machining-params

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.