| name | machining-params |
| description | Machining parameters — cutting speed, feed, depth of cut, power, surface finish, tool life (Taylor's equation), turning/milling/drilling/grinding. Material-specific recommendations. |
| metadata | {"priority":6,"promptSignals":{"phrases":["machining","cutting speed","feed rate","tool life","milling","turning","drilling","surface finish","Taylor"],"minScore":4}} |
Machining Parameters — Complete Skill
Fundamentals
Cutting speed: V = π×D×n/1000 [m/min] (n = spindle rpm, D = diameter mm)
n = 1000×V/(π×D) [rpm]
Feed: f [mm/rev] (turning), f_z [mm/tooth] (milling), f [mm/rev] (drilling)
Feed rate: v_f = f×n [mm/min] (turning) or f_z×Z×n [mm/min] (milling, Z=teeth)
Material removal rate:
Turning: MRR = V×f×a_p [cm³/min] (a_p = axial depth of cut mm)
Milling: MRR = a_e×a_p×v_f/1000 [cm³/min] (a_e = radial engagement)
Drilling: MRR = π×D²×v_f/4000 [cm³/min]
Recommended Cutting Speeds [m/min]
| Material | HSS | Uncoated Carbide | Coated Carbide | Ceramic |
|---|
| Low carbon steel | 30-60 | 60-150 | 100-300 | — |
| Alloy steel (HRC<30) | 20-40 | 50-120 | 80-200 | — |
| Cast iron | 20-40 | 60-150 | 100-250 | 300-600 |
| Stainless 304 | 15-30 | 30-80 | 50-150 | — |
| Aluminum | 100-300 | 200-1000 | 300-2000 | — |
| Titanium | 10-20 | 25-60 | 40-80 | — |
| Copper alloys | 60-150 | 100-300 | — | — |
| Plastics | 50-200 | 100-500 | — | — |
Note: Use lower speeds for larger depths of cut, higher feeds, interrupted cuts.
Feed Recommendations [mm/rev] — Turning
| Material | Roughing | Semi-finish | Finishing |
|---|
| Steel | 0.3-0.7 | 0.15-0.4 | 0.05-0.15 |
| Stainless | 0.2-0.5 | 0.1-0.25 | 0.05-0.10 |
| Aluminum | 0.3-1.0 | 0.15-0.5 | 0.05-0.20 |
| Cast iron | 0.3-0.8 | 0.15-0.4 | 0.05-0.15 |
Depth of Cut — Turning
Roughing: a_p = 2-8mm (up to D/4 for rigid setup)
Semi-finishing: a_p = 0.5-2mm
Finishing: a_p = 0.1-0.5mm
Tool Life — Taylor's Equation
V × T^n = C [Taylor's tool life equation]
T = (C/V)^(1/n) [tool life in minutes]
Empirical constants (approximate):
| Tool/Material | n | C [m/min] |
|---|
| HSS, steel | 0.1-0.15 | 60-100 |
| Carbide, steel | 0.2-0.3 | 300-600 |
| Ceramic, cast iron | 0.4-0.6 | 1000-3000 |
Extended Taylor (3 variables):
V × T^n × f^n2 × a_p^n3 = C
Maximum production rate:
T_opt = T_m/n × (1/n - 1) [minimum cost speed]
(T_m = machine time per piece for one cutting pass)
Cutting Power
F_c = k_c × f × a_p [N] (cutting force, k_c = specific cutting force)
k_c values [N/mm²]:
Low carbon steel: 1500-2000
Alloy steel: 2000-2800
Cast iron: 800-1500
Aluminum: 400-800
Stainless: 2500-3500
Power: P = F_c × V/60 [W] (V in m/min)
Spindle power: P_sp = P/η_machine (η ≈ 0.70-0.85)
Surface Finish (Theoretical)
Turning/boring: Ra_theoretical = f²/(8×r_ε) [mm] (r_ε = nose radius mm, f = feed mm/rev)
For Ra = 0.8μm: f ≤ √(8×0.0008×r_ε) = 2.53mm×√r_ε
At f=0.1mm, r_ε=0.8mm: Ra = 0.1²/(8×0.8) = 0.0016mm = 1.6μm
Actual Ra ≈ 2-5× theoretical (BUE, vibration, wear effects)
Milling: Ra_theoretical = f_z²/(8×R) [R = cutter radius]
Milling Parameters
End milling:
a_e (radial) = 0.05D to 0.5D (slotting = D)
a_p (axial) = 0.5D to 3D (side milling)
V (peripheral) from table above
f_z = 0.05-0.20mm/tooth (carbide, steel)
Face milling:
a_p = 2-8mm (roughing), 0.3-1mm (finishing)
a_e = 0.6D to 1.3D (overlap for consistent chip formation)
Climb vs. conventional milling:
Climb (down) milling: better finish, less vibration, work-holding must be rigid
Conventional (up) milling: less sensitive to backlash, traditional use
Drilling
V = π×D×n/1000 [m/min]
f = 0.01-0.05mm/rev (D<3mm) to 0.2-0.5mm/rev (D>25mm)
Thrust force: F_t ≈ 3.8×D×f^0.5×HB×1e-3 [N] (approximate for steel)
Drill geometry:
Point angle: 118° (general), 135° (hard materials), 90° (soft plastics)
Helix angle: 30° (general), 15° (hard), 45° (aluminum)
Grinding
V_wheel = 20-35 m/s (conventional), 40-120 m/s (high speed)
V_workpiece = 0.1-0.5 m/s (surface grinding)
Depth per pass: 0.005-0.05mm (finishing), 0.05-0.5mm (roughing)
Specific power: 15-60 W·s/mm³ (high — generates heat, use coolant)
Output
Provide: n [rpm], v_f [mm/min], MRR [cm³/min], P [kW], expected T [min], Ra_theoretical [μm], tool recommendation.
