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Description
DIAMETER Ø21 mm
MORSE TAPER MT2
OVERALL LENGTH 243 mm
FLUTE LENGTH 145 mm
Technical specifications of the Ø21 mm drill bit
Twist drill with Morse taper shank
| TECHNICAL DATA | |
|---|---|
| Diameter | Ø21 NWKc HSSE |
| Standard | DIN 345 |
| Drill type | NWKc — twist drill with taper shank |
| Material | HSSE (cobalt high-speed steel) |
| Overall length l1 | 243 mm |
| Flute length l2 | 145 mm |
| Morse taper | MT2 |
| Point angle | 118° |
| Diameter tolerance | h8 |
| Cutting direction | Right-hand |
Ø21 mm HSSE twist drill – MT2 Morse taper
Product description and key benefits
The Ø21 mm twist drill with an MT2 shank offers a significant advantage over straight-shank drills: mounting stability increases with load. The self-holding Morse taper seats deeper in the spindle in proportion to the cutting torque. At a diameter of 21 mm, the Ø21 Morse taper drill provides vibration-free operation and uniform cutting edge wear even during intensive use.
Key benefits of the Ø21 mm metal drill bit
- 5% cobalt in the HSS matrix — raises the tempering temperature to 650°C — 50°C higher than standard HSS
- Direct mounting in an MT2 spindle — eliminates the chuck as a source of runout — particularly important when drilling stainless steels, where runout reduces surface quality
- Drilling austenitic steels — the HSSE cutting edge handles work hardening in 304/316/321 steels
- h8 diameter tolerance — repeatable hole size even in difficult-to-machine materials
- Conforms to DIN 345 — dimensions identical to HSS — a replacement for use in existing machining cells
- Repeated resharpening — HSSE steel retains its properties after the cutting edge is reground on a tool grinder
The Ø21 Morse taper drill is suitable for drilling holes in hollow sections, medium-thickness sheet metal, and components used in machinery repairs. H12 tolerance (Ø21.000–Ø21.210 mm) is sufficient for assembly holes; if H7 tolerance is required, additional reaming is necessary.
Morse tapers – dimensions to DIN 228
Dimension table for all Morse tapers MT0–MT6
| Taper | Diameter D [mm] | Length [mm] |
|---|---|---|
| MT0 | 9.045 | 49.8 |
| MT1 | 12.065 | 53.5 |
| MT2 | 17.780 | 64.0 |
| MT3 | 23.825 | 80.5 |
| MT4 | 31.267 | 117.5 |
| MT5 | 44.399 | 149.5 |
| MT6 | 63.348 | 210.0 |
REDUCTION SLEEVES COMPATIBLE WITH THE Ø21 MM DRILL BIT:
| ✓ | MT2 → MT3 — for a spindle with an MT3 socket |
| ✓ | MT2 → MT4 — for a spindle with an MT4 socket |
| ✓ | MT2 drill drift — for removing the drill bit from the spindle |
Cutting data for the Ø21 mm drill bit according to ISO 513
Recommended machining conditions for a diameter of Ø21 mm
| ISO symbol | Workpiece material | Vc [m/min] | f [mm/rev] | n [rpm] | Vf [mm/min] |
|---|---|---|---|---|---|
| P Steel | Structural steel up to 900 N/mm² | 11÷20 | 0.20 | 167÷303 | 33÷61 |
| K Cast iron | Gray cast iron GG20–GG30 | 13÷16 | 0.20 | 197÷243 | 39÷49 |
| N Copper and Al alloys | Cu, CuZn, Al, and alloys | 25÷28 | 0.25÷0.32 | 379÷424 | 95÷136 |
Mounting the drill in the spindle
Before mounting the Ø21 mm drill, remove chips, oil, and contaminants from the taper and spindle socket. Residue between the contact surfaces causes radial runout and can damage the spindle socket.
Material compatibility of the Ø21 mm drill bit
Range of workpiece materials and application limitations
✓ Structural steel (S235, S355) up to 900 N/mm²
✓ Gray and ductile cast iron (GG20, GGG40)
✓ Low-carbon and medium-alloy steel
▲ Stainless steel (Vc reduced by 30%, ample coolant)
▲ Aluminum and Al alloys (emulsion coolant required)
✗ Hardened steels above 45 HRC
Frequently asked questions about the Ø21 mm drill bit
The HSS drill can be used for stainless steel with Vc reduced by 40% and ample cooling with a 8–10% emulsion. An HSSE (cobalt) drill of the same diameter is a more efficient option, retaining its hardness up to 650°C.
A pillar or box-column drilling machine with an MT2 spindle and a minimum power rating of 0.75–1.5 kW. Bench drilling machines with a drill chuck are not recommended — they cannot transmit the torque generated at a diameter of 21 mm.
It depends on the specific bolted joint. For metric coarse-thread bolts, the clearance hole diameter according to ISO 273 is 0.5–1 mm larger than the nominal thread diameter.
Product accessories
Long reduction sleeve MK1-2 PTPb 1762
Reference: 0000006908 In stock > 10 items
€15.79
€19.42 brutto
Reduction sleeve MK4 MK2 1751 PTPa DIN 228
Reference: 1181 In stock > 10 items
€15.79
€19.42 brutto
Reduction sleeve MK5 MK2 1751 PTPa DIN 228
Reference: 4910 In stock > 10 items
€22.37
€27.51 brutto
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Shipping
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| 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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