Full Answer
Why is a heat treated washer used in a wrenching bolt?
In Dural material, a special heat treated washer must be used to provide an adequate bearing surface for the head. The head of the internal wrenching bolt is recessed to allow the insertion of an internal wrench when installing or removing the bolt.
What type of bolts are used in Dural bolts?
In Dural material, a special heat treated washer must be used to provide an adequate bearing surface for the head. The head of the internal wrenching bolt is recessed to allow the insertion of an internal wrench when installing or removing the bolt. Special high strength nuts are used on these bolts.
What size bolts are not used in primary structures?
Alloy steel bolts smaller than No. 10-32 and aluminum alloy bolts smaller than 1/4 inch diameter are not used in primary structures. Aluminum alloy bolts and nuts are not used where they will be repeatedly removed for purposes of maintenance and inspection.
What does an3dd5a mean on a bolt?
For example, in the bolt part number AN3DD5A, the "AN" designates that it is an Air Force-Navy Standard bolt, the "3" indicates the diameter in sixteenths of an inch (3/16), the "DD" indicates the material is 2024 aluminum alloy.
What is a self wrenching bolt?
An internal wrenching nut, (also known as an Allenut or Allen nut), is a cylindrical nut that is internally threaded on one side and has an Allen socket on the other side; the outside of the nut is smooth or has knurling on it.
In what way are AN standard steel bolts identified?
Fasteners are identified by four or five attributes; Type, Material, Diameter, Length, and Thread Pitch or Count (machine thread fasteners only).
What are the three types of bolts?
Threaded Fasteners There are three main types of threaded fastener; Bolts, Screws and Studs. Bolts have a head on one end (this is usually a hex head) and are threaded on the other. They are generally used in conjunction with a nut (and sometimes a washer) to hold them in place.
What does B mean on a bolt?
ASTM A307 Grade B Grade B bolts and studs have a tensile strength between 60 ksi and 100 ksi.
What are internal wrenching bolts made of?
These bolts, (MS-20004 through MS-20024 or NAS-495) are fabricated from high strength steel and are suitable for use in both tension and shear applications. When they are used in steel parts, the bolt hole must be slightly countersunk to seat the large corner radius of the shank at the head. In Dural material, a special heat treated washer must be used to provide an adequate bearing surface for the head. The head of the internal wrenching bolt is recessed to allow the insertion of an internal wrench when installing or removing the bolt. Special high strength nuts are used on these bolts. Replace an internal wrenching bolt with another internal wrenching bolt. Standard AN hex head bolts and washers cannot be substituted for them as they do not have the required strength.
How to identify bolts?
Bolts can be identified by the shape of the head, method of securing, material used in fabrication, or the expected usage.
What are aircraft bolts made of?
Aircraft bolts are fabricated from cadmium or zinc plated corrosion resistant steel, unplated corrosion resistant steel, and anodized aluminum alloys. Most bolts used in aircraft structures are either general purpose, AN bolts, or NAS internal wrenching or close tolerance bolts, or MS bolts. In certain cases, aircraft manufacturers make bolts of different dimensions or greater strength than the standard types. Such bolts are made for a particular application, and it is of extreme importance to use like bolts in replacement. Special bolts are usually identified by the letter "S" stamped on the head.
What is a close tolerance bolt?
This type of bolt is machined more accurately than the general purpose bolt. Close tolerance bolts may be hex headed (AN-173 through AN-186) or have a 100° countersunk head (NAS-80 through NAS-86). They are used in applications where a tight drive fit is required (the bolt will move into position only when struck with a 12 to 14 ounce hammer).
What is a special bolt?
Special bolts are usually identified by the letter "S" stamped on the head. AN bolts come in three head styles - hex head, clevis, and eyebolt. NAS bolts are available in hex head, internal wrenching, and countersunk head styles. MS bolts come in hex head and internal wrenching styles.
What is the difference between a steel bolt and an aluminum bolt?
AN standard steel bolts are marked with either a raised dash or asterisk; corrosion resistant steel is indicated by a single raised dash; and AN aluminum alloy bolts are marked with two raised dashes. Additional information, such as bolt diameter, bolt length, and grip length may be obtained from the bolt part number.
How to identify an aircraft bolt?
AN-type aircraft bolts can be identified by the code markings on the bolt heads. The markings generally denote the bolt manufacturer, the material of which the bolt is made, and whether the bolt is a standard AN-type or a special purpose bolt. AN standard steel bolts are marked with either a raised dash or asterisk; corrosion resistant steel is indicated by a single raised dash; and AN aluminum alloy bolts are marked with two raised dashes. Additional information, such as bolt diameter, bolt length, and grip length may be obtained from the bolt part number.
What is the industry standard for screws?
Coarse threads are the industry standard; choose these screws if you don’t know the pitch or threads per inch. Screws that meet ASME B18.3, ASME B18.3M, ISO 21269, and ISO 4762 (formerly DIN 912) comply with specifications for dimensional standards.
What is the strength of a steel screw?
With a tensile strength of 170, 000 psi, these alloy steel screws are stronger than Grade 8 steel screws. Length is measured from under the head.
What is a class 8 screw?
These Class 8. 8 steel screws are suitable for fastening most machinery and equipment. Dimensions meet ISO (formerly DIN) specifications. Length is measured from under the head.
