GOST 10621-80 Self-Tapping Round-Head Screws for Metal and Plastic

GOST 10621-80 applies to self-tapping round-head screws for metal and plastic of product grade B with nominal thread diameter from 2.5 to 8 mm.

SELF-TAPPING ROUND-HEAD SCREWS FOR METAL AND PLASTIC Construction and dimensions Self-tapping round-head screws for metals and plastics. Construction and dimensions	GOST 10621-80*Supersedes GOST 10621-63, GOST 11650-65, in respect of screws with blunt end

The design and dimensions of the screws correspond to those shown in the drawing and in Tables 1, 2. Two versions are provided.

Table 1

Dimensions in mm

Nominal thread diameter d		2.5	3	4	5	6	8
Thread pitch P	coarse	1.25		1.75	2.0	2.5	3.5
	fine	1.0		1.5		1.75	2.0
Head diameter D	Nom.	4.5	5.5	7.0	8.5	10.0	13.0
	Tolerance per js15	± 0.24		± 0.29			± 0.35
Head height k	Nom.	1.7	2.1	2.8	3.5	4.2	5.6
	Tolerance per js15	± 0.2			± 0.24
Head sphere radius R₁≈		2.4	2.9	3.6	4.4	5.1	6.6
Radii under the head	R, min	0.10		0.20		0.25	0.40
	da, max	3.1	3.6	4.7	5.7	6.8	9.2
Slot width n	Nom.	0.6	0.8	1.0	1.2	1.6	2.0
	Min	0.66	0.86	1.06	1.26	1.66	2.06
	Max	0.80	1.00	1.20	1.51	1.91	2.31
Slot depth t	Min	0.9	1.0	1.6	2.1	2.3	3.3
	Max	1.3	1.4	2.0	2.5	2.7	3.7
Tolerance of head-to-shank coaxiality (2IT14)		0.60		0.72			0.86
Tolerance of slot symmetry relative to the shank, diametral (2IT14)		0.50		0.60			0.72
Cross recess number		1		2		3
Cross recess diameter m, max		2.8	3.1	4.2	5.0	6.6	7.7
Cross recess depth h		1.25	1.60	1.75	2.50	2.45	3.65
Gauge penetration depth into cross recess	Max	1.4	1.7	2.0	2.8	3.0	4.2
	Min	1.1	1.4	1.5	2.3	2.5	3.7
Thread run-out, max		0.8			1.0

Note. The cross recess is per GOST 10753-80.

Table 2

mm

Screw length l		Nominal thread diameter d
Nom.	Tolerance per js17	2.5	3	4	5	6	8
6	± 0.75			-	-	-	-
8					-	-	-
10						-	-
12	± 0.90						-
14							-
16
(18)				Standard lengths
20	± 1.05	-
(22)		-	-
25		-	-
30		-	-
35	± 1.25	-	-
40		-	-	-
45		-	-	-
50		-	-	-	-

Note. Lengths l shown in parentheses are not recommended for use.

Designation example:

screw of version 1, diameter 5 mm, length 30 mm, material group 01, without coating, with coarse thread pitch

Screw 5×30.01 GOST 10621-80

Same, version 2, diameter 5 mm, with fine thread pitch, length 30 mm, material group 01, with 6 μm zinc coating, chromated

Screw 2-5×1.5×30.01.016 GOST 10621-80

Technical requirements, thread, inspection methods, acceptance rules, packaging and marking are per GOST 10618-80.

The theoretical mass of the screws is given in Reference Appendix 1.

Appendix 1. Informative

Theoretical mass of self-tapping screws

Screw length l, mm	Nominal thread diameter d, mm
	2.5	3	4	5	6	8
	Mass of 1000 pcs of steel screws with coarse thread pitch, kg ≈
6	0.32	0.51	-	-	-	-
8	0.37	0.59	1.11	-	-	-
10	0.42	0.67	1.25	2.21	-	-
12	0.47	0.75	1.39	2.43	3.61	-
14	0.52	0.83	1.53	2.67	3.93	-
16	0.57	0.91	1.67	2.91	4.25	5.01
18	0.62	0.99	1.81	3.15	4.57	5.58
20	-	1.07	1.95	3.39	4.89	6.15
22	-	-	2.09	3.63	5.21	6.72
25	-	-	2.30	4.00	5.69	7.57
30	-	-	2.65	4.60	6.49	9.00
35	-	-	3.00	5.20	7.29	10.42
40	-	-	-	5.80	8.09	11.84
45	-	-	-	6.40	8.99	13.25
50	-	-	-	-	9.69	14.68

Corresponds to DIN 7981, DIN 7516.