Introducing frequently asked questions



Causes of Poor Welding in Stud Welding

Voltage is not correct.

If the voltage is too low, gaps will form in the weld zone, causing welding defects.
If the voltage is too high, the area around the weld will melt, causing welding defects.
Ensure that welding is carried out at the correct voltage to avoid creating gaps in the weld zone.

  • Even if welding is carried out at the correct voltage, the pressurization needs to be adjusted if the welding comes off when strength tests are carried out.

normal welds

Defective welds

Incorrect pressurization.

If a welding failure occurs despite welding at the correct voltage, the welding may be due to incorrect pressurization.

If you look closely at the photo on the left, you can see the dislodged surf ace glistening.
This type of disconnection can be seen when the pressure is not correct. Other possible causes include high impurities in the base material or the gun shaft not moving smoothly.
If the welding defect on the left is judged to be caused by incorrect pressurization, the gun cap should be removed and the internal pressurization screw slightly tightened. However, stronger pressure does not always guarantee a good weld.
On the contrary, depending on the base material, it may be possible to weld better with less pressure.
However, if welding defects occur for some reason, adjustments may be necessary.

Dust, etc. adhering to the position to be welded.

If the surface is covered with dust, dirt, oil, rust, a dry film of non-spatter or markings with a magic marker for positioning, the weld will certainly fail.
If non-spatter is applied to prevent spatter and welding is carried out before the non-spatter dries, welding can be carried out after adjustment.

Deep punches, with varying depths.

Normal welds

This is the standard punch depth - for M3, with a depth of no more than 0.15 mm. The picture on the right also shows the bolt being fitted into the punch. A space of the projection height can be seen between the base metal and the weld, so the weld can be welded almost normally.

Defective welds

This is an example of a punch that is too deep. The stud bolt is firmly in the hole, but the required space between the base metal and the weld is missing. This is a sure sign of a defective weld.

The surface coating of the base metal is thick. The film is not scraped off properly.

The surface paint is scraped off with a sanding tool.

Lack of use of positive and reverse polarity.

positive electrode connection

  • Iron and steel
    (pickling, polishing and blackening)
  • SUS304
  • Aluminum, etc.

The positive connection is where the gun and earth connections are connected to each other in the same colour as the camlock on the body.

negative electrode connection

  • Iron and steel (bonded steel sheet)
  • Other thin-film materials
  • Painted surfaces cannot be welded even if they are thin.

The reverse pole connection is to connect the gun and earth connection to the different colour of the camlock on the body.

Chuck burnt out.

After repeated welding, the chuck becomes a little less tight. In this case, it can be tightened with pliers, but if the chuck is used a s it is, the chuck may burn out and the welded stud bolt may also burn out, resulting in the nut not fitting and defective welding. Replace the chuck as soon as possible.

Poor grounding position.

When welding stud bolts of the smallest diameter, there appears to be little effect. However, when welding SUS and aluminium, welding defects may occur due to a phenomenon known as magnetic spraying, so consider the grounding position with reference to basic operation.

Poor material and shape of bolts and fukuro nuts.

The material and shape of the stud bolt is an important factor that significantly affects the welding of th e stud.
Use of other companies' products can cause welding defects. Use our products.

Poor movement of the gun shaft.

As the number of welds increases, debris may accumulate in the bearing, causing the gun shaft to move more slowly.
Occasionally move the gun shaft by hand to see if there is any snagging.
If it does not move properly, we recommend that you have it repaired as soon as possible.