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Countersink M12 - 20x13 HSS - Artykuły Techniczne
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  • Countersink M12 - 20x13 HSS - Artykuły Techniczne
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Artykuły Techniczne

Counterbore 20X13 M12 DIN 373 HSS

Artykuły Techniczne Artykuły Techniczne
0000003755
Diameter (mm): 2017 sizes of this countersink
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Net price: €22.89

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Description

Cutting diameterØ20 mm
Pilot diameterØ13 mm
Shank diameterØ12.5 mm
For threadM12

M12 20×13 mm counterbore with pilot

Type NWCa · DIN 373 · high-speed steel (HSS) · Artykuly Techniczne brand

M12 20×13 mm counterbore with pilot (type NWCa), manufactured to DIN 373, is used to machine predrilled holes for cylindrical screw heads M12. The fixed pilot Ø13 mm guides the tool in the clearance hole, preventing lateral drift of the counterbore and ensuring repeatable perpendicularity of the seat to the hole axis. As a versatile M12 counterbore for metal performs well in steel, aluminum, copper, and brass. The tool bears the Polish brand Artykuly Techniczne — manufactured in Poland.

Technical data
Counterbore diameter D 20 mm
Pilot diameter d₁ 13 mm
Shank diameter d 12.5 mm
Flute length l 22 mm
Pilot length l₁ 12 mm
Shank length l₂ 40 mm
Overall length L 100 mm
Number of cutting edges Z 3
For thread M12
Material HSS
Standard DIN 373 NWCa
Brand Artykuly Techniczne
Country of manufacture Poland
M12 20x13 mm DIN 373 HSS counterbore with guide pilot — dimensioned technical drawing

Applications and workpiece materials

Applications and materials for the M12 counterbore

Typical applications:

✓ Counterboring holes for cylindrical heads of M12 screws (DIN 912 / ISO 4762)
✓ Flat, perpendicular seat for the head and washer
✓ Spotfacing around the hole
✓ Use on CNC machines, drilling machines, and conventional machine tools

Workpiece materials

✓Structural and carbon steels
✓Copper, brass, bronze
✓Aluminum and light alloys
▲Alloy and stainless steels — with coolant
✗Hardened steels above 45 HRC

Fixed pilot — centering and perpendicularity

Pilot Ø13 mm enters the clearance hole and guides the tool coaxially, keeping the counterbore perpendicular to the hole axis and allowing full surface contact under the screw head. Steel HSS retains its cutting hardness up to an operating temperature of approx. 600°C.

Cutting data

Guideline values for HSS · Ø20 mm

Material group (ISO 513)Vc [m/min]fz [mm/tooth]n [rpm] · Ø20f [mm/min] · Z=3
PStructural and alloy steel 5–25 0.03–0.10 80–400 7–120
MStainless steel 6–15 0.03–0.06 95–240 9–45
KCast iron 10–20 0.08–0.12 160–320 40–110
NNonferrous metals (Al, Cu, brass) 15–80 0.06–0.14 240–1 250 45–530
SDifficult-to-machine alloys and titanium 8 0.04 ≈130 ≈15

Vc — cutting speed, fz — feed per tooth. Columns n and f calculated for D = 20 mm and Z = 3 (rounded). For tools made of steel HSS-E the cutting parameters can be increased by 25%.

How n and f were calculated (Ø20, Z = 3)

Spindle speed n = (Vc × 1000) ÷ (π × D), feed rate per minute f = fz × Z × n. Example for steel (Vc = 20, fz = 0.1): n = 20 000 ÷ 62.8 ≈ 320 rpm, f = 0.1 × 3 × 320 ≈ 95 mm/min. Start at the lower end of the range and adjust according to the material and clamping rigidity.

Tips and limitations

How to extend tool life

HSS limitations

The tool is not intended for hardened steels above 45 HRC. For stainless and alloy steels, reduce the speed and use coolant — overheating accelerates cutting edge wear. Make sure the clearance hole diameter matches the pilot Ø13 mm.

Frequently asked questions

The M12 counterbore produces a flat seat for cylindrical heads of M12 screws, including DIN 912 / ISO 4762 socket head cap screws. The Ø13 mm pilot enters the clearance hole for M12 and centers the tool. The Ø20 mm counterbore diameter accommodates an M12 socket head cap screw head (Ø18 mm per DIN 912) with a small clearance.

Yes — the tool has a Ø12.5 mm straight shank and fits drill chucks and collets. However, at a diameter of Ø20 mm, low speeds (approx. 80–400 rpm for steel) and rigid workpiece clamping are recommended — preferably a benchtop or pillar drill rather than a handheld drill.

Yes — for ISO M materials (stainless steel), operate at a reduced cutting speed (Vc approx. 6–15 m/min, or approx. 95–240 rpm for Ø20 mm) and use coolant to limit work hardening and overheating. Do not use the tool on hardened steels above 45 HRC.

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Counterbore 20X13 M12 DIN 373 HSS

Counterbore 20X13 M12 DIN 373 HSS

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