In visual inspection, there are more uniform traces on the surface of the nut after welding, which is a relatively normal phenomenon. However, if there are only local traces and they are serious, it is very likely that the welding will fail. Three solder joints can be clearly seen on the back of the welded part. If one or two of them are not obvious, the welding quality may not be sufficient.
After the visual inspection, in order to quickly determine the welding quality before production, the welding nut will be knocked directly with a tool. If the nut can tear the base material, the welding quality will be better. If it falls off very easily without any tearing of the base material, it is a virtual weld.
The second step uses fast destructive testing, which corresponds to a relatively high cost. Therefore, for nut welding, torque detection is more commonly used in our process. Set the required torque value, and then screw the nut. If the nut does not detach and the base material is not deformed at the torque value, the welding quality is qualified. Conversely, if the nut is screwed off without reaching the set torque value, it is unqualified. Torque detection method is also a non-destructive detection method.
In addition to torque, the pressure resistance value of the welded nut can also be tested by a press. Set the pressing speed according to the pressure test requirements, and then press until the nut is separated from the base material. At this time, the maximum pressure can be recorded, and then compared with the standard requirements for judgment. At the same time, you can see whether the nut has brought out the substrate, which has a similar effect to the second step.
Normally, in order to ensure the quality of the nut, we will comprehensively detect the quality of the nut in combination with the 4 methods mentioned above. From an economic point of view, torque detection is the most economical choice. If the preliminary research of the welding process is done well, torque testing can be selected, and then destructive testing will be performed again every quarter or every six months.
