📖 MATERIAL QUICK REF · ISO P–M–K–N–S–H

Material Parameters
Quick Reference

Material-by-material deep hole drilling data: cutting speeds and feeds for gundrilling and BTA/STS, machinability ratings, maximum L/D ratios, carbide grades, coatings, and coolant pressure/flow — organized by ISO material classification. Use it alongside the Feeds & Speeds Tables for complete parameter selection.

P·M·K·N·S·HISO classes45+ material grades covered

8–200%Machinabilityvs. AISI 1112 = 100%

300:1Max L/DGundrill, low-carbon steel

7–103 barCoolantPressure by drill Ø

MASTER DATA

Speed & Feed by Material Family & Method

Read this table first. It combines manufacturer-recommended cutting speeds for both gundrilling and BTA/STS with the machinability ratings from our material archive. Feeds scale with drill diameter — see the Feed by Diameter table below. All values are starting points: start low, inspect chips, then work upward.

⬇ Download this parameter table as CSV

Material family (ISO)	Machinability %	Carbide gundrill Vc (m/min)	BTA / STS Vc (m/min)	Feed range (mm/rev)	Coolant
P — Low-carbon steel (<0.25%C)	70%	60–150	70–120	0.05–0.35	Oil / Emulsion
P — Medium-carbon steel (≥0.25%C)	60%	50–120	70–120	0.05–0.30	Oil / Emulsion
P — Alloy steel, annealed (4140, 4340)	55%	50–100	70–100	0.05–0.30	Oil (preferred) / Emulsion
P — Alloy steel, Q&T (HRC 30–45)	35%	40–70	55–100	0.05–0.28	Oil only
P — Tool steel, annealed (H-13, D-2)	45%	50–100	50–85	0.05–0.30	Oil
M — Austenitic stainless (304, 316, 321)	40%	30–60	60–100	0.02–0.12	Oil, high EP
M — Ferritic / martensitic stainless (430, 410, 420)	45–50%	40–80	60–100	0.02–0.35	Oil / Emulsion
K — Gray cast iron (GG20, GG25)	110%	80–120	80–100	0.08–0.60	Emulsion / Dry*
K — Ductile cast iron (GGG40, GGG70)	90%	60–100	60–100	0.08–0.40	Emulsion
N — Aluminum, wrought (6061, 7075)	150%	80–160	65–130	0.05–0.30	Synthetic / Emulsion
N — Copper, brass, bronze	70–100%	35–100	65–130	0.05–0.30	Synthetic / Emulsion
S — Titanium alloy (Ti-6Al-4V)	25%	15–30	15–40	0.006–0.060	Oil, high EP
S — Inconel 718	12%	10–20	10–30	0.004–0.050	Oil, high EP (S additives)
S — Waspaloy / René 41	8%	15–30	10–50	0.02–0.06	Oil, high EP
H — Hardened steel (HRC 45–62)	12–20%	10–30	30–50	0.02–0.08	Oil, high EP

* Dry roughing is possible for cast iron, but guide pads still require lubrication on deep holes — reduce L/D by 30% for dry machining. Vc ranges compiled from ISCAR Drilling Handbook, Korloy, BOTEX, Gühring-style operating manuals, and Taegutec H-DRILL/TBTA data; carbide sits at the top of each range, HSS at the bottom.

⚠️ Chip shape is the universal check: tight C-shaped chips mean the parameters are right. Stringy, bird-nesting chips in steel or aluminum mean raise feed and/or reduce speed. Powdery chips in cast iron usually mean too much speed. Never run the first hole unattended.

FEED BY DIAMETER

How Feed Scales with Drill Size

Feed per revolution rises with drill diameter because the cutting edge gets longer. Use these feed-by-diameter tables instead of a single feed number. Gundrill data below is Gühring/BOTEX-style; BTA data is ISCAR FINEBEAM / Taegutec.

Gundrill feed (mm/rev) by diameter

Drill Ø (mm)	Carbon / structural steel	Alloyed steel (>700 N/mm²)	Austenitic stainless	Cast iron	Aluminum
Ø3–6	0.10	0.08	0.005–0.02	0.20	0.20
Ø6–12	0.15	0.10	0.010–0.02	0.30	0.30
Ø12–25	0.25	0.15	0.010–0.03	0.40	0.40
Ø25–50	0.35	0.20	0.020–0.04	0.60	0.60

BTA / STS feed (mm/rev) by diameter

Drill Ø (mm)	Feed (mm/rev)	Notes
Ø8–20	0.05–0.13	Small BTA heads, indexable inserts
Ø20–31	0.08–0.15	Common cylinder barrel range
Ø31–43	0.10–0.17	Medium bores
Ø43–65	0.13–0.20	Large bores; some sources to 0.30

💡 Rule of thumb (ToolCroze): for gundrilling, feed ≈ 0.001 in/rev per 1/16 in of drill diameter, ±0.001 in/rev. In metric: about 0.04 mm/rev at Ø3, 0.10 mm/rev at Ø6, and 0.18 mm/rev at Ø10.

ISO P — STEEL

Steels & Alloy Steels

Steels are the deep hole drilling backbone. The dominant failure modes are built-up edge at low speed and notch wear at high speed. Annealed grades drill far better than quenched-and-tempered grades — consider machining in the annealed condition whenever the design allows.

55–70%

Machinability

Annealed carbon & alloy steels

300:1

Max L/D

Low-carbon gundrill

K10–K40

Carbide grade

Micrograin to tough grades

Material	Machinability*	Max L/D (Gundrill)	Max L/D (BTA)	Carbide Grade	Coating	Coolant
Low-carbon steel (<0.25%C)	70%	300:1	200:1	K10–K20 (micrograin)	TiN or uncoated	Oil / Emulsion
Medium-carbon steel (≥0.25%C)	60%	250:1	180:1	K20–K30	TiN / TiAlN	Oil / Emulsion
Alloy steel, annealed (4140, 4340)	55%	200:1	150:1	K20–K30	TiAlN	Oil (preferred) / Emulsion
Alloy steel, Q&T (HRC 30–45)	35%	100:1	80:1	K30–K40	AlTiN	Oil only
Tool steel (H-13, D-2, annealed)	45%	100:1	80:1	K20–K30	TiAlN / AlTiN	Oil
Hardened steel HRC 45–55	20%	50:1	40:1	K40 / PCBN	AlTiN / TiSiN	Oil (high EP)
Hardened steel HRC 55–62	12%	30:1	25:1	PCBN	Uncoated (PCBN)	Oil (high EP)

⚠️ Hardness drives speed: as a gundrill starting rule (ToolCroze), run about 24 m/min (80 SFM) at 100 BHN and drop ~3 m/min (10 SFM) for every additional 50 BHN. Real-world reference: a Ø5 mm gundrill in 4140QT @ 235 BHN, 400 mm deep, ran 2800 rpm (~44 m/min) at 0.012 mm/rev with 1000 psi (69 bar) coolant; a Ø5 mm drill in 4340HT reliably produced ~20 holes per sharpening at 2400 rpm.

ISO M — STAINLESS

Stainless Steels

Stainless combines work hardening, long gummy chips, and low thermal conductivity — the worst chip-handling conditions in deep hole drilling. Never under-feed: rubbing the work-hardened skin destroys the edge. Keep the chip load positive and let high-pressure coolant do the chip evacuation.

30–50%

Machinability

Duplex hardest of the family

120:1

Max L/D

Ferritic gundrill

13–23 bar

Coolant pressure

190–329 psi for ~1″ holes

Material	Machinability*	Max L/D (Gundrill)	Max L/D (BTA)	Carbide Grade	Coating	Coolant
Austenitic stainless (304, 316, 321)	40%	100:1	80:1	K20–K30 (fine grain)	TiAlN (best)	Oil (high EP) — 8–10% concentration if emulsion
Ferritic stainless (430, 409)	50%	120:1	90:1	K20–K30	TiAlN	Oil / Emulsion
Martensitic stainless (410, 420, annealed)	45%	100:1	80:1	K20–K30	TiAlN / AlTiN	Oil
Duplex / Super Duplex stainless	30%	80:1	60:1	K30–K40	TiAlN / TiSiN	Oil (high EP)
Precipitation-hardening (17-4PH)	35%	80:1	60:1	K20–K30	TiAlN	Oil

⚠️ Coolant pressure is the control variable: published research on 304 stainless gun drilling (Springer, 2024) shows coolant pressure directly shapes chip curling and chip formation in the narrow chip-removal space — a blocked chip path fails the hole. Allied Machine data recommends 190–329 psi (13–23 bar) for 300/400-series stainless at ~1″ holes, among the highest of any family. If the pressure gauge dips, retract and clear chips before continuing.

ISO K — CAST IRON

Cast Irons

Cast iron is brittle and short-chipping with excellent machinability, but abrasive graphite dust wears tools fast and castings hide porosity and hard inclusions. Gray iron actually machines faster than most steels — it is one of the few families where dry roughing is feasible.

110%

Machinability

Gray iron — faster than steel

200:1

Max L/D

Gray iron gundrill

Dry*

Roughing

Guide pads still need lube

Material	Machinability*	Max L/D (Gundrill)	Max L/D (BTA)	Carbide Grade	Coating	Coolant
Gray cast iron (GG20, GG25)	110%	200:1	150:1	K10–K20	Uncoated / TiAlN	Emulsion / Dry**
Ductile cast iron (GGG40, GGG70)	90%	180:1	130:1	K10–K20	Uncoated / TiAlN	Emulsion
Compact graphite iron (CGI)	60%	100:1	80:1	K20–K30	TiAlN / AlCrN	Emulsion (7% concentration)

💡 Gundrill profiles: gundrill head profiles A, B and D suit cast iron — typically coated for wear resistance against the abrasive graphite. Keep a low helix (<0.30) and expect powder-like chips; if chip evacuation weakens, drop speed before dropping feed.

ISO N — NON-FERROUS

Aluminum, Copper & Magnesium

The easiest materials to cut and the easiest to ruin with a built-up edge. Long, stringy aluminum chips can wrap around the drill and starve the cutting edge of coolant. High feeds are possible — and desirable — because chip flow is excellent.

200%

Machinability

Magnesium — best of all

250:1

Max L/D

Leaded brass gundrill

No water

Magnesium

Mineral oil only — fire risk

Material	Machinability*	Max L/D (Gundrill)	Max L/D (BTA)	Carbide Grade	Coating	Coolant
Aluminum alloy (wrought, 6061, 7075)	150%	200:1	150:1	Uncoated K10 / Diamond	Uncoated (prevents BUE)	Synthetic / Emulsion
Aluminum alloy (cast, high Si >12%)	100%	150:1	120:1	PCD / Diamond-coated	Uncoated / Diamond	Synthetic / Kerosene
Brass / Bronze (leaded)	100%	250:1	150:1	Uncoated K10–K20	Uncoated	Synthetic / Emulsion
Copper (pure, OFHC)	70%	150:1	100:1	Uncoated K10–K20	Uncoated (polished)	Emulsion / Oil
Magnesium alloy	200%	150:1	100:1	Uncoated K10–K20	Uncoated	Mineral oil only (NO water)

🔥 Magnesium fire rule: magnesium must never see water-based coolant. Use mineral oil only and keep a Class-D fire extinguisher within reach. For high-silicon cast aluminum (>12% Si), move to PCD or diamond-coated tools and kerosene-based coolant to defeat the abrasive silicon particles.

💡 Speed headroom: wrought aluminum gundrills comfortably at 80–160 m/min (ISCAR) and up to 180–250 m/min (Korloy) with uncoated or polished carbide — the only family where speed, not tool wear, usually sets the limit.

ISO S — TITANIUM & SUPERALLOYS

Titanium & Nickel Superalloys

The hardest family to drill. Low thermal conductivity traps heat in the cutting zone, the material work-hardens and notches the edge, and titanium has a tendency to shrink and grab the tool once the outer corner dulls. Low speed, positive feed, and relentless high-pressure coolant are non-negotiable.

Machinability

Waspaloy / René 41

80:1

Max L/D

Ti-6Al-4V gundrill

70+ bar

Coolant

Extends carbide life 50–100%

Material	Machinability*	Max L/D (Gundrill)	Max L/D (BTA)	Carbide Grade	Coating	Coolant
Titanium alloy (Ti-6Al-4V)	25%	80:1	60:1	K10–K20 (fine grain)	TiAlN or TiSiN (best)	Oil (high EP) — 10–12% if emulsion
Titanium (pure, Grade 2)	35%	100:1	80:1	K10–K20	Uncoated / TiAlN	Oil
Inconel 718	12%	50:1	40:1	S10–S20 / fine-grain K	TiSiN or TiAlN (best)	Oil (high EP, S-based additives)
Inconel 625 / Hastelloy	10%	40:1	30:1	S10–S20	TiSiN / TiAlSiN	Oil (high EP)
Waspaloy / René 41	8%	30:1	25:1	S20–S30	TiSiN	Oil (high EP)

⚠️ Titanium rule of thumb: a 10% increase in cutting speed can cut tool life 30–50% in Ti-6Al-4V. Keep speeds conservative (15–30 m/min carbide) and hold adequate chip load — underfeeding causes rubbing, work hardening, and catastrophic failure. Deep-hole drills feed at 0.006–0.060 mm/rev by diameter. High-pressure coolant (70+ bar) extends carbide life 50–100%.

💡 Superalloy maintenance: gundrills in Inconel 718 need resharpening roughly every 50 mm of accumulated depth. Monitor spindle torque and coolant pressure in real time; a sudden pressure spike or torque rise means the edge has dulled — retract before the tool snaps in the bore.

ISO H — HARDENED

Hardened Steel & Chilled Cast Iron

High edge pressure and chipping risk dominate. Depth capability collapses because flank wear accelerates geometrically with hardness. If at all possible, drill before hardening; if you must drill hardened, PCBN or ceramic is the only realistic tooling.

12%

Machinability

HRC 55–62 steel

30:1

Max L/D

Gundrill, hardened steel

PCBN

Tool material

Ceramic for Ni-hard

Material	Machinability*	Max L/D (Gundrill)	Max L/D (BTA)	Carbide Grade	Coating	Coolant
Hardened steel HRC 45–55	20%	50:1	40:1	K40 / PCBN	AlTiN / TiSiN	Oil (high EP)
Hardened steel HRC 55–62	12%	30:1	25:1	PCBN	Uncoated (PCBN)	Oil (high EP)
Chilled cast iron (Ni-hard)	15%	30:1	25:1	PCBN / Ceramic	Uncoated	Emulsion

⚠️ High-pressure coolant is conditional here: research on high-hardness steels (SKD 11, HV 350–620) shows high-pressure coolant (7 MPa / 70 bar) only pays off once cutting conditions pass the critical temperature where tool hardness collapses. Below that threshold, conventional pressure actually causes less tool wear. Test both regimes on a scrap coupon before committing.

CORRECTIONS

Hardness, Depth & Holder Corrections

Every table on this page assumes a standard holder, a new tool, and a comfortable depth. Real jobs violate all three — apply these corrections before cutting.

Hardness correction (gundrill starting rule)

Start at ~24 m/min (80 SFM) for material at 100 BHN.
Reduce speed ~3 m/min (10 SFM) for every additional 50 BHN.
Above ~350 BHN, treat the material as a hardened grade — switch tooling and coating per ISO H above.

Extended holder multipliers (coolant pressure AND flow)

Holder length	Multiply pressure & flow by
Standard	×1.0
Extended	×1.3
Long	×1.5
Long Plus	×2.0
XL	×2.0
3XL	×3.0

Speed & feed for long holders

Reduce cutting speed to 0.75–0.90× standard.
Reduce feed to 0.90–0.95× standard.
Over ~40 diameters, drill in two steps — a shorter gundrill first, then a longer drill guided by the first hole.

L/D reductions

New or unfamiliar material: cut the max L/D by 20% for the first trial.
Dry-machined cast iron: cut L/D by 30%.
Hardness above the annealed baseline for a grade: cut L/D by a further 20–30%.

💡 Worked example: a Ø25 mm alloy-steel bore on an XL holder. Base coolant for Ø25 mm gundrill is ~21 bar; ×2.0 = 42 bar. Base Vc 80 m/min × 0.85 = 68 m/min. Base feed 0.25 mm/rev × 0.92 = 0.23 mm/rev. Start there and verify chips.

COOLANT

Coolant Pressure & Flow Requirements

Coolant does three jobs in deep hole drilling: cools the cutting edge, lubricates the guide pads, and evacuates chips through the drill body. Pressure and flow are size-dependent — small drills need high pressure, large drills need high flow.

Gundrill coolant by drill diameter

Drill Ø (mm)	Ideal pressure (bar)	Min pressure (bar)	Flow at ideal (L/min)
Ø3	103	34	4
Ø5	79	28	6
Ø6	64	24	10
Ø10	47	21	17
Ø13	36	17	27
Ø16	31	14	38
Ø19	28	12	53
Ø25	21	10	76
Ø32	17	9	106
Ø38	14	7	136

Converted from the carbideanddiamondtooling.com chart (PSI/GPM); a reduced coolant capability lowers penetration rate — it rarely causes sudden failure.

Coolant pressure by material (Allied Machine, ~Ø25 mm)

Material class	Hardness (BHN)	Pressure (psi / bar)
Free-machining steel	100–250	105–195 / 7–13
Low-carbon steel	85–275	80–180 / 6–12
Medium-carbon steel	125–325	70–175 / 5–12
Alloy steel (4140)	125–375	70–165 / 5–11
High-strength alloy (4340, 300M)	225–400	60–175 / 4–12
Tool steel (H-13)	150–250	35–155 / 2–11
Stainless 300/400 series	135–275	190–329 / 13–23
Hardened steel / wear plate	400–500	45–210 / 3–14
Titanium alloy	140–220	130–247 / 9–17
Aluminum	30–180	55–350 / 4–24

⚠️ Coolant type: high-EP cutting oil is the first choice for gundrilling — emulsions are generally unsuitable and synthetic coolant (no lubricity) should never be used. If you must use a water-soluble product, run it at 10–12% concentration. BTA/STS machines typically need 50+ bar and 100–400+ L/min; purpose-built machines (e.g., DeHoff) can supply up to 172 bar and 160 GPM.

💡 Pressure gauge is a diagnostic: a sudden pressure drop means a chip blockage or blowout past the seal; a steady climb means restriction, chip packing, or a worn guide pad. Either way, retract and inspect before resuming.

CLASSIFICATION

ISO Material Classification Guide

Tool manufacturers key every insert, drill, and coating recommendation to the ISO material group. Learn these six groups and every catalog becomes readable.

ISO Group	Color Code	Common Materials	Key Machining Challenge
P	Blue	Steel, alloy steel, tool steel	Built-up edge at low speed; notch wear at high speed
M	Yellow	Stainless steel (austenitic, duplex)	Work hardening; long chips; built-up edge
K	Red	Cast iron (gray, ductile, CGI)	Abrasive wear; fine graphite dust
N	Green	Aluminum, copper, magnesium, plastics	Built-up edge; excellent chip flow — high feeds possible
S	Brown	Titanium, nickel superalloys, cobalt alloys	High cutting temperature; work hardening; notching
H	Grey	Hardened steel, chilled cast iron	High edge pressure; chipping risk; low L/D only

💡 Machinability baseline: percentages throughout this page are relative to AISI 1112 free-machining steel (100%). A higher percentage means easier to machine — magnesium at 200% cuts over 25× easier than Waspaloy at 8%.

COATINGS

Coating Selection Quick Guide

Based on comparative drilling performance studies, coatings ranked by effectiveness for deep hole drilling:

TiSiN / TiAlSiN (nanolaminate): Best overall — lowest flank wear, best chip evacuation, highest temperature resistance (1100°C). Use for superalloys, titanium, and hardened steel.
TiAlN: Best general-purpose for deep hole drilling — excellent performance across steel, stainless, and titanium. Consistent results in production.
AlTiN: Higher aluminum content for better oxidation resistance at high speed. Good for hardened steel and dry machining.
TiN: Adequate for low-carbon steel only. Limited temperature resistance (600°C).
Uncoated: Best for aluminum, copper, and brass — prevents built-up edge formation.
Avoid AlTiCrN / Cr-containing coatings for drilling — studies show chromium oxides have lower protective capability, leading to higher adhesion, abrasive wear, edge breakage, and poor chip evacuation compared to TiAlN-based coatings.

⚠️ Matching rule: pair the coating to the failure mode. Titanium and superalloys fail by heat and notching → TiSiN/TiAlN. Hardened steel fails by chipping and edge pressure → AlTiN or uncoated PCBN. Non-ferrous fails by built-up edge → uncoated, polished.

WORKFLOW

How to Use This Page & Verify Parameters

Start with speeds & feeds

Use the Feeds & Speeds Tables guide for Vc and feed values, then come here to select the right carbide grade, coating, and coolant type.

Verify L/D capability

Confirm your target L/D is within the achievable range for the method and material. New materials: cut L/D by 20% for the first trial.

Consult the manufacturer

For any new material, read the tool maker’s recommended parameters first and start from the lower limit.

Watch the first hole

Inspect chip shape every 10 seconds during the first hole. Only increase parameters after confirming stable chip formation and acceptable tool wear rate.

Record everything

Log actual Vc, feed, coolant pressure/flow, tool life, and chip shape for each material. Build your own validated dataset — it beats any published table.

⚠️ Core principle: machinability ratings are relative — actual performance depends on machine rigidity, coolant system, and fixturing. A table value is a starting bid, never a guarantee. Chips, torque, and coolant pressure are the only true referees.

FIELD USE

Printing & Using This Page at the Machine

Print the master table and coolant tables at ~90% scale; keep the sheet at the machine in a clear sleeve.
Circle the three or four materials you run most so the eye lands instantly.
Use the pressure gauge as a live diagnostic — drops and climbs both mean stop-and-inspect.
Cross-check with the tool manufacturer’s app or catalog page before a production run — inserts and coatings change, tables age.
Standardize the first-hole procedure: start low, inspect chips every 10 seconds, log the result, then optimize.
Never exceed 50:1 L/D on hardened steel or 30:1 on superalloys without a dedicated machine and real-time monitoring.

✅ One-line summary: read the master table for speed, the feed tables for feed, the ISO tables for grade and coating, and the coolant tables for pressure and flow — then confirm every value with a test cut.

Material ParametersQuick Reference

Speed & Feed by Material Family & Method

How Feed Scales with Drill Size

Gundrill feed (mm/rev) by diameter

BTA / STS feed (mm/rev) by diameter

Steels & Alloy Steels

Stainless Steels

Cast Irons

Aluminum, Copper & Magnesium

Titanium & Nickel Superalloys

Hardened Steel & Chilled Cast Iron

Hardness, Depth & Holder Corrections

Hardness correction (gundrill starting rule)

Extended holder multipliers (coolant pressure AND flow)

Speed & feed for long holders

L/D reductions

Coolant Pressure & Flow Requirements

Gundrill coolant by drill diameter

Coolant pressure by material (Allied Machine, ~Ø25 mm)

ISO Material Classification Guide

Coating Selection Quick Guide

How to Use This Page & Verify Parameters

Printing & Using This Page at the Machine

Keep Reading

Material Parameters
Quick Reference