## Common ground
All options are self-tapping screws categorized by their base metal material.
## Options at a glance
**7318.14 – Iron/Steel**
- **Defining trait:** Most common and cost-effective material, offers high strength and durability.
- **Typical examples:** Standard machine screws for wood, metal, or plastic.
- **Best fit when:** General-purpose use where strength and affordability matter most.
**7415.33 – Copper**
- **Defining trait:** Excellent electrical conductivity and corrosion resistance; non-magnetic.
- **Typical examples:** Electrical connectors, marine applications, decorative fixtures.
- **Best fit when:** Applications requiring conductivity or resistance to corrosion in moist environments.
**7508.90 – Nickel**
- **Defining trait:** High corrosion and heat resistance; often used for plating or alloys.
- **Typical examples:** Aerospace components, high-temperature environments.
- **Best fit when:** Exposure to harsh chemicals or elevated temperatures.
**7616.10 – Aluminium**
- **Defining trait:** Lightweight with good corrosion resistance; non-ferrous and non-magnetic.
- **Typical examples:** Aircraft parts, electronics enclosures, outdoor fixtures.
- **Best fit when:** Weight reduction is critical and moderate strength suffices.
**7907.00 – Zinc**
- **Defining trait:** Often used as a coating (e.g., galvanized) but rarely for structural screws; soft and prone to wear.
- **Typical examples:** Galvanized fasteners, temporary or low-stress applications.
- **Best fit when:** Corrosion protection via plating is needed, not structural integrity.
**8101.99 – Tungsten**
- **Defining trait:** Extremely hard and dense; used in high-wear or high-strength alloys.
- **Typical examples:** Specialized industrial tools, cutting-edge engineering parts.
- **Best fit when:** Extreme hardness or wear resistance is required (rare for standard screws).
**8102.99 – Molybdenum**
- **Defining trait:** High melting point and strength at elevated temperatures; used in alloys.
- **Typical examples:** High-temp industrial equipment, aerospace components.
- **Best fit when:** Performance under extreme heat or stress is essential.
**8104.90 – Magnesium**
- **Defining trait:** Very lightweight but reactive; prone to corrosion and flammable.
- **Typical examples:** Aerospace or automotive parts where weight is critical.
- **Best fit when:** Weight savings outweigh durability concerns (rare for screws).
**8108.90 – Titanium**
- **Defining trait:** High strength-to-weight ratio, excellent corrosion resistance, biocompatible.
- **Typical examples:** Medical implants, aerospace, high-performance tools.
- **Best fit when:** Need for lightweight, strong, and corrosion-resistant fasteners.
## Key differences
| Material | Strength | Weight | Corrosion Resistance | Cost |
|----------------|----------|---------|------------------------|----------|
| Iron/Steel | High | Medium | Low (unless coated) | Low |
| Copper | Medium | Medium | Very High | High |
| Nickel | High | Medium | Very High | High |
| Aluminium | Medium | Low | High | Medium |
| Zinc | Low | Medium | Moderate (coated) | Low |
| Tungsten | Very High| High | High | Very High|
| Molybdenum | High | Medium | High | Very High|
| Magnesium | Low | Very Low| Low | Medium |
| Titanium | High | Low | Very High | High |
## How to choose
- Is strength and cost-efficiency the priority? → 7318.14
- Does the application involve electricity or moisture? → 7415.33 or 7616.10
- Is high heat or corrosion resistance needed? → 7508.90, 8102.99, or 8108.90
- Is weight reduction critical? → 7616.10 or 8108.90
## Overlaps & pitfalls
Some materials (e.g., titanium, nickel) may be used in alloys or coated forms, leading to overlap with other categories. Zinc is rarely used as a bulk material for screws—usually as a coating. If the product is primarily defined by its function (e.g., structural vs. electrical), prioritize that over material alone. No option is clearly dominant; choose based on **main functional need**