Screw callout
The dimension format of the thread mark is:
Thread code - thread tolerance zone code (pitch diameter, top diameter) - screw length
l) The code of the tolerance zone is represented by numbers and letters (uppercase letters for internal threads and lowercase letters for external threads), such as 7H, 6g, etc., it should be specially pointed out that 7H, 6g, etc. represent thread tolerances, while H7, g6 represent cylinder tolerances codename.
2) The length of rotation is specified as short (represented by S), medium (represented by N), and long (represented by L). In general, the thread engagement length is not marked, and the thread tolerance zone is determined by the medium engagement length (N). If necessary, add the screw length code S or L, such as "M20-5g6g-L". When special needs are required, the value of the screwing length can be indicated, such as "M20-5g6g-30".
Ordinary thread
Ordinary coarse thread: feature code M+ nominal diameter + rotation direction + thread tolerance zone code (pitch diameter, top diameter) - screw length
Ordinary fine thread: feature code M+ nominal diameter * thread pitch + rotation direction + thread tolerance zone code (pitch diameter, top diameter) - screw length
The right-hand thread is omitted, and the left-hand thread is indicated by "LH".
M 16－5g6g means coarse thread ordinary thread, nominal diameter 16, right-handed, the thread tolerance zone is 5g in the middle diameter and 6g in the major diameter, and the screwing length is considered as the medium length.
M16×1 LH-6G means fine thread ordinary thread, nominal diameter 16, pitch 1, left-handed, thread tolerance zone medium diameter and major diameter are both 6G, and the screwing length is considered as medium length.
The labeling format is: feature code (cylindrical pipe thread is represented by G, conical pipe thread is represented by NPT) + dimension code + tolerance grade code + rotation direction
G1A--LH represents the inch non-threaded sealing pipe thread, the size code is 1in, left-handed, and the tolerance class is A.
Rcl/2 means inch thread seal taper pipe thread, size code 1/2in, right-handed.
