Tungaloy TAC Coating: AH and T Series Explained

Tungaloy TAC Coating Technology: AH and T Series Carbide Grades Explained

Tungaloy Corporation, a member of the IMC Group alongside Iscar, has developed one of the most sophisticated PVD and CVD coating portfolios in the carbide industry. Their TAC (Titanium Aluminum Coating) technology platform encompasses two primary series — the AH series (PVD-coated) and the T series (CVD-coated) — each targeting distinct machining conditions and workpiece materials. Understanding the differences between these series is essential for optimizing tool life and productivity.

PVD vs CVD: The Fundamental Difference

Physical Vapor Deposition (PVD) coatings are applied at 400-500°C, preserving the substrate’s original toughness because the low process temperature avoids cobalt binder degradation. PVD coatings are thinner (1-5 µm), produce sharper cutting edges, and are ideal for sticky workpiece materials and interrupted cuts. Chemical Vapor Deposition (CVD) coatings are applied at 900-1,050°C, producing thicker coatings (8-20 µm) with superior crater wear resistance but at the cost of some substrate toughness due to the high-temperature process cycle.

AH Series: PVD-Coated Grades

The AH series uses Tungaloy’s proprietary PVD processes to deposit multi-layer nano-structured coatings on fine-grain carbide substrates. These grades excel in applications requiring sharp edges and strong adhesion to resist built-up edge.

T Series: CVD-Coated Grades

The T series utilizes multi-layer CVD coatings, typically combining TiCN + Al₂O₃ + TiN outer layers. The Al₂O₃ middle layer provides exceptional crater wear resistance at high cutting speeds, while the thick TiCN inner layer offers flank wear protection. The T series targets high-volume production where maximum tool life per edge is the priority.

AH vs T Series: Decision Framework

Application-Specific Recommendations

Stainless Steel Turning (SUS304, SUS316 / 1.4301, 1.4401)

For finishing stainless steel at high surface quality requirements, AH8015 with its AlTiN PVD coating prevents the built-up edge formation that plagues CVD-coated grades on austenitic stainless. Use Vc = 150-220 m/min with through-coolant. For roughing with higher depth of cut, AH8005 offers the hardness to handle the work-hardened layer.

Carbon Steel Production Turning (S45C, SCM440 / 1045, 4140)

High-volume continuous turning of medium carbon steel favors T9215 or T9225. The thick Al₂O₃ layer handles the 300+ m/min cutting speeds common in automotive production. T9225 is the most versatile grade, covering P15-P30 with excellent balance of crater and flank wear resistance.

Milling Operations

Milling inherently involves interrupted cutting, making the AH series dominant. AH130 and AH3150 are the primary milling grades for steel. AH725 is specifically formulated for heat-resistant alloys such as Inconel 718 and Waspaloy, where cutting temperatures exceed 800°C at the shear zone.

Cutting Speed Guidelines

Competitor Grade Equivalents

Key Takeaways

• Choose AH series (PVD) when sharp edges, interrupted cuts, or sticky materials are the priority
• Choose T series (CVD) for high-speed continuous turning where crater wear dominates
• T9225 is the most universal steel turning grade, covering the widest ISO P range
• AH725 is purpose-built for superalloys and should not be substituted with general-purpose grades
• Always match coating thickness to application: thin for sharpness, thick for wear resistance

Tungaloy’s dual-series approach ensures that machinists can optimize their insert selection for every condition. The AH series maximizes edge integrity and toughness, while the T series maximizes wear resistance and cutting speed capability.