Bolt detection is divided into two types: manual and machine. Labor is the most primitive and most commonly used consistent detection method. In order to minimize the outflow of defective products, general production company personnel conduct inspections by visually treating the packaged or shipped products to eliminate defective products (bad including dental injuries, mixed materials, rust, etc.).
Another way is automatic detection of the machine, mainly magnetic particle inspection.
bolt
Magnetic particle flaw detection is the use of the interaction between the leakage magnetic field at the bolt defect and the magnetic powder, and the magnetic permeability and the permeability of the steel against the possible defects of the bolt (such as crack, slag inclusion, mixing, etc.). These materials are discontinuous after magnetization. The magnetic field at the place will undergo a catastrophic change, forming a leakage magnetic field at the part of the magnetic flux leaking at the surface of the work piece, thereby attracting the magnetic powder to form a magnetic powder accumulation at the defect—a magnetic mark, and under proper lighting conditions, the position and shape of the defect will be revealed. The accumulation of these magnetic particles is observed and explained, and the purpose of rejecting defective products has been achieved.
General shape countersunk head for use on required connection bolts
The back surface is smooth and does not protrude because the countersunk head can be screwed into the part. The round head can also be screwed into the part. The square head tightening force can be larger, but the size is large.
In addition, in order to meet the need for locking after installation, there are holes in the head and holes in the shank. These holes can prevent the bolt from loosening when it is subjected to vibration.
Some bolts without screwed rods have to be fine, called lumbar bolts. This kind of bolt is conducive to the connection of variable force.
There are special high-strength bolts on the steel structure, the head will be bigger and the dimensions will change.
In addition there are special uses: T-slot bolts, the most used on the machine fixture, the special shape, both sides of the head should be cut off. Anchor bolts, used to attach the machine to the ground, come in many shapes. U-bolts, as previously described. and many more.
There is also a dedicated stud for welding, one head is not threaded, it can be welded to the part, and the other side is screwed directly.