sandviks CNMG 120412-PF 4225 Carbide Turning Insert CNMG 432 CVD Coated 80 Degree Rhombic Lathe Insert for Steel Finishing

Overview
The CNMG 120412-PF 4225 is a double-sided, negative-rake turning insert from sandvikss Coromant's T-Max® P range. It combines an 80° rhombic body with a 1.2 mm corner radius and the PF finishing chipbreaker, giving a sharp, low-force cutting action for finish turning, profile turning and light facing operations on steel components.
The insert is produced in GC4225, a CVD-coated carbide grade built on a gradient substrate. The coating sequence — MT-Ti(C,N) / Al₂O₃ / TiN — provides crater and flank wear resistance at elevated cutting temperatures, while the cobalt-enriched surface zone keeps the edge line secure under light interruption.
With an inscribed circle of 12.7 mm (1/2") and 4.76 mm thickness, this insert is the metric equivalent of ANSI CNMG 433 and fits any standard CNMG 1204 insert seat.

• 80° rhombic, negative geometry — four usable cutting edges per insert, lower cost per edge than single-sided positive inserts.
• PF finishing chipbreaker — designed for low depth of cut and low feed, producing short, controllable chips and good surface finish on finishing passes.
• R1.2 corner radius — a strong compromise between edge strength and surface quality; suits semi-finish to finish turning with moderate feed.
• GC4225 CVD-coated grade — thick, wear-resistant multilayer coating on a tough gradient substrate; handles continuous cuts and light interruptions.
• Cylindrical centre hole — clamped by a standard lever or screw-type holder, no special tooling required.

CNMG 12 04 12 -PF 4225

The PF geometry belongs to sandvikss's finishing family. It is intended for low depth of cut and low feed rates, where the priority is chip control and surface finish rather than metal removal rate.

• depth of cut is shallow (finishing and semi-finishing passes);
• surface finish and dimensional accuracy matter more than cycle time;
• the machine or workpiece setup is less rigid and cutting forces must be kept low.

• depth of cut exceeds roughly 1 mm on a regular basis;
• the operation is heavy interrupted cutting or scale removal;
• high metal removal rate is the main objective.

GC4225 is a CVD-coated carbide grade for finishing to roughing of steel and steel castings. Its gradient substrate combines a hard surface zone with a tough core, and the thick multilayer coating resists crater and flank wear at high cutting temperature.

• reliable in continuous turning and light interrupted cuts;
• broad working range, tolerant of varying material batches;
• suitable for wet and dry machining.

• Finish and semi-finish external turning of shafts, sleeves, flanges and general engineering parts
• Profile turning and copy turning where a 80° rhombic insert reaches shoulders and contours
• Light facing and chamfering on CNC lathes
• Steel and steel castings in the P material group; small-volume use in stainless steel and cast iron is possible but not the primary intent

• heavy roughing with deep depth of cut (use a roughing geometry and tougher grade);
• cast skin or scale with severe interruption (edge chipping risk);
• aluminium and non-ferrous finishing (use uncoated polished inserts instead).

CNMG 120412 uses the 12-size insert seat. Typical holder families (examples, not exhaustive):

• PCLNR / PCLNL 2525M12 — 95° approach, right / left hand
• MCLNR / MCLNL 2525M12 — 95° approach, neutral clamping style
• DCLNR / DCLNL 2525M12 — 95° approach, heavy-duty body

Always match the holder's insert seat code (12) and hand (R/L) to the operation. The same insert can be used for external turning, facing and, with the appropriate holder, boring.

• Standard pack: 10 pieces per box (confirm with the actual packing list before publishing)
• Order by full designation: CNMG 120412-PF 4225
• Confirm grade availability before ordering — GC4225 is an earlier-generation grade and stock varies by region

Is CNMG 120412 the same as CNMG 432? No. CNMG 120412 equals CNMG 433 (R1.2). CNMG 432 is 120408 with R0.8. The two are not interchangeable when corner radius matters for the finishing pass.

How many cutting edges does it have? Four. It is a double-sided negative insert, so both faces carry usable edges.

Can it be used for roughing? Only light roughing. The PF chipbreaker is designed for low depth of cut and low feed; heavy roughing should use a tougher geometry and grade.

What replaces GC4225 if it is discontinued? GC4325 first, then GC4425 — sandvikss's later P25 generations. Cutting data should be re-optimised rather than copied directly.