Screw taps MJ thread & UNJF thread according to aviation standard

MJ, UNJC, UNJF – Aerospace Threads

Under the term aerospace threads, thread types are grouped that are specifically designed for use in these highly demanding and safety-critical fields. They are often based on widely used thread forms but have been modified to guarantee the required safety even under high loads. These specialized variants can be recognized by the letter J in the designation – for example, MJ as a modification of the metric M thread or UNJF as a variant of the UNF thread. Are you looking for threading tools for aerospace threads? You will find them in the BAER online shop!

Everything you need to know about aerospace threads

Aerospace threads are designed to enable screw connections to withstand high forces, temperatures, and strong vibrations. The materials commonly used in this industry, such as titanium or aluminum, must also be taken into account. The common thread types M, UNC, and UNF are adapted so that acting forces are better distributed. Rounded thread roots reduce notch effects, and tighter tolerances ensure minimal play.

The MJ thread is a metric thread with a 60° flank angle. It is standardized according to DIN ISO 5855. The thread designation consists of the prefix MJ, the nominal diameter, and the pitch in millimeters. Since tolerances play an important role, they are also often specified. This also indicates whether the dimensions apply to the external or internal thread, e.g., MJ 8 × 1 – 4h6h for the bolt and MJ 8 × 1 – 4H5H for the nut.

UNJC and UNJF are standardized according to ASME B1.15. They are inch-based threads with a 60° flank angle. The designation includes the nominal diameter in inches, the number of threads per inch, and the abbreviation UNJC or UNJF, e.g., 7/16" – 20 UNJF.

Aerospace threads – Our range

In our BAER online shop, you will find a wide selection of threading tools for MJ and UNJF threads. Choose from our high-quality dies and taps of different types and benefit not only from excellent quality but also from competitive prices. Detailed information on each product can be found on the product page.

Metric aerospace threads

For metric aerospace threads, we offer machine taps in different designs as well as round dies. Our machine taps are available in Form B with lead-in chamfer for through holes (core hole passes completely through the material) and in Form C for blind holes (core hole ends in the material). The taps are made from high-quality, cobalt-alloyed HSSE steel and can easily handle difficult materials. They can be used in any machine with the appropriate tool holder.

Our round dies for MJ threads are also impressive. Unlike many dies for general use, they are not made of HSS but of HSSE, which makes them particularly hard and resistant to high temperatures and wear. Thanks to their special cutting geometry, they are suitable for stainless steels as well as other quenched and tempered steels up to 1200 N/mm² – perfect for demanding aerospace applications!

American fine aerospace threads

For the American UNJF thread, we also offer a wide range of options. Available are machine taps in Form B with lead-in chamfer for through holes and in Form C for blind holes. These tools are also made of HSSE, making them ideal for all aerospace applications.

External UNJF threads can easily be cut with our round dies made of HSSE. All common UNJF dimensions are available.

Discover aerospace threading tools and accessories in our online shop!

At BAER, we not only offer tools of excellent quality but also first-class customer service. From an easy ordering process and fast shipping to always having an open ear for your questions about availability, delivery times, and more. Just give us a try! Our friendly staff are available at any time by phone or conveniently via our contact form. We look forward to hearing from you!