CNMG and WNMG are common turning insert types with an 80° corner angle and a 0° clearance angle. Both can be used for turning and facing, but they differ in shape, cutting corner count, and toolholder requirements. This guide explains the main differences and what to check before choosing either type.

CNMG vs WNMG: Quick Comparison

Feature	CNMG	WNMG
Insert shape	80° diamond	80° trigon
Corner angle	80°	80°
Clearance angle	0°	0°
Standard double-sided cutting corners	4	6
Typical applications	General turning and facing	General turning and facing
Toolholder requirement	Compatible CNMG insert pocket	Compatible WNMG insert pocket
Material suitability	Depends on insert grade and chipbreaker	Depends on insert grade and chipbreaker

What Is the Main Difference?

The main difference is the insert shape. CNMG has a diamond shape, while WNMG has a trigon shape. A standard double-sided CNMG insert provides four 80° cutting corners, compared with six on a standard double-sided WNMG insert.

More cutting corners can reduce the insert cost per usable corner. However, the better purchasing choice also depends on insert price, tool life, machining performance, and the holders already installed on your machines.

Can CNMG and WNMG Use the Same Toolholder?

CNMG and WNMG should not be treated as interchangeable. Their different shapes require matching insert pockets and clamping arrangements. Even when two inserts have the same inscribed circle diameter, thickness, and nose radius, this does not mean they fit the same holder.

For example, CNMG 120408 and WNMG 080408 both have a 12.70 mm inscribed circle diameter, a 4.76 mm thickness, and a 0.80 mm nose radius. Always check the toolholder manufacturer’s insert compatibility information before ordering.

Which Is Better for Steel, Stainless Steel, or Cast Iron?

The CNMG or WNMG designation alone does not determine workpiece material suitability. The specific insert grade, chipbreaker, and cutting edge preparation must match the material and machining conditions.

When requesting a recommendation, provide the workpiece material and hardness, whether the operation is roughing or finishing, and whether the cut is continuous or interrupted. Include your current insert and holder models where possible.

How to Choose Between CNMG and WNMG

• Start with the insert type specified for your existing toolholder.
• Check the insert dimensions and nose radius.
• Choose a chipbreaker suitable for the feed rate, depth of cut, and machining operation.
• Confirm that the insert is suitable for the workpiece material.
• Compare cost per finished part, including usable cutting corners and tool life.

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