Maschio per fori ciechi – Alluminio e leghe leggere INNOT
Blind hole tap – Aluminium and light alloys – INNOT technical drawing

Blind hole tap – Aluminium and light alloys

45° right-hand spiral flute tap for blind holes in aluminium and light alloys: the chip flows back towards the shank. Bright, 20 – 25° rake.

ISO N

Blind holes

45° helix

Bright

M2 – M36

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Technical data sheet PDFCutting data, sizes and grades

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Geometry by material

Chamfer, helix and rake chosen for the material

DIN 371 / 376 sizes

Metric, fine, pipe and inch, also custom made

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Description

Technical drawing

Blind hole tapAluminium and light alloys · up to 600 N/mm²INNOTISO N ringright-hand helix 45°l threadL overall lengthchamferØ d1Ø d2square a3 flutesBLIND HOLEchip towards the shankblind holes up to 2×d45° helixbrightrake 20 – 25°

At a glance

Hole type Blind holes
Geometry Right-hand helix 45° · 3 spiral flutes
Chamfer Form C, 2 – 3 threads
Chip Flows back along the helix towards the shank: the bottom of the hole stays clean
Thread depth Up to 2 × d
Rake angle 20 – 25°
Tool material HSS-E
Coating bright (first choice) · alternatively CrN, DLC
Tolerance 6H; 6G and 7G for threads to be galvanised or painted
Design Reinforced shank from M2 to M10 (DIN 371), reduced shank from M12 (DIN 376); from M3 to M10 also with reduced shank for deep holes
Cutting direction Right-hand; left-hand on request

Workpiece materials

Group Aluminium and light alloysISO N
Strength up to 600 N/mm²
Examples EN AW-6082, 6061, 7075, 2011, 5083 and casting alloys with Si up to 10 %

Sizes – ISO metric thread

Thread Pitch P Tap drill Ø L overall l thread Ø d2 shank Square a
M2 0,4 1,6 45 8 2,8 2,1
M2,5 0,45 2,05 50 9 2,8 2,1
M3 0,5 2,5 56 7 3,5 2,7
M3,5 0,6 2,9 56 7 4 3
M4 0,7 3,3 63 8 4,5 3,4
M5 0,8 4,2 70 10 6 4,9
M6 1 5 80 12 6 4,9
M8 1,25 6,8 90 16 8 6,2
M10 1,5 8,5 100 16 10 8
M12 1,75 10,2 110 18 9 7
M14 2 12 110 20 11 9
M16 2 14 110 22 12 9
M18 2,5 15,5 125 25 14 11
M20 2,5 17,5 140 25 16 12
M22 2,5 19,5 140 25 18 14,5
M24 3 21 160 30 18 14,5
M27 3 24 160 30 20 16
M30 3,5 26,5 180 35 22 18
M33 3,5 29,5 180 35 25 20
M36 4 32 200 45 28 22

Dimensions in mm. M39 to M100 and fine, pipe and inch threads on request. The tap drill Ø is the one recommended for tolerance 6H. In blind holes the thread length is shorter to leave room for the chip in the helix.

Coatings for aluminium and light alloys

Coating When to choose it
Bright (uncoated) ★ The sharpest possible cutting edge: aluminium, copper and soft materials that do not tolerate rounded edges.
CrN – chromium nitride Anti-sticking surface: aluminium, copper, brass and titanium, where the chip tends to weld onto the thread.
DLC – amorphous carbon (diamond-like) Very low friction and no built-up edge: aluminium alloys, copper and engineering plastics in high-volume production.

★ INNOT first choice for this material. Every tap can be supplied with any coating in the range: specify it in your request.

Starting data

Printable cutting data tableAll the data on this page in an INNOT PDF to keep in the shop.Download PDF
Cutting speed Vc 12 – 25 m/min (lower value for uncoated substrate or machines with a compensating chuck)
Feed Equal to the thread pitch: synchronised tapping or chuck with axial compensation
Lubrication Plenty of emulsion or oil; never dry
Thread Spindle speed (n)
M6 640 – 1.330
M10 380 – 800
M16 240 – 500
M24 160 – 330

Guide values to be adapted to machine, clamping and lubrication. n = Vc × 1000 / (π × d).

Tips for use

  • Drill at least 3 pitches deeper than the thread: the tap must never touch the bottom of the hole.
  • The chip flows back along the helix: beyond 1.5 × d depth you need plenty of coolant or internal coolant (on request).
  • Set a smooth reversal at the end of the stroke: abrupt reversals chip the cutting edge.
  • Avoid lean emulsions: aluminium welds onto the thread. With high-silicon alloys (over 10 %) use the cast iron tap.
  • Chamfer the hole entry at 90°: clean start and no burr on the first thread.

Selection guide

Material
Through holes
Blind holes
P
Structural and annealed steelsup to 800 N/mm²
Spiral pointTiN35° helixTiN
P
Quenched and tempered and alloy steels800 – 1400 N/mm²
Spiral pointTiCN40° helixTiCN
M
Stainless steels450 – 1000 N/mm²
Spiral pointsteam oxide35° – 40° helixsteam oxide
K
Cast irons and short chipsup to 300 HB
Straight flutesTiCN
N
Aluminium and light alloysSi up to 10 %
Spiral pointbright45° helixbright
↻
Chiplesssteels, stainless steels, aluminium
Forming tapTiN · steam oxide · CrN

Fine, pipe, inch and left-hand threads: special and custom threads.

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