Generally, small diameter of the hexagon socket set screws, if it is tightened strongly in the hexagonal bar spanner, hexagonal hole is cracked. But our hexagon socket set screws is using the Ni-Cr-Mo Steel (SNCM240) to the material. And furthermore, the precision of the hexagonal hole is good. In addition, the hardness by the heat treatment is high (HRC50 - 53), there is also toughness.
Therefore, the hexagonal hole is not broken even if you tighten it until you can wrench off a hexagonal bar spanner. At that time, when you move the magnet to the hexagonal hole, because it does not have a hexagonal hole deformed, broken hexagonal bar spanner is attracted to the magnet, it will be drawn from the hexagonal hole.
Our hexagon socket set screw dries surface rust prevention oil with a vacuum hot-air drier after black oxide film (surface treatment). Therefore, the hand of the assembling worker does not get oil at the time of work. In addition, this setscrews is easy to use in automated assembly, and it is hard to rust.