Hex socket head cap screw CSHHNB

Brand :

NIHON_BYORA

Caution

The product images are representative only. Specifications may vary by part number, including shape and color.

Product Description

[Material]Steel, stainless steel
[Surface Treatment]None, Black oxide coating, Electroless nickel plating, Trivalent black, Trivalent white, Bright chromate plating, Chromate plating, Chrome plating, Geomet treatment, Tin cobalt, Dacrotized, dark bronze color plating, anti-seize coating, Black nickel plating, Black chromate

Drawing

Specifications Table

Nominal thread size (d)	Thread Pitch (p)	b	dk		da	d_s		k		r	S				t	v
Nominal thread size (d)	Thread Pitch (p)	Reference	Maximum	Minimum	Maximum	Maximum	Minimum	Maximum	Minimum	Minimum	Nominal dimensions	Max. (12.9)	Max. (10.9)	Minimum	Minimum	Maximum
M3	0.5	18	5.68	5.32	3.60	3.00	2.86	3.00	2.86	0.1	2.5	2.58	2.58	2.52	1.3	0.3
M4	0.7	20	7.22	6.78	4.70	4.00	3.82	4.00	3.82	0.2	3.0	3.08	3.08	3.02	2	0.4
M5	0.8	22	8.72	8.28	5.70	5.00	4.82	5.00	4.82	0.2	4.0	4.095	4.095	4.02	2.5	0.5
M6	1.0	24	10.22	9.78	6.80	6.00	5.82	6.00	5.70	0.25	5.0	5.14	5.14	5.02	3	0.6
M8	1.25	28	13.27	12.73	9.20	8.00	7.78	8.00	7.64	0.4	6.0	6.14	6.14	6.02	4	0.8
M10	1.5	32	16.27	15.73	11.2	10.00	9.78	10.00	9.64	0.4	8.0	8.175	8.175	8.025	5	1.0
M12	1.75	36	18.27	17.73	13.7	12.00	11.73	12.00	11.57	0.6	10.0	10.175	10.175	10.025	6	1.2
M14	2.0	40	21.33	20.67	15.7	14.00	13.73	14.00	13.57	0.6	12.0	12.212	-	12.032	7	1.4
M16	2.0	44	24.33	23.67	17.7	16.00	15.73	16.00	15.57	0.6	14.0	14.212	14.212	14.032	8	1.6
M20	2.5	52	30.33	29.67	22.4	20.00	19.67	20.00	19.48	0.8	17.0	17.23	17.23	17.05	10	2.0
M22	2.5	56	33.39	32.61	24.4	22.00	21.67	22.00	21.48	0.8	17.0	-	17.23	17.05	11	2.2
M24	3.0	60	36.39	35.61	26.4	24.00	23.67	24.00	23.48	0.8	19.0	-	19.275	19.065	12	2.4
M30	3.5	72	45.39	44.61	33.4	30.00	29.67	30.00	29.48	1.0	22.0	-	22.275	22.065	15.5	3.0

*b (for reference) indicates the length of the effective thread section of the partially threaded bolt.

Product Feature Details

Because tightening of screws can be performed with simple tools, it is often handled carelessly, but tightening is important for the reliability of the secured assembly. For this reason, it is necessary to select bolts and tightening methods that can provide the appropriate tightening force during the design stage, and to faithfully follow the tightening method during the tightening stage to ensure the target tightening force (initial tightening force).

1. Relationship Between Bolt Elongation and Tightening Axial Force

In general, when a bolt is tightened, it yields at a lower value than the normal tensile force b, as shown in figure a on the right, resulting in a relative decrease in axial force. This rate of decrease becomes greater as the coefficient of friction on the thread surface increases, and the coefficient of friction varies depending on the material of the tightened object and the female thread, as well as the lubrication condition. Generally, the appropriate tightening axial force when using the torque method is determined within the elastic range, with a maximum of 70% of the standard proof strength.

Bolt elongation and axial force

2. Representative tightening management methods

Tightening management methods	Indicators	Tightening range
Torque method	Tightening torque	Elasticity region
Rotation angle method	Tightening rotation angle	Elasticity region
Rotation angle method	Tightening rotation angle	Plastic region
Torque gradient method	With respect to tightening rotating angle	Elastic limit
Torque gradient method	Gradient of tightening torque	Elastic limit

Each tightening method has a tightening region corresponding to the deformation region of the bolt, and the range of tightening axial force differs. The figure below schematically illustrates the relationship between bolt elongation and tightening axial force. From the figure, it can be seen that the magnitude of the tightening axial force has the relationship: elastic region < elastic limit < plastic region.

Hex socket head cap screw CSHHNB bolt elongation and tightening axial force relationship diagram

Relationship between bolt elongation and axial tightening force

3. Tightening by torque method

An explanation of the general torque method is provided. The relationship between torque (Tf) and axial force is shown by Formula (1).
Tf = k · d · Ff · ····· (1)
As shown in the figure on the right, due to variations in K, allowable setting values of Tf, etc., Formula (1) is replaced by Formula (2).
T fA = 0.35k (1 + 1/Q) σy x As x d:: (2)
The tightening torque is determined by equation (2). K is determined by the friction coefficient of the thread surface and the friction coefficient of the seat surface, and the experimentally obtained torque coefficient considering these factors is shown in the figure on the right.
Q is called the tightening coefficient and can be expressed as Q = Ffmax./Ff min.; the standard values are shown in the table below.

Hex socket head cap screw CSHHNB Relationship Diagram of Bolt Elongation and Tightening Axial Force (Torque Method Tightening)

Relationship between bolt elongation and tightening axial force (torque method tightening)

Bolt Surface treatment Lubrication	Torque coefficient k	Combination Tightened part material - Female screw material (i) (ii)


Steel bolt Black oxide coating　 (Temper color? Black oxide, etc.) Oil	0.145	SCM-FC FC-FC SUS-FC
	0.155	S10C-FC SCM-S10C FC-S10C SCM-SCM FC-SCM
	0.165	SCM-SUS FC-SUS AI-FC SUS-S10C SUS-SCM SUS-SUS
	0.175	S10C-S10C S10C-SCM S10C-SUS A1-S10C A1-SCM
	0.185	SCM-A1 FC-A1 A1-SUS
	0.195	S10C-A1 SUS-A1
	0.205	-
	0.215	A1-A1
Steel bolt black oxide coating Not lubricated	0.250	SI0C-FC SCM-FC FC-FC
	0.350	S10C-SCM SCM-SCM FC-S100 FC-SCM Al-FC
	0.450	S10C-S10C SCM-S10C Al-SCM A1-S10C
	0.550	SCM-A1 FC-A1 A1-A1
Steel bolt Electrogalvanized None	0.250	S10C-SCM S10C-FC FC-SCM FC-FC
	0.350	S10C-S10C SCM-S10C SCM-SCM SCM-FC FC-S10C
	0.350	A1-S10C A1-SCM A1-FC
	0.450	S10C-A1 SCM-A1 FC-A1 A1-A1
Stainless steel bolt Gloss barrel None	0.250	FC-FC SUS-FC
	0.350	A1-FC
	0.450	FC-A1 FC-SUS SUS-SUS
	0.550	A1-A1 A1-SUS SUS-A1

Torque coefficient K by combining the surface treatment of the bolt, the surface to be clamped, and the female thread material

Tightening coefficient Q	Mounting Method	Surface Condition		Lubrication State
Tightening coefficient Q	Mounting Method	Bolt	Nut	Lubrication State
1.15	Torque gradient method	All cases	All cases	All cases
1.15	Rotating Angle Method (Elastic Region)	All cases	All cases	All cases
1.25	Torque Wrench	Manganese phosphate	not treated or phosphate	oil lubrication or MoS2
1.4	Torque Wrench,	not treated or phosphate		Paste
1.4	Wrench with torque limiter			-
1.6	Impact wrench			-
1.6	Bolt elongation measurement	All cases	All cases	All cases
1.8	Torque Wrench	not treated or phosphate	not treated	without lubrication
1.8	Wrench with torque limiter	not treated or phosphate	not treated
2	Impact screwdriver	Zinc or cadmium plating	not treated
	Powered screwdriver	Galvanized	Galvanized	Oil lubrication or no lubrication
	-	Cadmium plating	Cadmium plating	Oil lubrication or no lubrication
	Nut rotating angle method (elastic range)	All cases	All cases	All cases
3	Manual tightening with a long-handled wrench	All cases	All cases	All cases

The standard values of tightening coefficient Q

4. Calculation example of tightening torque for hex socket head bolts

Allowable maximum axial force (F) = 0.7 × yield load
Tightening torque (TfA) = 0.35k (1 + 1/Q) σy·As·d
Maximum tightening torque (Tf) = k × F × d
k: torque coefficient
Q: tightening coefficient
σy: yield point or proof strength
As: effective cross-sectional area
d: nominal thread size

Steel (10.9, 12.9) Minimum proof strength: 10.9 = 940 N/mm² (95.9 kgf/mm²), 12.9 = 1100 N/mm² (112 kgf/mm²), stainless steel (A2-70) Minimum proof strength: 450 N/mm² (45.9 kgf/mm<sup id="9">2</sup>)