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Blind hole tap – Stainless steels – INNOT technical drawing

Blind hole tap – Stainless steels

35° – 40° right-hand spiral flute tap for blind holes in stainless steels: the chip flows back towards the shank. Steam oxide, 8 – 10° rake.

ISO M

Blind holes

35° – 40° helix

steam oxide

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 tapStainless steels · 450 – 1000 N/mm²INNOTISO M ringright-hand helix 35° – 40°l threadL overall lengthchamferØ d1Ø d2square a3 flutesBLIND HOLEchip towards the shankblind holes up to 2×dhelix 35° – 40°steam oxiderake 8 – 10°

At a glance

Hole type Blind holes
Geometry Right-hand helix 35° – 40° · 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 8 – 10°
Tool material HSS-E; HSS-E-PM for series production
Coating steam oxide (first choice) · alternatively TiN, TiAlN, CrN
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 Stainless steelsISO M
Strength 450 – 1000 N/mm²
Examples AISI 303, 304 and 304L, 316 and 316L, 316Ti, 420, 430 and martensitic stainless steels

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 stainless steels

Coating When to choose it
Steam oxide (steam tempering) ★ Porous oxide layer that retains the lubricant and reduces cold welding: austenitic stainless steels and soft, "gummy" steels.
TiN – titanium nitride The universal coating: less friction and less sticking, longer life on structural steels and common materials.
TiAlN / AlTiN – titanium aluminium nitride Withstands high temperatures at the cutting edge: higher speeds, minimum quantity lubrication (MQL) or dry, alloy steels and stainless steels on powder-metallurgy substrate.
CrN – chromium nitride Anti-sticking surface: aluminium, copper, brass and titanium, where the chip tends to weld onto the thread.

★ 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 3 – 8 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 Cutting oil specific for stainless steel (preferable to emulsion)
Thread Spindle speed (n)
M6 160 – 420
M10 100 – 250
M16 60 – 160
M24 40 – 110

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.
  • Never dwell inside the hole: stainless steel work-hardens. Low, constant speed and oil specific for stainless steel.
  • 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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Thread, tolerance, length, substrate and coating: tell us the material, hole type and depth and we will propose the right tap with a quote within 30 minutes.

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