1. Marking of screws or bolts
Name, standard number, nominal diameter × pitch × nominal length - material - wrenching form - surface treatment
1. Name
Use the standard names specified in the national standard, such as: screws, bolts, nuts, self-tapping screws, screw assemblies, plastic screws, etc.
2. Standard number
Mark the national number, ministry number or enterprise number (do not write the year number). If it is designed by our company, mark the product model.
3. Pitch
It is only suitable for fine threads, and is omitted for coarse threads.
4. Material
If carbon steel is used, this part is omitted, otherwise it should be noted, such as Cu (copper), C1 (stainless steel. For details of stainless steel material codes, see GB3098.6, among which: austenite, A1, A2, A4; martensite, C1, C3, C4; ferrite, F1.)
5. If the wrenching form adopts the wrenching form specified in the standard, it is omitted, otherwise it should be injected, such as a composite groove.
6. Surface treatment
If it is a carbon steel material, zinc plating passivation is omitted, otherwise it should be poured out, such as Cu/Ni (copper with nickel plating), Cu/Ni6b (copper with bright nickel plating, nickel layer thickness 6μm), Cu/Sn (copper with tin plating), Cu /Sn(60)Pb (copper lead-tin plating), Fe/Ni6bCr0.3r (carbon steel nickel-chromium plating), O (surface oxidation), stainless steel materials usually do not require plating.
If the coating complies with the ROHS directive, it will be marked after surface treatment and placed in brackets.
Note ①: If the material and surface treatment are not indicated in the mark of the fastener, it means that the material of the fastener is carbon steel with galvanized passivation (i.e., colored zinc plating).
Note ②: There are two types of self-tapping screws, type C and type F. Type C has a pointed end surface and type F has a flat end surface. However, self-tapping locking screws are not classified.
Note ③: The difference between the pan head and the cylindrical head is that the diameter of the head of the pan head is slightly larger than that of the cylindrical head, but the thickness of the head is slightly thinner than that of the cylindrical head.
Note ④: The difference between a countersunk head and a semi-countersunk head is that the head of a countersunk head has a flat end surface, while the head of a semi-countersunk head has a curved end surface. The thickness of the head of a countersunk head is thinner than that of a semi-countersunk head.
Note ⑤: The difference between set screws and ordinary screws is that the head shape of ordinary screws is T-shaped, while set screws do not have a T-shaped head.
Note ⑥: Slotting means that the head is a straight slot. Composite grooves, cross grooves and straight grooves can be used universally, but products in the same batch should be unified.
Note ⑦: For stainless steel fasteners, since our company’s employees are not familiar with its codes, “stainless steel” can be noted after the material code and placed in brackets.
Note ⑧: Difference between screws and bolts
Screw: It consists of two parts: head and screw. It is used in places with prefabricated threads and does not need to be used with nuts. It is commonly used to twist with an internal wrench, and there are often holes in the head.
Bolt: It consists of two parts: the head and the screw. It needs to be matched with the nut and is used to fasten and connect two parts with through holes. External wrench, usually hexagonal head.
Note ⑨: If you choose a screw assembly that meets the XXXX enterprise standard, the marks are: screw assembly
ZBY1 (two combinations of screws and round flat washers), ZBYA1 (three combinations of screws, round flat washers, and round spring washers), ZBF1 (two combinations of screws and square flat washers), ZBFA1 (three combinations of screws, square flat washers, and square spring washers).
2. Marking of nuts
Name, standard number, nominal diameter×pitch-material-surface treatment
1. Name
Use the standard name specified in the national standard, such as: nut.
2. The standard number, pitch, material and surface treatment are marked in the same way as the screws.
3. Marking name, standard number, nominal diameter × pitch - material - surface treatment of the washer
1. Name
The national standard stipulates that the standard names of flat washers and spring washers are both "washers". However, in view of the actual situation of our company, in order to avoid confusion, the flat washers are uniformly named "flat washers" and the spring washers are uniformly named "spring washers".
2. Nominal specifications
Refers to the major diameter of the thread. For example, the major diameter of the external thread M8 is 8.
3. The standard number, material and surface treatment are marked in the same way as the screws.
4. If the material and surface treatment are not indicated in the mark of the spring pad, it means that the material is 65Mn and the surface treatment is surface oxidation.
4. The marking name, standard number and nominal specifications of the retaining ring
1. Name
They are collectively named "retaining rings". Nominal specifications: refers to the shaft diameter or bore diameter. The standard number is marked in the same way as the screws.
2. The material of the retaining ring is 65Mn, and the surface treatment is surface oxidation.
Note ⑩: In addition, cylindrical pins are commonly used fasteners when our company manufactures molds. Its standard number is GB/T119-86. Marking example: Pin GB/T119 A 6 × 40 (indicates the nominal diameter - the big end diameter is φ6, the nominal length is 40, the material is carbon steel, surface oxidation treatment, A-type shape.)
Note ⑾: When selecting fasteners, you should first select from the existing order numbers in the BOM list, and try to choose commonly used or large-stock fasteners. New selection is only allowed after confirming that all parts in the existing BOM database are not applicable.
Note ⑿: In the BOM system, all "×" signs in fastener markings are represented by "*" signs.
Note ⒀: When the fastener marking format specified in this rule cannot express all its elements, it is allowed to add a suffix at the end of this naming format and place it in brackets, such as (XX exclusive), (original color), etc.
(Source: Maintenance Circle)