Drilling Speed & Feed Calculator
RPM & feed rate for HSS and carbide drills on MS, SS, Aluminium, Cast Iron
HSS और carbide drills के लिए RPM और feed rate — MS, SS, Aluminium, CI
Drilling speed and feed determine how fast the drill spindle rotates and how quickly the drill advances into the workpiece per revolution. Spindle speed (RPM) is calculated as N = (Vc × 1000) / (π × D), where Vc is cutting speed (m/min — depends on material and tool), and D is drill diameter (mm). Feed rate is expressed as mm per revolution and depends on drill diameter — typically 0.01 to 0.3 mm/rev. For mild steel with a HSS drill, Vc is roughly 25–30 m/min; with a solid carbide drill (Miranda / Dormer Pramet), Vc can reach 60–100 m/min. So a 10 mm HSS drill on mild steel should run at around 860–950 RPM, while a 10 mm carbide drill can safely hit 1900–3200 RPM with the right coolant. This calculator covers common Indian workshop materials (MS, SS 304/316, aluminium, cast iron, brass) and both HSS and carbide drill types.
Calculator
Nominal drill diameter in millimetres
Cutting speed Vc = 28 m/min (HSS on mild steel). If your drill press maximum is lower than 891 RPM, run at the press maximum. Use flood coolant for SS and hardened materials.
ƒFormula
N (RPM) = (Vc × 1000) / (π × D) | Feed (mm/min) = N × f_rN is spindle speed in RPM. Vc is cutting speed in m/min (material × tool dependent). D is drill diameter in mm. f_r is feed per revolution (mm/rev) — typically 0.01 × drill diameter for steel, 0.02 × drill diameter for aluminium.
Units: Speed: RPM · Cutting speed Vc: m/min · Feed: mm/rev or mm/min
Drill ki sahi speed aur feed kaise set karein?
Drill bahut slow chalayenge toh time lagega aur hole kharab hoga; bahut fast chalayenge toh drill jal jayega ya tut jayega. Sahi RPM formula: N = (Vc × 1000) / (π × D). Vc cutting speed hai — MS (mild steel) ke liye HSS drill par 25-30 m/min, SS ke liye 15-20 m/min, aluminium ke liye 75-100 m/min. Carbide drills (Miranda, Dormer Pramet) HSS se 2-3x faster chalte hain — lekin coolant zaroori hota hai. Feed rate (mm per revolution) drill ke diameter ke hisaab se decide hoti hai — chhota drill slow feed, bada drill faster feed.
Worked Examples
Drilling mild steel with a 10 mm HSS drill
Problem: You need to drill 4 holes of 10 mm diameter through 20 mm thick mild steel plate.
Solution: Vc for HSS on MS = 28 m/min. N = 28 × 1000 / (π × 10) = 891 RPM. Feed ≈ 0.15 mm/rev = 134 mm/min. Use cutting oil. Standard drill press works fine.
Drilling stainless steel 304 with 6 mm carbide
Problem: Tight hole pattern on SS 304 bracket — switched from HSS to Miranda carbide.
Solution: Vc for carbide on SS 304 = 55 m/min. N = 55 × 1000 / (π × 6) = 2918 RPM. Feed ≈ 0.10 mm/rev = 292 mm/min. Mandatory flood coolant — SS work-hardens if coolant fails.
Aluminium fast drilling
Problem: 500 holes of 5 mm in aluminium plates. Speeds?
Solution: Vc for HSS on aluminium = 90 m/min. N = 90 × 1000 / (π × 5) = 5730 RPM — but most drill presses max out at 3000 RPM, so run at machine max and accept conservative. Feed ≈ 0.20 mm/rev = 600 mm/min. Use light oil mist coolant.
Cutting Speed Vc (m/min) — By Material and Drill Type
| Material | HSS Drill | Carbide Drill | Typical Feed (mm/rev, 10 mm drill) |
|---|---|---|---|
| Mild Steel (MS) | 25–30 | 60–100 | 0.10–0.20 |
| Medium Carbon Steel | 20–25 | 50–80 | 0.08–0.15 |
| Stainless Steel 304 | 12–18 | 40–70 | 0.06–0.12 |
| Stainless Steel 316 | 10–15 | 35–60 | 0.05–0.10 |
| Aluminium | 75–100 | 150–250 | 0.15–0.30 |
| Brass | 50–80 | 120–200 | 0.10–0.20 |
| Cast Iron (grey) | 20–28 | 60–90 | 0.12–0.25 |
| Copper | 40–60 | 100–150 | 0.10–0.20 |
| Hardened Steel (up to 45 HRC) | — | 25–50 | 0.05–0.10 |
Lower Vc values are conservative (longer drill life, rigid setups not required). Higher values demand flood coolant, rigid setup, and quality drills like Miranda carbide.
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