Round Head Machine Screw Metric Machine Screws Washer Attached

Round head machine screw is the screw with round head and washer under the head and then machine threaded. The round washer head design could possibly be the most versatile head design available. It combines the advantages of the round head but has a washer built onto the head to increase head diameter and prevent overdriving in soft materials while providing a maximum bearing surface. These fasteners have Square-Phillips combo recess drive designed to offer the dependability of a square drive recess with the convenience and after-market serviceability of a Phillips drive. In addition, they have machine thread design for superior holding power while reducing splitting or crumbling of the material, allowing the fastener to install rapidly with full thread engagement after just one revolution. The threaded surface is nearly perpendicular to the screw axis, providing great resistance to pullout. Ever Hardware provides custom-made fasteners and customizable packaging.

Galvanization, or galvanisation, (or galvanizing as it is most commonly called in that industry), is the process of applying a protective zinc coating to steel or iron, to prevent round head machine screw rusting. The most common method is hot-dip galvanizing, in which parts are submerged in a bath of molten zinc. Galvanizing protects in three ways:
It forms a coating of zinc which, when intact, prevents corrosive substances from reaching the underlying steel or iron.
The zinc serves as a sacrificial anode so that even if the coating is scratched, the exposed steel will still be protected by the remaining zinc.
The zinc protects its base metal by corroding before iron. For better results, the application of chromates over zinc is also seen as an industrial trend.