Bolt Specification Representation Method

 Bolt: A type of fastener consisting of a head and a screw (a cylinder with external threads), which needs to be matched with a nut to fasten and connect two parts with through holes. This connection form is called bolt connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolt connection is a detachable connection.

  Bolt specification representation method:

  Bolt specification M14 means a metric bolt with a thread diameter of 14mm. M stands for "metric, metric" thread. A complete thread mark is composed of: thread feature code + size code + tolerance zone code + other information + standard code (such as: add national standard code for domestic screws)
  1. The characteristic code of the thread uses the letter "M"
  2. Size code
  The size code of the single thread is "nominal diameter × screw moment". For coarse thread, the thread torque item can be omitted. The size code of the multi-thread thread is "nominal diameter × Ph lead P thread moment".
3. The tolerance zone code is represented by numbers and letters (capital letters for internal threads and small letters for external threads), such as 7H, 6g, etc. It should be pointed out that 7H, 6g, etc. represent thread tolerances, while H7, g6 represent cylinder tolerances code name.
  4. There are three types of screw-in lengths: short (indicated by S), medium (indicated by N), and long (indicated by L). Under normal circumstances, the screw-in length of the thread is not marked, and the thread tolerance zone is determined according to the medium screw-in length (N). If necessary, add the screw-in length code S or L, such as "M20-5g6g-L". For special needs, the value of the screw-in length can be indicated, such as "M20-5g6g-30".
  5. For left-handed threads, "LH" should be marked after the screw-in length. The screw-in length code and the rotation code are separated by "-", and the right-hand thread is omitted.
  6. Marking example:
  M 16-5g6g means ordinary coarse thread, nominal diameter 16, right-handed, thread tolerance zone middle diameter 5g, major diameter 6g, screwing length is considered as medium length.
  M16×1 LH-6G means ordinary thread with fine pitch, nominal diameter 16, pitch 1, left-handed, thread tolerance zone middle diameter and major diameter are both 6G, and the screwing length is considered as medium length.