Optimas Parts Imperial Blog Series: Technical Insight Into Phillips 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. 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.

Specification Resources

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

Phillips Fillister Head Machine Screws

THREAD SIZE	#4		#5		#6		#8		#10		1/4"		5/16"		3/8"		7/16"		1/2"
THREAD PITCH	40 UNC	48 UNF	40 UNC	44 UNF	32 UNC	40 UNF	32 UNC	36 UNF	24 UNC	32 UNF	20 UNC	28 UNF	18 UNC	24 UNF	16 UNC	24 UNF	14 UNC	20 UNF	13 UNC	20 UNF
HEAD DIAMETER	.166/.183		.187/.205		.208/.226		.250/.270		.292/.313		.389/.414		.490/.518		.590/.622		.589/.625		.710/.750
HEAD HEIGHT	.088/.107		.100/.120		.111/.132		.133/.56		.156/.180		.207/.237		.262/.295		.315/.355		.321/.368		.362/.412
HEAD SIDE HEIGHT	.069/.079		.078/.088		.086/.096		.102/.113		.118/.130		.155/.170		.194/.211		.233/.253		.242/.265		.273/.297
THREAD LENGTH	Fully threaded up to 1-1/8” included. Longer lengths are 1” min. thread length.		Fully threaded up to 2” included. Longer lengths are 1-1/2” min. thread length.
DRIVER SIZE	1		2								3		4
1/8 - 1/2 (Lengths)	–.02 (Length Tolerance)										–.03 (Length Tolerance)
5/8 - 1 (Lengths)	–.03 (Length Tolerance)										–.03 (Length Tolerance)
1-1/8 - 2 (Lengths)	–.03 (Length Tolerance)
2-1/4 - Over 6 (Lengths)	–.03 (Length Tolerance)

Phillips Oval Head Machine Screw

Phillips Oval Head Machine Screws

THREAD SIZE	#4		#5		#6		#8		#10		1/4"		5/16"		3/8"		7/16"		1/2"
THREAD PITCH	40 UNC	48 UNF	40 UNC	44 UNF	32 UNC	40 UNF	32 UNC	36 UNF	24 UNC	32 UNF	20 UNC	28 UNF	18 UNC	24 UNF	16 UNC	24 UNF	14 UNC	20 UNF	13 UNC	20 UNF
HEAD DIAMETER	.191/.212		.215/.237		.238/.262		.285/.312		.333/.362		.442/.477		.556/.597		.670/.717		.715/.760		.765/.813
HEAD HEIGHT	.067 ref		.075 ref		.083 ref		.100 ref		.116 ref		.153 ref		.191 ref		.230 ref		.223 ref		.223 ref
ANGLE	80°/82°
HEAD HEIGHT	.037 ref		.041 ref		.045 ref		.052 ref		.060 ref		.079 ref		.099 ref		.117 ref		.122 ref		.131 ref
THREAD LENGTH	Fully threaded up to 1-1/8” included. Longer lengths are 1” min. thread length.		Fully threaded up to 1-1/8” included. Longer lengths are 1” min. thread length.
DRIVER SIZE	1		2								3		4
1/8 - 1/2 (Lengths)	–.02 (Length Tolerance)										–.03 (Length Tolerance)
5/8 - 1 (Lengths)	–.03 (Length Tolerance)										–.03 (Length Tolerance)
1-1/8 - 2 (Lengths)	–.03 (Length Tolerance)
2-1/4 - Over 6 (Lengths)	–.03 (Length Tolerance)

Phillips Pan Head Machine Screw

Phillips Pan Head Machine Screws

THREAD SIZE	#4		#5		#6		#8		#10		1/4"		5/16"		3/8"		7/16"		1/2"
THREAD PITCH	40 UNC	48 UNF	40 UNC	44 UNF	32 UNC	40 UNF	32 UNC	36 UNF	24 UNC	32 UNF	20 UNC	28 UNF	18 UNC	24 UNF	16 UNC	24 UNF	14 UNC	20 UNF	13 UNC	20 UNF
HEAD DIAMETER	.205/.219		.205/.219		.205/.219		.205/.219		.205/.219		.205/.219		.205/.219		.205/.219		.205/.219		.205/.219
HEAD HEIGHT	.205/.219		.205/.219		.205/.219		.205/.219		.205/.219		.205/.219		.205/.219		.205/.219		.205/.219		.205/.219
THREAD LENGTH	Fully threaded up to 1-1/8” included. Longer lengths are 1” min. thread length.		Fully threaded up to 1-1/8” included. Longer lengths are 1” min. thread length.
DRIVER SIZE	1		2								3		4
1/8 - 1/2 (Lengths)	–.02 (Length Tolerance)										–.03 (Length Tolerance)
5/8 - 1 (Lengths)	–.03 (Length Tolerance)										–.03 (Length Tolerance)
1-1/8 - 2 (Lengths)	–.03 (Length Tolerance)
2-1/4 - Over 6 (Lengths)	–.03 (Length Tolerance)

Phillips Truss Head Machine Screw

Phillips Truss Head Machine Screws

THREAD SIZE	#4		#5		#6		#8		#10		1/4"		5/16"		3/8"		7/16"		1/2"
THREAD PITCH	40 UNC	48 UNF	40 UNC	44 UNF	32 UNC	40 UNF	32 UNC	36 UNF	24 UNC	32 UNF	20 UNC	28 UNF	18 UNC	24 UNF	16 UNC	24 UNF	14 UNC	20 UNF	13 UNC	20 UNF
HEAD DIAMETER	.241/.257		.272/.289		.303/.321		.364/.384		.425/.448		.546/.573		.666/.698		.787/.823		.907/.948		1.028/1.07
HEAD HEIGHT	.059/.069		.066/.078		.074/.086		.088/.102		.103/.118		.133/.150		.162/.183		.191/.215		.221/.248		.250/.280
THREAD LENGTH	Fully threaded up to 1-1/8” included. Longer lengths are 1” min. thread length.		Fully threaded up to 2” included. Longer lengths are 1-1/2” min. thread length.
DRIVER SIZE	1		2								3		4
1/8 - 1/2 (Lengths)	–.02 (Length Tolerance)										–.03 (Length Tolerance)
5/8 - 1 (Lengths)	–.03 (Length Tolerance)										–.03 (Length Tolerance)
1-1/8 - 2 (Lengths)	–.03 (Length Tolerance)
2-1/4 - Over 6 (Lengths)	–.03 (Length Tolerance)

Get a Technical Consult

For more information on Phillips machine screws or any type of fastener, contact our experts at optimas.com/contact.