What does mh written on the screw mean?

Mh written on the screw is the screw factory mark, which means that this screw is produced by this manufacturer.

The marking format of thread marks is: thread code-thread tolerance zone code (middle diameter and top diameter)-thread length.

1, the code of the tolerance zone is represented by numbers and letters (capital letters for internal threads and lowercase letters for external threads), such as 7H and 6g. In particular, 7H and 6g represent thread tolerance, and H7 and g6 represent cylindrical tolerance codes.

2. Thread length is specified as short (indicated by S), medium (indicated by N) and long (indicated by L). Generally, the thread engagement length is not marked, and the thread tolerance zone is determined according to the medium engagement length (n).

If necessary, the thread length code S or L can be added, such as "M20-5G6g-L". If necessary, the numerical value of thread length can be indicated, such as "M20-5G6g-30".

Extended data:

How to use screws:

1. First, remove the silt on the surface of the broken wire, use a center chisel to make a countersink in the center of the section, and then use an electric drill to mount a bit with a diameter of 6-8 mm to drill a countersink in the center of the section, paying attention to the hole must be drilled through. After the hole is drilled through, remove the small drill bit and replace it with a drill bit with a diameter of 16 mm, and continue to expand and drill through the hole of the broken bolt.

2. Take covered electrode whose diameter is less than 3.2 mm, and carry out surfacing welding from inside to outside with medium and small current. At the beginning of surfacing, take half of the total length of the broken bolt. When surfacing welding is started, the arc should not be too long to avoid burning through the outer wall of the broken bolt. After surfacing to the upper end face of the broken bolt, continue surfacing to 14- 16 mm in diameter and 8- 10 mm in height.

3. After surfacing, knock the end face with a hammer to make the broken bolt vibrate along its axial direction. Due to the heat generated by the previous arc and the subsequent cooling and vibration at this time, the thread between the broken bolt and the machine body will become loose.

4. Observe carefully. When the fracture surface is found to be rusty after knocking, the nut of M 18 can be sleeved on the surfacing stud and welded together.

5. After welding is completed, put the ring wrench on the nut and twist it back and forth from left to right, or tap the nut end face with a small hammer while twisting it back and forth, and then take out the broken bolt.

6. After taking out the broken bolt, process the thread on the frame with a suitable tap to remove the rust and other sundries in the hole.

References:

Baidu encyclopedia-screw