Torx® Pan Head, Slot Pan Head and Flat Head Machine Screws

Optimas designed the Parts Imperial Blog Series to provide detailed information about the fasteners you use and the ones you may need. Curated to help you find the right parts, these technical releases supply information on components’ specifications, applications and standards. This Imperial Series is comprised of five types of components: flat washers, hex cap screws, locknuts, machine screws and tapping screws. Once you have determined the parts suited for your application, Optimas can source them through manufacturing and distribution, ensuring you get the parts you need.

The Torx® slot, pan and flat head machine screws are designed to hold metal components together and have a specified minimum tensile strength of 60,000 psi. They are designed to be used with a mating machine screw nut, a standard hex nut of Grade 2 or higher strength, or a mating tapped thread. The threads are Class 2A thread fit and thread length is 1” minimum for diameters up to #5 included and 1-1/2” minimum for all sizes #6 and larger.

The Torx® drive allows installation and removal with a mating Torx® driver bit.* The Torx® recess provides excellent ability to apply sufficient torque to the fastener. Serviceability will require access to a Torx® driver bit.**

*Installation and removal of the Torx® slot pan head machine screw can be done with a slotted screwdriver. The added slot of a slot pan head allows serviceability with common tools.

** The countersunk head of the Torx® flat head machine screw requires an 80° included angle countersink.

Specification Resources

Dimensional and material requirements are controlled by ASME B18.6.3 and Torx® licensed standards. This type of fastener is generally available in sizes #4 through 1/2” diameter and length as shown in the tables listed below. Other lengths are possible.

 Torx® Pan Head Machine Screws

 Torx® Slot Pan Head Machine Screws

 Torx® Flat Head Machine Screws