BTA Drill Insert Grades: ISCAR vs Sandvik vs Tungaloy

A deep hole drilling job shop runs BTA drilling on a wide variety of materials — low-carbon steel shafts, 4140 alloy steel for oilfield tools, 316 stainless for chemical equipment, and Inconel 718 for aerospace components. The shop uses ISCAR TPMX inserts and wants to know: is IC908 the best grade for all materials, or would Sandvik or Tungaloy perform better on specific jobs? IC908 is a versatile PVD AlTiN-coated grade covering ISO P, M, K, S, and H — adequate across the board. But for Inconel 718, IC806 delivers 2.5× longer tool life. For 4140 steel, Tungaloy AH725 at higher speed produces better throughput. For standard low-carbon steel, the uncoated Sandvik H13A still holds its own at lower cost per edge. The answer is not that one manufacturer is universally better — each has strengths in specific material groups.

ISO Material Group Classification ​

BTA drilling insert grades are selected primarily by the ISO material group of the workpiece. The ISO classification system divides workpiece materials into six groups:

Each manufacturer maps their grades to these ISO groups. A single grade may cover multiple groups, but optimal performance in a specific group typically requires a grade engineered for that group's dominant wear mechanism.

ISCAR BTA Insert Grades ​

ISCAR offers the most comprehensive grade portfolio for BTA drilling, built around the IC-series naming convention. Their BTA insert families include TPMX (triangular, most common), NPHT/NPMT (precision peripheral), and TOGT (small diameters).

Primary Grades ​

IC908 — The Workhorse ​

IC908 is ISCAR's primary BTA drilling grade. It is a PVD TiAlN-coated submicron carbide grade that covers all ISO material groups except the most demanding applications. It accounts for the majority of BTA insert sales globally.

Strengths: Versatility, availability, predictable wear, good resistance to both abrasive and diffusion wear mechanisms.

Limitations: In superalloys (ISO S), IC908 is out-performed by IC806 by a factor of 2–3× in tool life. In high-speed steel cutting, CVD grades like IC9025 can run at higher speeds.

IC806 — For Superalloys and Hardened Materials ​

IC806 was introduced specifically for heat-resistant superalloys, titanium alloys, stainless steels, and hardened materials. It uses a PVD coating with higher aluminum content than IC908, forming a more stable Al₂O₃ thermal barrier at the tool-chip interface.

Strengths: More than double the tool life of IC908 in Inconel, duplex stainless, and titanium. Excellent resistance to crater wear and built-up edge.

Limitations: Higher cost per edge than IC908. Not necessary for standard steel applications.

Tip: If your work is predominantly steel (ISO P) with occasional superalloy jobs, stock both IC908 for steel and IC806 for the superalloy work. The two grades use the same TPMX insert geometry, so no tooling changes are needed — just swap the insert.

Guide Pad Grades ​

ISCAR guide pads are available in the GPS (standard) series with sizes ranging from GPS-05 (18 mm length) to GPS-18 (40 mm length), covering diameters from 25 mm to 65+ mm.

Sandvik Coromant BTA Insert Grades ​

Sandvik's CoroDrill 800 system was one of the most widely used BTA drilling platforms. In 2020, Sandvik exited the deep hole drilling tool market, and the product line was replaced by Sunnen's DirectDex line, which offers direct dimensional interchangeability with CoroDrill 800 tooling.

H13A — The Legacy Standard ​

H13A is an uncoated fine-grain carbide grade. It was Sandvik's primary BTA drilling grade for the CoroDrill 800 system.

Strengths: Low cost per edge, predictable wear, good toughness, excellent for stainless steel and non-ferrous materials where built-up edge is a concern with coated grades.

Limitations: Lower wear resistance than any modern PVD-coated grade. Cannot be used at the cutting speeds that coated grades permit. In steel (ISO P), tool life is significantly shorter than IC908 or AH725.

DirectDex (Sunnen) Replacement ​

After Sandvik's exit, Sunnen developed the DirectDex line as a direct replacement. DirectDex inserts are dimensionally identical to Sandvik CoroDrill 800 inserts and fit existing Sandvik drill heads and tubes.

The TES coating on DirectDex inserts provides significant improvement over the uncoated H13A — typically 2–3× longer tool life at the same cutting parameters.

Tip: If you have existing Sandvik CoroDrill 800 tooling, DirectDex is the simplest upgrade path. The inserts fit without any modification to drill heads or tubes, and the TES coating delivers modern coated-grade performance without changing the tooling system.

Other Sandvik Grades ​

Sandvik's general drilling grade portfolio includes grades that were available for the CoroDrill 800 system:

These grades are no longer actively marketed for BTA drilling but may still be available through stockists.

Tungaloy BTA Insert Grades ​

Tungaloy's BTA drilling portfolio is built around the FineBeam and Unidex series of drill heads, with grades designed for specific material groups.

Primary Grades ​

AH725 — General Purpose ​

AH725 is Tungaloy's primary BTA grade, covering ISO groups P, M, K, and S. It provides a good balance of wear resistance and chipping resistance.

Strengths: Versatile across steel and stainless steel. Available in multiple chip former geometries. Good cost-performance balance.

Limitations: In superalloys (ISO S), AH725 is out-performed by AH8015. In hardened materials (ISO H), it has limited application.

AH8015 — For Difficult Materials ​

AH8015 uses a nano-structured multilayer PVD coating with high aluminum content. It was specifically developed for BTA drilling of difficult-to-cut materials.

Strengths: Excellent wear resistance in Inconel, duplex stainless, and titanium. Nanoscale multilayer structure provides crack deflection and high temperature stability.

Applications: Aircraft landing gear components, oil country tubular goods (OCTG), chemical processing equipment.

UC2220 — For Stainless Steel ​

UC2220 is a specialised grade for stainless steel machining. In published case studies, UC2220 demonstrated 80% longer tool life than competitor grades in SUS316 (90 m/edge vs 50 m/edge) and 55% longer life in duplex stainless steel (14 m vs 9 m).

Side-by-Side Grade Comparison ​

By ISO Material Group ​

Coating Comparison ​

Tool Life Comparison (Relative) ​

Values are relative to IC908 = 1.0× in each material. Higher is better.

Selection Guidelines ​

By Material Mix ​

By Cutting Speed ​

By Cost per Edge ​

Lowest cost:   H13A (uncoated) → adequate for low-speed steel
Best value:    IC908, AH725 → good tool life at moderate cost
Premium:       IC806, AH8015 → highest tool life in difficult materials

Warning: Grade selection must account for the specific BTA head geometry. Not all grades are available in all insert shapes (TPMX, NPHT, TOGT). Before selecting a grade, verify that the required insert style and chip former geometry are available in that grade from the manufacturer.

Common Selection Mistakes ​

FAQ ​

Which BTA insert grade is the most versatile? ​

ISCAR IC908 is the most versatile BTA insert grade available — it covers ISO P, M, K, S, N, and H material groups with good performance across all of them.

Can I use uncoated H13A for all materials? ​

H13A works adequately in stainless steel (M), cast iron (K), non-ferrous (N), and superalloys (S) at moderate cutting speeds. For steel (ISO P) at production volumes, coated grades like IC908 or AH725 provide significantly better tool life.

What replaced Sandvik CoroDrill 800 inserts? ​

Sunnen's DirectDex line is the direct replacement. DirectDex inserts are dimensionally interchangeable with Sandvik CoroDrill 800 inserts and are available with TES coating (CVD and PVD options).

Is IC806 worth the extra cost over IC908? ​

For standard steel applications, no. For superalloys (Inconel, Hastelloy), duplex stainless steel, and titanium, IC806 delivers 2–3× the tool life of IC908 — the cost per edge is lower despite the higher purchase price.

What is the best grade for BTA drilling Inconel 718? ​

ISCAR IC806 and Tungaloy AH8015 are both excellent choices. In comparative testing, both grades deliver 2–3× tool life over general-purpose grades in Inconel 718.

Does Tungaloy offer BTA insert grades for hardened steel? ​

Tungaloy's primary BTA grades (AH725, AH8015) have limited application in hardened steel (ISO H). For hardened materials, ISCAR IC806 is a better choice.

What is the difference between PVD and CVD coatings for BTA inserts? ​

PVD coatings (IC908, IC806, AH725) are thinner, have sharper cutting edges, and are better for smaller diameters and lower speeds. CVD coatings (DirectDex TES CVD, IC9025) are thicker and more wear-resistant at higher cutting speeds.

How do I select guide pad grades? ​

Match the guide pad grade to the workpiece material. Use IC950 for steel and cast iron. Use IC928 for stainless steel and superalloys. Sandvik-style pads use the same grades as the inserts.

Can I mix grades from different manufacturers in the same BTA head? ​

Not recommended. Different manufacturers use different insert geometries, thicknesses, and chip former designs. Even if the insert fits physically, the cutting edge position and chip control may not be compatible.

What is the most cost-effective grade for high-volume steel drilling? ​

For high-volume steel (ISO P) production, ISCAR IC908 or Tungaloy AH725 provide the best cost-per-edge balance. At high cutting speeds (above 60 m/min), a CVD-coated grade like DirectDex TES CVD may be more cost-effective.

Summary ​

The choice of BTA insert grade depends primarily on the workpiece material group and cutting speed:

• ISCAR IC908 is the most versatile BTA grade — it covers all material groups and is the default choice for mixed-material shops
• ISCAR IC806 and Tungaloy AH8015 are the best choices for superalloys, duplex stainless, and titanium — delivering 2–3× tool life over general-purpose grades
• Sandvik H13A is a capable uncoated grade for low-speed applications, now replaced for new purchases by DirectDex (Sunnen) with TES coating
• Tungaloy AH725 is a strong general-purpose alternative to IC908, particularly good in steel and cast iron
• Guide pad grades must be selected independently from insert grades — match to the workpiece material and coolant type
• The job shop in the opening scenario keeps IC908 in stock for routine steel work, adds IC806 for Inconel and duplex jobs, and maintains a small stock of Tungaloy AH725 for high-speed 4140 runs — maximising tool life and productivity across their material mix