M48 Grade 4.8 Torque Specification

Torque Values by Surface Condition

Stress area: 1473.19 mm² · Proof load: 456,689 N · Clamp load (75%): 342,517 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	3288.2	2425.3	29103.0	33530.4
Oiled	0.15	2466.1	1818.9	21826.8	25147.3
Zinc Plated	0.18	2959.3	2182.7	26192.0	30176.6
Waxed	0.1	1644.1	1212.6	14551.5	16765.2
MoS₂	0.12	1972.9	1455.1	17461.6	20118.1
Galvanized	0.25	4110.2	3031.5	36378.4	41912.5

Stress area: 1602.9 mm² · Proof load: 496,899 N · Clamp load (75%): 372,674 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	3577.7	2638.8	31665.3	36482.5
Oiled	0.15	2683.3	1979.1	23749.2	27362.1
Zinc Plated	0.18	3219.9	2374.9	28498.5	32834.0
Waxed	0.1	1788.8	1319.4	15832.2	18240.8
MoS₂	0.12	2146.6	1583.3	18999.0	21889.3
Galvanized	0.25	4472.1	3298.5	39581.4	45602.9

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 310 MPa × 1473.19 mm² = 342,517 N

Step 2 — Torque (dry): T = 0.20 × 0.0480 m × 342,517 N = 3288.2 N·m

Proof stress per ISO 898-1:2013 Table 4. Stress area per ISO 898-1 Annex A. K-factor per VDI 2230.

Light structural connections, furniture assembly, non-load-bearing joints

• Torque values are for standard hex bolts with ISO metric threads. Socket head cap screws may have different requirements.
• Lubrication reduces required torque significantly — using dry torque values on lubricated bolts risks exceeding yield strength.
• For critical or safety-related applications, always consult the manufacturer's specifications or applicable design standard (e.g., VDI 2230).
• Re-used bolts may have altered friction characteristics. Inspect threads before reuse.

SizeM48

Class4.8

Diameter48 mm

Pitch (coarse)5.0 mm

Tensile420 MPa

Yield340 MPa

Proof310 MPa