5 things you need to know about thread milling challenging aerospace materials

1) For high stability and performance, select thread mills with a left-hand helix flute design, requiring a left-hand spindle rotation.

The combination of left-hand cutting geometry used in a conventional milling cutting path, entering the hole and threading from the outside in or from top-to-bottom, creates a very stable cutting action for this interrupted thread cutting process. Also, the combination of the left-hand helix and left-hand spindle rotation, moving clockwise into the part, creates a climb milling cutting effect resulting in better tool life.

2) The unique design offers advantages with 3 tooth pitches that simultaneously rough and finish-cut threads.

The first cutting tooth on this type of tool is an incomplete thread profile of the pitch, which acts as a rougher, removing most of the material ahead of the following cutting teeth finishing the threads. This design, in combination with the clockwise movement of the cutter into the part (conventional milling move), works perfectly to increase tool life when cutting very difficult and edge-wearing materials found in the aerospace industry.

3) Carbide cutting edges extend tool life and reduce cycle time.

When thread milling, challenging super alloy materials – such as 718 Inconel, Haynes 25, Ti-6Al-4V, 455 stainless steel, or high-temp alloy steels – carbide cutting edges will significantly enhance tool life and increase productivity. For example, single plane carbide Emuge-Franken ZGF-S-Cut Thread Mills reduce cycle time by minimizing the need to use cutter compensation for edge wear. By dividing the material load of the cutting edge between 3 carbide cutting teeth, the cutting edge wears more slowly. This decreases the need for operator involvement to stop the machine to add more compensating values for tool wear. Machine uptime is tremendously increased when the need to resize threads is reduced, resulting in less cycle time per part.

4) Use one efficient tool for multiple functions.

Select a thread mill that will cut through or blind holes and also produces STI threads and different tolerances by modifying the programming instructions. Emuge-Franken ZGF-S-Cut thread mills have internal coolant supply starting at 1/4" and above, and are guaranteed to produce a thread within 1 pitch from the bottom of the hole.

5) Pay attention to all details – tool coating and more.

Emuge-Franken ZGF-S-Cut Thread Mills feature TiAlN-T46 proprietary PVD coating designed to harden and protect the cutting edge from heat generated when using rotating tools to cut high-temp steel alloys and nickel-based alloys that resist heat and fracture in demanding jet engine components. ZGF-S-Cut tools encompass the three principles of a successful thread-milling process: 1. Efficient chip evacuation and control; 2. High feed rate security by following the Emuge programming instructions; and 3. Stability due to their geometry and design. Starting at #2-56 to 1/2-20 at 2XD and at #4-40 to 1/2-20 in 3XD and at M3 to M16, the Emuge-Franken ZGF-S-Cut Thread Mills hold h6 tolerance in metric cylindrical shanks and should be used with very rigid tool holders.