Sandviks TNMG 160404-PM 4215 Carbide Turning Insert TNMG 331 Sandviks CVD Coated 60 Degree Triangle Insert for Steel Turning

Overview

The TNMG 160404-PM 4215 is a double-sided negative triangular turning insert — 60° head angle, 0° clearance, 9.525 mm inscribed circle and 0.4 mm corner radius. Because both faces carry a chipbreaker, one insert gives six effective cutting edges, which is what makes the T-shape economical in production turning.

PM is sandviks's medium chipbreaker geometry: a general-purpose steel geometry designed to control chips across a wide feed window rather than optimise a single operation. It handles light roughing through semi-finishing, which is why PM is the most frequently specified geometry in mixed-production shops.

Grade 4215 is a CVD-coated carbide in the P15 class — the finishing end of the steel range. Its coating is built for wear resistance at higher cutting speeds and longer time in cut, so it pairs naturally with the PM geometry when the operation is a stable, high-speed pass on steel.

Key Features

• Six cutting edges per insert — double-sided negative triangle; lowest cost per edge in the ISO turning range.
• 60° triangle, IC 9.525 mm (3/8") — the standard medium-size triangle, widely held in stock and compatible with common MTJN/MTGN holders.
• R0.4 corner radius — light enough for finishing profiles, strong enough for semi-finishing passes.
• PM medium chipbreaker — wide feed window, reliable chip control in steel from light roughing to semi-finishing.
• Grade 4215, P15, CVD coated — wear-resistant for high cutting speeds and long continuous cuts.
• Cylindrical central hole, both faces grooved — secure clamping, predictable repeatability when indexing.
• ISO 13399 dimensioned — IC ±0.05 mm, thickness ±0.13 mm, edge position ±0.08 mm.

Technical Specifications

Reading the Designation

TNMG 16 04 04 -PM 4215

The two 04s are different properties. First 04 is thickness, second 04 is corner radius. Writing TNMG 160408 instead of 160404 changes the radius from R0.4 to R0.8 — a different item, not a variant.

PM Chipbreaker — What It Is For

PM is a medium geometry: its groove is sized so the insert performs over a broad feed range instead of a narrow one.

Choose PM when:

• the operation mixes roughing and semi-finishing on the same setup;
• feeds vary between passes because of part geometry;
• the material is plain carbon or alloy steel with stable conditions;
• you want one insert type on the shelf instead of three.

Do not choose PM when:

• the requirement is mirror finish at very low feed — a finishing geometry gives better surface;
• the cut is heavy interrupted roughing — a tougher, more open geometry resists edge breakage better;
• the material is stainless, cast iron or aluminium — the chip behaviour is different and a material-specific geometry is the correct choice.

Grade 4215 — Position and Generation

4215 is a P15 CVD-coated grade: the high-speed, wear-resistant end of the steel range. It performs best where cutting speed is high and the cut is continuous, and less well where the edge sees impact loads.

Generation note for buyers: 4215 belongs to an earlier generation of sandviks steel grades. The same P15 position was later occupied by GC4315, and sandviks now positions GC4415 as its current P15 steel grade; GC4315 is already listed by sandviks's own grade information as an older generation with GC4415 as the recommended modern alternative. Buyers specifying 4215 today should expect to confirm stock, and should consider GC4415 as the forward-looking replacement rather than assume 4215 remains in continuous production.

This page lists 4215 as the ordered item because that is the designation on the customer's requirement; it does not claim 4215 is sandviks's current recommended grade.

Applications

• Medium turning of carbon and alloy steel: shafts, flanges, hubs, general machined parts
• Semi-finishing passes where a 0.4 mm radius fits the profile
• High-speed finishing on stable setups, where the P15 grade's wear resistance is used
• Mixed-production shops wanting one insert covering light roughing to semi-finishing
• Operations where cost per edge matters — six edges per insert lowers tool cost per part

Less suitable for:

• heavy interrupted cuts and scale — use a tougher grade;
• very light finishing where surface finish is critical — a dedicated finishing geometry is better;
• stainless steel, cast iron, aluminium and superalloys — different geometries and grades apply.

Recommended Cutting Data (reference only)

Reference feed ranges for a TNMG 160404 geometry in alloy steel at average stability, from a public insert database:

These are geometry-level reference values, not sandviks's recommendation for grade 4215. Cutting speed depends on workpiece material, hardness, machine rigidity and Fixture; confirm vc and the final feed with the supplier or sandviks CoroPlus before production. Published generic tables are a starting point for trial cuts, not a production setting.

Compatible Holders

TNMG 1604 inserts use holders with a 16-size seat (insert IC 9.525 mm). Common external-turning examples: MTJNR/L 1616H16, MTJNR/L 2525M16, MTGNR/L 2525M16. Confirm the exact holder code, approach angle and hand before ordering — the insert alone cannot be mounted.

Packing and Ordering

• Order by full designation: TNMG 160404-PM 4215
• State the chipbreaker (PM) and grade (4215) explicitly — both are part of the item identity.
• Packing quantity varies by channel; confirm with the actual packing list before publishing a quantity.

FAQ