Aerospace Drill Type Classifications Explained

When browsing Titan USA’s selection of available drill bits, you may come across descriptions like “Type B,” “Type C,” or “Type J.” The following will serve to explain the origins of these designations and what each “Type” means; information that will help you when selecting the optimal drill bit for your operation.

Origin of Drill Type Classifications

The drill “Types” referenced above are creations of the National Aerospace Specification Committee (NASC), a subset of the Aerospace Industries Association (AIA). The Committee is responsible for the creation and maintenance of part standards for aerospace parts and components within AIA’s National Aerospace Standards (NAS) library. These part standards are recognized for meeting the high strength, close tolerance, and rigorous acceptance testing requirements of the aerospace industry.[1]

Aerospace Drill Standards & Types

The NASC identifies three different “standards” for drills: NAS907, NAS937, and NAS965. Each of these standards can be broken down into different “types.” The “standard” represents the size range and shank options, and the “type” represents a unique combination of other attributes including material, surface treatment, web construction, back taper, point type, and lengths. For example, NAS 937 drills have a size range of Ø1/8” through Ø1/2” and the following shank options: Straight, straight w/ tri flats, quick change, reduced shank, reduced shank with tri flats, and Tang. Type B within that same standard would indicate that the material is High Speed Steel (M2 or M7), that the drill has a bright finish, a web construction where thickness increases uniformly at 0.017” ± 0.003” per inch taper, a back taper of 0.0002” to 0.0005” per inch for all diameters, a P-3 (135°) split point, and a jobber or aircraft extension length.

All the drills that call out a type in Titan USA’s catalog are NAS907 standard drills as they all have drill diameters of 1/16” through 1/2” and straight shanks. Below are examples of Titan USA drills of types B, C, and J within that standard:

Type B

Type C

Type J

Choosing the right drill bit for your job is key to ensuring accuracy and efficiency in any project, and knowing what these type designations represent can help you identify the size and material that’s right for you more quickly.

Do you have an application that requires a miniature drill? Learn about Selecting the Right Harvey Tool Miniature Drill.

1. [1] National Aerospace Standards Committee (NASC). “About NASC.” Aerospace Industries Association, www.aia-aerospace.org/membership/committees/national-aerospace-standards-committee-nasc/. Accessed [April 26, 2024].

Ryan O'Connell

As a member of Harvey Performance Company’s Technical Development team, Ryan assists the team in developing strong, innovative eCommerce strategies and tactics while contributing to an industry leading digital marketing footprint and enhancing a powerful marketing technical stack.