## Common ground
All options are machine screws made from different metallic materials.
## Options at a glance
**7318.1X – Iron or steel**
- **Defining trait:** Most common material for general-purpose machine screws due to strength and cost-effectiveness.
- **Typical examples:** Hex bolts, cap screws in machinery.
- **Best fit when:** Need high tensile strength, durability, and low cost.
**7415.33 – Copper**
- **Defining trait:** Used for electrical conductivity and corrosion resistance, not structural strength.
- **Typical examples:** Electrical connectors, marine hardware.
- **Best fit when:** Conductivity or non-magnetic properties are required.
**7508.90 – Nickel**
- **Defining trait:** Resists corrosion and high temperatures; often used in harsh environments.
- **Typical examples:** Aerospace fasteners, chemical equipment.
- **Best fit when:** High corrosion resistance or heat stability needed.
**7616.10 – Aluminium**
- **Defining trait:** Lightweight with moderate strength; resists corrosion but less durable than steel.
- **Typical examples:** Aircraft parts, consumer electronics.
- **Best fit when:** Weight reduction is critical and load is low.
**7907.00 – Zinc**
- **Defining trait:** Typically used for plating (e.g., zinc-coated screws), not as base material.
- **Typical examples:** Galvanized screws for outdoor use.
- **Best fit when:** Corrosion protection via coating, not bulk material.
**8101.99 – Tungsten**
- **Defining trait:** Extremely hard and dense; used in specialized high-stress applications.
- **Typical examples:** Cutting tools, high-temperature fasteners.
- **Best fit when:** Extreme hardness or wear resistance required (rare for screws).
**8102.99 – Molybdenum**
- **Defining trait:** High melting point and strength at elevated temperatures.
- **Typical examples:** Aerospace, furnace components.
- **Best fit when:** High-temperature performance needed.
**8104.90 – Magnesium**
- **Defining trait:** Very lightweight but flammable; used in niche applications.
- **Typical examples:** Aerospace, racing vehicles.
- **Best fit when:** Weight savings outweigh fire risk concerns.
**8108.90 – Titanium**
- **Defining trait:** High strength-to-weight ratio and excellent corrosion resistance.
- **Typical examples:** Medical implants, aerospace, marine.
- **Best fit when:** Strength, lightness, and corrosion resistance are key.
## Key differences
| Material | Strength | Weight | Corrosion Resistance | Temperature Stability | Common Use Case |
|----------------|----------|--------|------------------------|------------------------|----------------------------|
| Iron/Steel | High | Medium | Low (unless coated) | Medium | General fastening |
| Copper | Low | Medium | High | Medium | Electrical, marine |
| Nickel | Medium | Medium | Very High | High | Harsh environments |
| Aluminium | Medium | Low | High | Medium | Lightweight applications |
| Zinc | Low | Medium | High (as coating) | Low | Corrosion protection |
| Tungsten | Very High| High | Medium | Very High | Extreme wear/heat |
| Molybdenum | High | Medium | Medium | Very High | High-temp environments |
| Magnesium | Low | Very Low | Low | Low | Weight-critical, niche |
| Titanium | High | Low | Very High | High | Aerospace, medical |
## How to choose
- Is the screw used in high-temperature or corrosive environments? → 7508.90, 8102.99, 8108.90
- Does weight matter most? → 7616.10, 8104.90, 8108.90
- Is electrical conductivity needed? → 7415.33
- Is it primarily for general-purpose fastening? → 7318.1X
- Is it coated (e.g., galvanized)? → 7907.00
## Overlaps & pitfalls
- Zinc (7907.00) is often a coating, not the base material—confusion with galvanized steel screws.
- Titanium and nickel both offer high corrosion resistance but differ in weight and strength.
- Tungsten and molybdenum are rare for standard machine screws; use depends on extreme conditions.
- No option clearly prioritizes "main function" — choose based on the **primary purpose** (e.g., strength, weight, environment)