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Description
Material HSSE
Thread size M20
ChamferC (2–3) threads
Standard DIN 376
Technical data for the M20 blind-hole tap
| Technical Data | |
|---|---|
| Nominal Diameter d1 | M20 |
| Thread Pitch P | 2.5 mm |
| Helix Angle | 40° |
| Overall Length l1 | 140 mm |
| Flute Length l2 | 34 mm |
| Length l3 | 48 mm |
| Shank Diameter d2 | 16 mm |
| Square Drive Size a | 12 mm |
| Tap Drill Diameter | 17.5 mm |
| Chamfer | C (2÷3) P |
| Thread tolerance | 6H |
How a spiral flute tap evacuates chips from a blind hole
The 40° flute works like a screw conveyor
The flutes of this tap follow a right-hand helix at an angle of 40° to the axis. The tap rotates clockwise and advances into the hole. Chips cut by the chamfer enter the flute, and the helix carries them upward like the screw in a meat grinder. The bottom of the hole stays clean, and the cutting edges do not encounter packed chips. The M20 x2.5 tap has a reduced shank according to DIN 376: diameter 16 mm, square size 12 mm.
1
The 40° spiral flute carries chips upward from the chamfer.
2
The stepped chip exits the hole and breaks into short pieces.
3
The tap rotates clockwise to cut a right-hand thread.
4
Chamfer C: 2–3 incomplete threads on the tapered lead.
5
Clearance below the tap tip – min. 2 thread pitches above the bottom.
6
Feed 2.5 mm/rev, equal to the pitch of the M20 x2.5 thread.
M20 spiral flute machine tap – with a 40° spiral flute
The M20 spiral flute machine tap from the large-diameter series is designed for tapping blind holes up to 2.5D deep. HSSE steel with 5% cobalt provides a hardness of 65-67 HRC and high cutting-edge heat resistance up to 650°C. The 40° spiral flute ensures aggressive chip evacuation when tapping deep blind holes. Its form C chamfer makes the tool particularly suitable for blind hole tapping close to the bottom of the hole. The 6H tolerance in accordance with DIN 376 meets industrial production requirements.
Key features of the M20 spiral flute machine tap
- Manufacturing precision to 6H tolerance guarantees dimensional repeatability and full thread interchangeability in series production of mechanical components
- Compliance with DIN 376 confirms quality and ensures standardized long-shank dimensions compatible with European machine tool holders
- Durability of HSSE steel with 5% cobalt allows operation at temperatures up to 650°C without loss of the cutting edge's mechanical properties
- Compatibility with ER40 holders and tapping heads for CNC machining centers with synchronous tapping capability
- Designed for series production includes machine housings, structural components, engine blocks, and industrial gearboxes
- 40° spiral flutes ensure aggressive chip evacuation when tapping blind holes up to 2.5D deep without the risk of breakage
The M20 spiral flute tap is suitable for maintenance departments restoring threads and repairing production machinery. The standard pitch of the M20 thread is 2.5 mm, with a tap drill diameter of 17.5 mm. The tool is compatible with standard mineral oil-based tapping lubricants and coolant emulsions.
Cutting data for the M20 blind-hole machine tap
| Material | Cutting speed Vc [m/min] | Spindle speed n [rpm] | Feed f [mm/min] |
|---|---|---|---|
| PSteel | 5-20 | 80-318 | 200-795 |
| MStainless steel | 5-10 | 80-159 | 200-398 |
| KCast iron | 5-15 | 80-239 | 200-598 |
| NAluminum | 10-25 | 159-398 | 398-995 |
Thread preparation M20 in a blind hole
1 Spot drilling
NC spotting drill 90°
2 Drilling
Ø 17.5 mm
3 Tapping
M20
✓ Done!
Tolerance 6H
Standard: DIN 376 | Chamfer: C (spiral flute) | Application: blind holes
Tolerance 6H — metric thread tolerance classes
| Class | Accuracy | Application | Status |
|---|---|---|---|
| 4H / 4g | High | Precision connections, hydraulics | — |
| 6H / 6g | Standard | Machine building, general-purpose | SELECTED |
| 7H / 8g | Low | Large clearance, easy assembly | — |
6H = internal thread (nut, hole) | 6g = external thread (screw)
Frequently asked questions
The M20 HSSE spiral flute machine tap is suitable for structural steels up to 900 MPa, 304/316 austenitic stainless steels, aluminum, brass, and gray cast iron. The M20 size is used in steel structures and machine building.
For the M20x2.5 thread in tolerance class 6H, the tap drill diameter should be 17.5 mm. The permissible hole tolerance range is 17.5-17.75 mm. A smaller hole increases cutting torque, while a larger hole reduces the thread class.
Yes, cooling with an oil emulsion at a minimum concentration of 8% or with tapping oil is recommended and extends tool life by a factor of 2-3. Intensive cooling is required when machining stainless steels, while aluminum can be tapped with minimal lubrication.
Product accessories
HSSE 17.5 cobalt metal drill bit DIN 338
Reference: 13297 In stock > 10 items
€17.11
€21.04 brutto
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Shipping
All orders are delivered by courier company GLS. For orders exceeding 369 PLN gross shipping is FREE
| Courier GLS | Przelew24 / Prepayment | 14,76 zł gross | Delivery time 1 working day |
| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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