🔌 N-GROUP · HIGH SPEED · CHIP TANGLING

Aluminum Alloys

Inherently easy to machine, but chip tangling and surface quality are the biggest deep hole challenges. High speed, high feed, and adequate lubrication are key. Use polished uncoated carbide to prevent aluminum adhesion. For high-silicon cast alloys, PCD tooling is recommended.

6Alloys6061 to hypereutectic

50–220m/min VcBy alloy type

30–60barCoolant pressure

23μm/m·KThermal expansion

ALLOYS

Alloy Comparison

Alloy	Type	Vc (m/min)	Key Notes
6061-T6	Wrought, general	100–160	Clean cuts, good finish, excellent for general deep hole work
7075-T6	Wrought, high-strength	80–120	Abrasive (zinc). Tool wear higher than 6061. Adhesive at high speed
2024-T3	Wrought, aerospace	100–150	Stringy chips — needs aggressive chip breaker. Best hole quality at 3000–6000 rpm with 100 mm/min feed (Ibrahim et al., 2025)
A356-T6	Cast, automotive	80–130	Si content abrasive. Use K10 grade. Eutectic Si accelerates flank wear
AlSi10Mg	Cast, high-Si (~10%)	60–100	Abrasive. PCD recommended for production. 3–5× tool life vs carbide
AlSi12/390	Cast, hypereutectic (>12% Si)	50–80	Extremely abrasive primary Si. PCD mandatory. Coolant ≥50 bar to flush debris

PROS & CONS

Challenges & Advantages

✅ Advantages

High achievable cutting speeds (2–3× steel)
Low cutting forces, low power requirement
Good surface finish achievable as-drilled
Excellent thermal conductivity moves heat into chips
Wide range of machinable alloys

⚠ Challenges

Chip tangling — long ribbons wrap around the tool
Built-up edge at moderate speeds (40–80 m/min)
High thermal expansion (23μm/m·K ≈ 2× steel)
High-silicon alloys highly abrasive on carbide
Surface scoring from chip evacuation

SPECS

Key Data

80–220

m/min

Vc range

0.07–0.28

mm/rev

Feed (D=10mm)

30–60

bar

Coolant pressure

Uncoated K

Carbide

Best for most alloys

PCD

Tooling

For high-Si (>10%)

20–22

°C

Stable coolant temp

💡 Gundrill geometry for aluminum: outer relief ~15° (steel runs 8–12°), point angle 45° general or 140° for automotive parts, zero rake on both edges, and a V-flute angle of 110–130°. A small zero-point core rod (~0.03–0.05×D, max 0.4 mm) breaks away with the chips — keep the rod small or it raises thrust.

CHIP CONTROL

Chip Breaking Strategies

💡 Feed is the primary chip control lever: Target ≥0.10 mm/rev for D=10mm. Low feed (<0.04 mm/rev) produces thin continuous ribbons that tangle. Higher feed = thicker chips = natural breaking. For Al2024-T3, Ahmad et al. (2024) found 0.260 mm/rev optimal for low circularity error.

💡 Cycle selection: G73 (small retract 0.1–0.5mm) for moderate depths. G83 (full retraction) for L/D >15 or severe tangling. Chilled coolant (10–15°C below ambient) reduces chip length 20–30%.

⚠️ BUE avoidance: Aluminum adhesion peaks at moderate speeds (40–80 m/min). Stay above 100 m/min or use polished uncoated carbide to prevent built-up edge. High spindle speed + low feed = long continuous chips requiring manual removal.

PROCEDURE

Setup & Start-of-Cut

Control coolant temperature

Stabilize at 20–22°C (±2°C); aluminum’s 23 μm/m·K expansion makes dimensions temperature-sensitive.

Select tool by alloy

Uncoated polished K-grade for most alloys; PCD for >10% Si cast grades.

Start at high speed, adequate feed

Keep Vc above 100 m/min to avoid BUE; target feed ≥0.10 mm/rev for chip breaking.

Use G73 / G83 for long holes

G73 for moderate depth; G83 full retract for L/D >15 or severe tangling.

Verify chip form

Short, broken chips confirm the feed is right; ribbons mean raise feed or add a chip breaker.

Monitor finish & size

Watch for scoring (raise coolant flow, verify filtration <20 μm) and size drift (temperature).

COMMON PROBLEMS

Troubleshooting

Problem	Cause	Solution
Chip tangling	Feed too low; chip breaker insufficient	Increase feed; add chip breaker geometry; use G73/G83
Surface scoring	Chips scratching bore during evacuation	Increase coolant flow; verify filtration <20μm
BUE on cutting edge	Speed in 40–80 m/min range; uncoated tool	Increase Vc above 100 m/min; use polished carbide
Dimensional deviation	Coolant temperature fluctuation	Maintain ±2°C; 23μm/m·K expansion rate
Rapid tool wear (high-Si)	Abrasive primary silicon particles	Switch to PCD tooling; coolant ≥50 bar

RESEARCH DATA

Published Results

Material	Condition	Key Finding	Source
Al6061-T6	Dry drilling, HSS bits	Optimal feed 0.260 mm/rev for low circularity error. Higher feed increases chip thickness and circularity error.	Ahmad et al., 2024
Al2024-T3	High-speed (1000–9000 rpm)	3000–6000 rpm + 100 mm/min = best hole quality. High rpm + low feed = continuous tangling chips requiring manual removal.	Ibrahim et al., 2025
Al2024-T3	Speed/feed sweep	Ra range 1.1–3μm. Microhardness increased 13–25% above base 137 HV at higher speeds/feeds.	Brunel / MDPI, 2024

APPLICATIONS

Where Aluminum Deep Holes Are Drilled

🚘 AutomotiveEV motor shafts, valve bodies, and structural castings (A356 / AlSi10Mg)

🛡️ Aerospace7075/2024 airframe fittings and hydraulic manifolds

🏯 Mold CoolingCooling channels in aluminum mold plates

🔗 Hydraulic ManifoldsCross-drilled passages in 6061 valve blocks

🔧 Heat ExchangersTube sheet and header deep bores

🔌 Medical DevicesLightweight instrument housings in 6061/7075

SAFETY

Key Safety Points

⚠️ High-pressure coolant: 30–60 bar lines are under pressure — relieve at the pump before maintenance and use whip-checks on high-pressure hoses.

🔥 Sharp, tangling chips: aluminum ribbons are razor-sharp and tangle easily — use dedicated chip hooks, never pull chips by hand.

🛡️ Fine aluminum dust: airborne aluminum dust from high-speed cutting is a fire/explosion hazard in enclosed machines — maintain mist/dust extraction and clean accumulations on a schedule.

Aluminum Alloys

Alloy Comparison

Challenges & Advantages

✅ Advantages

⚠ Challenges

Key Data

Chip Breaking Strategies

Setup & Start-of-Cut

Troubleshooting

Published Results

Where Aluminum Deep Holes Are Drilled

Which Method for Aluminum Bores

Key Safety Points

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