Bohrer Drehzahl- & Vorschubrechner
Berechnen Sie Spindeldrehzahl (U/min), Schnittgeschwindigkeit (Vc in m/min), Vorschub pro Umdrehung (f) und Vorschubgeschwindigkeit (Vf in mm/min).
Parameters & Machining Setup
Bidirectional speed & feed solver with Machine Reality Mode
Ductile and gummy; requires positive feed to avoid work hardening and bird-nesting chips.
Theoretical speed was 1,200 RPM. Spindle clamped to machine limit of 1,000 RPM. Actual cutting speed reduced accordingly.
Soluble oil (flood). Sulfurized cutting oil for manual drilling. Use pecking cycle for hole depth > 3× diameter.
Mathematical Breakdown & Formulas
Transparent engineering steps calculated with ISO standard equations
How to Calculate Drill Speeds and Feeds
Drilling calculations center on two fundamental machine motions: rotary cutting speed ($V_c$ or SFM) and axial penetration rate ($V_f$). Incorrect values cause premature drill flank wear, work hardening, or catastrophic drill fracture.
Spindle Speed & Feed Rate
Where $V_c$ is cutting speed in meters per minute, $D$ is drill diameter in mm, and $f_n$ is feed per revolution in mm/rev.
Spindle Speed & Feed Rate
Where $SFM$ is surface feet per minute, $D$ is drill diameter in inches, and $f_n$ is feed per revolution in inches per revolution (IPR).
Understanding "Machine Reality Mode"
Theoretical equations frequently dictate spindle speeds that surpass a shop machine’s capabilities. For instance, a 1/16" (1.5mm) solid carbide drill in 6061 aluminum theoretically requires over 24,000 RPM at 400 SFM. On a standard knee mill or older VMC limited to 4,000 or 8,000 RPM, running at maximum available speed causes the drill to operate at a lower surface footage.
When you enable Machine Reality Mode in this calculator, the engine clamps the RPM to your machine's physical ceiling, recalculates the true surface speed, and maintains the required feed per tooth ($f_n$) so you avoid rubbing and premature drill failure.
Recommended Cutting Speeds by Workpiece Material
| Material | Hardness | HSS Speed (SFM) | Cobalt (SFM) | Carbide (SFM) | Recommended Coolant |
|---|---|---|---|---|---|
| Aluminum 6061-T6 | 95 HB | 200 - 350 | 300 - 500 | 500 - 1000 | Flood / Mist |
| Mild Steel (1018) | 130 HB | 80 - 120 | 110 - 160 | 250 - 450 | Soluble Oil |
| Alloy Steel (4140) | 28-32 HRC | 45 - 75 | 60 - 100 | 180 - 300 | High Pressure Flood |
| Stainless Steel 304 | 180 HB | 40 - 60 | 55 - 85 | 140 - 240 | Rich Soluble (10%) |
| Titanium Ti-6Al-4V | 340 HB | 25 - 45 | 35 - 60 | 90 - 160 | High Pressure Synthetic |
Frequently Asked Questions on Drill Speeds & Feeds
What happens if my drill RPM is too high?▼
Excessive spindle RPM generates extreme friction and thermal stress at the outer cutting corners of the drill lips, annealing the cutting edge and causing rapid flank wear or cratering. In stainless steel or titanium, excessive speed causes instantaneous work hardening.
Why must I maintain feed per revolution (chip load) when machine RPM is limited?▼
Every twist drill requires a minimum chip thickness to shear metal cleanly rather than rubbing and burnishing the hole bottom. If your spindle hits its maximum RPM ceiling, you must maintain the feed per revolution ($f_n$: mm/rev or IPR) even though linear feed rate ($V_f$) drops. Never reduce feed per rev below the material's minimum chip load.
What is the difference between HSS, Cobalt (M42), and Solid Carbide drills?▼
Standard HSS handles low-to-medium speeds with high toughness (resisting chipping on interrupted cuts). Cobalt (M35/M42) contains 5–8% cobalt for superior red hardness up to 600°C, making it ideal for stainless steel. Solid carbide offers 3× to 5× higher cutting speeds and superior rigidity, but requires a rigid CNC machine with low spindle runout.
When should I switch from a standard drilling cycle to a peck drilling cycle (G83)?▼
As a general engineering rule, use a pecking cycle whenever hole depth exceeds 3× to 4× the drill diameter ($3D$ to $4D$) without through-tool high-pressure coolant. Pecking breaks stringy chips, clears packed flutes, and allows coolant to re-lubricate the drill tip.
Authoritative Engineering Guides
Read our in-depth machining guides to master chip formation and hole geometry: