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. In this blog, we will focus on Phillips machine screws.
Phillips Machine Screws
Phillips 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 Phillips drive allows installation and removal with a mating Phillips driver bit. This recess is prone to the driver bit slipping out of the recess by design to help prevent over-torqueing of the fastener. The Phillips drive provides serviceability with common tools. The small head diameter allows this screw to fit into tight spaces.
Dimensional and material requirements are controlled by ASME B18.6.3. This type of fastener is generally available in sizes #4 through 1/2” diameter and length as shown in the table below. Other lengths are possible.
Phillips Fillister Head Machine Screw