Westfield Fasteners Product Specification:

ISO 14583 - Torx Drive Pan Head Screws

This product guide contains the specification for metric threaded hexalobular or torx drive pan head screws, a aeries of standard parts available from Westfield Fasteners. The basis of this specification is the ISO standard ISO 14583.

Product Description

Also known as star, 6 lobe, and hexalobular internal. Torx screws are commonly found on cars, motorcycles, bicycle brake systems, hard disk drives, computer systems and consumer electronics and are becoming increasingly popular. The Torx design allows for a higher torque to be exerted than a similarly sized conventional hex socket head.

Scope of the ISO standard.

This variant of torx pan screws is made to ISO 14583. This international standard specifies the dimensions, tolerances and the variation in form of this screw type, for sizes from M2 up to and including M10. Refer to figure 1 and table 1 below for dimensions and tolerances. Table 2 shows the tolerances on the shank length.

Before the introduction of ISO 14583 torx pan head screws were manufactured to dimensions based on the phillips or pozi pan head screws defined in DIN 7985. The two standards specify slightly different head dimensions from each other.

Thread, d			M2	M2.5	M3	M3.5	M4	M5	M6	M8	M10
Thread Pitch, p			0.4	0.45	0.5	0.6	0.7	0.8	1.0	1.25	1.5
a		max	0.8	0.9	1	1.2	1.4	1.6	2	2.5	3
b		min	25	25	25	38	38	38	38	38	38
d_a		max	2.6	3.1	3.6	4.1	4.7	5.7	6.8	9.2	11.2
d_k		nom=max	4.0	5.0	5.6	7.0	8.0	9.5	12.0	16.0	20.0
d_k		min	3.7	4.7	5.3	6.64	7.64	9.14	11.57	15.57	19.48
k		nom=max	1.60	2.10	2.40	2.60	3.10	3.70	4.60	6.00	7.50
k		min	1.46	1.96	2.26	2.46	2.92	3.52	4.30	5.70	7.14
r		min	0.1	0.1	0.1	0.1	0.2	0.2	0.25	0.4	0.4
r_f		=	3.2	4	5	6	6.5	8	10	13	16
x		max	1.0	1.1	1.25	1.5	1.75	2.0	2.5	3.2	3.8
Hexalobular Socket	Socket No.		6	8	10	15	20	25	30	45	50
	A	ref	1.75	2.40	2.80	3.35	3.95	4.50	5.60	7.95	8.95
	t	max	0.77	1.04	1.27	1.33	1.66	1.91	2.42	3.18	4.02
	t	min	0.63	0.91	1.01	1.07	1.27	1.52	2.02	2.79	3.62

Shank Length (mm)	+/- (mm)
3	0.2
4-6	0.24
8-10	0.29
12-16	0.35
20-30	0.42
35-50	0.5
55-60	0.6

ISO 14583 - Torx Drive Pan Head Screws

Figure 1: Hexalobular Socket Pan Head Screw

Notes to figure 1:

Table 1: Dimensions & Tolerances according to ISO 14583

Table 2: Shank Length Tolerance according to ISO 14583