4FLUT FLAT 55HRC COATED

Here are precision-matched options for a 16 mm × 300 mm (flute length or overall assumption) 4‑flute flat solid-carbide end mill, HRC 55, coated (TiSiN/TiCN)—perfect for copper and similarly “gummy” materials:

 Product Recommendations

 16 mm HRC 55 Solid‑Carbide End Mill
• ₹3,127 – 16 mm dia, likely 150 mm overall; HRC‑55, TiSiN-coated. Ideal for copper and steels. TiSiN enhances wear resistance and minimizes adhesion – good starting point with trusted performance

16 mm Carbide End Mill 4‑Flute EXTRA‑LONG
• ₹6,540 – 16 mm dia, 150 mm overall length. Designed for deeper reach (possibly up to 300 mm customization), HRC‑55, TiSiN-coated. Provides stiffness and rigidity for long-reach milling .

Key Product Insights

• HRC 55 grade & TiSiN coating: Confirms suitability for copper, steel, even up to 55 HRC materials .

• Flute & geometry: Flat end (square) design, 4 flutes optimal for finishing operations — but ensure strong machine rigidity and good coolant/mist to avoid chip clogging 

• Length options: The "Extra‑Long" variant suits deep grooves or tall work; standard length is great for typical pocketing and facing.

 Machining Tips (from Reddit Best Practices)

“Stop using four flute tools. Use 2 for copper and 3 for aluminum. Use sharp, new, uncoated carbide with as much coolant as you can deliver for copper.” 
“Copper is like bubble‑gum. Lots of coolant, sharp tools… bring down SFM a bit and you’ll be fine.” 

Cooling: Flood coolant or mist is essential—copper sticks easily.

RPM/SFM: Use 300–500 SFM; treat copper similar to aluminum but slightly slower.
Flutes: Four flutes ok for finishing, but chip evacuation becomes critical—consider 2–3 flute variants if clogging occurs.
Sharp tools: Polish/coated carbide helps prevent work sticking to edges—TiSiN is a good choice.
Rigidity & lengths: Minimize overhang and chatter, especially for long tools.

 Final Recommendation

• Use the standard-length 16 mm cutter for precision finishing and general milling in copper.

• For deep cavities or tall workpieces, opt for the Extra‑Long variant to ensure reach without compromising rigidity.

Let me know if you'd like help tuning speeds/feeds, coolant setups, or alternate flute counts (2/3 flutes) for even better copper machining performance