## Common ground
All options are spaced thread screws made from different metallic materials.
## Options at a glance
**7318.14 – Iron or steel**
- **Defining trait:** Most common and cost-effective base material; offers high strength and durability.
- **Typical examples:** Machine screws, structural fasteners, general-purpose bolts.
- **Best fit when:** High strength, low cost, and widespread availability are priorities.
**7415.33 – Copper**
- **Defining trait:** Excellent electrical conductivity and corrosion resistance; non-magnetic.
- **Typical examples:** Electrical connectors, marine hardware, specialized electronics.
- **Best fit when:** Conductivity or resistance to corrosion in harsh environments is key.
**7508.90 – Nickel**
- **Defining trait:** High corrosion and heat resistance; often used for durability under stress.
- **Typical examples:** Aerospace components, chemical processing equipment.
- **Best fit when:** Resistance to high temperatures or corrosive chemicals is required.
**7616.10 – Aluminium**
- **Defining trait:** Lightweight with good corrosion resistance; non-magnetic and easy to machine.
- **Typical examples:** Aircraft parts, consumer electronics, outdoor fixtures.
- **Best fit when:** Weight reduction and moderate strength are important.
**7907.00 – Zinc**
- **Defining trait:** Primarily used for coating (e.g., galvanizing); not common as a base material for screws.
- **Typical examples:** Galvanized fasteners, sacrificial coatings.
- **Best fit when:** Corrosion protection via plating is the main purpose.
**8101.99 – Tungsten**
- **Defining trait:** Extremely high density and melting point; used in extreme environments.
- **Typical examples:** High-temperature tools, specialized industrial fasteners.
- **Best fit when:** Exceptional heat or wear resistance is needed.
**8102.99 – Molybdenum**
- **Defining trait:** High thermal stability and strength at elevated temperatures.
- **Typical examples:** Aerospace, furnace components.
- **Best fit when:** Performance under extreme heat or pressure is critical.
**8104.90 – Magnesium**
- **Defining trait:** Lightest structural metal; prone to corrosion and flammability.
- **Typical examples:** Lightweight vehicle parts, aerospace applications.
- **Best fit when:** Weight savings outweigh material limitations.
**8108.90 – Titanium**
- **Defining trait:** Excellent strength-to-weight ratio and superior corrosion resistance.
- **Typical examples:** Medical implants, aircraft, marine hardware.
- **Best fit when:** High performance, light weight, and long-term durability are essential.
## 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 | High | High |
| Aluminium | Medium | Low | High | Medium | Medium |
| Zinc | Low | Medium | Medium (via coating) | Low | Low |
| Tungsten | Very High| High | High | Very High | Very High |
| Molybdenum | High | Medium | High | Very High | Very High |
| Magnesium | Low | Very Low | Low | Low | Medium |
| Titanium | High | Low | Very High | High | High |
## How to choose
- Is weight a major concern? → 7616.10 (Al), 8104.90 (Mg)
- Does the screw need to resist corrosion in harsh environments? → 7415.33 (Cu), 7508.90 (Ni), 8108.90 (Ti)
- Is high temperature or extreme wear expected? → 8101.99 (W), 8102.99 (Mo)
- Is cost the main factor? → 7318.14 (Steel)
- Is electrical conductivity needed? → 7415.33 (Cu)
## Overlaps & pitfalls
- Zinc (7907.00) is rarely used as a base material; most zinc screws are galvanized steel. Misleading if not coated.
- Titanium, nickel, and molybdenum may overlap in aerospace/industrial use—choose based on primary need: strength (Ti), heat resistance (Mo), or corrosion (Ni).
- No single priority rule applies; select based on the **main function** of the screw