Next-Generation Deep Hole Drills
Solid carbide drill technology has advanced rapidly, with new tool families offering depth capabilities that were previously only achievable with gun drills or BTA tools. These extended-length drills combine advanced carbide substrates, optimized geometries with multiple guide lands, polished flute surfaces, and nano-layer coatings to reach depths of 20×D, 30×D, and even 50×D.
This guide covers the major new product families introduced in 2024–2025, their capabilities, selection criteria, and applications where they compete with or complement traditional deep hole drilling methods.
Product Comparison
Dormer Pramet Force DHD (Deep Hole Drill)
Announced: Late 2025 Key capability: Up to 20×D depth
| Feature | Specification |
|---|---|
| Depth range | Up to 20×D |
| Diameter range | 3–12 mm (metric); 1/8"–1/2" (inch) |
| Substrate | Fine-grain carbide |
| Coating | Nano-Tip multilayer (TiAlN-based) |
| Coolant | Internal coolant channels |
| Guide lands | Four guide lands for directional stability |
| Geometry | Self-centering point, polished flutes |
Force X Generation 2 (companion line):
- TiAlN-top coating optimized for ISO P, M, K materials
- 5×D, 8×D, 12×D lengths available
- Force Micro series: 0.7–2.95 mm diameter, AlCrN coating
Best for: General production deep holes in steel, stainless steel, and cast iron at depths up to 20×D.
CERATIZIT WTX-UNI and WTX-Deep UNI
Announced: Late 2025 Key capability: WTX-Deep UNI reaches 50×D
| Feature | WTX-UNI | WTX-Deep UNI |
|---|---|---|
| Depth range | 3×D, 5×D, 8×D, 12×D | Up to 50×D |
| Diameter range | 3–14 mm (metric) | 3–8 mm (metric) |
| Substrate | CT-GS20Y upGRADE (99% recycled carbide) | CT-GS20Y upGRADE |
| Coating | DPA74S | DPX74-M (high-performance coating) |
| Guide lands | Standard margin design | Four precision-ground guide lands |
| Flute design | Standard polished flutes | Redesigned geometry, polished chip spaces |
| Point geometry | Self-centering | Self-centering with enhanced chip splitting |
| Max material hardness | Up to 54 HRC | Up to 54 HRC |
Key design features for 50×D depth:
- Four guide lands stabilize the drill against bending and wandering
- Redesigned flute geometry with polished chip spaces reduces friction and improves chip flow
- DPX74-M coating provides thermal stability for extended drilling cycles
- CT-GS20Y substrate (99% recycled carbide) — most sustainable carbide option available
Best for: Very deep small holes in steel and cast iron where gun drilling would otherwise be required. Also suitable for hardened steel up to 54 HRC.
Guhring Micro-Precision Drills
Announced: 2025 Key capability: 0.5–3 mm diameter, up to 20×D depth
| Feature | Specification |
|---|---|
| Depth range | Up to 20×D |
| Diameter range | 0.5–3.0 mm |
| Substrate | Sub-micron carbide |
| Point geometry | Ground facet point with concave cutting edge |
| Web thinning | Aggressive web thinning for reduced thrust |
| Coolant | Internal coolant (standard on 3 mm+; optional smaller) |
| Materials | Stainless steel, titanium, Inconel, Hastelloy, Monel |
Best for: Micro deep holes in difficult materials — medical components, fuel injectors, aerospace small-diameter cooling passages.
Kennametal B21SGL (Aerospace)
Announced: 2024–2025 Key capability: Up to 12×D, optimized for aerospace alloys
| Feature | Specification |
|---|---|
| Depth range | 5×D, 8×D, 12×D |
| Diameter range | 3–20 mm |
| Coating | PVD AlTiN |
| Substrate | Fine-grain carbide optimized for aerospace alloys |
| Performance claim | 2–6× tool life vs standard carbide in Inconel and Ti |
| Feed rate | Up to 50% higher than standard deep hole drills |
Best for: Aerospace production in titanium, Inconel 718, and PH-series stainless steels.
When to Choose Extended Solid Carbide vs Gun Drilling
| Factor | Extended Solid Carbide Drill | Gun Drill |
|---|---|---|
| Depth ratio | Up to 50×D (CERATIZIT WTX-Deep) | Up to 300×D |
| Diameter range | 0.5–14 mm (practical up to 20 mm) | 0.5–50 mm |
| Hole tolerance | IT8–IT10 | IT6–IT9 |
| Surface finish | Ra 0.8–2.0 µm | Ra 0.4–0.8 µm |
| Penetration rate | Higher (two-flute design) | Lower (single-lip) |
| Machine requirement | Standard CNC (coolant-through capability) | Dedicated or retrofitted gun drilling machine |
| Tool cost per edge | Lower (indexable/regrindable) | Comparable |
| Straightness | Good (four guide lands) | Excellent (guide pads + bushing) |
Choose extended solid carbide when:
- Depth ratio ≤ 50×D (within the tool’s capability)
- Hole tolerance IT8 or wider is acceptable
- Existing standard CNC machine available — no need to invest in gun drilling equipment
- Higher penetration rate is needed than gun drilling can provide
- Secondary operations (reaming) can fix tolerance if needed
Choose gun drilling when:
- Depth ratio > 50×D
- IT6–IT7 precision required
- Best possible surface finish and straightness needed
- Diameter below 0.5 mm or above 14 mm
Application Examples
Example 1: Hydraulic Manifold, 8 mm × 240 mm deep (30×D)
Options:
- CERATIZIT WTX-Deep UNI (50×D capable): Run on standard machining center with coolant-through spindle. No special equipment needed.
- Gun drilling: Requires gun drilling machine or retrofit. Slower penetration.
Recommendation: Extended solid carbide drill. The depth (30×D) is well within the tool’s 50×D capability, and the existing machining center can handle it with through-tool coolant.
Example 2: Medical Bone Screw Blank, 2.5 mm × 50 mm deep (20×D)
Options:
- Guhring micro-precision drill (20×D capable): Short enough for the tool’s depth limit. Fine point geometry for good centering.
- Gun drilling: Overkill for 20×D depth and IT9 tolerance requirement.
Recommendation: Extended solid carbide micro-drill. Faster cycle time, standard Swiss lathe or CNC machine, no gun drilling equipment needed.
Example 3: Turbine Shaft, 12 mm × 1,800 mm deep (150×D)
Options:
- Extended solid carbide drill: 50×D maximum — not applicable.
- Gun drilling: Only option for 150×D depth ratio.
Recommendation: Gun drilling. Extended solid carbide drills cannot reach this depth.
Selection Decision Framework
Depth ratio required?
├── < 12×D → Any extended carbide drill (all brands)
├── 12×D to 20×D → Force DHD or WTX-UNI
├── 20×D to 50×D → WTX-Deep UNI (only option at this depth)
└── > 50×D → Gun drilling (extended carbide not applicable)
Material?
├── Steel, cast iron → WTX-UNI / Force DHD
├── Stainless steel → Force DHD (nano-Tip coating) / Guhring
├── Titanium → Kennametal B21SGL / Guhring micro
├── Inconel / superalloys → Kennametal B21SGL / Guhring micro
├── Hardened steel (≤ 54 HRC) → WTX-UNI / WTX-Deep UNI
└── Aluminum → Any (standard carbide, uncoated or DLC)
Machine capability?
├── Standard CNC with through-tool coolant → Fits all extended carbide drills
├── No through-tool coolant → Cannot use extended carbide for deep holes
└── Swiss-type lathe → Guhring micro for small diameters
Key Development Trends
| Trend | Detail |
|---|---|
| Guide lands replacing standard margins | 4-guide land designs (CERATIZIT WTX-Deep, Dormer Force DHD) provide directional stability for extreme depths |
| Polished chip spaces | Reduces chip friction — critical for long flute evacuation paths at 50×D |
| 99% recycled carbide substrates | CERATIZIT CT-GS20Y upGRADE — performance without virgin material environmental cost |
| Nano-layer coatings | TiAlN/AlTiN/AlCrN multi-layer structures provide thermal stability for extended drilling cycles |
| Targeted material-specific designs | Kennametal B21SGL for aerospace alloys; Guhring micro for difficult materials |
Summary
Extended solid carbide drills now reach 50×D in diameter ranges up to 14 mm, overlapping with the lower end of gun drilling capability. For depth ratios up to 50×D, they offer higher penetration rates and the ability to run on standard CNC machines without gun drilling equipment. Below 20×D, multiple product families compete; above 20×D to 50×D, the CERATIZIT WTX-Deep UNI is currently the only option. Above 50×D, gun drilling remains the only practical method. For tool material selection, see cutting tool materials guide. For the complete tooling overview, see deep hole drilling tooling guide.