5 Things You Need to Know about Thread Locking in challenging, safety-critical aerospace applications

1. Safety critical aerospace manufacturing applications demand secure threads that won’t loosen. Adhering to the guidelines for thread manufacturing, their different classes of fit, and proper tolerancing and gaging when machining threads, is the first step toward making strong, dependable screw threads. Manufacturers now have an excellent, comprehensive SELF-LOCK™ solution that produces self-locking threads for thread milling and tapping which feature a wedge ramp angle on the thread’s flank.

2. This successful solution to secure screws involves modifying the conventional 60° form by cutting a locking ramp on the internal thread, securely and predictably locking the screw in place while making it easy to assemble and disassemble multiple times. A 30° ramp or wedge form is adjacent to the thread’s root and oriented perpendicular to the direction of stress. This wedge surface engages with the crests located at the screw’s major diameter – as the screw is tightened, it forms a continuous and concentrated point of contact along the thread’s entire length.

3. The wedge-ramp design prevents any transverse movement, locking the screw securely in place while also making the thread much stronger. Studies show where a traditional tapped or thread-milled hole concentrates as much as 75% of the load on the first two threads, the wedge lock design carries the load evenly along the thread’s entire length. EMUGE SELF-LOCK internal threads provide constant, maximum holding power under dynamic stress. This remains true even after repeated loosening and re-tightening of the thread connection.

4. EMUGE expanded its line of SELF-LOCK thread locking tools to include EMUGE ZGF-S-Cut SELF-LOCK thread mills with helical flutes, multiple teeth, and TiAlN-T46 coating to produce self-locking threads that are ideal in demanding industry applications such as aerospace where nickel alloys, titanium, and stainless steel are the norm. A unique design enables three tooth pitches to simultaneously rough and finish-cut threads, dramatically increasing tool life and reducing cycle times. Other EMUGE SELF-LOCK products include UNC and UNF cut taps, UNC and UNF form taps; metric cut taps, metric form taps, and metric thread mills, in addition to GO / NO-GO thread gages for gaging SELF-LOCK threads.

5. For precise thread gaging, it’s recommended to use the EMUGE two-piece gage system that corresponds to the usual combination of GO /NO-GO gages and is perfectly sufficient for the gaging of threads, provided the threads are produced with EMUGE true-to-profile taps and thread mills. There’s no generally applicable standard (e.g., DIN standard) for EMUGE SELF-LOCK threads, so other manufacturers may use different limit sizes for their threads. For this reason, EMUGE recommends gaging EMUGE SELF-LOCK threads exclusively with EMUGE SELF-LOCK gages.