Overview

• Flat head types have flat surfaces that taper toward the screw body to allow for countersinking
• The flat head lies flush against the workpiece
• Machine screws without washers can be used with both flat and lock washers
• Phillips drive types have a cross-shaped slot and are used with Phillips drivers
• To prevent damage to the fastener head and fastened surface, the drive design forces the driver to cam out when the fastener is sufficiently tightened
• Steel is strong and durable but less corrosion resistant than stainless steel
• To improve its resistance to corrosion, it may receive additional finishes and coatings.