GOST 10618-80 Self-Tapping Screws for Metals and Plastics

SELF-TAPPING SCREWS FOR METALS AND PLASTICS

GOST 10618-80

State Standard of the Union of Soviet Socialist Republics

SELF-TAPPING SCREWS FOR METALS AND PLASTICS General specifications Self-tapping screws for metals and plastics. General specifications	GOST 10618-80*Supersedes GOST 10618-63

By Decree of the USSR State Committee for Standards dated December 30, 1980 No. 6109, the effective date is set as 01.01.82.

This standard applies to self-tapping screws for metals and plastics, product grade B, with blunt and pointed ends.

The requirements of this standard are mandatory.

1. Dimensions

1.1. The shape and dimensions of self-tapping screws shall comply with the standards on the design and dimensions of specific screw types.

1.2. The thread and screw-end dimensions shall conform to those shown in Fig. 1, 2 and Tables 1, 2.

(Revised edition, Amendments No. 1, 2).

1.3. The designation scheme for self-tapping screws is given in mandatory Appendix 1.

Fig. 1

Table 1

mm

Thread diameter d	Nom.	2.5	3		4	5	6	8
	Tolerance per h13	-0.14			-0.18		-0.22
Internal thread diameter d₁, max		1.7	2.1		2.8	3.5	4.2	5.6
Thread pitch P		1.25			1.75	2.00	2.50	3.50
Flat width b, max		0.10		0.15		0.20
Length of tapered end l₁≈		2.9			4.3	5.7		6.1

Note. Depending on the thread-forming method, the edges of flat A may have rounding.

Fine-pitch thread

Fig. 2

Table 2

mm

Thread diameter d	Nom.	2.5	3	4	5		6	8
	Tolerance per h13	-0.14		-0.18			-0.22
Internal thread diameter d₁, max		2.0	2.3	2.9	3.9		4.9	6.2
Thread pitch P		1.0		1.5			1.75	2.0
Flat width b, max		0.10				0.15
Length of tapered end with 4° angle l₁≈		3.5		5.0			6.0	7.0
Length of tapered end with 7° 30’ angle l₂≈		1.00		1.50			1.75	2.00

Note. (Deleted, Amendment No. 1, 2).

2. Technical requirements

2.1. Limit deviations of dimensions and surface location, and the surface roughness of self-tapping screws, shall comply with the standards on the design and dimensions of specific screw types.

2.2. Material grades and their designations shall conform to those specified in Table 3.

Table 3

Material name	Material grade	Designation of material grade (group)
Carbon steels	08kp, 10, 10kp to GOST 10702-78	01
	20, 20kp, 25 to GOST 10702-78	04
Alloy steels	20Kh, 40Kh to GOST 4543-71	10
	30KhGSA to GOST 4543-71	12

2.3. Material grades not specified in Table 3 may be used for manufacturing screws, provided their mechanical properties are not lower than those of the material grades established in Table 3.

In this case, the screw designation shall indicate the material grade instead of the material designation.

2.4. Self-tapping screws shall be subjected to heat treatment or thermochemical treatment.

The hardness of screws with coarse-pitch thread shall be HRCe 57 … 63, and with fine-pitch thread - HRCe 37 … 47.

The surface hardness of screws after thermochemical treatment shall be not less than 450 HV₀₃; 83HR15N.

The depth of the thermochemical treatment layer shall be:

for diameters from 2 to 3 - 0.04 - 0.01 mm;

for diameters from 4 to 6 - 0.05 - 0.18 mm;

for diameters from 7 - 0.1 - 0.23 mm.

(Revised edition, Amendments No. 1, 2).

2.5. The thread pitch and profile angle, and the angles of the tapered part of the shank, shall be ensured by the manufacturing accuracy of tools or templates, for which the permissible deviation from the nominal value shall not exceed ± 10 %.

2.6. A decrease in the outer diameter of the screw within the tolerance field is permitted only towards the end of the screw.

2.7. Self-tapping screws with a pointed end shall have a cylindrical shank with full-profile thread up to the tapered part.

2.8. For screws having fewer than four thread turns, the length of the tapered end shall not exceed 30 % of the total screw length.

(New edition, Amendment No. 2)

2.9. The thread shall be clean, free from galling and burrs. Partial undercuts, thickening or tearing of the thread turns are not permitted.

2.10. Types of coatings and their designation - per GOST 1759.0-87.

2.11. Tolerances of dimensions, form and location of screw surfaces - per GOST 1759.1-82.

Permissible surface defects of screws - per GOST 1759.2-82.

(New edition, Amendment No. 2).

2.12. On screws with a pointed end, blunting of the gimlet point by more than 15 % of the thread diameter is not permitted.

(New edition, Amendment No. 2)

3. ACCEPTANCE RULES

3.1. Rules for acceptance of screws - per GOST 17769-83.

4. TEST METHODS

4.1. Visual inspection of screws, checking of dimensions, surface roughness, surface defects, hardness, coating thickness and measurement of the decarburized layer depth - per GOST 1759.0-87.

If screws have no flat for hardness measurement, hardness shall be measured on witness specimens that underwent heat treatment together with the screws.

It is permitted not to inspect the head sphere radius, the sphere height of the raised countersunk head, the diameter and depth of the cross recess, and the radii under the screw head, provided these dimensions are ensured by the tool or manufacturing process.

4.2. Screwing-in testing of screws shall be performed at the customer’s request by the following method:

screws are screwed into a steel test plate;

the hardness of the steel test plate shall be 125…165 HB, and the carbon content of the plate steel shall not exceed 0.23 %;

the plate thickness S, as well as the hole diameters, shall conform to those shown in Fig. 3 and Table 4.

The end of the screwed-in screw shall protrude from the plate by at least two full-profile thread turns. Screws having fewer than four thread turns shall be screwed into the plate with a gap between the head and the plate not exceeding the permissible thread run-out.

After unscrewing, the thread turns shall show no chipping, cracks, stripped or crushed thread turns, and no crushing of the recess bearing surfaces on the head.

Fig. 3

Table 4

mm

Nominal thread diameter d	2.5	3	4	5	6	8
S for screws:
with coarse-pitch thread	1.25	1.25	1.75	2.00	2.50	3.50
with fine-pitch thread	2.5	3.0	4.0	5.0	6.0	8.0
d₁ (H13) for screws:
with coarse-pitch thread	2.0	2.5	3.0	3.8	4.8	6.0
with fine-pitch thread	2.1	2.5	3.5	4.5	5.5	7.5

4.1., 4.2. (Revised edition, Amendment No. 1, 2).

5. PACKAGING AND MARKING

5.1. Packaging, marking, transportation and storage - per GOST 18160-72.

(New edition, Amendment No. 2)

APPENDIX 1

Mandatory

Designation scheme for screws

Note. Version 1, coarse thread pitch and no coating are not indicated in the designation.

Example of designation of a screw in version 2, with thread diameter d = 5 mm, with fine thread pitch, length l = 30 mm, made of carbon steel with zinc coating 6 µm thick, chromated:

Screw 2-5×1.5×30.01.016 GOST… (Revised edition, Amendment No. 1).

APPENDIX 2. (Excluded, Amendment No. 1).