| Name |
Bi-metal Self-drilling Screws |
| Size |
6.3/5.5 |
| Drill Point |
#1, #2, #3, #5 |
| Material |
SUS304+SCM435, SUS316+SCM435 |
| Head |
Hex Washer |
| Thread |
Double Thread |
| Washer |
SUS304+EPDM |
| Washer Specification |
E14, E15, E16, E19 and etc |
| Surface Treatment |
Chrome, Ruspert, Decromet, etc |
| Application |
Solar Mounting and Outdoor |
| Brand |
Union |
| Certification |
ETA, ISO, BSCI |
| Origin |
China |
Bi-metal screws sometimes referred to as twin-fast screws, are made of two separate metals joined together. They have a carbon steel core and stainless steel exterior. Carbon steel provides strength while stainless steel provides corrosion resistance. This makes bi-metal screws ideal for use in outdoor applications like solar power systems and roofing.
Bi-metal screws are hardened through heat treatment to maximize their toughness and resistance to stripping and breaking. They can withstand high torque and grip well into materials like wood and metal. Their unique composition gives them excellent resistance to rust and corrosion compared to regular carbon steel screws.
Uses for Solar Mounting
For solar panel installations, bi-metal screws are commonly used to secure:
- Rails and brackets to the roof surface
- Frames that hold panels together
- Junction boxes and conduits
- Panels to racks and frames
Their threading grips tightly, while their stainless steel exteriors eliminate rust stains on the roofing materials. Bi-metal screws also hold up well to thermal expansion and contraction of the roof.
The combination of strength and corrosion resistance makes bi-metal screws well-suited for roofing needs. They help roofs stand up to sun, rain, snow, and wind. Their versatility allows use with many roofing materials like asphalt shingles, slate, metal sheeting, and more.
Corrosion Resistance
Stainless steel combined with a carbon steel core gives bi-metal screws excellent resistance to rust and corrosion. The stainless steel exterior protects against oxidation, allowing long-term outdoor use.
Bi-Metal Specification
| Specification |
| Diameter(mm) |
Length(mm) |
Thread Size |
Drill Point |
| 4.8 |
25-220 |
16 |
#1, #2, #3, #5 |
| 5.5 |
25-300 |
14 |
#1, #2, #3, #5 |
| 6.3 |
19-300 |
14 |
#1, #2, #3, #5 |
| 6.3/5.5 |
25-50 |
14 |
#1, #2, #3, #5 |
| 6.3/5.5 |
60-300 |
Double Thread |
Bi-Metal Coating
| Surface Treatment |
| Types |
Class2 |
Class3 |
Class4 |
Dacromet |
| Coating Material |
Mechanical Galvanized |
Mechanical Galvanized |
Mechanical Galvanized |
Zinc and Aluminum |
| Salt Spray Test |
500Hours |
1000Hours |
2000Hours |
1000Hours |
Report Result
Audited Supplier 
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