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Metal drill bit 21 NWKc HSS DIN 345
934791
Diameter (mm): 21301 sizes of this drill
33,13,23,33,43,53,63,73,83,944,14,24,34,44,54,64,74,84,955,15,25,35,45,55,65,75,85,966,16,26,36,46,56,66,76,86,977,17,157,27,257,37,47,57,67,77,757,87,988,18,28,258,38,48,58,68,78,88,999,19,29,259,39,49,59,69,79,759,89,91010,110,210,310,410,510,610,710,7510,810,91111,111,211,2511,311,411,511,611,711,811,91212,112,212,312,412,512,612,712,812,91313,113,213,2513,313,413,513,613,713,7513,813,91414,2514,414,514,751515,2515,515,751616,2516,516,751717,2517,517,751818,2518,518,751919,2519,519,752020,2520,520,752121,2521,521,752222,2522,522,752323,2523,523,752424,2524,524,752525,2525,525,752626,2526,526,752727,2527,527,752828,2528,528,752929,2529,529,753030,2530,530,753131,2531,531,753232,2532,532,753333,2533,533,753434,2534,534,753535,2535,535,753636,2536,536,753737,2537,537,7537,83838,538,753939,2539,539,754040,2540,54141,54242,54343,54444,54545,54646,546,75474848,54949,55050,55151,55252,553545556575858,55960616263646566676869707172737475767778798081828384858687888990919293949596979899100
€25.89 tax inc.
Net price: €21.05
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 HSS |
| Standard | DIN 345 |
| Drill type | NWKc — twist drill with taper shank |
| Material | HSS (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 HSS metal drill bit – Morse taper MT2
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
- Morse taper MT2 — self-holding mounting in the spindle eliminates slipping under full cutting torque
- HSS high-speed steel — the cutting edge retains its working hardness up to 600°C in structural and low-alloy steels
- Full compliance with DIN 345 — ensures interchangeability and compatibility with reduction sleeves and Morse taper spindles
- 118° point angle — versatile cutting geometry performs well in structural and medium-hard steels, cast iron, and aluminum
- Diameter tolerance h8 — repeatable hole size within a tolerance class that ensures consistent parameters in series production
- Resharpenable cutting edges — repeated sharpening on a grinder while maintaining the 118° angle and cutting edge symmetry
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 |
Deep-hole drilling (over 3×D)
When drilling holes deeper than 63 mm (3×Ø21), periodically retract the drill every 1–1.5×D to remove chips. Use ample emulsion cooling (minimum concentration of 6–8%). Reduce the feed by 30–50% from nominal values.
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 40%, 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
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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