Common standard aviation nut types, markings and applications

Update:14-07-2020
Summary:

(1) AN310 slot nut (castlenut) Name: This type of nut i […]

(1) AN310 slot nut (castlenut)
Name: This type of nut is also called castellated nut
Application: It is used in conjunction with AN3~AN2O body bolts
Thread: NF (fine thread)
Material: nickel alloy steel, stainless steel and 2024 aluminum alloy
"-", "C" and "D"
Example 1: Mark AN3l0 C 6
Expressed as: slotted nuts made of stainless steel and used with AN6 bolts;
(2) AN320
Name: Shear castle nut
Application: Only the part with shear stress, it is used with AN2l~AN36 shaft pin bolt.
Construction, manufacturing materials: the same as AN310 nuts, but the thickness of the nut is slightly thinner.
Example: Mark AN320D6
Expressed as: shear-resistant hexagonal flat nuts made of 2024 aluminum alloy and used with AN26 shaft pin bolts.
(3) AN315
Name: Ordinary nut
Application: It is used for the parts under high tension. Its disadvantage is that a locknut or an elastic washer must be used to ensure its tightness.
Material: same as AN310 nut.
Thread: There are two kinds of right-hand thread and left-hand thread.
Example: Mark AN315-7R
Representation: Right-hand threaded nut made of nickel alloy steel and used with AN7 bolts.
Mark:AN3l5C4L
Representation: Left-hand threaded nut made of stainless steel with a thread diameter of 1/4 inch.
(4) AN316
Name: Locknut
Features: This is a hexagonal anti-loosening nut with double-nut anti-loosening measures. It is used on AN315 common nuts to prevent them from loosening. However, due to the increased weight compared with other types of anti-loosening measures, it is rarely used in aircrafts at present.
(5) AN340 and AN345
Name: Mechanical screw nut
Application: Used in conjunction with mechanical screws, therefore, the thread specifications are manufactured according to the specifications of the screws.
Thread: AN340 is coarse threaded nut; AN345 is fine threaded nut.
Materials: Carbon alloy steel (-), stainless steel (C), brass (B) and 2024 aluminum alloy (DD).
Example: Mark AN340B6
Expressed as: Coarse threaded nuts made of brass and used with 6-32 mounting screws.
(6) AN350
Name: Butterfly Nut
Application: It is specially used for assembly parts that are frequently disassembled and assembled, and only need to be tightened with fingers. This nut can be used in conjunction with mounting screws or bolts. The nut that fits the mounting screw is given by the number of the screw.
Material: alloy steel or brass.
Example: Mark AN350-6
Indicates: a nut used in conjunction with 6-40 mounting screws. The nuts used with the bolts are given in 1/16-inch bolt specifications, plus the number 16.

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