Common screw types:
A: Machine Screw
B: Tapping Screw: Self-tapping screw (for metal and plastic)
B-1: Sheet Metal Tapping Screw. (Iron die self-tapping screw)
B-2 : Plastic Tapping Screw. (For plastic, self-tapping screw)
C: Wooden Screw : Woodworking screw
D: Drywall Screw : Cement wall screw
E: Self Drilling Screws
E-1:STAINLESS STEEL SELF DRILLING SCREWS
E-2:Bi-Metal Self Drilling Screws
Common screw materials：
a.Low Carbon Steel
b. Stainless Steel 304
c. Stainless Steel 302: good structural toughness
d. Aluminum alloy 5052
d. Brass
e. Bronze
f. UNS C11000 Copper: Antimony Copper
