M8 Square Welded Nut

（1）Product Definition

The M8 Square Welded Nut is a special fastener with a square shape and four welding protrusions at the bottom corners. It is permanently fixed to the metal sheet through resistance spot welding and provides a reliable internal thread hole for subsequent bolt connections. This nut complies with the DIN 928 standard and is one of the most commonly used welding nut specifications in industries such as automobiles, home appliances, and agricultural machinery.

（2）enforce standards

The M8 Square Welded Nut is produced in strict accordance with the DIN 928:2013-12 standard. This standard specifies the dimensions and technical requirements for square welded nuts with coarse thread ranging from M4 to M16 and fine thread ranging from 8mm to 16mm. The product grade is A. The DIN 928 standard requires that the steel used for the welded nuts contain a carbon content of ≤0.25% to ensure good welding performance.

Welding process parameters

Welding parameters are the core factor for ensuring welding quality. The welding parameters for M8 Square Welded Nut need to be adjusted according to the material of the base plate and its thickness, etc. The following are reference parameters under typical working conditions:

（1）Welding current

The recommended value is 5,000 - 8,000 A

For small-sized nuts (such as M4-M6), the current can be controlled within 3000 - 5000 A; for medium-sized ones (M8-M10), for example, the M8 Square Welded Nut, the welding current is 5000 - 8000 A; for large-sized ones (M12 and above), it needs 8000 - 10000 A

（2）Electrode pressure

The recommended value is 2.5 - 4.0 kN

The pressure should cause multiple protrusions to be uniformly flattened by about 1/3 before power is applied. If the pressure is too high, the protrusions may be flattened prematurely; if it is too low, it may cause splashing.

（3）Welding time

The recommended value is 8 - 15 cycles (approximately 0.16 - 0.3 seconds)

The welding time is shorter than that of spot welding the same weld point. After determining the appropriate electrode pressure and current, adjust it to obtain satisfactory weld points.

Quality inspection

To verify the welding strength of the nuts, post-weld quality inspection must be carried out. The main methods include:

（1）Torque test: Insert the matching bolt into the welded nut, and apply the specified torque using a torque wrench. If the M8 Square Welded Nut does not rotate and the weld point is not torn, it is considered qualified.

（2）Push-out force test: Apply axial pushing force to the welded nut, and record the maximum breaking load using a universal testing machine. The fracture should occur in the base material.

（3）Visual inspection: Conduct a visual check to see if the nuts are tilted, if they are fully in contact with the sheet material, and for any splashing or cracks. At the same time, use a gauge block to verify if the threads have been deformed due to welding.