Bi-metal Spiral Point Self-drilling Screws

Stainless steel such as A2 or A4 grade has outstanding anti-corrosion properties, but not a good material to serve as a tool and drill a hole. In contrast, carbon steel can be hardened but poor in chemical resistance.This is why Sun Through put them together to cover each other's weakness.
"A chain is only as strong as its weakest link." This saying perfectly points out the difficulty of this product. If the drilling point isn't designed properly, the bonding point breaks easily, no matter how hard the drilling tip is.
The smooth flutes of the spiral point dramatically lower friction of chip removal, and users are no longer worried about the weakest link.
*The sample in the photo is not plated or coated to demonstrate bi-metal appearance. It will not be distinguishable from steel screw after galvanized or coated.