fit when:** The shank must conduct electricity or resist oxidation in harsh environments.
**7508.90 – Nickel**
- **Defining trait:** High resistance to corrosion and heat; ideal for extreme conditions.
- **Typical examples:** Aerospace components, chemical processing equipment, high-temp fasteners.
- **Best fit when:** Exposure to corrosive chemicals or elevated temperatures.
**7616.10 – Aluminium**
- **Defining trait:** Lightweight with moderate strength; good for weight-sensitive applications.
- **Typical examples:** Aircraft parts, consumer electronics, lightweight machinery.
- **Best fit when:** Weight reduction is critical and loads are moderate.
**7907.00 – Zinc**
- **Defining trait:** Often used as a coating (e.g., galvanized) but can be solid in some fasteners; low cost and sacrificial protection.
- **Typical examples:** Galvanized bolts, outdoor fixtures, low-stress fasteners.
- **Best fit when:** Corrosion protection via sacrificial layer is needed, or budget is tight.
**8101.99 – Tungsten**
- **Defining trait:** Extremely high density and melting point; used in extreme environments.
- **Typical examples:** High-temperature tools, radiation shielding components.
- **Best fit when:** Exceptional heat resistance or density is required (rare for standard shanks).
**8102.99 – Molybdenum**
- **Defining trait:** High melting point and thermal stability; resists creep at high temperatures.
- **Typical examples:** Furnace components, aerospace engine parts.
- **Best fit when:** Operating in very high-temperature environments.
**8104.90 – Magnesium**
- **Defining trait:** Lightest metal used; prone to corrosion and flammability.
- **Typical examples:** Aerospace housings, racing equipment.
- **Best fit when:** Weight is the top priority and environment is controlled.
**8108.90 – Titanium**
- **Defining trait:** High strength-to-weight ratio and excellent corrosion resistance.
- **Typical examples:** Medical implants, aerospace fasteners, marine hardware.
- **Best fit when:** Need for lightweight, strong, and corrosion-resistant performance.
## Key differences
| Material | Strength | Weight | Corrosion Resistance | Heat Resistance | Cost |
|--------------|----------|--------|------------------------|------------------|------|
| Iron/Steel | High | Medium | Low–Medium | Medium | Low |
| Copper | Medium | Medium | High | Medium | Medium |
| Nickel | High | Medium | Very High | Very High | High |
| Aluminium | Medium | Low | Medium | Low | Medium |
| Zinc | Low | Medium | Medium (sacrificial) | Low | Low |
| Tungsten | Very High| High | High | Extremely High | Very High |
| Molybdenum | High | Medium | High | Extremely High | Very High |
| Magnesium | Low | Very Low | Low | Low | Medium |
| Titanium | High | Low | Very High | High | High |
## How to choose
- Is the shank used in high heat or extreme environments? → 8101.99, 8102.99, 7508.90
- Does weight matter most? → 8104.90, 7616.10, 8108.90
- Is electrical or thermal conductivity needed? → 7415.33
- Is corrosion resistance critical? → 7508.90, 7616.10, 8108.90
- Is cost the main factor? → 7318.15, 7907.00
## Overlaps & pitfalls
A shank may combine traits (e.g., titanium is strong, light, and corrosion-resistant). If multiple options apply, choose based on the **main function**—e.g., use 8108.90 for aerospace fasteners even if other materials also fit. Avoid assuming "zinc" means galvanized; solid zinc shanks are rare