MTFNR/L Series: ISO Standard M-Type Multi-Lock 91° Approach Angle External Turning Tool Holder for TNMG Inserts

Technical Breakdown: The MTFNR/L Nomenclature

The ISO code reveals the precise engineering behind the tool’s performance:

Why the 91° Approach Angle Matters

The “F” style (91°) geometry is a strategic choice for CNC machinists. By meeting the workpiece at 91°, the tool can create a perfect 90° shoulder while the secondary cutting edge maintains a slight 1° offset from the finished surface. This:

• Reduces heat generation and tool wear.
• Prevents “chatter” or vibration caused by side-cutting pressure.

• Allows for light facing operations toward the center of the part.

Key Performance Features

• Dual-Lock Rigidity: The M-type mechanism eliminates insert “micro-movement,” extending tool life and ensuring dimensional consistency.
• Optimized Chip Flow: The negative rake geometry, combined with TNMG chipbreakers, ensures efficient chip evacuation even at high feed rates.

• Versatile Application: Excellent for roughing to semi-finishing in a wide range of ISO materials (P, K, M, S).

Frequently Asked Questions (FAQs)

Q: Why is the approach angle 91° instead of exactly 90°?
A: A 90° approach angle (Style G) would cause the entire side of the insert to rub against the shoulder of the workpiece. The 91° angle (Style F) provides a $1^\circ$ clearance, which is essential for reducing friction, preventing vibration, and achieving a superior surface finish on the vertical face.

Q: Which inserts are compatible with the MTFNR holder?
A: It is designed for TNMG (Triangular, Negative, with Hole and Chipbreaker) inserts. The size of the insert must match the last two digits of the holder code (e.g., MTFNR 2525M16 requires TNMG 16 size inserts).

Q: Can I use this holder for facing?
A: Yes. The 91° angle allows the MTFNR/L to perform light facing operations. However, it is primarily optimized for longitudinal (O.D.) turning and shoulder work.

Q: Is the M-Type clamp better than a simple screw-on (S-Type) holder?
A: For negative inserts like the TNMG, the M-Type is significantly stronger. Screw-on types are generally reserved for smaller, positive inserts. The Multi-Lock system is the industry standard for high-productivity CNC turning.