Head Styles for Machine Screws

Schematic	Head Style	Description	Application & Advantages
	Pan	Slotted pan heads have a flat or gently rounded top surface, cylindrical sides and a flat bearing surface. Phillips and Torx® pan heads have a rounded top surface, cylindrical sides and a flat bearing surface.	Has a general purpose bearing area. Can be substituted in most applications for round, truss or binding heads.
	Binding	Has a rounded top surface and slightly tapered sides. The bearing surface is flat with the slotted variety having an annular undercut adjacent to the shank.	Preferred design for making a firm electrical connection.
	Flat 82°	A countersunk head with a flat top surface and a cone-shaped bearing surface with a head angle of approximately 82°.	Used in applications where protrusion of the fastener above the mating sufrace is unaccepttable. Use a protrusion gage when measuring head height.
	Flat Undercut	Similar to an 82° flat head except that the head is undercut to 70% of its normal side height.	Standard for short lengths because it allows greater length of threads. Also avoids transition fillet and assembly interference.
	Flat 100°	A countersunk head with a flat top surface and a cone-shaped bearing surface with a head angle of approximately 100°.	Preferred over an 82° flat head when fastening in soft materials. The 100° countersunk head distributes pressure over a larger surface area.
	Fillister	Has a rounded top surfave, cylindrical sides, and a flat bearing surface. The greater side height is what distinguishes a fillister head from a pan head.	Preferred style for use in counterbored holes.
	Indented Hex	Has an indented top surface, six flat sides, and a flat bearing surface.	Preferred in high volume assembly where pneumatic equipment is used to drive the screw. Can transmit significantly higher tightening torque levels than other head styles.
	Indented Hex Washer	Has an indented top surface, six flat sides with a flat washer which projects beyond the sides and provides a flat bearing surface. The washer and hex are formed together as one piece.	Offers greater protection to the mating surface than a standard indented hex head. Increased bearing surface reduces likelihood of crushing mating surfaces.
	Truss	Has a low rounded top with a flat bearing surface greater in area than a round head screw of the same nominal size.	Weaker than pan or round heads but preferred in applications where minimal clearance exists above the head. Truss profile provides a trim finished assembly appearance.
	Oval	A countersunk head with a rounded top surface and a cone-shaped bearing surface of approximately 82°.	Preferred over a flat head in conical applications, or when a more decorative finished look is desired. The countersunk surface nests into mating countersunk application sites.
	Oval Undercut	Similar to an 82° oval head except that the head is undercut to 70% of its normal side height.	Standard for short lengths because it allows greater thread length.
	Round	Has a semi-eliptical top surface and a flat bearing surface	Sometimes preferred over pan head for its smooth surface and appearance.

See also Machine Screw Drive Types